Patent Application
20230033068
The present disclosure is related in general to hydronic HVAC systems, and particularly to such systems that are configured to provide thermal energy management for large and/or complex facilities.
As fuel costs increase and greenhouse gas emissions control requirements become more stringent, there is a great deal of attention and effort toward improving efficiency of heating and cooling systems, and particularly systems that are employed to provide and manage the temperature conditioning for large facilities, such as hospitals, institutional buildings, high-rise buildings, campuses, and manufacturing facilities.
Currently, hydronic systems are the most common types of HVAC systems, particularly in large facilities. A hydronic system is a closed-fluid system in which a working fluid is used as a thermal energy transfer medium. In a hydronic HVAC system, the working fluid is heated or chilled at the central plant, then piped to remote locations in a facility, where the fluid passes through heat exchangers of various types to transfer thermal energy between the working fluid and other media, such as air, for heating or cooling, water, to produce ice or hot water, or a secondary working fluid, etc.
As shown in
Although not shown, the load 112 includes a pump that can be controlled to draw fluid from the supply conduit 108 at a rate that corresponds to a local demand for heat. Fluid that is passed to the return conduit 120 by the load 112 is carried to an input 122 of the source 104, to be reheated.
The system 100 also includes a decoupler 126 coupled, at a first decoupling tee 124, to the supply conduit 108 and the output 106 of the source 104 and, at a second decoupling tee 125, to the return conduit 120 and the input 122 of the source. This configuration is commonly known as a primary/secondary piping arrangement. The decoupler 126 is configured to permit a differential flow of fluid—meaning that the source flow and the load flow do not need to be equal—directly between the supply and return conduits 108, 120 of the system 100 in either direction (as indicated by the bi directional arrows shown on the decoupler), in response to a flow differential between the conduits. The decoupler 126 decouples the source 104 from the load 112 so that the source and the load operate in overlapping but semi-independent loops. The source 104 can therefore produce heated fluid at a rate that is not directly limited or controlled by the rate at which the load 112 demands heated fluid, while the load can draw fluid at a self-determined rate that is not constrained by the output flow of the source. If the source 104, for example, produces more heated fluid than is required by the load 112, this produces a difference in the flow rate between the supply conduit 108 and the return conduit 120, which causes the surplus fluid flow to pass through the decoupler 126 to the return conduit 120, where it mixes with fluid returning from the various loads 112. Similarly, if the total fluid demand from the load 112 is greater than the flow supplied by the source 104, a flow difference in the opposite direction causes fluid to pass through the decoupler 126 from the return conduit 120 to the supply conduit 108, where it mixes with conditioned fluid flowing from the source toward the load 112.
Such a system is typically referred to as having a primary loop 128 and a secondary loop 130. The primary loop 128 is defined by a fluid flow path that passes through the source 104, while the secondary loop 130 is defined by a fluid flow path that passes through the load 112. It can be seen that if the decoupler 126 were not present, the primary and secondary loops 128, 130 would necessarily be identical, with the flow rate of the primary loop being exactly equal to that of the secondary loop. However, because the decoupler 126 provides an alternative path, fluid that flows in the primary loop 128 can flow through the load 112, the decoupler 126, or both, while fluid in the secondary loop 130 can likewise flow through the source 104, the decoupler 126, or both. Furthermore, the flow of the primary loop 128 and the flow of the secondary loops 130 can have different values. Because the paths of the various loops (and sub loops, as described below) overlap significantly, and can vary depending upon operating conditions, the reference numbers indicating each of the loops point to flow arrows through which fluid of the respective referenced loop necessarily passes.
In the system 100, a flow indicator 152 is provided to monitor the direction and volume of flow in the decoupler 126.
As with the load 112, the source 104 can be more complicated than suggested in
Although not shown, the thermal source elements 136, and load elements 118 each can include one or more fluid pumps configured to draw fluid through the respective element according to the fluid requirements of that element or components thereof. Source and load elements of the kinds employed in HVAC systems, and the pumping systems are well known and understood in the art.
The examples of system configurations shown in
During normal operation, the source 104 provides a flow of conditioned fluid from its output 106 to the first decoupling tee 124. Assuming a constant output temperature of fluid from the source 104, each of the load elements 118 meets a varying demand for heat by controlling a respective load pump to regulate the fluid flow passing through the corresponding sub-loop 110. If a load element 118 has an increased demand for thermal energy, the corresponding load pump is controlled to increase the draw of fluid from the supply conduit 108. If the flow from the source 104 is about equal to the total volume of fluid drawn by the load 112, all of the fluid supplied by the source will pass through the first decoupling tee 124 to the supply conduit 108 and through the respective sub-loops 110 to the return conduit 120. From the return conduit 120, the fluid passes through the second decoupling tee 125 to the source input 122.
If the total fluid demand is more or less than the supply, fluid will flow in the decoupler 126 to compensate for the difference. For example, if the total fluid demand of the system 100 exceeds the fluid output of the source 104, the difference in fluid volume is made up by fluid that passes through the decoupler 126 from the return conduit 120 to the supply conduit 108 in response to the difference in the flows produced by the collective operation of the pumps of each of the load elements 118 of the sub-loops 110, against the fluid flow produced by the source 104. The fluid passing through the decoupler 126 combines with the fluid from the source output 106 at the first decoupling tee 124 to flow into the supply conduit 108. Of course, this means that the conditioned fluid from the source is diluted by “used” fluid entering from the decoupler 126, and the temperature of the fluid in the supply line 108 is reduced before it reaches the sub-loops 110 by the addition of the bypass fluid from the decoupler 126.
In response to the reduced fluid temperature, the load elements 118 will increase the volume of fluid drawn from the supply conduit to extract sufficient thermal energy from the cooler working fluid to meet their requirements, so that the total demand increases further, which increases the volume of fluid transiting the decoupler 126, and the fluid that returns to the input 122 of the source 104 is further cooled. Essentially, the load 112 is extracting more thermal energy from the fluid than the source 104 is introducing, so, absent a change in the operating conditions, the fluid will get progressively cooler until the system reaches an equilibrium, in which the fluid temperature drops to a point where the load cannot extract more heat from the fluid than the source can provide.
According to an embodiment, a thermal management system is provided, including a thermal source, first and second thermal loads, and a decoupler. A first terminal of the decoupler is coupled in a first three-way coupling with an output of the source and a input of the first load. A second terminal of the decoupler is coupled in a second three-way coupling with an input of the source and an output of the first load. The output of the source is coupled in a third three-way coupling with an input of the second load and the first terminal of the decoupler, via the first three-way coupling, and the input of the source is coupled in a fourth three-way coupling with an output of the second load and the second terminal of the decoupler, via the second three-way coupling.
According to an embodiment, the decoupler is unregulated, such that fluid can pass in either direction, according to differential fluid flows within the system.
According to an embodiment, the source comprises a plurality of source elements sharing a common input and a common output.
According to an embodiment, one or both of the first and second thermal loads comprises a plurality of load elements.
According to an embodiment, the first and second thermal loads, the decoupler, and the thermal source are components of a first hydronic system. The thermal source includes a component of a heat pump, and is configured to transfer thermal energy between a working fluid of the first hydronic system and a refrigerant of the heat pump. The thermal management system further includes a second hydronic system that itself includes a thermal source configured to transfer thermal energy between a working fluid of the second hydronic system and the refrigerant of the heat pump.
According to an embodiment, a hydronic system is provided that comprises first and second thermal loads, a decoupler, and a thermal source. The system further includes first, second, third, and fourth fluid tees. The first fluid tee has a first terminal coupled to a first terminal of the decoupler, a second terminal coupled to an input of the second load, and a third terminal coupled to a terminal of the third tee. The second fluid tee has a first terminal coupled to a second terminal of the decoupler, a second terminal coupled to an output the second load, and a third terminal coupled to a terminal of the fourth tee. The third fluid tee has a first terminal coupled to an output of the source, a second terminal coupled to the third terminal of the first fluid tee, and a third terminal operatively coupled to an input of the first load. Finally, the fourth fluid tee has a first terminal coupled to an input of the source, a second terminal coupled to the third terminal of the second fluid, and a third terminal operatively coupled to an output of the first load.
According to an embodiment, the thermal source is one of a plurality of source elements. The third tee is one of a first plurality of tees coupled in series between the first terminal of the decoupler and the input of the first load, each having a respective terminal coupled to the output of a corresponding one of the plurality of source elements. The fourth tee is one of a second plurality of tees coupled in series between the second terminal of the decoupler and the output of the first load, each having a respective terminal coupled to the input of a corresponding one of the plurality of source elements.
According to an embodiment, a thermal management system is provided, including first and second hydronic systems. The first and second hydronic systems each include first and second thermal loads, a decoupler, and a thermal source, together with first, second, third, and fourth fluid tees arranged substantially as described with respect to the hydronic system of the previous embodiment. The thermal management system further includes a heat pump, of which the thermal sources of the first and second hydronic systems each form a part. The thermal source of the first hydronic system includes an evaporator of the heat pump, configured to extract thermal energy from a working fluid of the first hydronic system, while the thermal source of the second hydronic system includes a condenser configured to impart the thermal energy extracted by the evaporator to a working fluid of the second hydronic system.
According to an embodiment, a hydronic system is provided, which includes first, second, third, and fourth fluid tees with respective first, second, and third terminals. The first terminals of the first and third fluid tees are coupled to each other, and the first terminals of the second and fourth fluid tees are coupled to each other. A thermal source has a source output coupled to the second terminal of the first fluid tee and a source input coupled to the second terminal of the second fluid tee. A decoupler has a first terminal coupled to the second terminal of the third fluid tee and a second terminal coupled to the second terminal of the fourth fluid tee. A first thermal load has a first load input coupled to the third terminal of the first fluid tee and a first load output coupled to the third terminal of the second fluid tee. Finally, a second thermal load has a second load input coupled to the third terminal of the third fluid tee and a second load output coupled to the third terminal of the fourth fluid tee.
According to an embodiment, the thermal source is one of a plurality of thermal sources, each having a respective source input and source output. The first fluid tee is one of a first plurality of fluid tees, which are coupled in series with a second terminal of each of the first plurality of fluid tees being coupled to the source output of a respective one of the plurality of thermal sources, a first one of the first plurality of fluid tees having a third terminal coupled to the first load input, and a last one of the first plurality of fluid tees having a first terminal coupled to the first terminal of third fluid tee. The second fluid tee is one of a second plurality of fluid tees, which are coupled in series, with a second terminal of each of the second plurality of fluid tees being coupled to the source input of a respective one of the plurality of thermal sources, a first one of the second plurality of fluid tees having a third terminal coupled to the first load output, and a last one of the first plurality of fluid tees having a first terminal coupled to the first terminal of the fourth fluid tee.
According to an embodiment, each of the plurality of thermal source elements has a respective temperature set point, and the source elements are arranged such that one of the plurality of source elements configured to produce the highest-grade fluid, from among the plurality of source elements, is positioned closest to the decoupler, and one of the plurality of source elements configured to produce the lowest-grade fluid, from among the plurality of source elements, is positioned closest to the second thermal load. The thermal loads are selected such that the first thermal load requires a grade of fluid that is higher than that required by the second thermal load.
According to an embodiment, a hydronic system is provided, which includes supply side and return side conduits. A source has an output coupled to the supply side conduit and an input coupled to the return side conduit; a decoupler conduit has a first end coupled to the supply side conduit and a second end coupled to the return side conduit, and is configured to allow bi-directional flow between the supply side and return side conduits. A plurality of loads is provided, each load having an input coupled to the supply side conduit and an output coupled to the return side conduit.
The plurality of loads includes a preferred load and a non-preferred load. The preferred load is coupled to the supply side and return side conduits on a same side of the decoupler conduit as the source, and the non-preferred load is coupled to the supply side and return side conduits on a side of the decoupler conduit opposite the source.
According to an embodiment, the source is one of a plurality of source elements, each having an output coupled to the supply side conduit and an input coupled to the return side conduit. The preferred load is coupled to the supply side and return side conduits on a side of the plurality of source elements opposite the decoupler conduit.
According to an embodiment, each of the plurality of source elements has a respective temperature set point, and the plurality of source elements is arranged such that one of the plurality of source elements that is configured to produce the highest-grade fluid, from among the plurality of source elements, is positioned closest to the decoupler conduit.
According to an embodiment, the non-preferred load requires a grade of fluid that is higher than that required by the preferred load.
According to an embodiment, each of the plurality of source elements has a respective temperature set point, and the plurality of source elements is arranged such that a source element configured to produce the lowest-grade fluid, from among the plurality of source elements, is positioned closest to the preferred load.
All patents, applications, and publications referred to and identified herein are hereby incorporated by reference in their entirety, and shall be considered fully incorporated by reference even though referred to elsewhere in the application.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the disclosure.
In referring to elements of embodiments that are described below with reference to the drawings, terms such as upper and lower , and related terms, are used to distinguish otherwise similar elements according to their relative positions in the drawings. This is for convenience and clarity but is not intended to imply any absolute or relative characteristics or positions of physical embodiments that operate under the principles disclosed herein. Even where the terms are used with reference to elements of such physical embodiments, there is no implied limitation, nor are the claims limited by the use of these terms in the specification.
In many of the drawings, elements are designated with a reference number followed by a letter, e.g., 182a, or 182b. In such cases, the letter designation is used where it may be useful in the corresponding description to differentiate between or to refer to specific ones of a number of otherwise similar or identical elements. Where the description omits the letter from a reference, and refers to such elements by number only, this can be understood as a general reference to any or all of the elements identified by that reference number, unless other distinguishing language is used.
Definitions
A working fluid is a gas or liquid that is used to transfer thermal energy into or out of a region of interest. Typically, a working fluid is transmitted in a closed loop, so that the fluid is retained in the system for reuse. In the embodiments described below, the working fluid is assumed to be water, but this is not essential. Other fluids that are commonly used in hydronic systems include glycol, but except where a working fluid is explicitly identified, the claims are not limited to any particular fluid.
HVAC is used to refer genetically to thermal energy management systems described herein. Such systems are not limited to heating, ventilation, and air conditioning systems as suggested by the acronym. Embodiments are contemplated in which hydronic systems are also configured to provide thermal energy management and control for various other applications, such as might be found in kitchens, laboratories, gymnasiums, industrial facilities, etc., and that might require e.g., hot and/or cold water, steam, food or specimen refrigeration, surface temperature control, etc. Accordingly, where used, the term HVAC is to be construed broadly so as to include such additional applications.
As used herein, a tee is a three-way fluid junction with three branches, or terminals, through which fluid can flow from any of the three branches to any one or both of the other branches. It is not necessary that a tee have the same physical arrangement or orientation shown in the drawings. Instead, it can be any coupling whereby a flow can diverge into at least two flows and/or two flows can merge into one flow.
The term source is used in the specification and claims to refer to a thermal transfer element that operates to condition a working fluid by transferring thermal energy to or from the working fluid for the purpose of modifying a temperature of the fluid, while the term load is used to refer to a thermal transfer element that operates to modify the temperature, or at least a thermal energy content of a thermal demand element , by transferring thermal energy between a working fluid and the thermal demand element. For example, a heat source operates primarily to impart thermal energy to a working fluid, and can be an element such as a boiler or the condenser of a heat pump, etc., configured to heat the working fluid that is circulated therethrough.
Likewise a cooling source operates primarily to extract thermal energy from a working fluid, and can be an element such as the evaporator of a heat pump configured to chill the working fluid, or a cooling tower configured to transfer heat from the working fluid to exterior air, etc. Conversely, a heat load operates to transfer thermal energy from a working fluid to a thermal demand element, and can be, e.g., an air handling unit (AHU) with a coil through which the working fluid passes and across which air, i.e., the thermal demand element, is circulated, to warm ambient air of a work space, or the evaporator of a secondary heat pump configured as a component of an AHU or a domestic water heater, to transfer thermal energy from a working fluid to a thermal demand element, in this case ambient air or water in a tank, etc. Finally, a cooling load operates to transfer thermal energy from a thermal demand element to a working fluid, and can be, for example, the condenser of a heat pump that is configured to transfer heat from the ambient air of a workspace, or from a refrigerator or freezer, etc., to the working fluid.
It should be noted that a heat source and a cooling load both increase the temperature of the working fluid, and, similarly, a heat load and a cooling source both decrease the temperature of the working fluid. Ultimately, the distinction depends upon the system in which they are used. A heating system is configured to provide heat in a facility, such as for environmental heating, hot water, etc., and includes heat sources and heat loads, while a cooling system is configured to “provide” cooling—i.e., remove thermal energy—in a facility, such as for air conditioning, refrigeration, etc., and includes cooling sources and cooling loads. It will be recognized that there are many more types and configurations of heat transfer elements that might be used with an HVAC system than can be described here. Nevertheless, the examples provided will suffice for the purposes of the present disclosure, inasmuch as most of those elements are known or discoverable, and adaptable for the disclosed purposes by a person having ordinary skill in the art.
Current Technology and Associated Deficiencies
Typically, facilities that use hydronic systems have requirements for both heating and cooling. Thus, it is common for the HVAC plants of such facilities to include both heating and cooling systems. The central plant might include a boiler plant to heat the fluid in the primary loop of a heating system, and a chiller plant to cool the fluid in the primary loop of a cooling system. However, more modern systems commonly employ heat pumps, or heat reclaim chillers, to provide both the heated and cooled fluid. Heat pumps are generally more efficient in HVAC systems because they do not generate heat by conversion from another form of energy, such as electricity, through resistive heating, or fossil fuels via combustion. Instead, a heat pump extracts thermal energy from a lower temperature first medium on the evaporator side of the heat pump and transfers the energy to the condenser side, where it is transferred to a higher temperature second medium. Thus, apart from heat produced by the compressor, no thermal energy is generated by the system. Heat extracted while chilling a first working fluid for a cooling system can be used to heat a second working fluid for a heating system. To do this, a heat pump operates simultaneously as a heat source of the heating system and as a cooling source of the cooling system, transferring thermal energy from the working fluid of the chiller system to the working fluid of the heating system. An example of an embodiment with such a configuration is described below with reference to
Broadly speaking, the layouts of a heating system and a cooling system are very similar. The diagram of the heating system 100 described above could just as easily have been described as a cooling system in which the source 104 is a cooling source rather than a heating source, and the loads 112 are cooling loads rather than heating loads. In fact, the embodiments disclosed below are described as heating systems primarily because for most people it is simpler to visualize the transmission of thermal energy (as heated fluid) in a system rather than the transmission of a relative lack of thermal energy (as cooled fluid). Nevertheless, the principles described herein with reference to a heating system can be applied with equal effectiveness to a cooling system, simply by substituting cooling sources and cooling loads for the heat sources and heat loads described. Furthermore, except where explicitly defined in the claims, the claims are not limited specifically to either heating systems or cooling systems.
Depending upon the physical characteristics of a facility, the local climate and weather, and the time of year, the heating and cooling demands of a facility are generally not perfectly balanced such that waste heat from a cooling system is exactly equal to the thermal energy demand of a heating system and vice-versa. Instead, facilities typically require supplemental heating in winter and cooling in summer.
As noted, heat pumps can provide significant improvements in operating efficiency of an HVAC plant, as compared to traditional systems. However, the efficiency of a heat pump varies significantly depending upon the operating conditions. An important factor in the overall efficiency of a heat pump is the temperature of the conditioned fluid as it leaves the device, either from the evaporator or from the condenser. For example, in a heat pump operating as a heat source so as to heat a working fluid in a hydronic system, a difference of a few degrees in a temperature set point of the fluid exiting the heat pump condenser can have a very significant impact on the efficiency of the device—set point refers to a fixed output temperature of a device such as a fluid heater or cooler. So, for example, reducing the set point of a heat-pump based heat source from 80° to 78° (F.) can produce a disproportionate improvement in the efficiency of the heat pump. Likewise, by raising the set point of a heat pump working as a chiller from 50° to 52°, its efficiency can again be significantly improved.
In the HVAC field, fluid of a more extreme temperature is sometimes referred to as high-grade fluid or high-quality fluid, as compared to fluid that is closer to ambient temperature, which is referred to as being low grade or low quality. In other words, in a heating system, high-grade fluid has a higher temperature than low-grade fluid, while in a cooling system, high-grade fluid is colder than low-grade fluid. To transmit a given amount of energy, it is typically more efficient to produce a larger volume of a relatively low-grade fluid than a smaller volume of a relatively high-grade fluid.
Another—albeit less significant—factor in system efficiency is the fluid temperature entering the device. For example, in a heat pump operating to heat a working fluid, it is more efficient to heat colder fluid, even though more thermal energy is transferred to bring the colder fluid up to the set point. The transfer of thermal energy between the refrigerant of a heat pump and the working fluid is a function of both the temperature difference between the two fluids and their time in contact with the refrigerant. For example, if the incoming fluid is colder, it will require longer time in contact with the hot refrigerant to reach the set point temperature than if the fluid enters at a higher temperature. However, in this case, the controlling element is the fluid pump that moves fluid through the device. The dimensions of the heat exchanger are fixed, which means that to increase time in contact, the flow rate must be reduced, i.e., the fluid pump must be slowed. Of course, slowing the pump reduces the energy consumption of the pump, so that less electrical energy is required to heat colder fluid to the same temperature.
The inventor believes that although recent advances have resulted in significant improvements in operational efficiency of known hydronic systems, further improvements can be achieved. For example, the inventor has recognized that an inherent problem in systems like the heating system 100 of
The inventor has also recognized that system efficiency and capacity could be increased for all operating conditions of an HVAC system if working fluids supplied to various load elements could be selectively supplied to the loads according to their relative temperature requirements, and if, in the case of multiple heating or cooling sources, fluid from sources with higher-temperature outputs could be selectively supplied to loads that require a higher temperature fluid, and sources with lower-temperature outputs could supply loads that require lower temperature fluid.
One distinction between the system of
The provision of the supply and return tees 148, 150 is another significant distinction between the system 140 of
It should be noted that in the embodiment shown in
Broadly speaking, the system 140 operates in a manner that is similar to the operation described above with reference to the system 100 of
These principles are illustrated in the examples shown in
However, because the total demand for conditioned fluid exceeds the output of the source 104, there is a flow from the second decoupling tee 125 toward the first decoupling tee 124, as a portion of the returning fluid of the upper secondary loop is diverted back to the upper supply conduit 108, substantially as described with reference to the prior art system 100 of
A more extreme example of this condition is illustrated in
It can be seen that when the source 104 cannot meet the requirements of the lower secondary loop 142, all of the fluid produced by the source 104 is supplied to the lower secondary loop, while none is supplied to the upper secondary loop 130. This operating condition also results in another aspect that distinguishes the system 140 from the prior art: in the example of
As illustrated in the examples of
A comparison of the flow patterns illustrated in
The arrangement described above with reference to the system 140 of
According to an embodiment, during the planning and construction of the hydronic system 155, the load elements 118 of the system are sorted according to criticality. The load elements associated with more critical or essential functions are incorporated into the lower secondary loop 142, and the remaining load elements, presumably those serving functions that are of lower importance or criticality, are incorporated into the upper secondary loop. Accordingly, under operational conditions in which the source is not able to meet the requirements of all of the load elements of the system, the more critical elements are prioritized over the other elements.
According to another embodiment, during the planning and construction of the hydronic system 155, the load elements 118 of the system are sorted according to the fluid temperature requirements of each of the elements. The load elements 118 that require relatively higher-grade working fluid—i.e., higher temperature fluid—as compared to the other load elements, are incorporated into respective sub-loops of the upper secondary fluid loop 130. Meanwhile, the load elements 118 that require relatively lower-grade working fluid are incorporated into respective sub-loops of the lower secondary fluid loop 142. The distribution can, according to an embodiment, be selected such that most of the load elements of the system are in the lower secondary loop 142. In this arrangement, if the set point of the source 104 is maintained, most of the load elements 118 will continue to be provided with their nominal fluid temperature requirements even, to an extent, after the output flow of the source drops below the total flow required by the load elements of the lower secondary loop 142. This is because, inasmuch as the set point temperature of the source 104 will have been set to meet the highest temperature requirements, which are from load elements of the upper secondary loop 130, the set point may be significantly higher than is required by any of the load elements of the lower secondary loop 142. As a result, even when the output flow from the source 104 drops to a point that the lower secondary loop 142 begins to receive a mixed flow that includes cooler fluid from the decoupler 126, as described above with reference to
This advantage can be improved even further. According to an embodiment, the set point of the source 104 is configured to be reduced under circumstances like those described, i.e., when the demands on the system exceed the capacity or current output of the source. For example, when the flow rate through the source 104 is reduced to a selected threshold, or the temperature of fluid at a selected point in the upper secondary loop drops to a selected temperature threshold, the set point of the source is reduced to a temperature that is about equal to the highest temperature required by any of the load elements of the lower secondary loop 142. With a reduced set point, the source 104 will not be able to fully meet the high-grade fluid requirements of the load elements of the upper secondary loop 130. However, with the lower set point, the source 104 will be able to maintain a higher fluid flow rate while still providing conditioned fluid that meets the requirements of all of the load elements of the lower secondary loop 142.
The operation described above, and the improvements in efficiency and performance provided, are automatic, and independent of any control or monitoring system. This is surprising, because it is achieved by a simple rearrangement of a few of the elements of the system, and is self-regulating, while some known hydronic systems employ extremely complex control systems without achieving comparable results.
It should be noted that the efficiency advantages described above with respect to the HVAC systems 140 and 155 of
In contrast, the operation described below with respect to the hydronic system 180 of
Furthermore, these advantages and benefits are inherent in the system, and are independent of any control system associated with the hydronic system, etc. Of course, when the system 180 of
According to an embodiment, during the planning and construction of the hydronic system 180, the load elements of the system are sorted according to the fluid temperature requirements of each of the elements. The load elements that require relatively higher-grade working fluid are incorporated into respective sub-loops of the upper secondary fluid loop 130, while the load elements that require relatively lower-grade working fluid are incorporated into respective sub-loops of the lower secondary fluid loop 142.
According to another embodiment, the load elements are divided into two groups according to their temperature requirements, with the division between the groups being selected to correspond to a large temperature gap between a first group of load elements and a second group of load elements, the group with the higher-grade fluid requirements being incorporated into the upper secondary loop 130, and the lower-grade load elements being incorporated into the lower secondary loop 142.
According to an embodiment, the source loops 182a-c of the system 180 are arranged and configured so that the source element 136a, which is closest to the decoupler 126, has the highest set point of the plurality of sources 136a-c. The set point of the uppermost source element 136a is selected to be sufficient to meet the highest-grade fluid requirement of the plurality of load elements of the upper secondary loop 130. The set points of the remaining source elements 136b, 136c are selected to be sufficient to meet the low-grade fluid requirements of the load elements of the lower secondary loop 142.
It will be recalled that in the system 140 of
The source loop (or loops) 182b that is positioned between the upper source loop 182a and the lower source loop 182c provides conditioned fluid to, and receives returning fluid from the sub-loops of the upper and lower secondary fluid loops 130, 142 according to the flow of fluid drawn by the respective loads 112a, 112b and the flow conditioned by the sources 136a, 136c of the other source loops 182a, 182c. For example, if the load 112b of the lower secondary loop 142 draws more fluid than can be provided by the source 136c of the lower source loop 182c alone, the balance will be drawn first from the second-lowest source loop 182b, which will also receive the same proportion of fluid in the lower return conduit 146 from the lower secondary loop. The balance, if any, of the working fluid conditioned by the middle source loop 182b will of course be carried upward in the supply conduit 108 to the upper secondary loop 130 and the decoupler 126.
According to an embodiment, the system 180 operates in a facility in which a majority of load elements require relatively low-grade fluid, with a minority of load elements having high-grade fluid requirements. Accordingly, the smaller number of high-grade load elements are configured as elements of the upper secondary loop 130 of the system 180 and the remaining load elements are configured as elements of the lower secondary loop 142. The lower fluid source element 136c, or the two lower fluid source elements 136c and 136b together, are configured to condition most of the working fluid of the system 180 as low-grade fluid, with a relatively small proportion of the fluid being conditioned by the upper source element 136a as high-grade fluid.
During operation, the load elements of the lower secondary loop 142 are automatically supplied with lower grade primarily fluid by the lower most source element 136c or elements 136c, 136b, while the elements requiring high-grade fluid are automatically supplied primarily by the upper source element 136a. Because the temperature difference between high- and low-grade fluids in a given system can be 50° or more, and because even a change of one or two degrees in the set point temperature of a source element can have a noticeable impact on operational efficiency of that element, by conditioning most of the fluid in a system as low-grade, a very significant improvement in total system efficiency can be achieved, particularly as compared to a system in which all of the source elements operate at a common set point that is at least equal to the highest-grade load requirement in the system in spite of the fact that most of the load elements of the system could operate with much lower grade fluid.
Depending upon the respective flows of the upper and lower secondary loops 130, 142 relative to the flow of the primary loop 128 and the flows of the individual source loops 182, the flows within the lower supply conduit 144 and the lower return conduit 146 can divide at any of the supply and return tees 148, 150 and flow in opposite directions within the respective conduits. For example, if the flow drawn by the lower load 112b is greater than the flow in the lower source loop 182c, but less than the flows in the lower and middle source loops 182c, 182b, then the flow in the middle source loop 182b will divide at the middle supply tee 148b, with a portion flowing downward toward the load 112b and the balance flowing upward toward the upper secondary loop 130. The downward portion will combine with the flow in the lowermost source loop in the lower supply tee 148c, which will also flow downward toward the load 112b, and the upper portion of the flow from the middle supply tee will combine, in the upper supply tee 142, with the flow from the upper source loop 182a. Thus, flow within the lower supply conduit 144 will flow in opposite directions, outward from the middle supply tee 148b. The lower return tee 146 will have a corresponding flow pattern, with fluid flowing in opposite directions toward the middle return tee 150b.
As operating conditions change, flow within the supply conduit 144 can reconfigure, and divide and flow in opposite directions from any of the supply tees, or can divide at the first decoupling tee 124 so that all of the flow in the lower supply conduit 144 is toward the lower load 112b, while any flow in the upper supply conduit 108 is upward, toward the upper load 112a. With any such changes of flow configuration in the lower supply conduit 144, a corresponding reconfiguration will occur in the lower return conduit 146.
This arrangement, in which multiple source elements are coupled in parallel between supply and return conduits via respective supply and return tees, provides the system 180 with significant flexibility to accommodate changes in operating conditions, while also providing the potential for significantly improved efficiency, compared to the prior art in equivalent conditions.
The source 104a of the first hydronic system 162 is a heat source, configured to impart thermal energy to the working fluid of the first system, while the source 104b of the second system 164 is a cooling source, configured to remove thermal energy from the working fluid of the second system. The loads 112a, 112b of the first system 162 are heat loads, configured to transfer thermal energy from the working fluid of the first system to respective thermal demand elements, while the loads 112c, 112d are configured as cooling loads, configured to transfer thermal energy from respective thermal demand elements to the working fluid of the second system.
According to an embodiment, the source 104a of the first hydronic system 162 and the source 104b of the second system 164 are, respectively, the condenser and the evaporator of a heat pump 166 that is configured to transfer thermal energy H from the working fluid of the second hydronic system 164 to the working fluid of the first hydronic system 162.
It is common, even in systems that employ heat pump technology, for heating and cooling systems to be completely separate and independent. However, this means that all of the heat collected in a cooling system must be disposed of as waste heat, while, in a heating system operating in the same environment, heat must be separately generated or drawn in from the exterior of the facility, to dispose of what might be thought of as “waste cold.” However, during operation of the integrated system 160 of
During periods in which the relative demands on the first and second hydronic systems 162, 164 are approximately equal, there is no requirement for supplemental heat production or cooling. However, when one of the systems has a relatively higher demand, the other system can be configured to make up the difference.
In operation, when the available thermal energy in the first hydronic system 162 exceeds the system requirements—as in the illustrated hypothetical case—the flow rate in the primary loop 128a is increased by increasing pump speed. This passes the working fluid through the source 104a more quickly and thereby reduces the amount of thermal energy transferred to the fluid, so as not to heat the fluid above the set point. When the flow in the primary loop 128a exceeds the total demand for conditioned fluid, the excess flow passes through the decoupler 126 and returns to the source 104a, as previously described, for example, with reference to
As the flow rate in the second heat load element 118e increases, this increases the flow from the supply tee 148 downward toward the lower load 112b and thereby also decreases the flow from the supply tee upward toward the first decoupling tee, causing the flow in the decoupler 126a to drop. Cooled fluid from the output 116 of the second heat load element 118e returns to the input 122 of the source 104a where it combines with fluid from the lower return conduit 146 in the return tee 150, reducing the temperature of the fluid entering the source 104a. In response to the reduced input temperature, the source 104a reduces pump speed to permit the cooler fluid to reach the set point temperature, which further reduces the flow toward the decoupler.
It should be noted that because the second heat load element 118e is in the lower secondary fluid loop 142, fluid flow from its output 116 is carried directly to the return tee 150 and the input 122 of the source 104a, without the possibility of any portion being diverted through the decoupler 126—under these operating conditions there is a downward flow in the lower return conduit 146 toward the return tee 150, so the upward flow from the second heat load element 118e can only pass into the source input 122 from the return tee. Thus, the source 104a receives a greater proportion of the cooled fluid from the second heat load element 118e than it would if the same element were part of a single secondary loop, as in prior art systems.
According to an embodiment, the flow rate in the second sub-loop 110e is controlled to increase until the combined flows in the upper and lower secondary loops 142, 130 of the first system 162 is about equal to the flow rate in the primary loop 128 of that system, at which point the first system is disposing of all the waste heat from the second system, and the first and second hydronic systems 162, 164 are balanced. In this way, while operating as a heat load element of the first hydronic system 162, the load element 118e acts, effectively, as part of the cooling source 104b of the second hydronic system 164. The effectiveness of this configuration is enhanced by the position of the second heat load element 118e in the lower secondary loop 142 of the first hydronic system 162.
By selectively bypassing fluid from the output 116 of the load 112b to the input 114, the temperature of the fluid that is supplied to the load 112b can be controlled, which also modifies the temperature of the fluid returning to the source 104c. For example, in the case of a heating system, fluid at the output 116 of the load 112b is cooler than at the input 114. By returning a portion of the cooled fluid in the lower secondary loop 142 directly to the input of the load 112b, the fluid temperature at the input is reduced, and thus the output temperature is also reduced, which in turn reduces the fluid temperature at the input 122 of the lower source element 136c. By selectively controlling the flow in the bypass loop 192, the temperature of the fluid that is returned to the source 104c can be selected, at least within a range.
Similarly, by selectively bypassing fluid from the output 122 of the upper source element 104a, via the source bypass loop 198 the temperature at the output of that element can be regulated independently of the rate of flow through the source.
In describing various embodiments of the invention, a number of different schemes for distributing the load elements of a given system between the various secondary loops and sub-loops, in order to obtain particular results and advantages. However, these schemes are provided as examples, only. The actual selection of which load elements are to be incorporate into each of the secondary loops is a matter of design choice, and can be made according to schemes like those described above, or by any other criteria chosen by a system's designers. The claims are not limited to any particular scheme except where such limitations are explicitly recited therein.
Ordinal numbers, e.g., first, second , third , etc., are used in the claims according to conventional claim practice, i.e., for the purpose of clearly distinguishing between claimed elements or features thereof, etc., without imposing further limitations on those elements. Ordinal numbers may be assigned arbitrarily, or assigned simply in the order in which elements are introduced. The use of such numbers does not suggest any other relationship, such as order of operation, relative position of such elements, etc.
Furthermore, an ordinal number used to refer to an element in a claim should not be assumed to correlate to a number used in the specification to refer to an element of a disclosed embodiment on which that claim reads, nor to numbers used in unrelated claims to designate similar elements or features.
Unless the context dictates otherwise, directional language used in the claims is to be construed schematically. For example, in a hypothetical claim that recites terminals of first, second, and third elements coupled to a conduit, with the first element coupled to the conduit on a side of the second element opposite the third element, this does not require that the second element be physically positioned between the first element and the third element. Instead, this means that fluid passing through the conduit from the first element would pass a coupling to the second element before reaching a coupling to the third element.
The abstract of the present disclosure is provided as a brief outline of some of the principles of the invention according to one embodiment, and is not intended as a complete or definitive description of any embodiment thereof, nor should it be relied upon to define terms used in the specification or claims. The abstract does not limit the scope of the claims.
Elements of the various embodiments described above can be omitted or combined to provide further embodiments. Any and all U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety.
Aspects of the embodiments can be modified to employ concepts of the various patents, applications and publications to provide yet further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
This application is a continuation of U.S. patent application Ser. No. 17/309,944, filed Jul. 1, 2021, which application is a 371 national phase of PCT/IB2020/000298, filed Apr. 6, 2020, published as WO 2020/183244 on Sep. 17, 2020, which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/801,792, filed Feb. 6, 2019, the disclosures of which are incorporated, in their entirety, by this reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17309944 | Jul 2021 | US |
| Child | 17938280 | US |
