Dual Evaporator Heat Pump Systems with Heat Recovery Source

This application claims priority to and benefit of U.S. provisional patent application No. 63/659,433 filed Jun. 13, 2024, which is herein incorporated by reference.

This disclosure relates generally to vapor compression cycle systems. In particular, embodiments of the disclosure are related to vapor compression cycle systems, such as heat pump systems, that use a hot fluid for enhancing heating capability in cold environments.

Conventional vapor compression cycle systems that include an air-to-water heating system have difficulty in maintaining heat within a facility when the ambient air temperature is low. The low ambient air temperature reduces the heat transfer capability in an evaporator and the refrigerant in the evaporator cannot be heated to the requisite temperature. This causes the temperature, pressure, or both of the refrigerant to be below the desired respective thresholds as it leaves the evaporator. If such refrigerant enters the compressor, the compressor has to work harder to compress and heat this refrigerant. This may affect the vapor compression cycle system's ability to maintain temperature within a facility and shorten the usable life of the vapor compression cycle system, as the vapor compression cycle system may run for longer periods of time to maintain the desired temperature within a facility. This also results in a lower coefficient of performance (COP) for the vapor compression cycle system.

This disclosure relates generally to vapor compression cycle systems that may be used in commercial or residential facilities. More specifically, embodiments of the present disclosure relate to vapor compression cycle systems having two or more evaporators that provide extra heating capacity. In environments where the temperature of the ambient air within a facility is low, such as less than 50° F., the evaporator may not be able to extract enough thermal energy out of the ambient air to heat the refrigerant to its requisite temperature. If the refrigerant is not heated to its requisite temperature, the compressor has to work harder to compress and heat this refrigerant before the refrigerant can be circulated in the heat pump system. This reduces the efficiency and effectiveness of the vapor compression cycle system. This disclosure provides systems and methods that can augment the heating capacity of the evaporator by using an additional evaporator along with a supply of a hot fluid, such as water, that helps in heating the refrigerant to its requisite temperature. This extra or added heating capacity improves the efficiency of the vapor compression cycle system and enables operation of the vapor compression cycle system in environments that have low or extremely low ambient air temperature as explained below.

A “vapor compression cycle system” may broadly encompass any system that is configured to heat and/or cool a conditioned space, heat and/or cool a fluid that is provided to a load, and/or perform any other actions associated with a vapor compression cycle. Non-limiting examples of types of a vapor compression cycle systems can include air conditioners (e.g., no reversing valve, only provides cooling mode), heat pumps (e.g., air source or geothermal; has a reversing valve and operates in both heating and cooling modes), heat pump water heaters, integrated heat pump water heaters, split system heat pump water heaters, heat pump water heaters with a circulation pump and a brazed plate heat exchanger, split systems, packaged systems, mini-splits, PTACs, window units, vertical packaged systems, VRF systems, etc. Reference is made herein to a specific use case in which the vapor compression cycle system is a heat pump system, however, this is not intended to limit the type of vapor compression cycle system to which the configuration described herein may be applicable.

In a standard cooling mode, a compressor compresses (and thus warms) refrigerant that is provided to an outdoor heat exchanger coil, thus heating the outdoor heat exchanger coil as the warm refrigerant flows through the outdoor heat exchanger coil. One or more fans are provided in the outdoor coil portion of a single-package system that push or pull air across the outdoor heat exchanger coil. As the air flows across the outdoor heat exchanger coil, heat is transferred from the warm outdoor heat exchanger coil to the air that flows across the outdoor heat exchanger coil. Condensed refrigerant from the outdoor heat exchanger coil then passes through an expansion valve, lowering the refrigerant's pressure and cooling the refrigerant. The refrigerant from the expansion valve then passes through an indoor heat exchanger coil and returns to the compressor to complete the refrigerant cycle. One or more fans push or pull air over the indoor heat exchanger coil, thereby transferring heat from the air to the refrigerant (and thus cooling and/or humidifying the air). Ductwork then directs the conditioned air throughout the building to cool the building using the conditioned air.

Likewise, in a standard heating mode, a reversing valve may be transitioned to direct refrigerant from the compressor to the indoor heat exchanger coil as opposed to directing it to the outdoor heat exchanger coil as is done in the cooling mode. In a heating mode, the refrigerant absorbs heat from the outdoor air through the outdoor heat exchanger coil. The refrigerant then passes through the compressor, which compresses (and thus warms) the refrigerant. The heated refrigerant is transferred to the indoor heat exchanger coil. One or more fans push or pull air over the indoor heat exchanger coil, thereby transferring heat from the indoor heat exchanger coil to the indoor air. Ductwork then directs the conditioned air throughout the building to heat the building using the conditioned air. One or more supplemental heating sources, such as an electric heating kit, and/or a gas furnace with a heat exchanger in the indoor coil portion, may additionally be used.

In a typical air-to-water heat pump system used in a facility, indoor ambient air from the facility is used to heat up the refrigerant flowing in the evaporator. However, in some instances, the indoor air temperature may be below a threshold, such as below 50° F., which limits the amount of heat transfer that can occur in the evaporator. This may result in limiting the extent to which a refrigerant flowing within the evaporator is heated and converted to vapor form. This in turn affects the functioning of the associated compressor since the refrigerant may not be heated to the appropriate temperature or may not have the right pressure before reaching the compressor due to the low ambient air temperature in the facility.

In order to ensure that the evaporator is functioning efficiently, there may be a need to boost the capacity of the evaporator so that the refrigerant is heated up to the right temperature in order for the compressor and the heat pump system to work efficiently. The present disclosure provides details about various systems and methods that can be used to provide extra heating capability to the evaporator in a heat pump system.

illustrates a block diagram of an overall environmentin which the various systems and methods disclosed below can be implemented according to an embodiment of the present disclosure. The environmentmay include a facility. The facilitymay be a residential or a commercial facility. Residential facilities may include a single family home, a multi-unit dwelling, or the like. A commercial facility may include a single or multi-story building, warehouses, retail establishments or the like. Facilitymay be served by one or more vapor compression cycle systems. The vapor compression cycle systemmay include any commonly known vapor compression cycle system in the art (examples are provided above). In one or more embodiments, the vapor compression cycle systemmay be a heat pump, such as an air-to-air heat pump system, air-to-water heat pump system, or the like. Vapor compression cycle systemoperates to control the temperature and other environmental parameters within the facility.

The environmentmay also include a storage tank. In one embodiment, storage tankmay store hot water that may be circulated throughout the facility. Storage tankmay receive hot water from the vapor compression cycle systemand then circulate that hot water through the facility. The hot water may be used for controlling the climate within the facility. In other embodiments, the hot water from the storage tankmay be provided to sinks, showers, etc. and to fulfill other hot water needs of the facility. Used water from the facility, such as, drain water from the sinks, showers, etc. may be returned to the vapor compression cycle systemfor reheating via one or more drain pipes associated with the facility.

The environmentmay also include a heat source. Heat sourcemay be any heat source such as a gas hydronic boiler, an electric heater, a solar heater, or the like. Heat sourceis coupled to the vapor compression cycle systemto provide additional heating capacity for an evaporator of the vapor compression cycle system, as will be explained below. In some embodiments, the heat sourcemay receive the used water from the facilityand reheat that used water and provide that reheated used water to the evaporator of the vapor compression cycle system. In other embodiments, the heat sourcemay receive the water circulated through the evaporator and reheat that water and provide it back to the evaporator of the vapor compression cycle system.

In some embodiments, the storage tankmay be part of the vapor compression cycle system. In other embodiments, the storage tankmay be separate from the vapor compression cycle systembut in fluid communication with the vapor compression cycle system. As will be explained below, the heat sourceprovides extra heating capacity via a dedicated evaporator within the vapor compression cycle system. This extra or added heating capacity is used to ensure that the refrigerant in the evaporator reaches the desired temperature before being directed to the compressor. The vapor compression cycle systemalso provides hot water to storage tankfor use in the facility. In some embodiments, vapor compression cycle system, storage tank, and heat sourcemay all be physically located within the facility.

is a block diagram illustrating the details of the structure and operation of the vapor compression cycle system, the storage tank, and the heat sourceaccording to an embodiment of the present disclosure.

illustrates a systemthat includes the vapor compression cycle system, the water storage tank, and the heat source. Systemincludes a compressor. Compressorhas an input portand an output port. Compressorcan be any known compressor in the art. In some embodiments, more than one compressor can be used based on the capacity needs of the facility. In one embodiment, a tandem scroll compressor or the like may be used. Compressoris configured to compress and heat a fluid that is circulated in the vapor compression cycle system. This fluid may include, but is not limited to, refrigerants like water, R134A, R454B, R32, Hydrocarbons, Hydrocarbon blends, R717, CO2 R744, R-22, R411, R600 series, hydrofluoroolefins (HFOs) and HFO blends, and the like. In general, “fluid” as used throughout the specification includes materials in liquid, liquid-vapor mix, and vapor form. For example, fluid may include a refrigerant in its liquid, vapor, or liquid-vapor mix form. “Fluid” can also include air, water, gases, etc.

The output portof compressoris in fluid communication with a first portof a first heat exchanger. It is to be noted that throughout the disclosure, ports described as being in “fluid communication” with each other may have one or more refrigerant lines or other appropriate means of fluid communication that facilitate flow of a fluid between these ports. The first heat exchangercan be any suitable type of heat exchanger such as a plate heat exchanger or the like. For ease of explanation,depicts a plate heat exchanger, but one skilled in the art will realize that any other heat exchanger that can perform a similar function can be used. The specific type of heat exchanger is not germane to the systems and methods disclosed herein.

The first heat exchangerhas a second port, a third port, and a fourth port. The second portof the first heat exchangeris in fluid communication with an expansion valve. The third portof the first heat exchangeris in fluid communication with an input portof the water storage tank. An output portof the storage tankis in fluid communication with the facility. The fourth portof the first heat exchangeris in fluid communication with a used water line of the facility. One skilled in the art will realize that there may be one or more components, such as filters, purifiers, etc., disposed along the used water line between the facilityand the fourth port. In some embodiments, the first heat exchangermay be located inside the facility. In other embodiments, the entire vapor compression cycle systemmay be located inside the facility.

Expansion valvemay be realized using any known device in the art. The function of the expansion valveis to expand a first fluid, such as a refrigerant, as it passes through it, converting the first fluid to a liquid-vapor mix, and lowering the pressure of the first fluid. The expansion valveis also in fluid communication with a first portof a first flow control valve. A second portof the first flow control valveis in fluid communication with a third portof a third heat exchanger. A third portof the first flow control valveis in fluid communication with a first portof a second heat exchanger. The first flow control valvemay be realized using any known device in the art. In one embodiment, the first flow control valvemay be a 3-way flow control valve known in the art.

The second heat exchangeris disposed between the first flow control valveand compressor. In particular, a second portof the second heat exchangeris in fluid communication with the input portof the compressor. In some embodiments, the second heat exchangermay be a coil-type heat exchanger that is coupled to a fanthat may blow the ambient air from within the facilityover the second heat exchanger. In some embodiments, the second heat exchangeris located within the facilityor otherwise is in thermal communication (e.g., via one or more air ducts) with an ambient environment within the facility.

The second portof the first flow control valveis in fluid communication with the third portof the third heat exchanger. The third heat exchangermay include a first portthat is in fluid communication with an input of a heat source. A second portof the third heat exchangeris in fluid communication with a variable speed pump. A fourth portof the third heat exchangeris in fluid communication with the input portof the compressor. In an embodiment, a first portion of the first fluid that is output from the second portof the second heat exchangerand a second portion of the first fluid that is output from the fourth portof the third heat exchangermay be combined at pointbefore being directed to the compressor. Similarly, the first flow control valvemay be used to split the first fluid into two portions after the first fluid exits the first expansion valve, with the first portion of the first fluid being directed to the second heat exchangerand the second portion of the first fluid being directed to the third heat exchanger. It is to be noted that the third heat exchangercan use various types of hot fluids in order to heat the refrigerant, such as, gas, liquid, geothermal energy, air, and the like.

The first portof the third heat exchangeris in fluid communication with an input of the heat source. The heat sourcemay be any appropriate heat source that is able to heat a second fluid, such as water, and output the heated second fluid. In some embodiments, the heat sourcemay be a gas hydronic boiler, an electric heater, a solar heater, or the like. The exact type of heat sourceis not germane to the disclosure. In some embodiments, heat sourcemay not be needed to accomplish the systems and methods discussed in this disclosure. The heat sourceis also in fluid communication with the input portof the storage tank. In some embodiments, a first portion of the second fluid output by the heat sourcemay be combined with a second portion of the second fluid output from the third portof the first heat exchangerat pointand the combined second fluid is then directed to the storage tank.

In some embodiments, used second fluid from the facilitymay be routed to the fourth portof the first heat exchangeror to the heat source. For instance, the used second fluid coming out of the facilitymay be split at pointwhere a first portion of the used second fluid is directed to the first heat exchangerand a second portion of the used second fluid is directed to the heat source. In some embodiments, the used second fluid from the facilityis combined with the second fluid output from the first portof the third heat exchanger, using a second flow control valve, before it is provided to the heat source. Second flow control valvehas a first portthat is in fluid communication with the used second fluid line of the facility. A second portof the second flow control valveis in fluid communication with the first portof the third heat exchanger. A third portof the second flow control valveis in fluid communication with the input of the heat source. The second flow control valveis operated to control the amount of the second fluid going into the heat source. Depending on the operation of the system, the appropriate amount of used second fluid from the facilitycan be mixed with the second fluid coming out of the third heat exchangerand sent to the heat source.

Similarly, hot second fluid that is output from the heat sourcemay be split into two portions by a third flow control valve. The third flow control valvehas a first portthat is in fluid communication with the output port of the heat source. A second portof the third flow control valveis in fluid communication with the input of the variable speed pump. A third portof the third flow control valveis in fluid communication with the input portof the storage tank. In one embodiment, the third flow control valvemay direct a first portion of the hot second fluid that is output by the heat sourceto the variable speed pump, via the third port, and direct a second portion of the hot second fluid to the input portof the storage tank, via the second port.

In order to explain the operation of the systemofand the rest of the figures, the following will be used to help simplify the explanation. However, it is to be noted that the systems and methods disclosed inor any of the following figures are not limited to these assumptions. For example, other types of fluids than the ones mentioned below may be used, any or all the heat exchangers may be of the same type or different, etc. The solid lines between the various components represent flow of the first fluid (e.g., a refrigerant), the dashed lines between the various components represent flow of the second fluid (e.g., water). A third fluid (e.g., air) can be used in conjunction with the second heat exchangerto effect heat transfer between the first fluid and the third fluid.

In an embodiment, the systemmay be operational to provide hot water to the facilityand control the climate within the facility. The hot water may be used for various purposes within the facility. For example, the hot water may be used for climate control within the facility, such as to heat the inside of the facility, or used in sinks, showers, etc. for consumption by the occupants of the facility. The hot water may be provided to the facilityvia the storage tank. Storage tankmay be the primary or sole means for storing hot water before being provided to the facility.

In an embodiment, the systemmay have two modes of operation. A first mode of operation may be triggered if the ambient air temperature within the facilityis at or above a certain threshold, such as 50° F. The second mode of operation may be triggered when the ambient air temperature within the facilitydrops below the threshold. In the second mode of operation, the systemis provided with a boost in its heating capacity by activating the third heat exchangerand the heat source, as will be explained below.

In the first mode of operation, heated and pressurized refrigerant is output by the compressor. This hot and pressurized refrigerant is directed to the first portof the first heat exchanger. The refrigerant flows within the first heat exchangerand is output via portof the first heat exchanger. Within the first heat exchanger, the refrigerant transfers some of its heat to the water that is flowing between the fourth portand the third portof the first heat exchanger. The water absorbs the heat from the refrigerant and gets heated. The hot water that is output from the third portof the first heat exchangeris directed to the storage tankfor use in the facility.

After the refrigerant leaves the first heat exchanger, it is at a lower temperature than when it entered the first heat exchanger. This refrigerant is directed to the expansion valve. As the refrigerant passes through the expansion valve, it expands into a liquid-vapor mix and the pressure of the refrigerant is also lowered. This liquid-vapor mix refrigerant is then directed to the first flow control valve. The first flow control valvemay be operated such that all or substantially all of the incoming refrigerant via the first portis directed out of the third porttowards the first portof the second heat exchanger.

The fanthat is coupled to the second heat exchangerblows inside ambient air from within the facilityover the second heat exchanger. As the temperature of this ambient air is at or greater than the threshold, the refrigerant absorbs heat from this ambient air and rises in temperature or boils and converts to a vapor form. The high-temperature refrigerant vapor is then directed to the compressor, where it is pressurized and heated further. This cycle repeats to ensure that the hot water supply to the facilityis maintained.

However, in some instances, the temperature of the ambient air within the facilitymay fall below the threshold such that the air does not have enough thermal energy that can be transferred to the refrigerant flowing through the second heat exchanger. In this instance, the refrigerant flowing out of the second heat exchangermay not be at the requisite temperature before it enters the compressor. This results in the drop in the efficiency of the overall system. In one example, the efficiency of the system may be measured in terms of a coefficient of performance (COP). In the instance noted above, the COP may drop below a desired value. In such instances, there may be a need to boost the heat transfer capability of the vapor compression cycle systemso that the refrigerant is at the right temperature and pressure before it enters the compressor.

In some embodiments, the pressure and temperature of the refrigerant at the input portof the compressoris continually monitored. Whenever the pressure or the temperature of the refrigerant drops below a corresponding predetermined threshold, the second mode of operation can be triggered. The threshold values for the temperature and pressure can be set according to the specifications of the heat pump system. In addition to or in lieu of the temperature and the pressure of the refrigerant entering the compressor, a temperature of the ambient air within the facilityis also monitored and may be used to trigger the second mode of operation. For instance, if the temperature of the ambient air within the facilityfalls below a predetermined threshold, the second mode of operation can be triggered. Thus, the second mode of operation can be triggered if one or more of the refrigerant temperature, the refrigerant pressure, or the ambient air temperature within the facilityfalls below their corresponding thresholds. The facilitymay have a central control system that monitors various aspects of the functioning of the components of systemincluding the refrigerant temperature at the compressor input port, the refrigerant pressure at the compressor input port, or the ambient air temperature within the facility. This central control system may control the mode of operation of the system.

In the second mode of operation, after the refrigerant enters the first flow control valvevia port the first port, the first flow control valveis operated such that it splits the refrigerant into two portions. A first portion of the refrigerant is directed to the first portof the second heat exchangerand a second portion of the refrigerant is directed to the third portof the third heat exchanger. Determination of the amount of the first portion and the second portion of the refrigerant (e.g., volume) is based on several factors including a difference between the threshold refrigerant pressure and the actual measured pressure of the refrigerant at the compressor, a difference between the threshold refrigerant temperature and the actual measured temperature of the refrigerant at the compressor, or a difference between the threshold ambient air temperature and the actual measured ambient air temperature within the facility. The larger the difference between one or more of these measured parameters and their respective thresholds, the larger the second portion of the refrigerant that is directed to the third heat exchangercompared to the first portion of the refrigerant directed to the second heat exchanger.

In addition, in the second mode, the heat sourcemay be activated to provide hot water to the third heat exchanger. As the second portion of the refrigerant flows through the third heat exchanger, it absorbs the heat from the hot water provided by the heat source. This increases the temperature of the second portion of the refrigerant to its boiling point, thereby also increasing the pressure of the second portion of the refrigerant. The second portion of the refrigerant is output from the fourth portof the third heat exchangerand is mixed with the first portion of the refrigerant output via the second portof the second heat exchanger, at point. The combined refrigerant now has the requisite pressure and temperature before it enters the compressor.

In this mode of operation, the heat sourceprovides the hot water to the third heat exchanger. The hot water enters the third heat exchangervia the second portand exits via a first port. In the third heat exchanger, the hot water loses some of its thermal energy to the second portion of the refrigerant. So, the water exiting the first portof the third heat exchangerhas a lower temperature than the water entering via the second portof the third heat exchanger. This lower temperature water may be returned to the heat sourcefor reheating and the heated water is supplied back to the third heat exchanger.

In the instance where there is no need for the hot water from the heat sourceto heat up the refrigerant (e.g., in the first mode of operation), the hot water output by the heat source may be routed to the storage tankfor use in the facility. In this instance, the variable speed pumpis turned off and a third flow control valveprevents any hot water from being directed to the second portof the third heat exchanger. In the instance where the boost or extra heat capability of systemis activated (e.g., in the second mode of operation), the variable speed pumpis operated accordingly to provide the right amount of hot water to the third heat exchanger. Control of the variable speed pump may be provided from the central control system of the facility. The amount of hot water supplied to the third heat exchangermay be based on the ambient air temperature within the facility, the pressure of the refrigerant at the input portof the compressor, or the temperature of the refrigerant at the input portof the compressor. In other embodiments, when there is no need to operate the third heat exchanger, such as in the first mode of operation, the heat sourcemay be turned off or not used.

In an embodiment when the second mode of operation is activated, the heat sourcemay be also used to reheat the used water expelled from the facility. For instance, the used water from the facilitymay be recycled, purified, etc. and provided to the heat source. At the second flow control valve, the lower temperature water exiting the third heat exchangeris combined with the used water expelled from the facilityand provided to the heat source. The heat sourceheats up this water. After the hot water exits the heat source, it may be split into two portions by the third flow control valve. A first portion of the hot water is directed towards the variable speed pumpand a second portion of the hot water is directed towards the input portof the storage tank. In one embodiment, the second portion of the hot water exiting the heat sourceis combined with the hot water exiting the third portof the first heat exchangerat point. The combined hot water is then directed to the storage tank. The determination of how much water to include in the first portion and the second portion after the hot water exits heat sourcemay depend on the requirements for the boost capacity in the second mode of operation. The variable speed pumpmay be operated accordingly to control the draw of the hot water and thus control the amount of hot water entering the third heat exchanger.

illustrates a block diagram of systemaccording to an embodiment of the present disclosure. Systemis similar in structure to systemwith the following difference. Systemuses the flue gases expelled from the heat sourceto heat the refrigerant flowing within the third heat exchangerinstead of using hot water from the heat source. Thus, the operation of systemis different from system. Systemoperates as follows.

If it is determined that systemneeds the enhanced or boost heat capacity, such as, if one of the refrigerant pressure at port, or the refrigerant pressure at port, or temperature of the ambient air temperature within the facilityis below the corresponding threshold, heat sourcemay be activated. However, instead of providing hot water to the third heat exchanger, the heat sourceinstead traps the flue gases that are expelled after burning of fuel within the heat sourceto heat the water. These flue gases have significant thermal energy. Instead of directly exhausting the flue gases to the atmosphere, the flue gases are routed to the second portof the third heat exchanger. The flue gases pass through the third heat exchangerand exit via the first portof the third heat exchanger. The flue gases are then exhausted to the atmosphere. In this manner, the thermal energy in the flue gases can be utilized to heat up the refrigerant flowing in the third heat exchanger.

Similar to system, the used water expelled by the facilityis routed to the heat sourcefor reheating and is then routed to the storage tank. None of the hot water output by the heat sourceis provided to the third heat exchanger. So, even in system, the heat sourceperforms dual functions of heating the used water expelled by the facilityand providing a fluid (flue gases in this instance) having thermal energy to the third heat exchanger. The rest of systemoperates in a manner that is similar to system.

illustrates a block diagram and operation of a systemaccording to an embodiment of the present disclosure. Systemincludes the compressor. Compressorhas an input portand an output port. Compressorcan be any known compressor in the art. In some embodiments, more than one compressor can be used. For example, a tandem scroll compressor or the like may be used. One skilled in the art will realize that systemcan include more than two compressors based on the size or capacity needed to serve the facility. Compressoris configured to compress or pressurize and heat a fluid that is circulated in the system.

The output portof compressoris in fluid communication with the first portof the first heat exchanger. The first heat exchangercan be any suitable type of heat exchanger, such as a plate heat exchanger or the like. For ease of explanation,depicts a plate heat exchanger, but one skilled in the art will realize that any other heat exchanger that can perform a similar function can be used. The specific type of heat exchanger is not germane to the techniques disclosed herein.

The second portof the first heat exchangeris in fluid communication with a first expansion valve. The third portof the first heat exchangeris in fluid communication with the input portof the water storage tank. The fourth portof the first heat exchangeris in fluid communication with a used water line of the facility. One skilled in the art will realize that there may be one or more components, such as filters, purifiers, etc. disposed between the used water line and the fourth portof the first heat exchanger. In some embodiments, the first heat exchangermay be located inside the facility. In other embodiments, all the components shown inmay be located inside the facility.

The second portof the first heat exchangeris also in fluid communication with a first portof a first flow control valve. A second portof the first flow control valveis in fluid communication with a second expansion valve. The first expansion valveand the second expansion valvemay be realized using any known devices in the art. The second expansion valveis in fluid communication with the third portof the third heat exchanger.

The first expansion valveis in fluid communication with the first portof the second heat exchanger. The second portof the second heat exchangeris in fluid communication with input portof compressor. The second port of the second expansion valveis in fluid communication with the third portof the third heat exchanger. The first portof the third heat exchangeris coupled to a first portof a second flow control valve. The second portof the third heat exchangeris in fluid communication with an output port of a variable speed pump. The input port of the variable speed pumpis in fluid communication with a second portof a third flow control valve. A first portof the third flow control valveis in fluid communication with the output of the heat source. A third portof the third flow control valveis in fluid communication with the fourth portof the second flow control valve.

The second flow control valveis located at a junction between the used water line of facility, the input of the heat source, and the first portof the third heat exchanger. The first portof the second flow control valveis in fluid communication with the first portof the third heat exchanger. The second portof the second flow control valveis in fluid communication with the used water line of facility. A third portof the second flow control valveis in fluid communication with the input of the heat sourceand the fourth portof the second flow control valveis in fluid communication with a portof the third flow control valve. In this embodiment, the first portof the third flow control valveand the output of the heat sourcemay be coupled to each other at point.

The systemcan be configured to be operated in several modes. A few exemplary modes are described below. One skilled in the art will realize that systemmay be operated in additional modes not specifically described in this disclosure and all such operational modes are within the scope of this disclosure.

In a first mode of operation, systemmay operate in a similar manner to the first mode of operation described above in relation to. In this mode, systemdoes not need the extra boost or heating capacity and hence there is no refrigerant or hot water flowing through the third heat exchanger. The first flow control valvemay be closed so that no refrigerant is directed to the third portof the third heat exchanger. Also, the third flow control valvemay be operated to prevent flow of hot water from heat sourceto the second portof the third heat exchanger. In this first mode of operation, the used water expelled from the facilityarrives at the second portof the second flow control valve. The second flow control valvethen directs this used water to the heat sourcevia the third port. No portion of this used water is allowed to exit via the fourth porttowards the third flow control valve. The heat sourcethen heats this used water and directs the heated water towards the storage tank.

In a second mode of operation, systemmay re-use the water that is circulated via the third heat exchanger. In this mode of operation, if it is determined that the additional heat or boost capacity is needed for system, the second portion of the refrigerant is directed to the third heat exchangerby operating the first flow control valve. The amount of refrigerant directed towards the third heat exchangermay depend on the one or more of the three parameters mentioned above in relation to the first mode of operation. Once the amount of refrigerant in the second portion of the refrigerant that is to be directed towards the third heat exchangeris determined, the first flow control valveis operated accordingly to allow that amount of refrigerant to pass through the second expansion valveand towards the third heat exchanger. Concurrently, the heat sourcemay also be activated to output heated water. In some embodiments, the heat sourcemay receive the used water expelled from the facilityvia the third portof the second flow control valve. The heat sourcemay output hot water and that hot water is directed towards the third flow control valve. The third flow control valvein conjunction with the variable speed pumpdirects a first portion of the hot water towards portof the third heat exchanger. After transferring some of its thermal energy to the second portion of the refrigerant that is flowing between the third portand the fourth portof the third heat exchanger, the first portion of the hot water exits the first portof the third heat exchanger.

Although the first portion of the hot water exiting via the first portmay have a lower temperature than the first portion of the hot water entering the second port, there may be enough thermal energy still left in the first portion of the hot water. The temperature of the first portion of the hot water exiting via the first portof the third heat exchangeris monitored to determine whether that temperature is at or above a threshold. This threshold may be determined based on the type of refrigerant, the boiling point of the refrigerant, etc. If it is determined that the first portion of the hot water exiting the first porthas a temperature at or above the threshold, that first portion of the hot water is directed by the second flow control valvetowards the third flow control valve. In order to accomplish this, the second flow control valveis placed in a state in which it receives the first portion of the hot water exiting from the first portof the third heat exchangerat its first port. The first portion of the hot water is then output via the fourth porttowards portof the third flow control valve. The first portion of the hot water is then fed back into the second portof the third heat exchanger. This cycle may repeat until the temperature of the first portion of the hot water exiting the first portfalls below the threshold or the systemdetermines that it no longer needs the boost or extra heating capacity. Concurrent to the above cycle being repeated, the used water from the facilitymay be directed to the heat sourcevia the second portand the third portof the second flow control valve. This used water is heated by the heat sourceand directed towards the storage tankand back to the facility.

In a third mode of operation, systemmay use both the first portion of the hot water exiting the first portof the third heat exchangerand hot water output from the heat source. In this mode, once it is determined that the systemneeds the boost or extra heat capability, the systemoperates the third flow control valveand the variable speed pumpto direct the first portion of the hot water outputted from the heat sourceto the second portof the third heat exchanger. In the third heat exchanger, the first portion of the hot water transfers some of its thermal energy to the second portion of the refrigerant flowing between the third portand the fourth portof the third heat exchanger. The first portion of the hot water exists the first portof the third heat exchangerand is received by the second flow control valveat the first port. The second flow control valvemay also receive used water expelled from the facilityat the second port. In this mode of operation, the second flow control valve may close the fourth portand direct all or substantially all of the used water received at the second portand the first portion of the hot water received at the first porttowards the heat source, via its third port. The heat sourceheats up this combined water and outputs the hot water. In some embodiments, the first portion of this hot water may be drawn by the third flow control valveand the variable speed pump. The rest of the hot water is directed towards the storage tankand may be fed back to the facility. Thus, in this mode of operation, the systemoperates the heat sourceto heat a mix of the used water from facilityand water exiting the third heat exchanger. This hot water is provided to the third heat exchangerto effect the extra heat or boost mode for the system. In some embodiments, the second flow control valvemay be omitted and replaced by a 4-way adapter that fluidly couples the first portof the third heat exchanger, the input port of heat source, the third portof flow control valveand the output of the facility.