Patent Application
20240200791
The present invention relates to an electric tankless heating system. More specifically, the present invention is directed to an electric tankless heating system utilizing an improved heat pump.
In water heating systems, the potential for Legionella is more pronounced in a tank system or a large fluid conductor, e.g., in a tank water heater, etc., due to the low velocity of the contents of the tank water heater and the contents that are disposed in a suitable temperature range for Legionella proliferation. Although one or more temperature sensors may be used for providing feedback to the heating of the contents of the tank water heater to achieve a setpoint temperature, the effect of stratification can cause layers of fluid having different temperatures. Therefore, although portions of the contents of a water heater may be disposed at a setpoint temperature that is unfavorable for Legionella proliferation, there potentially exists other portions that may be disposed at temperatures suitable for Legionella proliferation. Further, in a tank heating system, potable water is drawn from a large reservoir of heated water to meet a hot water demand, increasing the risk of Legionella proliferation as the opportunity for a tank heating system to harbor Legionella is significantly higher than a tankless heating system where hot potable water is prepared just-in-time.
Scaling and corrosion are longstanding problems encountered in the water heating industry which limit the life span of equipment. Although many corrosion and scale inhibitors are known and used in high temperature application, many of these systems have limitations and do not provide the type of protection to allow significant extension of equipment life span. Conventional water heaters cannot store potable water at a very high temp due to the potential for scaling and hence corrosion.
Solar heating systems or heaters have become increasingly popular solutions either as a supplemental heating system or as a sole heating system whether or not municipal electricity is available. Where thermal batteries and swing tanks are involved and are made to function in conjunction with solar heaters, the overall heating solutions are often complicated to set up, involving set up procedures which are not only challenging for trained professionals to set up but also difficult for a user to detect a problem or the root cause of a problem if they malfunction during use. Further, these systems are often not easily scalable as there is very little reuse in the way of common subsystems being sourced as modules that can be added or removed.
Thus, there is a need in the heating art for a system which operates with operating conditions that do not promote scaling and corrosion and therefore do not require the application of conventional scale and corrosion inhibitors. There is also a need in the heating art for a system in which a working fluid can be stored at higher temperatures and hence increased heat transfer efficiency.
In accordance with the present invention, there is provided a heating system including:
In one embodiment, the storage container is a non-pressurized container. In one embodiment, the heating system further includes a heat source configured to supply the first fluid with thermal energy. In one embodiment, the opening includes a trap. In one embodiment, the trap includes a bent portion configured to hold a fluid to prevent intrusion of foreign objects through the opening into the storage container and to at least reduce the escape of the first fluid through the opening. In one embodiment, the storage container further includes an outlet fluid conductor and an inlet fluid conductor, the storage container is configured to hold the first fluid in at least two distinct temperatures, the outlet fluid conductor is disposed at a portion of the storage container exposed to the first fluid disposed at a first temperature of the at least two distinct temperatures and the inlet fluid conductor is disposed at a portion of the storage container exposed to the first fluid disposed at a second temperature of the at least two distinct temperatures, wherein the second temperature of the at least two distinct temperatures is higher than the first temperature of the at least two distinct temperatures. In one embodiment, the storage container is configured to hold the first fluid in at least two distinct temperatures and the inlet point is disposed in the first fluid at a first temperature of the at least two distinct temperatures and the outlet point is disposed in the first fluid at a second temperature of the at least two distinct temperatures and the second temperature of the at least two distinct temperatures is higher than the first temperature of the at least two distinct temperatures. In one embodiment, the first fluid is glycol. In one embodiment, the heating system further comprises a glycol concentration sensor configured for detecting the concentration of the first fluid to determine a suitability of the first fluid to resist freezing. In one embodiment, the heating system further comprises a controller and a glycol concentration sensor functionally connected to the controller, the controller configured for receiving data from the glycol concentration sensor and determining a suitability of the first fluid to resist freezing based on a location data. In one embodiment, the heating system further includes a fill valve configured to fill the storage container. In one embodiment, the heating system further includes an isolation valve connected to the inlet point, wherein the isolation valve is configured for selectively allowing a flow of the second fluid. In one embodiment, the heating system further includes a solar heater and the storage container further includes an outlet fluid conductor and an inlet fluid conductor, wherein the solar heater is connected to the storage container via the outlet fluid conductor and the inlet fluid conductor.
In one embodiment, the present heating system further includes:
In one embodiment, the heating system further includes a heat exchanger including an upstream fluid conductor and a downstream fluid conductor thermally coupled to the upstream fluid conductor, wherein the upstream fluid conductor is configured to be connected to an inlet port of the first fluid conductor and the downstream fluid conductor is configured to be connected to an outlet port of the evaporator and heat transfer is configured to occur from the working fluid in the upstream fluid conductor to the working fluid in the downstream fluid conductor. In one embodiment, the first fluid conductor includes a featureless outer surface. In one embodiment, the working fluid is a refrigerant. In one embodiment, the mode of convection is configured to be aided by a blower.
An object of the present invention is to provide a fluid heating system that is tankless to reduce the potential for the heated output from contamination of pathogens, e.g., Legionella.
Another object of the present invention is to provide a non-pressurized storage container, thereby avoiding the additional procurement and maintenance costs associated with a pressurized storage container.
Another object of the present invention is to provide a heating subsystem having improved thermal energy capture rate.
Whereas there may be many embodiments of the present invention, each embodiment may meet one or more of the foregoing recited objects in any combination. It is not intended that each embodiment will necessarily meet each objective. Thus, having broadly outlined the more important features of the present invention in order that the detailed description thereof may be better understood, and that the present contribution to the art may be better appreciated, there are, of course, additional features of the present invention that will be described herein and will form a part of the subject matter of this specification.
In order that the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
As the present heating system is an on demand or tankless heating system, only a small amount of fluid is held in the system when no demands exist, significantly reducing the amount of trapped water in the present heating system to harbor Legionella as the thermal charging of the contents of the storage container is fluidly decoupled from thermal discharging of the contents of the storage container by a fluid flow through a fluid conductor disposed through the storage container. Even if this small amount of fluid can potentially be grounds for Legionella proliferation, it is generally not consumed but rather drained as the user awaits heated water to arrive at the point of use. Further, during use, the potable water traversing the heat exchanger is heated to a range of temperature unsuitable for Legionella proliferation, unlike the case of a tank heating system where a suitable temperature range always exists in the tank due to the ever-present stratification of the contents of the tank.
As there is only a small amount of water is kept in the coil disposed through the storage container and the contents of the storage container are not replenished during normal operation of the storage container, the opportunity for the storage container and the heating system to scale is minimal. As there is a limited amount of minerals in the contents of the storage container and the contents of the storage container are reused indefinitely or until the storage container is refilled, no new supply of minerals is available to add to scaling. Further the velocity of the fluid flow through the coil disposed through the storage container is relatively high, minimizing the opportunity for minerals to deposit on the internal surfaces of the coil.
The term “about” is used herein to mean approximately, roughly, around, or in the region of. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 20 percent up or down (higher or lower).
In the embodiment shown, subsystem 42 further includes a heat source configured to supply the first fluid 52 with thermal energy via the working fluid exiting the storage container 17 through the outlet fluid conductor 84 and returning to the storage container through the inlet fluid conductor 86. Here, thermal energy is received via a flow motivated by pump 18 through heat exchanger 22. Due to the location of the pump 18 relative to the first fluid 52 in the storage container, it is self-priming. No manual priming is required prior to its use as long as the thermal battery 16 has been properly set up. In one embodiment, the pump 18 is a variable speed pump to allow the system to modulate the flowrate through the heat supply loop 56, thereby affecting the thermal charging rate of the thermal battery 16. For instance, the thermal charging rate of the thermal battery 16 may be correlated to the rate at which thermal energy may be transferred from subsystem 44 to avoid unnecessary circulation of the first fluid 52. The first fluid 52 held in the storage container is stratified, i.e., the temperature of the first fluid near the top of the storage container is disposed at a temperature higher than the first fluid near the bottom of the storage container. Therefore, the inlet point 48 is disposed in the first fluid 52 at a first temperature and the outlet point is disposed in the first fluid 52 at a second temperature where the second temperature is higher than the first temperature. As the first temperature is lower and the thermal energy of the contents in the lower region of the storage container has been largely depleted, this ensures that the first fluid drawn by the pump 18 is devoid of thermal energy and ready to draw thermal energy from heating system 44. In one embodiment, the first fluid is glycol.
Subsystem 42 further includes a fill valve 20 configured to control the filling of the storage container 17. A glycol solution can be formed by adding water via fill valve 20 to glycol already disposed in the storage container 17. A glycol concentration sensor is further provided to determine whether the concentration of glycol is suitable for the locale the heating system is used in. In the embodiment shown, a fluid level sensor 78 is provided to allow the level of the storage container contents to be determined. This allows the exact level of the contents to be determined and the amount of glycol to be replenished. The present heating system is shipped to site with the storage container 17 void of fluid to avoid unnecessary shipment of weighted storage container and the storage container 17 is filled on site to make transportation of the heating system more cost effective and the heating system easier to set up. Subsystem 42 further includes a bypass conductor 54 connecting an inlet and an outlet of the fluid conductor 14. A valve 12 is interposed in the bypass conductor 54 to control the magnitude of a bypass flow that is allowed to occur through the bypass conductor 54. An inlet valve 8 is disposed at the inlet of the fluid conductor 14 to control the magnitude of a flow through the fluid conductor 14. A coil isolation valve 10 is connected to the inlet point 48, wherein the coil isolation valve is configured for selectively allowing a flow of the second fluid. The coil isolation valve 10 serves as a fail-safe mechanism for an inlet valve 8 which fails as the coil isolation valve 10 is a spring-returned valve configured to close automatically should the inlet valve 8, e.g., a proportional valve fails. This way, a failed inlet valve 8 would not inadvertently cause a flow to be heated indefinitely in the thermal battery 16 to cause a scalding hot output at the outlet 6. Once the coil isolation valve 10 is closed, an incoming flow through the cold water inlet 4 will be diverted to the bypass conductor 54. A user of the demand will experience unheated water but will avoid potentially scalding hot water due to the failed inlet valve 8. A pump 18 interposed in a heat supply loop 56 connected to the storage container 17 at an outlet 66 and at an inlet 68, controls the magnitude of circulation of the contents of the storage container 17 and hence controls the rate at which heat energy is supplied to the contents of the storage container 17.
Regarding subsystem 44, the heating system includes a first fluid conductor 28, an evaporator 32, a second fluid conductor 62 and an expansion valve 30. The evaporator 32 is thermally connected to the first fluid conductor 28 by a mode of convection. The second fluid conductor 62 connects the first fluid conductor 28 to the evaporator 32. The expansion valve 30 is interposed in the second fluid conductor 62. A working fluid received at the first fluid conductor 28 is configured to be supplied to the evaporator 32 through the second fluid conductor 62 and the expansion valve 30. Heat loss from the working fluid in the first fluid conductor 28 is at least compensated by a heat gain by the evaporator 32 due to the working fluid in the first fluid conductor 28 disposed at a lower temperature caused by the heat loss. Subsystem 44 further includes a heat exchanger 26 including an upstream fluid conductor 58 and a downstream fluid conductor 60 thermally coupled to the upstream fluid conductor 58. The upstream fluid conductor 58 is configured to be connected to an inlet port of the first fluid conductor 28 and the downstream fluid conductor 60 is configured to be connected to an outlet port of the evaporator 32 and heat transfer is configured to occur from the working fluid in the upstream fluid conductor 58 to the working fluid in the downstream fluid conductor 60. The first fluid conductor 28 includes a featureless outer surface. Applicant discovered that by lowering the temperature of the working fluid going into the expansion valve 30 due to heat loss from the working fluid via the first fluid conductor 28, the heat gained by the working fluid in the evaporator 32 by convection between the first fluid conductor 28 and the evaporator 32 and the evaporator 32 and its surroundings, exceeds the alternative, thereby improving Coefficient of Performance (COP) of the heat pump 44. COP is defined as the relationship between the power that is drawn out of a heat pump as cooling or heat, and the power that is supplied to the compressor, e.g., compressor 38 of the heat pump. However, Applicant also discovered that if the outer surface of the first fluid conductor 28 had been equipped with heat transfer fins, rather than being featureless, heat loss from the working fluid through the first fluid conductor 28 or the temperature drop in the working fluid via convection would have been too severe for the evaporator 32 to regain heat, resulting in a net thermal energy loss instead of a net thermal energy gain as in the case of the featureless first fluid conductor 28. In one embodiment, the working fluid is a refrigerant. The mode of convection is configured to be aided by a blower 34. The upstream fluid conductor 58 and the downstream fluid conductor 60 are fluidly connected via fluid conductor 40. Upon leaving downstream fluid conductor 60, the working fluid flows through a separator 36, where the separator is disposed downstream from the downstream fluid conductor 60. Upon leaving the separator 36, the working fluid flows through a compressor 38 disposed downstream from the separator 36. Upon leaving compressor 38, the working fluid flows through a heat exchanger 22, e.g., a gas cooler, disposed downstream from the compressor 38. The heat exchanger 22 thermally connects fluid conductor 40 of subsystem 44 with heat supply loop 42 of subsystem 42. Upon leaving heat exchanger 22, the working fluid flows through a filter 24. In heat exchanger 22, a gas cooler, thermal energy is transferred from the working fluid in fluid conductor 40 to the working fluid of the heat supply loop 56. It shall be noted that the heat energy supplied to the first fluid 52 originates from subsystem 44. Although subsystem 44 is shown as a heat pump, the first fluid 52 may instead receive its heat energy from another source, e.g., a solar heater and a resistive heater 88, etc., provided that the heat supply loop 56 remains fluidly isolated from the fluid flow of fluid conductor 14. In one embodiment, the heating system 2 further includes a solar heater 90 connected to the storage container 17 via the outlet fluid conductor and the inlet fluid conductor of the storage container 17. Therefore, in addition to subsystem 44, the thermal battery 16 may additionally or alternatively receive thermal energy from the solar heater 90. A pump 92 is provided to allow circulation of the working fluid through the solar heater 90 to add thermal energy to the contents of the storage container 17. Again, the flow exiting the storage container 17 at the outlet fluid conductor is preferably disposed at the lowest temperature possible due to stratification of the contents of the storage container 17 to maximize heat transfer to the working fluid at the solar heater 90.
In one embodiment, the opening 46 includes a trap.
The detailed description refers to the accompanying drawings that show, by way of illustration, specific aspects and embodiments in which the present disclosed embodiments may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice aspects of the present invention. Other embodiments may be utilized, and changes may be made without departing from the scope of the disclosed embodiments. The various embodiments can be combined with one or more other embodiments to form new embodiments. The detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, with the full scope of equivalents to which they may be entitled. It will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations of embodiments of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive, and that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Combinations of the above embodiments and other embodiments will be apparent to those of skill in the art upon studying the above description. The scope of the present disclosed embodiments includes any other applications in which embodiments of the above structures and fabrication methods are used. The scope of the embodiments should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
