Patent Application
20110192172
None
This application is a method to optimize the application of vaporization for cooling purposes. The process is applied in this application for upgrades on air conditioning and refrigeration systems to improve efficiency with extension of the performance on the effect of ambient environment temperature and humidity. This feature would yield a significant improvement in energy usage in locations where the temperature and humidity are high where the equipment undergoes very high usage. The added cooling capacity due to the improvement in efficiency could be strategically used to improve comfort level with the attendant advantage of reducing energy because of the possibility of raising the temperature control setting.
The process also is applicable to new equipments where the new refrigerants and techniques are applied. Application of the process for these higher efficiency units benefits at a higher rate than the upgrade by the ratio of the COPs of the new to the old systems.
Application to new systems results in reduction in initial capitalization besides the savings on recurring cost and maintenance cost. Another embodiment presented for this cooling process is to improve performance and maintain reliability of computers, both personal and supercomputing architectures by cooling the computer chip.
The known practical limitations of vaporization are addressed in the process. Vaporization of water applied to cooling processes is accompanied by scaling. Scaling is the buildup of both bio film and carbonate deposits in slow water flow around heated surface of metal. The process decreases and simplifies the maintenance requirement due to scaling because of metering of the water delivery for vaporization.
The process results in the following benefits. The efficiency for cooling, the reduction of scaling with improvement in both economics and logistic of maintenance, extension and improvement of the range of ambient environment conditions for the air conditioner or refrigeration systems and the computer chip cooling. The process introduces other control parameters that enable the capabilities mentioned. In particular, this application presents an airflow temperature and humidity control such that the limitations because of ambient temperature and relative humidity to perform required cooling especially for large loads are alleviated with further improvement in system efficiency. The reduction in the demand for air flow enables bringing the condensing equipments indoor and enables other control strategies to achieve system efficiency, maintenance, reliability performance.
This application is for a procedure to apply vaporization for heat transfer processes, particularly condensers in air conditioning and refrigeration systems both for upgrading units using the discontinued R22 refrigerant and for new equipments.
The application can be applied to other cooling processes such as computer chip cooling, garments for medical, personal garments for military personnel.
The application points to the features of different manifestations of vaporization for cooling in both natural and other equipments. The embodiment cited for upgrade of air conditioning and refrigeration systems that are using R22 and other refrigerants. These are refrigerants disallowed for new equipments by EPA. The process is discussed in detail to show the effective improvement in efficiency, cooling capacity, ambient temperature of operation. The process can be extended for small and compact implementation on new equipments with maintenance improvement compared to water tower coolers, lower capitalization costs, modularity and ease of maintenance, and indoor installations enabling extension of capability of the cooling system with application of air flow condition.
The advantages and implementation on new equipments for residential, industrial and large cooling units enable several advantages both economic, reliability, maintainability, indoor operation, reduction of cost of scaling problems and flexibility.
The implementation of the whole gamut of listed advantages presupposes the development of embedded controllers and digital interface devices for sensors, drives and communication.
The other embodiment is for high power computer chip cooling. The embodiment on computer chip allows the cooling of 1 kilowatt per square centime computer chip heat dissipation with reduced air flow volume and heat sink physical volume.
The application is on heat transfer. The process is an optimization procedure for the heat transfer that uses the common processes of conduction, convection, radiation and reflection.
Conduction is the process by which the energy of a source which is usually manifested by the temperature of the material is routed out via the material or other materials through the passage that allow the energy in the form of “heat flux” to the recipient or absorbing material. The process is dependent on the material property of thermal resistance which is inversely proportional to the area the flux would flow and the length of the path or thermal path.
Convection is the actual transport of materials that have acquired the energy from the source. The transport of the material enables the flow of the heat flux. The usual convection medium is air where the air around a highly conductive material like the enclosure for the refrigerant acquires the heat energy by conduction. The thermal resistance of the air and also the specific heat which is the amount of energy needed to raise its temperature one degree per unit weight is relatively low. Therefore the method of convection demands a large amount of air mass to be transported.
Radiation is a transport phenomenon similar to the convection process. However in this case, there is no material that is physically transported. The energy of radiation is in the form of electromagnetic waves that is able to be conveyed even in vacuum or space. The energy is manifested and proportional to the fourth power of the temperature of the source.
The application shall discuss only the conduction and convection heat transfer process. The convection process uses water as the transport material.
The vaporization of water has been applied for cooling for over several decades in air conditioners and refrigeration equipments. Vaporization is also a natural phenomena associated with our weather and life on earth. The vaporization in vegetation and open waters are primary contributors for our weather.
The vaporization of water involves a large amount of energy. Under the usual situations where the pressure is at one atmosphere, the amount of energy to vaporize a gram of water is 2260 joules. This is quite significant when compared to the sensible heat needed to change a gram of water by one degree centigrade, which is 4.18 joules per gram per degree C. In the case of air, the sensible heat absorbed by air is very small, 0.001 joules/cubic centimeters. FIG. (3) shows the typical topology of cooling a material. It uses material property that enables the diffusion of heat energy along the material. The degree of efficiency of conduction is determined by the thermal conductivity path from the material to be cooled to the next material. This metric is dependent on the material and the physical dimensions. In particular metals are very good heat conductors and the heat flux is improved by increasing the area for which the heat flux flows and by reducing the length of the path involved in the flux passage. The second normal medium is air because it serves as a medium of transport for the heat energy to the ambient environment by convection. The higher temperature from the “heat sink” is acquired through the conduction of heat from the metal surface to the air. This starts the diffusion process. The region between the heat sink to the distance where the ambient temperature is acquired is usually called the boundary layer. This layer under steady state conditions establishes the effective thermal conductivity from the second interface to the ambient air. Since the boundary layer is air which has very low thermal conductivity, the effective resistance of the boundary layer is large. The high thermal resistance of the boundary layer is minimized by modifying the thickness of the boundary layer. This is achieved by the process of convection where air flow with ambient temperature reduces the thickness of the boundary layer by removing the warm material on the boundary layer. The boundary layer is between the surface of the metal surface and the edge where the boundary layer reaches the temperature of the ambient air temperature. The boundary layer temperature profile is dependent on the effective diffusion process modified with the convection transport mechanism. If the diffusion gradient is maintained with the air flow, then continuous higher heat flux flow occurs. The efficiency of removing the warm air from the boundary layer is obviously dependent on the velocity of the air flow and the temperature difference between the second interface and the ambient temperature. The practical limits therefore are the effectiveness of the air flow for removing the heated mass of air. This affects the efficiency of the system because a higher air flow means more power usage for the fan. Raising the air flow velocity causes higher noise levels.
The resulting thermal resistance of the boundary layer imposes practical limits for higher cooling capacity. For example computer chips need cooling requirements around 150 watts. The silicon chip technology is improving and following Moore's law on speed and feature sizes. At present, the power levels that is possible with the feature sizes of the silicon devices developed by the technology and the natural desire to integrate as much as of the system in the chip is predicted requires at least 1 kilowatt per square centimeter for cooling. The present cooling towers that require cooling for 150 watts and uses heat pipes and fins that occupy over 100 cubic inches with attendant noisy fan for air flow. The present technology for the cooling requirement would demand a large mass of air to transport the needed heat and larger physical size and other complication plumbing if heat pipes were applied. The application addresses these practical problems.
This application is the process of modifying the process discussed above with the use of water as the medium that is created and removed from the boundary layer. The process applies a similar structure as used in prior art technology of using conduction and convection of air to convey the heat energy absorbed with the air flow to the environment. The specific heat of the air is 0.001 joules per cubic centimeter. Water when vaporized to form the boundary layer extracts 2260 joules per gram for cooling. The process uses water that is vaporized by the introduction of water on the interface from the high conductivity heat sink to carry the heat energy to ambient environment. The vaporization of water involves the large heat and requires only a small amount of water to support the cooling process. For example, if the heat sink is to provide cooling for one kilowatt, the water needed is less than one half (½) grams per sec. Air however can support a limited amount of water vapor that is dependent on the air temperature. The capacity of air to support water vapor product of cooling is limited and increases as an exponential function of temperature.
The process of vaporization is the separation from the liquid to vapor of very high energy molecules. The rate by which this occurs is dependent on the temperature. The temperature establishes the density or the vapor pressure created from the surface of the water film at the given temperature. The vapor pressure created at the immediate boundary from the source of heat to the air continues receiving higher energy molecules up to the level determined by the saturated capacity of the air. At this state, the amount of molecules leaving the liquid state are the same as the amount converted back to liquid. The relationship between the maximum water vapor content for a cubic meter of air is called saturated humidity and is dependent on the air temperature. The relationship is exponential with increasing temperature. FIG. (1) shows this relationship. When the saturated condition of the water vapor is reached, the heat flux is reduced. If the container is enclosed, the heat flux completely stops because there would be zero net transformation of water molecules from one phase to the other. If the environment is not enclosed, the boundary layer laminar sheets undergo diffusion process because the concentration of water vapor immediate to the heat source is much higher initially than the succeeding layers from the metal or water film surface. The water vapor in the air is usually lower than the maximum it could support called the saturation content. The ratio of the water vapor to the saturated level is called the relative humidity. The dew point of air is the temperature where the water vapor content starts condensing, that is when the water vapor content of the air is equal to the saturated air. FIG. (1) shows the saturated humidity and also the amount of water vapor available before saturation when the relative humidity is 40%.
If one were to assume for example initially that the next layer to the saturated layer from the water film were at the vapor pressure corresponding to the incoming air flow then a large difference would exist because of the probability that the immediate surface to the water film would be saturated. This difference in vapor pressure creates effective diffusion mechanism where the water vapor content on the immediate area from the water film surface migrates to the lower water vapor density layers. This process continues outwards perpendicular to the surface until the steady state boundary layer is established and the heat flux flow is dependent on the vapor pressure gradient created by the diffusion. This is dependent again on the corresponding difference between the saturated vapor pressure at the temperature and the vapor pressure presented from the ambient air flow. Note that the transport of the water vapor to create the heat flux flow is not dependent so much on the temperature but primarily on the vapor pressure gradient along the flux path. The main parameter is that the diffusion gradient is established and determines the capability of the supporting heat sink circuit to convey the heat flux. When steady state is reached without air flow, the air chamber would reach the same temperature as the heat sink interface. The introduction of air flow to facilitate convection removes the water vapor from the chamber. This completes the flow of heat flux from the heat source to the ambient environment. This is enhanced when there is convection to transport of vaporized water. The air flow removes the vapor material in the chamber and creates a thin boundary layer between the heat sink and the incoming air flow. The boundary layer is sustained with higher continuous heat flux from the saturated interface of the water from the heat sink when the boundary layer gradient is maximized. If the heat flux increases, the vapor gradient has to correspondingly increase such that the flux is accommodated. The air flow therefore has to be high enough such that the vapor generated does not accumulate to the level of degrading the heat flux flow needed. The process is dependent on the diffusion created by the difference in vapor pressure or gradient of the water molecule concentration starting from the interface to the effective region where the air flow transports the water vapor. The thickness of the boundary layer is reduced depending on the air flow velocity. This improves the efficiency of transporting the water vapor cooling product. The diffusion process implicitly creates a temperature gradient. However the magnitude is minimal. Thus the difference in the sensible temperature change between the heat sink interface and the output air flow is small. The diffusion process has a time constant. It is possible that the immediate surface of the water film might not be completely saturated if the air flow is such that the vaporization time constant cannot be supported by the rest of the thermal circuit.
FIG. (2), FIG. (2a), FIG. (2b) show the physical relationship between the fins, the water film, boundary layer and the effect of air flow velocity. In FIG. (2, 10 is the fin structure at a distance of qfin from each other. 12 is the water film and 16 is the boundary layer region. 14 is the midpoint of the fin separation. q(0) is the saturated vapor pressure heat flux flow at the interface of the water film and start of the boundary layer. qin(x) shows how the heat flux along x distance from the fin in the boundary layer. Together with qout(x) and qflow(x) are the variation of the heat flux at x when the air flow removes the heat flux qflow(x). The laminar velocity profile of the air flow which has a maximum velocity Vmax is shown in
FIG. (1) and also FIG. (3) shows the increase in the saturated water vapor capacity of air with temperature. The equation came from the NOAA branch of the federal government. FIG. (1) also shows the remaining water vapor that can be contained with the same volume when air has the relative humidity of 40%. FIG. (3) shows the comparison of saturated water vapor and relative humidities of 40% and 75%. The other curve shows the effect of heating the ambient air when it is low (68 F) to a higher temperature to open up more capability for air to absorb water vapor. Heating has to be performed without undue acquisition of water vapor.
The criteria above on sensing the inception of sensible heat mechanism in the boundary layer as the increase of air flow temperature will be used for a sensing mechanism to generate feedback signal for the water delivery controller to optimize the contribution of the transport mechanism using vaporization.
a assumes that the relative humidity of the incoming air is constant. If the relative humidity gets lower, then the boundary layer gradient profile will be steeper. This means that the cooling capacity would be higher because it will take more heat flux to bring the boundary layer edge to the midpoint of the fins. Note that when there is no air flow, the development of the diffusion vapor pressure gradient is that in steady state, the space between the fins would acquire the same temperature as the source of heat. On the other hand, it is possible that the temperature of the water film interface vapor is at a lower saturation because of the time constant for vaporization and attendant diffusion process.
The practical air flow velocities under the aesthetic and power constraints are usually such that it would be laminar. The laminar profile of air flow is characteristic of the velocity at the immediate heat source surface is almost zero increasing at parabolic rate to its maximum at half the distance of fins. Since this is the highest concentration of the water vapor, then a little higher air flow than what would calculate to have an effective mass flow transfer is needed. Nevertheless because of the large energy for vaporization, the amount of air necessary to convey the water vapor is less. Since the boundary layer could be designed with the airflow control to be thin, then the effective “thermal resistance” of the boundary layer is minimal. The contribution of heat flux flow because of the thermal resistance is negligible compared to the heat flux because of the transport of the created water vapor. This means that the “temperature head” on the boundary layer in the air medium for convection is significantly higher than the resulting “temperature head” with the water vapor as a transport material for convection. The resulting improvement on the “temperature head” allows lowering the temperature at the computer chip and increases its reliability.
The following are manifestations of vaporization in both the natural environment and also in some cooling practices. We shall discuss them to emphasize the differences and point the main factors affecting the efficiency of the processes.
The flow of heat flux is a circuit where the heat source, usually at a higher temperature generates diffusion to transport heat from the source down the thermal circuit. The magnitude of the heat flux would be dependent on the resistance presented by the materials along the circuit to the flow. This is called the thermal resistance of the material. It is a physical characteristic of the material and also dependent on the topology. There could be several materials involved along the thermal circuit before the heat flux is conveyed to the water film as shown in FIG. (8). Thermal efficiency using the water for vaporization is to maintain the capability to support the vaporization from the water film by sufficient heat flux flow.
The process of vaporization is when liquid water changes from a liquid state to a vapor state and is called either transpiration or evaporation. The term is mostly correlated with the system. Vegetation vaporization which is one of the main contributors to our weather is usually called transpiration. The term could be applied to processes where the water source is introduced to the vaporization process through small pores or channels from other materials.
It is my opinion that the difference is whether the liquid water is introduced to acquire the energy from some controlled enclosure or available in open environment. For our purposes here I will not distinguish the terms and use vaporization.
Transpiration is the term used on vaporization in vegetation, FIG. (4) shows a schematic on the vaporization. The energy from the sun 44 maintains the temperature on the surface of the leaves and around the immediate area of the leaves. These are balanced by the natural properties of color, stomata reactions, wind to achieve an energy balance. The water from the roots rises up by capillary action through tubes 46 to the leaf structure and exposed to the atmosphere by the opening of the stomata pores on the leaves. The water within the leaves chamber has established saturated vapor pressure. When the stomata 42 opens, the leaf opening chambers 40 are exposed to the lower concentration of water vapor in the immediate surface of the leaves and enables vaporization. The vaporization process is controlled by the vegetative plants in response to its need. The response of the leaves is dependent on the available energy from the sun and also the transport mechanism on the resulting boundary layer by wind action. The vaporization process effectively reduces the temperature of the air around the general area of the tree or vegetation. The transpiration process allows the vegetation to undergo photosynthesis with the attendant transformation of sun's energy into the vegetative materials from which we get our food, air to breathe and among others control our weather. It needs to be pointed out that the temperature inside the leaf where the saturated vapor barrier is generated before the stomata opens could be at a lower temperature than the ambient air. This is true provided the vapor pressure of the ambient air is lower than the saturated vapor barrier when the stomata opens. This is magnified when wind blows to carry the vapor materials out and lowers the boundary layer thickness. In nature, the requirement for vegetation for the magnitude of vaporization is small (typically 0.7 grams/day),
The energy from the sun 50 is absorbed by the water body in open areas. FIG. (5) shows the sketch of the vaporization for open surface or water. Some molecules of water have more energy and able to escape and form a vapor barrier above the surface. There is also at the same time energy extracted from the air above the water surface qair but because of the relatively larger thermal resistance to the air, most of the vaporization energy qflux is taken from the water. The vaporization process continues to steady state conditions depending on the effective “thermal resistance” on the boundary layer. The boundary layer is maintained such that a continuous vapor qflux is sustained. This is the limiting rate by which vaporization occurs. The vapor pressure gradient of this layer could be altered by wind motion above the surface and the variation in temperature of the air. In most cases the heat of vaporization is manifested with small amount of sensible heat temperature changes but mainly by vaporization that is aided considerably by the vapor transport with wind action.
Evaporative coolers or swamp coolers shown in FIG. (6), These are economical and effective cooling equipments especially in low humidity and high temperature environments, The block diagram of the equipment is shown in FIG. (6). 50 is a fan enough to provide sufficient air flow through a porous mesh usually made of fibrous tree material 52 that allows distribution of water uniformly on the pad. The air from the blower 50 serves both as the boundary layer that forms when the fan changes the water into mist. Also it might carry some particles of water to the ambient environment where the velocity of the water droplets has the eventual falling and route exposed to the environment for the extraction of the material around the boundary layer of the droplets. Notice that the effective thermal conduction at the boundary layer is not consistent. The movement of the spray drop from the equipment provides the air flow discussed above to create a low thermal conductivity. The velocity of the water drop as it is generated by the misting process effectively provides the convection to remove the water vapor on the water drop surface. Also the relative humidity of the air increases and affects the effectiveness of vaporization because of the attendant increase in relative humidity. The increase in water vapor in the area affects the comfort level in spite of the reduction of the temperature. The efficiency is low because it is hard to control and direct air flow to be able to create the complete vaporization of the water mist. This leads to high water usage and also energy for the fan. Nevertheless under environments stated above of high temperature and low humidity, the economic benefits and added comfort levels overcome any efficiency issues. The effectiveness of these devices are dependent on low relative humidity environments that is capable of absorbing large amount of vapor for cooling without affecting the relative humidity and comfort zone in the area.
FIG. (7) is the sketch for water tower cooling. The heat exchanger 54 is a water tank surrounding the labyrinth of pipes containing the refrigerant circulating through pipe 66. The slow water flow together with the relatively high thermal conductivity of the water intimately in contact with the refrigerant enclosure walls enables relatively efficient heat flux transfer. The heat from the refrigerant is routed to the water tower with the transfer pump 56. The warm water is sent to a system that drops the water from 58 into skids or crates 60 that mechanically present the water to the high velocity air from the fan 62. Water from the skids and crates form water fall of droplets falling again the air fan blown air. The droplets have the vapor barrier around and these are exposed for removal with the relative motion of the air flow from the fan 62 and the fall with gravity.
The system is an effective cooling system that has drawbacks on optimizing the potential of vaporization. The heat flux has to be conveyed from the refrigerant to the refrigerant enclosure. From the enclosure the next thermal component is the transfer from the enclosure to the water. The transfer is improved because of the velocity of the water across the enclosure tubes carrying the refrigerant The flow of water is routed to water skid crates that creates films of water to the air flow from either an air flow fan above or below the water cooling tower. The efficiency of the implementation is dependent on the flow of heat from the refrigerant to the water for vaporization. The present mechanization for taking advantage of the large latent heat of phase change for water is not optimized. There are a number of materials from the refrigerant to the introduction of the water film for vaporization. This lowers the available saturated vapor pressure on the water film. The thermal circuit consisting of the following accumulates and increases the thermal resistance from the refrigerant to the presentation of the water for vaporization. The heat flux flow and the resulting temperature drop is significant. Thus at the transition where the liquid water is presented for vaporization, the effective vapor pressure which is dependent on the temperature has decreased from the temperature of the refrigerant. Also there is a net result of wasted air flow energy because the air flow is not focused on the boundary layers. The effectiveness of concentrating the fan energy to carry as much of the vaporized material as possible is not optimal Another practical issue is that since the usual manner of water delivery exposes the material to ambient air especially at the water tray 64 results in the accumulation and increase in bio film enabling materials and organisms. Bio film scaling is product of interaction of bio components with the water to cling in an ionic manner to the metal surface. This is affected because of the high temperature at the surface together with the low water flow velocity giving the ionic process time to be effective. Bio film buildup is usually the precursor to the formation of permanent adhesive materials for further scaling from other sources like carbonates from the water. The initial bio film serves as initial anchor for the carbonates and has the property that after a certain threshold in time, the permanency of the adhesion to the metal surface increases exponentially. This leads to the acceleration of degradation of the thermal conductivity of the transfer of heat from the refrigerant to the water medium. Expensive total downtime for maintenance of the system therefore is an economic and logistic issue.
The process in this application consists of several procedures that is to maximize the tremendous cooling capacity of vaporization when used as a transport medium for convection. FIG. (8) represents a general thermal circuit in terms of possible topology for the heat flux path for presentation to the water film for vaporization. The thermal circuit shown could represent the various topologies possible in the creation of a flux path for the heat flow from 80 the refrigerant to the ambient environment 78. The different contributors to the thermal circuit are shown to be 82 as a series component, 70, 72, 74 as parallel components configured to form an equivalent component, 84 as another series component. 74, 88, 86 is a general representation on how the water film maybe introduced to enable vaporization. 88 could be eliminated. It is shown here to represent a water delivery topology where the water chamber 76 acquires the heat energy from the previous materials and creates the water film on the other side of 88 if 88 is a porous material that has microchannels that allow water to move from 76 to the water film area 86. This type of topology is used for example in water cooling jars prevalent in South East Asia and also presented as a possible embodiment in the computer chip cooling. The different material medium that are in “series” or “parallel” are indicated. The main objective is to minimize the accumulation of material contributions to the net thermal resistance from the source to the water film. The procedure of optimizing the thermal conductivity of the usual metal container or transfer material to maximize the heat flux is very well known and understood. The thermal conductivity of metal, e.g. copper is 400 while the thermal conductivity of water is 0.6 watts/m/sec. One can see that assuming the areas involved are the same, the ratio of the thickness of the copper to the water film would be 666:1 (400/0.6) for both to exhibit the same thermal resistance. Thus water film thickness of 1 mm would have the same thermal resistance as copper with thickness of 66.6 centimeters. The process therefore would require that the water be delivered to the warm surfaces such that the effective water film is as thin as possible. Vaporization with convection results in minimal temperature change within the boundary layer.
Metering of the amount of water delivered so that only the required cooling requirement is delivered would use the measurement of the temperature rise from the incoming air flow for the condenser fins to the outgoing air flow temperature. Since the process of vaporization with convection results in minimal temperature change (mainly to establish the boundary layer gradient), then metering could be implemented as a feedback control system where the water delivery is enabled only when the output air flow temperature is very close to a certain threshold to the incoming air flow temperature. The threshold as a control parameter indicates the approach of the air flow to vapor saturation with the start of the sensible heat transfer. The value of the threshold is a subjective decision for the designer or user. It could be before or after the inception of sensing the saturation of the air. The magnitude and effectiveness of vaporization is both affected by the water delivery and the transport mechanism of convection. In upgrades, since the fan has a fixed speed, then the remaining control parameter is the water delivery rate.
There is an added benefit to the metering of precise water requirement for cooling because it automatically retards the occurrence of bio film scaling buildup on the metal surfaces. In ordinary heat exchangers, bio film buildup occurs because of the presence relatively slow velocity continuous water around the metal surfaces. The slow moving water with the high temperature result in the formation of bio films on the surface of the metal. These present themselves as anchoring points also for the accumulation of carbonate deposits. The combination leads to expensive maintenance of cooling systems. The metering of the water avoids the presence of continued liquid water that enables the formation of bio film. The metering also enables prediction of the magnitude of carbonate scaling buildup with knowledge of the hardness of the water. This would result in a logistical maintenance strategy since the extent of degradation of thermal conductivity is predictable to the level that the economic benefits could be maximized.
The other aspect pointed by the process is that the vapor barrier gradient in the boundary layer has to be optimized such that the heat flux is maintained at the maximum where the initial vapor pressure at the immediate water film boundary. The high vapor gradient should be maintained by the effective removal of the water vapor. This involves adjusting the air flow such that with the laminar flow it is sufficient to carry most of the material within the quadratic profile inherent with laminar flow. It is desirable therefore that the chamber for the air passage have minimum thickness. This however could lead to higher velocity and more noise. There are some cases where the topology of the presentation of the water film to the air flow is such that turbulence along the length of the air motion is possible. This would be effective in getting the vapor barrier gradient very steep and improve diffusion mechanism.
FIG. (1) shows that the amount of saturated water vapor at low temperature is relatively small. The cooling capability is limited at low ambient temperatures because of the available water vapor capacity of the air. When the magnitude of cooling required is large the need for high heat flux then the needed higher water vapor is limited by the ambient air temperature. In the case of the air conditioners, the temperature of the refrigerant on the condenser is high. The ambient temperature of the air when the air conditioner is needed is usually at a temperature where there is adequate room for the air to accommodate the needed vaporization for cooling. Therefore, the normal ambient temperature for condensers operations in air conditioners allow vaporization to work effectively for the power level and the present topology of the condenser fins and tubes. The condensers used for refrigeration however would operate under lower ambient temperatures. The limited volume of water vapor that could be supported by air at the low temperature for high cooling loads are degraded. Notice that the vaporization process is such that the heat source temperature will be almost the same as the ambient temperature air flow because of the low thermal gradient of the boundary layer. This means that if vaporization of applied to the level that it is the complete process for cooling the condenser, then the condenser refrigerant temperature is almost very close to the temperature head between the refrigerant and the enclosure. The limited water vapor capacity at lower temperature could be increased by raising the resulting temperature head higher than the ideal mentioned. The temperature is almost close to the temperature head of the refrigerant to the enclosure. Under this situation, the immediate compensation is to adjust air flow volume rate. This could lead to higher noise level and demand from the fan. However with upgrades, air flow adjustments are not available. FIG. (3) show that warming up the incoming air flow temperature would raise the capability of the air to sustain and support the higher vapor pressure product needed for the cooling.
The heating process for the incoming air flow could be done several ways.
One way would be to use the actual condenser cooling process to be adjusted such that sections of the condenser would operate the usual convective process with air as the transport material. The output air flow from that section of the condenser with the increase in sensible heat is used for the air flow need on the section of the condenser that will utilize the vaporization process. Since the sensible convection does not affect the amount of water vapor, the output would have lower relative humidity at the raised temperature. For example, in air conditioner condensers, part of the fins and tube system modified in an arrangement where the incoming ambient air does not make use of vaporization and stays on the sensible region for heat exchange. The heat is absorbed by the air and is manifested as an increase in temperature. The output air can now be routed mechanically to the other sections of the condenser where vaporization cooling mechanism is implemented.
When the air flow through 110 fins, it has an increase in temperature because the transport mechanism is air and would have an increase in sensible temperature. This output air flow is now used for 112 section of the condenser where the vaporization procedure is applied with the water delivery implemented through the valve 114.
Another process would be to preheat the air with controllable power source.
Another would be to use hybrid of the two methods to obtain the flexibility that might be required in some systems. The procedure is discussed in the third embodiment.
FIG. (1) Graph of saturated air of temperature F
FIG. (2) FIG. (2a), FIG. (2b Heat flux and air flow at the boundary layer
FIG. (3) Graph of saturated air and emphasis of warm air allowing more cooling capability
FIG. (4) Sketch of transpiration in vegetation
FIG. (5) Sketch of evaporation in open water
FIG. (6) Sketch of vaporization in swamp coolers and evaporative coolers
FIG. (7) Sketch of vaporization in water tower coolers
FIG. (8) Sketch of general material path for heat flux to the water film for vaporization
FIG. (9) Diagram of location air flow sensor
FIG. (9a) Sketch showing averaging with topology of construction of temperature sensor
FIG. (10) Block diagram of water metering control circuit using temperature sensors and pump
FIG. (11) Block diagram of air pre conditioning by using air flow from condenser that uses sensible heat of air for convection transfer
FIG. (12) Sketch of how vaporization is created to show components
FIG. (13) General block diagram of vapor compression and recovery system of cooling
FIG. (14) Phase diagram for R22 to show operation within saturated region
FIG. (14a) Magnified phase diagram on the compression cycle
FIG. (15) Phase diagram for an actual AC system indicating non ideal operation
FIG. (16) Magnified phase diagram for an actual AC system with pressure and enthalpy
FIG. (17) Phase diagram for an actual AC system with vaporization process applied
FIG. (18) Phase diagram for actual AC with vaporization applied (pressure vs. enthalpy)
FIG. (19) Water delivery block diagram
FIG. (20) Water delivery tray
FIG. (20a) delivery to implement uniform water droplet distribution
FIG. (21) Block diagram of general implementation of vaporization and pre conditioning on upgrades
FIG. (22) Implementation of upgrade without air pre conditioning
FIG. (23) Implementation of upgrade with air pre conditioning
FIG. (24) Block diagram of upgrade with maximum flexibility on air flow pre heating
FIG. (25) Alternative implementation using spray nozzles as alternative to water delivery trays and pegs
FIG. (26) Sketch of top view (orthogonal drawing) Computer chip heat sink
FIG. (27) Sketch of front view (orthogonal drawing) Computer chip heat sink
FIG. (28) Sketch cross section of heat sink 1st module (looking down)
FIG. (29) Sketch cross section of heat sink 1st module (middle)
FIG. (30) Sketch cross section of heat sink 1st module (looking up)
FIG. (31) Sketch cross section of heat sink 2nd module (looking down)
FIG. (32) Sketch cross section of heat sink 2nd module (looking up)
FIG. (33) Sketch cross section of heat sink 1st and 2nd module (fins and air flow heating)
FIG. (34) Sketch of water distribution sock arrangement
FIG. (35) Sketch of cell structure creating hierarchical system organization
The first embodiment is on improving the efficiency of the condensers on air conditioning or refrigeration equipments. This embodiment in particular is for the upgrade of existing air conditioning systems.
The government has mandated through the Department of Energy a gradual improvement on the required efficiency of new air conditioning and refrigeration equipment following policies similar to the gas mileage on cars. Also the Department of Environment and Protection last January 2010 has prohibited particular refrigerants for the new manufactured equipments. The usual refrigerants on the old systems are the R22. The installed base of these old equipments however are at least 75% of the market for saturated capacity. Thus if the efficiency of the old equipments is improved by economically viable process, then the planned policy of energy use for the nation would be accelerated. The known life expectancy of the air conditioning and refrigeration equipments are about 20 years. Therefore statistically, there is a percentage of 9 more years remaining in the life of these units for availing on efficiency improvements afforded by this procedure.
The theoretical ideal efficiency of vapor compression refrigeration system which are the usual technology used for air conditioners and refrigeration is the COP or the coefficient of performance. Under some assumptions, particularly that the refrigerant operates within its saturated boundaries on the different phase used for the purpose, the COP is obtained as the temperature of the evaporator refrigerant (using absolute temperature units such as Kelvin or Rankin) divided by the difference in temperature of the condenser refrigerant and the evaporator refrigerant temperature. Again using ideal conditions, assuming the condensers and evaporators are considered as infinite heat sinks or sources, then the refrigerant temperatures are either the ambient temperature or the control setting for the air conditioners. This is not the case however because of practical inefficiency in the heat transfer process for these equipments. These devices uses the conduction and convection process discussed above using fins and tubes for the condenser enclosure and surfaces and electric fan for the air flow. The standard design for air flow is 400 cubic feet per minutes of airflow for each ton of cooling capacity for condensers. Therefore for a 3 ton unit and the typical dimensions for the tubes and fins, one can compute for the “temperature head” to be approximately 18.5 C for the condenser. I defined the term “temperature head” to be the difference in the refrigerant temperature between the heat flow source to the recipient heat environment. The Department of Energy defines a standard metric for efficiency for air conditioners and refrigeration systems. The standard is the SEER or seasonal electrical energy rating. Since the performance of an air conditioning system is dependent on the ambient temperature and the room temperature setting, the SEER metric is specified for ambient temperature of 85 F and room setting temperature of 82 F. The standard is computed the same as the COP (under the actual equipment performance, and not ideal to operating within the refrigerant saturated region). The SEER could be obtained from the COP by dividing by 0.29. SEER uses BTU/hr for energy instead of watts for COP. Assuming that the evaporator coil also has the same “temperature head”, then the total difference on the refrigerants of the two devices is approximately 37 C. There is approximately 3.5 C temperature head due to the thermal conductivity of the refrigerant together with the usual implementation of the enclosure for the conduit for the refrigerant. We may consider approximately the same for the evaporator. For the sake of discussion, under the ideal COP computation that the condenser were to use the vaporization method and result in a “temperature head” reduction of 18 C, this would imply an improvement of 61%. This theoretical unit would have a COP of 6.73 and reduction of the temperature head of the condenser by 18 C results with a COP of 10.5.
The new equipments mandated by DOE for efficiency performance would have higher SEER ratings. If the vaporization process were applied to these equipments, the resulting efficiency improvement would have a larger rate of improvement. This could be seen by getting the derivative of the theoretical expression for COP with the condenser temperature head change. The rate of change is directly proportional to the existing COP or SEER performance.
This application is a method by which the efficiency for the refrigerant heat extraction is improved. The method is applied to the usual fin and tube type of heat exchange by exposing the heated fin and tube of the condenser to water to induce the vaporization and extract the heat from the refrigerant by the usual thermal conduction and convection using air flow. The vaporization of the water is enabled by reducing the thermal resistance from the refrigerant to the receiving medium which is ambient air. The usual structure of the fin and tube is not changed, but the introduction of water on these surfaces together with the high temperature of the refrigerant induces the conduction of heat energy to vaporize the water on these surfaces. The vaporization of the water is very efficient heat transfer mechanism. The latent heat of water is 2260 joules if 1 gram of water is vaporized. In comparison the sensible heat change of the air with the convection and conduction with the standard process employed with existing equipments provides only 0.001 joules/cubic centimeter/degree celsuis change of the airflow. The standard fan requirement followed in industry is approximately 400 CFM per ton of cooling capacity. When water is vaporized from the condenser, the boundary layer consist of water vapor in the immediate surface area of the fins and tubes that form a similar boundary layer of heated air as with the usual fins and fans arrangement. If the boundary layer is maintained to a steady state allowed by the diffusion mechanism, then the thermal resistant would increase to the point that the heat transfer is degraded. The effectiveness of vaporization for cooling capacity improves if the relative humidity of the air is low together with higher temperature of the air. The saturation level of water vapor content of air increases exponentially with temperature. Therefore, for the same relative humidity (which is the ratio of the water vapor content of the air to the saturated water vapor content) at a given temperature, there is more water vapor that could be absorbed by the airflow at higher ambient temperature. In order to optimize the design the air flow volume is sustained only up to air saturation. With the standard fan capacity of condensers, the 400 CFM volume capacity of the fan is adequate to maintain the total cooling requirements under all practical ambient temperature the condenser is allowed to operate.
The air conditioning and the refrigeration technology had been implementing the vapor phase change and recovery for cooling for a long time. The basic components are known and established. The components of this cooling system are shown in FIG. (13). The cooling system is a close system where it uses a medium called the refrigerant that is subjected to changes in its phase as it goes around the cooling system. The change in phase is implemented by means of equipments that are designed to enable the flow of energy as required by the laws of thermodynamics. The phase changes are such that in suitable sections of the system heat can either be absorbed or removed from the refrigerant. The equipments involved are situated in the area being cooled (the evaporator) and the area where the heat is dumped to the environment (condenser). The thermodynamic cycle that the refrigerant undergoes is enabled by introducing some form of energy (in this particular block diagram, electric compressor) and a metering system. The design and implementation of the processes by which the phase change of the refrigerant are factors that determine the efficiency of the cooling system. Practical constraints on the design stage are however always a factor.
This application is for the improvement of the heat transfer performance of the condenser. Embodiments to apply both to existing and manufactured new equipments are presented.
The efficiency metric for the cooling system maybe understood by examining the thermodynamic cycle of the refrigerant under an ideal condition where the phase transformation of the refrigerant is limited to the saturated region. FIG. (14) shows the phase diagram for the air conditioning refrigerant. The usual thermodynamic diagram that the refrigerant undergoes can be presented in a combination of ways. The refrigerant exhibits the same pressure and temperature and are called the saturated temperature and pressure of the refrigerant. Therefore, measurement of either parameter will describe completely the state of the refrigerant in this saturated phase.
I have to beg forgiveness for the deviation of the usual way of presenting the phase diagram. However since in this discussion, we are concerned about the idea of COP as a function of the operation within the saturated region, I believe the choice of the parameters for the phase diagram shown would make the migration to the practical system more understandable. The phase diagram is shown as temperature versus enthalpy. The usual choices are pressure against enthalpy, and temperature against entropy.
On the left of the phase diagram is the boundary of liquid and mixed state (liquid and vapor coexist) for the refrigerant. On the right is the boundary of changing from the mixed liquid and vapor (saturated region) to a completely vapor phase. The independent (horizontal axis) variable is shown as the energy content of the refrigerant per gram that flows through the evaporator or condenser devices. The energy increase or decrease of the refrigerant as it traverses along the cycle is indicated by the enthalpy H. The enthalpy change H is dependent on the entropy S of the refrigerant. The entropy changes with the corresponding changes in energy flow in or out of the refrigerant. The enthalpy change is manifested as the temperature (absolute) T multiplied by the change in entropy along the cycle. The accumulation of the changes in energy content of the refrigerant are shown at the indicated transition points as the resulting energy per gram of refrigerant. During the phase change within the saturation region, both the temperature and the pressure are constant, e.g. from (1,2) to (2,3). Since the temperature is constant, the changes in enthalpy are all related to the absolute temperature and the effective change in entropy. Outside of the saturated region of operation the temperature and pressure change with corresponding changes in entropy. One can see now why it is a rational strategy to assume operation of the vapor compression recovery system to occur only for purposes of deciding strategies for efficiency improvement with the understanding that this region of operation contributes to most of the energy involved with the metric of efficiency.
The mechanical losses with the movement of the refrigerant through the tubes could amount to a significant loss in energy and thus efficiency. For example if the pressure drop through the evaporator results in a saturated temperature change of 3 C, this is approximately 1 percent on the cooling capacity of the evaporator. Other factors are ignored. For example the mixed presence of liquid and vapor in the tubes creates mechanical states of blobs of empty spaces or sections of completely liquid refrigerant or vapor along the tube. Another are the losses in the throttling process where some of the energy during the transformation from the liquid output of the condenser to the lower temperature results in a phenomena called flashing where vapor is created with the throttling process resulting in loss of energy. Suffice it to say that it is mentioned here but the impact of their contributions to the losses are ignored.
The solid line depicts the boundaries by which the phase of the refrigerants changes to being completely liquid or vapor to a combination of liquid and vapor when the refrigerants acquires heat. The right side of the phase diagram shows the boundary by which the refrigerant phase changes from the saturated phase (combination of liquid and vapor) to a completely vapor state. This is the region as shown in
The COP metric disregards all these factors but serves as a guide to achieve higher efficiency for the cooling system. The term superheating results from requiring practical air conditioning systems to have adequate assurance that the refrigerant to the compressor at the suction line are all in vapor phase. Otherwise the compressor could be ruined. The term sub cooling is similar to superheating except it is the degree by which the refrigerant from the condenser is cooled lower than the saturated temperature of the refrigerant. Flashing is when the energy of the liquid during throttling converts some to vapor with the attendant loss in energy. We neglect inefficiency on energy based on the relative total energy contributions compared to the thermodynamic processes within the saturated regions.
Note for trivia that under the specifications of the ambient temperature and control temperature set for the definition of SEER, the corresponding COP under ideal condition of infinitely capable heat sinks and heat source for the evaporator and condenser respectively that the COP is 180 with a corresponding SEER of 622. It is a very far target to achieve but hopefully could serve as encouragement that indicates there is a lot of room for improvement over the horizon.
FIG. (13) shows the transition points where the VCRS process within the close loop cycle. FIG. (13) transition points pairs to indicate that are practical necessities for an actual unit where further processes have to be implemented. The sequence of the transition follows an increasing order with the system cycle following a counterclockwise direction. Point (1) is when the refrigerant enters the evaporator as a combination of liquid and vapor after undergoing “throttling” where the refrigerant pressure is changed from the high saturated pressure (8) to the lower saturated pressure and temperature (1). This refrigerant phase enables the extraction of heat from the room because the saturated temperature of the refrigerant is lower than the room temperature setting. When the heat from the room is extracted in reaching (2), the refrigerant undergoes mechanical work. This transition point in FIG. (10) also shows transition (3). This is to show that in an actual cooling system, it is mandatory to operate the cooling system such that there is assurance that the refrigerant is completely in the vapor phase before undergoing mechanical work by the compressor. Otherwise, the presence of liquid in the refrigerant could ruin the compressor. From (3), the compressor changes the pressure and temperature of the refrigerant by introducing work. This raises the temperature and pressure of the refrigerant to (4,5) in FIG. (14). Transition point (4) is the state of the refrigerant after the compressor. FIG. (15) shows the full phase change cycle for the refrigerant for an actual system tested with R22 refrigerant. The compression of the refrigerant is not in the saturated region (4,5) to (6,7) because of the reason on maintaining complete vapor on the input to the compressor. FIG. (13) disregards this in order to simplify the explanation on how to achieve thermodynamic efficiency. Cooling of the refrigerant brings it to the saturated region (5). The transition regions (4,5) to (6,7) is when the condenser rejects it's heat content to the ambient environment. Therefore the energy used for cooling the room would be the changed in the enthalpy (horizontal axis) from transition point (1) to transition point (3). The condenser on the other hand removes the energy corresponding to the difference in enthalpy at transition point (4) to transition point (8). The work provided by the compressor would be the enthalpy change from transition point (3) to (4). Examination of the phase diagram
FIG. (15) shows the phase diagram that an actual air conditioning system undergoes. The FIG. (16) in a similar fashion as FIG. (14) are shown to scale such that the magnitude of the energy of the refrigerant is indicated graphically. The saturated regions (1,2) and (5,6) have energy changes relatively larger than the energy changes on the refrigerants during (2,3), (3,4) and (4,5) and (6,7). The region (2,3) is to assure that the refrigerant enters the compressor to be completely vapor. This is termed “superheating” at the suction line. (3,4) is the compression cycle of the refrigerant. The resulting phase at (4) is both a result of the superheating and also the compression process. The region (4,5) cools the refrigerant to bring it to the saturated region. Note that at the states (4,5) and (2,3) the saturated pressure of the refrigerants are maintained to be almost the same as the saturated temperatures at (1) and (4). At (5), the refrigerant is completely liquid. When the condenser has more cooling capability, then the liquid refrigerant is cooled to (7) with the pressure still maintain as from transition point (4) to (7). This region is called the sub cooling of the refrigerant. This is desired similar to super heating the throttling process for a more desirable liquid state of the refrigerant before throttling. From
FIG. (14) through FIG. (18) are all drawn to scale as a result of analysis using the R22 refrigerant. One may verify for example in FIG. (14) that the ideal COP definition is satisfied under the condition that the refrigerant operates within the saturated boundaries of the phase diagram.
The reduction of the “temperature head” on the condenser is addressed. Particular application is on the process of upgrading older installed air conditioning systems which have efficiencies that are much lower than the requirements for system efficiency for new equipments as mandated by the Department of Energy.
This application uses the vaporization of water as a vehicle to conduct the heat flux from the refrigerant in the condenser to the ambient environment to improve the cooling performance and capacity of the condenser.
The process consist of—(1) water delivery metering (2) air flow volume rate control (3) air flow temperature and humidity conditioning. These processes results in improvement in efficiency over a wider range of temperature and relative humidity. Also the effect of scaling buildup is reduced with predictable maintenance requirements.
The vaporization process occurs at any temperature. It is the result of the equilibrium between the high energy molecules from the liquid balanced by an equal amount of vapor molecules losing energy and changing back to liquid. When the enclosure does not loss any of the material water vapor, then the equilibrium state is called the saturation level at that given temperature. The saturation level is exponentially related to temperature. The saturation level implies that it creates a vapor pressure because of the high concentration of water vapor. The vapor pressure is dependent on the temperature. Diffusion therefore starts together with a negligible amount of sensible temperature change perpendicular and away from the water film. Diffusion creates a water vapor profile and temperature profile toward the steady state where the whole chamber would acquire saturated conditions After this, the heat flux flow stops. An upper limit on the gradient of the vapor boundary layer is dependent on the saturated water vapor content as it traverses away from the water film surface. Thus theoretically, the temperature of the water film could be made to be close to the ambient environment. The temperature gradient could be made very sharp by ensuring that the vapor pressure from the surface of the water film is as high as possible. This would be adequate if the air flow can effectively keep up with the generation of water vapor and establish a very sharp gradient for diffusion. The process of air carrying the water vapor is the mechanism that enables this. As a best case scenario, for example under the condition that the air flow is adequate in removing the water vapor created by the vaporization, that the thermal resistance for the heat flow from the refrigerant energy is limited by the refrigerant and the water film effective thermal conductivity. The thermal conductivity of the copper or metal tube is so much greater than the refrigerant or the water film.
The following factors are design parameters for the effective application of vaporization for the upgrade. The first is to meter the delivery of water to the fins and fans such that the needed amount for the vaporization contribution is maintained. This improves the use of water for the cooling process. Also careful metering of the amount of water minimizes the thickness of the water film on the surface of the fins and tubes. Thus the contribution of the water film to the total thermal resistance from the refrigerant to the ambient environment is minimized. This is particularly clear because the thermal conductivity of water is very close to the refrigerant. The second is to maintain the minimum thermal resistance presented by the boundary layer by controlling the air flow. The metric for this is the difference in temperature from the ambient air and the exhaust air from the condenser. In the case of the cooling that is applied using the sensible heat transfer of the airflow, the change in temperature is proportional to the heat energy extracted per unit time for a fixed topological cooling structure. With the combination of the two heat transfer processes, the latent heat of vaporization mechanism tends to decrease this differential in proportion to the percentage of cooling attributed to sensible heat transfer. If the latent heat of vaporization of water were to be optimized, the cooling effect would reduce the sensible temperature change. Thus the difference in inlet and outlet air flow temperature is used as a feedback control for the efficiency in the delivery of the optimum amount of water. The limits would be dependent on the relative humidity of the ambient air since the amount of water vapor that can be generated from the heat transfer would be limited theoretically by the saturated air. The normal temperature range of humidity and the temperature operation for existing equipments however have SOP equipment performance that saturation is not reached. The second metric is to have a strategy of maintaining the cooling efficiency of vaporization by maintaining the high conductivity of the interface between the fins and tubes to the ambient air. This is maintained by minimizing the water vapor boundary layer thickness and also the conductivity between the refrigerant to the immediate surface of the boundary layer. The boundary layer explanation is a catch all explanation of why air flow is needed. The control of the air flow is needed to avoid getting close to the boundary of saturation for the outlet air. The control of these parameters has to be combined and coordinated with the water delivery system. Analysis applying the assumption that laminar flow occurs on the installed AC fin and tube condensers shows the validity of the adequacy of the fan installed in these equipments that are candidates for upgrade. The standard operational design for these condensers has been 400 CFM per ton of AC capacity.
The use of water always presents practical problems of scaling. The scaling problems are addressed knowing the following information about their formation and development. The PH factor is an indication of the possible magnitude of the potential of the problem. A more acidic water would minimize the probability. The interface to the water film where the amount of carbonate material that would potentially develop to scaling is contained by minimizing the volume of the water involved. The amount of carbonates that end up deposited on the metal surfaces are predictable. This is because the metering process of the water achieves the total vaporization of the delivered water and all the carbonates are precipitated and deposited on the surfaces. The amount of deposit would be dependent on the hardness of the water and the total accumulated cooling energy. The metering of water for vaporization optimizes the use of water and extend the time for which maintenance due to formation of scaling would be needed. The maintenance could be divided into two segments. The first segment is the actual delivery equipment to the fins and tube of the condenser. The second segment would be the scaling on the fins and tubes themselves. The latter would lend to mechanical cleaning since in most cases access to the fins and tubes are available because of the inherent topology of the present condensing devices. Thus mechanical cleaning with high volume and low pressure cleaning water, is a convenient and economical process. The water delivery material is selected for high contact angle which is a measure of the adhesive property of water to the surface. Maximizing the contact angle for the material would reduce the formation of scaling on the material.
The water delivery system is designed such that the metered and controlled manner of delivery of the water shall be distributed evenly on the fins and fans. This would help extend the time necessary for maintenance because it avoids the localization of water distribution flow which accelerates the build up on these local regions. Also it is known that the scaling that forms has the property that the adhesion develops stronger after a certain threshold of time and from that point on accelerates the build up and formation on this initial scaling to aggravate the conductivity of the device. This property however might be very dependent on the action of bio film buildup and would have minimal impact. This is true when the amount of water is sufficient that bio film maintain on the heated surfaces. This development of bio film accelerates the scale buildup due to carbonates. Therefore the strategy is to allow periodically a mechanical cleaning of the surfaces of the water delivery. It is proposed to flood the water delivery from another vessel and then while it is flooded subject the container to mechanical pressure forces in terms of ultrasonic frequency that would be designed such that the spectrum scans the possible resonance of the initial scaling particles formed. This can be easily done by both the frequency change on the ultrasonic signal and also varying the resulting harmonics with the waveform of the signal such that the natural resonance of the particles are achieved with very good certainty. This procedure is well known in testing electronic devices for electromagnetic compatibility issues and performance. Since the timing logistic is designed to be done during the initial formation of the scaling, the mass of the particles would be low and therefore the resonance of the particle is high and could be amenable to ultrasonic pressure waves. After a dwell time of mechanical cleaning, a flushing with large amount of water would be used to carry out the particles removed from the walls of the delivery system. The duration for the mechanical ultrasonic cleaning is extended with occasional use of chemical cleaning in terms of reducing the PH of the water solution. Analysis was made on the assumption that with controlled metering of the delivered water, the water with known hardness would deposit all the carbonates it carries with it because of total vaporization. The maintenance of the scale buildup maybe guided by an empirical test with results that determines the time threshold by which maintenance for the heat transfer surfaces have to be implemented because of undue degradation of the heat transfer property. The test data from the literature and the predictability on the magnitude of the scale buildup because of the metering process of water delivery predicts a result that it would take a year to degrade the thermal conductivity of the system using water vaporization.
The general idea on how to implement the delivery of water for vaporization with consideration on minimizing water usage, scaling, maintenance and initial capitalization is addressed. There are two possible implementations for the existing fin and tube condenser structure.
FIG. (19) shows schematic of the metered water delivery. The schematic consist of a dual tank 196 and 198 which are respectively the source tank from the water utility 190 and the pressure controlled tank 198. The water source tank is controlled by a float switch that regulates the water coming from the utility. 200 is a small peristaltic pump able to be driven in a bidirectional manner such that the water delivery is capable of increasing or decreasing the pressure head. 222 is the peristaltic tube port for the water delivery pressure tank, and 224 is the peristaltic tube port for the source tank. 226 is the port outlet for the pressure tank 198 where the water delivery to the tray 204 can be closed with electric solenoid 202. The utility water comes in through a float and valve arrangement 192 and 194 to maintain automatically sufficient water supply from the utility line.
The water delivery control is shown. 210 shows the temperature sensor made of thin wire of controlled length. 210 is shown with the wire grid arranged so that the sensor is exposed to the whole air flow area and automatically sense the average temperature. For example in the diagram the wire is wound sequentially 1, 2, 3, 4, . . . , 8, 9, 10. The block diagram and schematic of the water delivery sensing and control consist of the condenser fin and tube arrangement 208 and the water delivery tray 204 and peg arrangement 206 and the temperature sensors 210 and 212. Precisely equal current sources 214 and 216 for each of the temperature sensors 212 and 210 generates a voltage proportional to the temperature measured by each sensor. The difference in the voltage which is a measure of the degree of sensible temperature rise of the air flow is measured and amplified by 218. 220 receives the output of 218 and generates the power signal to control the flow of water in the dual tank which is connected to the water supply. Transfer of water from one chamber or the other is controlled by a simple peristaltic pump that could transfer water either direction for the purpose of maintaining a water head at the chamber for the water metering. The head of the water in this chamber creates the flow rate needed for the metering of the water for vaporization. FIG. (19) shows the structure of the dual chambers. The tank has to be situated above the water delivery nozzles to establish the necessary hydraulic head H. Delivery to the nozzle equipments shall be with small tubing either metal or plastic.
FIG. (20) and FIG. (20a) are the details on the structure of the water delivery tray and the uniform distribution pegs for the water droplets. 204 is the water distribution tray. The water from the pressure tank 198 comes into the tray through a entry port 244 where a layer of water film forms above nozzles 240. These nozzles are uniformly spaced on the tray. The water pressure head generated in the water pressure tank provides the necessary head to maintain a frequency of droplet formation. The nozzle diameter determines the size of the droplets. FIG. (20a) shows the elevation of the structure to emphasize the regularity and the arrangement for the pegs with relation to the nozzle locations.
FIG. (20) shows one implementation of the water delivery trays. The trays would be installed above the condenser fins so that the metered water shall fall uniformly under the condenser coil axis. Upgrades shall be custom activities and this might involve cutting a slot opening on the plate covering and protecting the original condenser enclosure. The tray material shall be selected such that it has high contact angle to hinder the formation of scales on the nozzles. The nozzle are uniformly separated with nozzle diameter selected such that metered water delivery is in the form of droplets.
It is everyone's observation after a medium rain on a loose or even firm soil that veins of channels are formed because of preferred paths for the water flow. A similar occurrence could happen when there is sufficient water volume for flow. The propensity for such phenomena is preempted by using the second section for the water delivery. When the veins are formed on the condenser structure, the thermal efficiency of the process is degraded. The second structure 206 below the tray is a series of pegs that again are selected to be of a material that has high contact angle. The uniform location of the nozzles and the opening of the orifice determines the spacing of the pegs. When water droplets from the nozzle falls, the water drop forms spherical shape because of the high water surface tension. The peg location is such that the droplets formed on the tray falls on the pegs. The high contact angle on the pegs causes the droplet to roll to either side of the peg. The next peg is located such that the falling droplet will again encounter the next peg falling with uniform probability to either side of the upper peg. Subsequent layers of pegs therefore will distribute statistically the distribution of the water film to the condenser fins and tubes and avoid or slow down the formation of veins. The metering of droplets formed is controlled by the peristaltic pump that transfers water from one chamber of the tank to the other.
The effective implementation of the water metering delivery would alleviate the maintenance of the condenser fins and tubes for scaling buildup. The probability of bio film formation is reduced because of the limited presence of liquid water with the metering system. Also the carbonates that the water delivering system carries would be predictable when water hardness are known. Therefore the maintenance and logistics on when it is done is predictable. Extrapolation from empherical test data by others on condensers showed that under conditions of the worse case hardness of water source, the maintenance for scaling buildup would be needed in about one year. The empherical testing was done under conditions favorable for bio film buildup. Thus the interval stated is conservative and the maintenance frequency is practical and affordable. The maintenance for removal of the scaling is improved such that high volume and low pressure water cleaning is adequate. This is because the bio film formation is avoided as much as possible with the water metering process. Otherwise it would require more often maintenance using complicated maintenance equipment. Empherical test showed that under the formation of bio film, the threshold where the adhesive property of the bio film is accelerated occurs approximately 2 months. The conditions by which this result was obtained are avoided in this process.
The theoretical COP improves with decreasing ambient temperature, assuming the “temperature head” of the condenser does not change. However when higher cooling capacity is needed, the low ambient temperature limits the available water vapor from the low temperature air. Under this situation the air flow control would demand more air volume. With the upgrade on the systems, this convenience for adjustment is not available.
The vaporization process has the advantage assuming there is adequate room to support water vapor formation for the cooling load. The capability of the air conditioning or refrigeration systems on low ambient temperature is degraded especially with large cooling systems because of the magnitude of the saturated humidity at the low temperature.
This limitation is alleviated if the air flow is raised to a higher temperature than the low ambient temperature to increase the available water vapor content for vaporization. The procedure is to configure sections of the condenser to operate normally using the sensible heat air transport for convection. From FIG. (12a) and FIG. (12b) one can see that heating and/or cooling first but with the air flow temperature adjusted to a higher temperature, the capacity of the system is increased.
The upgrade is implemented as follows. The block diagram of the upgrade for a central air conditioner condenser or refrigeration system is shown in FIG. (23a). The existing condenser is conveniently divided into three (3) sections by suitable baffling arrangement. Each of the three sections 210, 212, 214 are equipped with the water delivery system for vaporizations. These are shown as 206a, 206a and 204b, 206b and 204c, 206c. A section is designated as the section that would make use of vaporization for cooling. Each of the sections have the water delivery valve 114a, 114b, 114c such that the system can be operated using fully vaporization. Section (210, 204a, 206a, 114a) is mechanically baffled to operate under vaporization when there is an inadequate vapor capability because of the ambient environmental conditions. The condenser air flow from the fan has the baffle arrangement such that a portion is routed to section A. When sections of the whole condenser is denied of water delivery by controlling 114b, 114c then the fan output air flow would exhaust warmer temperature than the incoming ambient air. A portion of the warmer air is routed via the baffle arrangement to section a. The warmer air would allow the condenser section to have a larger cooling capacity using vaporization because of the added water vapor cooling capacity.
The benefits in the reduction of the head discussed before is compromised to the level where the needed cooling capacity for the equipment is reached. Still the vaporization augments the original air material convection for the condenser.
If one were again to allow the application of the vaporization technique to another remaining and trailing section of the condenser, this will achieve the sub cooling which improves the capacity further.
Notice that FIG. (22) has an implied configuration where vaporization technique is applied to the whole condenser equipment. Thus we could eliminate the individual valve controllers and leave only one at the most.
FIG. (22) is the embodiment for an upgrade where total water delivery is made on the full condenser fin and tube arrangements. 210 are the average temperature sensors, 204a, 206a, 204b, 206b, 204c, 206c are the water delivery tray and peg structures. 220 is the opening for the condenser fan air flow.
FIG. (22) is modified such that the various valves needed for individual section control on water delivery is added as shown in block diagram FIG. (21) FIG. (23) shows the implementation which is the same as FIG. (22) except the shroud of baffle 230 is installed. The side panels of 230 indicated as 232 could be removed so that full vaporization operation can be implemented.
The tradeoff of a compromise on the resulting efficiency and the noise from the fan air flow volume is a tradeoff decision that comes into the picture. The full potential of reduction of the temperature head in the condenser with the use of latent heat of vaporization may be compromised. When there is a need to warm up the air for the vaporization process, the procedure would lead to a higher “temperature head” than when we have complete latent heat of vaporization applied. The preconditioned air then is used for the latent of vaporization heat exchanger that would have the remaining cooling capacity to maintain that effective temperature head. This will be a dynamic parameter that will be dependent on the ambient temperature, humidity and cooling load. This increased temperature of the air would lead to a demand for lower air flow for the heat exchanger using the latent heat of vaporization. Since the latent heat of vaporization does not involve increase of sensible heat and that the preconditioned air is exhausted to the environment, the condenser could be installed indoors where the operating conditions are controlled and would lead to simpler control and uniform performance. The desired resulting efficiency for the system can be weighed with the benefits of a smaller unit because of the lower air flow. This implies a physically smaller refrigerant enclosure would be required. The smaller size enables users to enjoy the configuration of having the system indoors. The ramifications of indoor locations are discussed in the third embodiment
FIG. (24) shows a schematic of the upgrade where full flexibility in selecting sections of the condenser could be made to operate on vaporization. It is similar to FIG. (22) except the addition of the electronic controller for valve and motor control. It is used also for the temperature sensor to determine the effectiveness and control of the vaporization procedure. The water delivery trays will have controllable valves from the water delivery tank system. These are the valves 114a, 114b, 114c. Water delivery control and selection of condenser sections to operate on sensible or latent convection is implemented with the controller 240.
With the larger capability for cooling to the point that the air conditioner can be cooled to sub cooling region, the efficiency of the vaporization process for the air conditioning is more capable of providing improve efficiency in these situations where the cooling is needed. In situations such as refrigeration systems the equipment has to operate on lower ambient temperatures than usually required for air conditioners, The lower temperature limits the available room for the same volume of air to absorb the cooling capacity needed from the vaporization process to accommodate larger cooling load. This is because of the lower saturated humidity at the lower temperature.
FIG. (24) shows the block diagram of the routing of the air flow by means of physical means such that the problem stated is alleviated. The problem at the lower ambient temperature could be alleviated with a compromise on the theoretical limit of achieving the full capacity of efficiency that could be obtained from the vaporization process This would be in between the ambient temperature and the “temperature head” addition to the original equipment. The block diagram shows a portion of the incoming air flow to be operating in the normal sensible temperature cooling process that generates an increase in the temperature of the incoming air. Since no vaporization process occurs here, the relative humidity of the outgoing air from this portion of the condenser is much lower than the incoming air. The increase in temperature of the outgoing air opens more cooling capability from vaporization process. A compromise on the magnitude of the temperature rise available with the SOP “temperature head” of 18.5 C is possible leading to increase efficiency and performance for the refrigeration than is afforded by the original configuration. The pre heated air flow for vaporization is used for the vaporization cooling process in another section of the overall condenser cooling arrangement. The output from this section is then routed out and mixed with the output of the first evaporator operating in the sensible temperature region of the air flow. The idea can be extended such that the water delivery is divided into three sections. The delivery system water metering control shall have the capability of operating all of the sections on vaporization. The first and the third sections could be turned on and off. Operation of mixing both sensible temperature operation and full vaporization cooling process could be achieved with an overall higher system efficiency extended to a wider range of ambient temperature and humidity conditions. FIG. (26) through FIG. (28) inclusive are sketches of the implementation for upgrade using this process. The block diagram for the electronics control needed is shown in FIG. (29).
The equipment with the preheating chambers are shown in FIG. (26) through FIG. (29). The flexibility afforded by the scheme of three condenser sections with the associated valves for water delivery is possible only if an embedded controller were designed and implemented for system input parameter measurements and control.
The technology use on the equipments for upgrade has the inherent reduction in efficiency with increase temperature and humidity. It is at these situations where the efficiency performance is important because of the high usage.
Another method for water delivery is the use of spray nozzles suitably located to effect a uniform distribution of water spray. It is shown in FIG. (30). It is a more expensive procedure with the high pressure needed and pump to for the pressure tank and associated valves. It is of course a very practical option that is a mature process.
The upgrade process is inherently limited in scope. Since an air conditioning or refrigeration system is designed with all components considered, upgrading the performance of an equipment comprising the system will not necessarily result in the achievement of the objective. This is particularly true in the upgrade when the compressor is not a viable component to replace. The compressor is designed with the evaporator characteristics and the condenser in consideration. Improving the theoretical COP with vaporization process is one of the items that have to be modified. Since the compressor physical characteristics are not changed, there is a need for other control devices or strategies in order to accommodate the improvement in the cooling efficiency of the condenser for upgrades. The details on this will be presented as another separate application. Actual tests have been made to verify that the procedure as a companion for the usual hysteretic control on residential and small air conditioning systems had been verified.
The second embodiment is the application on cooling computer chips. The fabrication of computer chips and associated digital devices had been following Moore's law of speed and density. At the present, computer chips are dissipating over 100 watts. The fabrication of silicon devices have developed to the point that the limiting factor is the dissipation of the heat produced in the silicon chip. The reliability of any electronic is dependent on the operating temperature margin from maximum temperature that the solid state devices operate in. The devices are rated from 125 C to at least 150 C depending on the technology used. The feature size (relative size of the basic transistor cell) has been reduced considerably by several orders of magnitude. The technology is that a system on a chip is the desired topology. With this the CPU, memory, dedicated hardware computation algorithm components such as DSPs, and other system functions that make use of the wide CPU bus are desired for processing efficiency to be integrated into a chip. This architecture is beneficial in that the bottleneck of access to the other devices are not slowed down by any parasitic that are natural when they are mounted on the PC board. The projection is that if this were done, the power dissipation of such devices could reach a power density of 1000 watts per square centimeter. The cooling towers that are presently used in desktops are heat pipes where the thermal conductivity is maximized from the chip to the heat sink. The heat sinks physical size using this technology together with the implementation of convective air flow are larger than 100 cubic inch in volume. The fan speed generate approximately 2.5 meters per second velocity for the air flow.
The process is applied to computer chip cooling enabling smaller than the 100 cubic inch volume to cool the projected 1000 watts per square centimeter power density. FIG. (25) through FIG. (34) is an implementation following the procedure discussed above.
The embodiment is such that practical considerations are included. The invention does not preclude other means but the basic idea of applying the maintenance of good thermal conductivity path with suitable presentation of water for the vaporization process.
There is a base 260 such that when the heat sink module is installed would be mounted to the computer chip. FIG. (26) is an elevation and top view of the heat sink. It would be mandated that the material which in all probability is metal should have the highest thermal conductivity allowed with practical economic constraints applied. It consist of three pieces. 260 is the bottom block. It has mounting means such that it could be mounted with the computer chip. The mounting for the block is shown such that the heat sink orientation is vertical with the other configurations that the PC board might be oriented. That is there is mounting provision on the bottom of the block and the side of the block 264. This block shall have the precautions needed before such that the air gaps that are present in the interface between the computer chip package and this block are minimized with thermal compound application. This block is configured such that the other part of the module could be detached easily for either maintenance or replacement. This is necessary because of the scaling problem that is inherent with the process. Strategies for the design of the heat sink for maintenance and reliability. Also the second block 262 attachment is designed for ease of replacement or maintenance. Block 262 has the chamber where the vaporization occurs.
264 consist of a port for input for air flow. The heat sink has the capability of having the temperature higher than ambient because of the high temperature tolerance of the silicon computer chip. The cooling process therefore is to initially warm the incoming air. The high conductivity block 264 has a labyrinth of air passages as indicated in cross section view FIG. (28), FIG. (29), FIG. (30), FIG. (31) and FIG. (32). The air flow temperature is raised during its passage through these labyrinth of holes. It is not shown in the figures that there is an associated air flow pump externally that pushes the air for the required air flow. This control is provided by an external embedded controller. The temperature sensor that is needed to maintain the metering of the water are 266a and 266b. The sensors are designed in a similar manner as previously discussed in the air conditioner systems. An averaging feature is designed in. The circuit is similar for converting the temperature differences to control the water delivery system 260 block has an input port 270 for the ambient air. FIG. (28) shows the bottom of the labyrinth of holes. There are chambers that serve as conduit for the incoming air to the holes running vertically on the block. Similar network of chambers acts to receive the air flow on top of the block. It is exhausted to the bottom of block 262 and serves as the conditioned air flow for the vaporization. FIG. (31) is a view looking towards the interface to block 260. 310 shows the need for effective seal at the interface between block 260 and 262 to avoid any air leaks When the input air is warmed up, the capacity for cooling increases because of the larger amount of water vapor air can support. It is also beneficial in another way in that the volume of air needed to carry the transport material of water vapor is less.
262 as shown in
There would be situations where smaller volumes and possibly higher cooling capacity requirements would be needed. The volume of the heat sink can be reduced if the vaporization rate that is required by the heat flux is supported physically by the surface for the diffusion. Together with this is the rate of transport provided by the air flow. The diffusion gradient can be optimized by the temperature of the air flow to provide a larger difference in the vapor pressure from the vaporization surface of the water film to the airflow.
The temperature of the air as pre conditioned by the labyrinth of passages in the heat sink body may not be sufficient under some of the stated conditions to affect the low vapor pressure needed for the cooling load, External heating could be implemented to achieve this.
The latter requirement could be alleviated by implementing auxiliary heating external to the heat sink to augment the physical limitation of providing the chamber for heating within the heat sink. This procedure would provide the flexibility of extending almost at will the capability of the heat sink. The process of preheating the air adds a favorable contribution to this problem. When the air is heated, the saturation level for water vapor rises exponentially with the temperature rise. This implies that lower volume of air flow is needed to carry the water vapor product of vaporization. The silicon devices are capable of at least reaching 125C. With proper care and design on both the interface to the computer chip and the pre heating higher temperature for the air flow could be achieved. This further reduces the rate of air flow needed. Tradeoffs are the reliability issue desired for the semiconductor. The cooler the silicon more reliable and longer life for the device. The other factors are aesthetic on the practical temperature for the output air flow, and requirement for better materials to handle the higher air temperature. The design of the pre heater will dictate the volume of the heat sink. The pre heater should not eliminate much of the highly conductive material used for the heat sink to the point that it reduces the thermal conductivity from the computer chip to the fins to which the water film is introduced. The fins should be as short as possible to reduce the effective thickness of the fins. Thus under some circumstances the external preheating of the air flow is more acceptable. This is true from the point of view that the power needed to heat the reduce volume of air flow is small compared to the benefits that would accrue with the cooling process. The fins total surface area has to be designed such that the diffusion rate and the capacity will not be limited by the area used for the diffusion to convey the heat flux. Increasing the fin surface area and minimizing the gaps between them would be parameters to be considered. Decreasing the gap between the fins makes the air flow laminar. If the boundary layer is desired to have as much vapor pressure gradient as possible to enable the heat flux capacity needed, then the air flow should be adjusted correspondingly. Again in order to assure that the water delivery is metered to prevent saturation in the air flow chambers.
Other procedures of implementing the delivery of water are possible. The considerations on scaling buildup are one of the factors of importance. These are subjective decision and amenable to various degrees of variation.
For example the water delivery could be via other means of transpiration using other topologies of the relationship between the water container vessel and its introduction to the air flow stream. Compromise on the ease of maintenance of scaling problem to the economics of replacing the components are tradeoffs that have to be considered. Also the maintenance as a result of scaling does not have to require maintenance but if economically justifiable a strategy of throw away replacement. The circuit for the decision on how the air flow is controlled are subjective and not absolute. Therefore the process indicated in this application would include such possibilities and variations
Another version of the heat sink would be a modification of FIG. (26) and FIG. (26a). The technology called Peltier heating and cooling which depends on the Seebek effect on semiconductors are well developed for commercial applications and are economically viable. The implementation of added external heating is a practical and natural extension of using the Peltier effect heating elements. Packaging them would be also amenable to the size of the heat sink because they can be small enough and that the energy requirement for the pre conditioning of the air flow is minimal on heating and/or cooling capability The Peltier heating elements could be mounted on the side of the side sink as an extension of FIG. (26) and FIG. (26a) where they would be attached modules on the side of main block 260.
The third embodiment is an application of the process to new air conditioning and refrigeration equipments.
Air conditioning or refrigeration systems are system level type of designs. It is different from the upgrade discussed previously because all tradeoff are available to be considered together as an aggregate to be weighed with all attendant requirements of economics, capitalization, reliability, maintenance, aesthetics. This section as an embodiment shall focus on the changes that could be implemented with the advantages of vaporization in new designs for air conditioning or refrigeration system of various sizes. Different applications shall be touched on from small ones like portable units, central type as used in residential units and the large units that are for example represented for the condenser cooling by the use of water towers. Embodiments that typically would apply the various items discussed previously shall be considered. The implications of the advantages provided by the use of vaporization shall also be discussed.
Considering only the condenser and also using the same fin and tube technology that is very mature and economically viable, the following are advantages in implementing the process. The other developments that addresses the enclosure for the refrigerant to improve its thermal conductivity which is a major portion of temperature head with this process could be adopted when the manufacturing process and volume is at the point of economic viability. It does not of course preclude the activity of devising other implementation of the condenser structure considering the inherent physics of the vaporization process requirement. For example modules that are extruded with chambers for the refrigerants that do not necessarily depend on the linear feature of the flow of refrigerant could be designed. Parameters to optimize the labyrinth that would be created in this modules had been studied by others using the existing copper tubes but adapted to other internal and external configurations. It is known that for a given geometry with considerations of thermal conductivity and problems of liquid and vapor globs on the tubes, there exist optimal length and dimensions The implementation of the vaporization process is not altered because of these variations in the physical nature of the refrigerant flow and enclosure.
The implementation of the vaporization process with the attendant addition of various parameters for controlling the system adds to flexibility, reliability, more effective maintenance program, robustness and capability of synergistic operation with other energy using equipments in the area or home.
The implementation also automatically reduces the size and air flow needed for the cooling unit. Using the fin and tube condenser as modules to create easy maintenance. It enables a hierarchy of cells or modules as basic units for building and upgrading systems. This enables the elimination or extension of economic losses due to system downtime for maintenance. The flexibility afforded for upgrades, e.g. the rule that there is always a diminishing capability on large computer system installation would make upgrades on cooling capacity easier and could be predicted. This hierarchical structure would enable seamless additions for increase cooling load requirements. The upgrades could be implemented without system downtime since tapping into the existing system could be designed such that such operation is seamless. The progressing building block of FIG. (35) of creating the system enables the scheduling of the maintenance of portions of the system without affecting the capacity and performance required of the system. Also the process enables the location of the condenser indoors and reduction of size and capitalization cost.
The basic cell module as an architecture can be as shown in FIG. (21). The source of water head can of course be modified together with the solenoid valve with other methods. However the basic topology of being able to mix sensible and latent heat of convection transport is shown in FIG. (21). A basic “cell” for example could be 10 ton capacity system for large systems. Systems for smaller commercial systems can have “cells” of smaller capacity.
The implementation of the control, both from the cell level and system level might be seamless to accommodate other existing controllers if the basic “cell” structure has an independent controller with the capability of communicating with the rest of the “higher level cells” hierarchy. Breaking up the demarcation between the other parts of the refrigeration system such as the compressor, air handling systems will also be affected with regards to the architecture of the system but I am not addressing these issues.
Air conditioning systems with externally located water towers could be implemented with smaller sizes that could be located indoors. The system indoors can be designed to have a hierarchy of components that would distinguish the level of both cooling contribution and maintenance segmentation. The basic condenser cell shall have a minimum cooling capacity that could be configured to have embedded pre heating (pre conditioning) or a basic condenser which will have all condenser fins and tubes to be operated with vaporization with the use of a pre conditioning chamber FIG. (21) and provide the pre conditioning of cooling and/or heating as discussed previously. This process enhances the efficiency and capability of cooling capacity and performance to ambient temperatures that are high with corresponding high relative humidity. The inputs to these pre conditioning chambers shall have dampers to regulate the portion of ambient outside air or indoor air for replenishment. The plumbing of the air flow and also the water delivery valve control have to be implemented per situation of type of pre conditioning.
FIG. (21) is a concept for a general pre conditioning of air as source for the condenser using vaporization for cooling. We know that warming up the air increases the water vapor capacity of the air and allows us to use less volume of air with the controller to transport the heat flux. This was applied to the computer chip cooling and enabled us to cool and get rid of high heat flux. This is a case in large systems where a general air pre conditioning is applied, i.e. both cooling and heating of the air is used for pre conditioning. FIG. (21a) is a curve that justifies the concept. The equation for saturated water vapor at temperature i is given on first line. Ilow is the number of degrees C. that the cooling is performed. The curves show when the air is warmed in this case 3 times ilow above the ambient temperature. The total energy to cool and heat for pre conditioning the air is trace 5. It consist of the latent heat to condense to the dew point extra water vapor at 90.5° F. with a relative humidity of 80% and the sensible heat of lowering the temperature by 4.5° F. and raising the temperature by 13.5° F. above 90.5° F. The enabled capacity for cooling with the transpiration with this process is trace 2. The graph shows that if the cooling 9F and warm the air temperature by 13.5 F above original ambient (90.5 F), then 1 cubic meter per second air flow would enable 100 kilowatts of cooling with transpiration. The SOP for the cooling using original equipment would require approximately 7 kilowatt of fan power. The effective power that is used on the air volume is approximately also 7 kilowatts. However since we are using an air conditioner with a given COP, then assuming the air conditioner has a COP or 3.5, then the actual power usage is 2 kilowatts. The advantage is not only on the net power consumption but also it enables lowering the air flow by a factor of 25 for the vaporization Thus the air pre conditioning is beneficial both on energy and also lower the air flow with reduction in physical size of the condenser
The equipment used for this would be a standard air conditioning system. A tighter control on the temperature and monitoring the cooling to avoid freezing may be alleviated with an external controller 518 where sensor information from the cooled chamber and the warm chamber are obtained from sensor 508 and sensor 510 respectively. The cooling equipment air flow are separated as typical for air conditioners. The cooled air output 521 is routed from the output of the evaporator 520. The input air to the evaporator consist of metering mixture of air from the cooled chamber 526 and the outside ambient air 500 and the air flow output from the transpiration equipment with the dampers 504 and 502 and 506. Similarly the warm air is circulated through the condenser. The input air to the condenser is 516. The air pre conditioning equipment is the usual convective type condenser and evaporator with air as the transport material. The cooling strategy is to bring the room air temperature to a low level with the intent of removing all water vapor such that the cooled air is at its dew point. The warm air chamber 528 on the other hand is the air that is involved with the condenser. This warm air chamber will circulate the air just like the evaporator 520 in the cool chamber. Assuming care is exercised such that further heat energy losses in both chambers are mitigated, then the energy required would be as defined by the COP of the equipment. The air pre conditioning chamber 524 consist of cooled air chamber 526 and a warm air chamber 528. The air conditioner used for the air pre conditioning circulates air separately through the evaporator (cooled chamber) and the condenser (warm chamber)
Rough economic study had been made on applying the process on new plants and the return on investment showed promising benefits. They are contributed both by the initial reduction of capitalization and also on the large savings on the recurring cost because of the advantages of efficiency and maintenance.
The method followed in the process for addressing the problems of scaling reduces the recurring cost of maintenance and also avoids or logistically delay total system downtime for maintenance.
The implementation of the different aspects of the process to new equipments would result to the following:
This application has priority to currently pending U.S. Provisional Application Ser. No. 61/335,474 filed on Jan. 7, 2010 titled TEMPERATURE CONDITIONING which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61335474 | Jan 2010 | US |
