Heat Pump Systems with Reheat Features

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. provisional patent application No. 63/653,351 filed May 30, 2024, which is herein incorporated by reference in its entirety.

FIELD

This disclosure relates generally to heat pumps and more particularly to heat pump systems that include de-humidification or a reheat function.

BACKGROUND

Conventional heat pump systems operating in a humid environment are unable to adequately remove humidity from the air. This deficiency in conventional systems is more pronounced when the heat pump system is operating in a cooling mode. In that mode, conventional systems are unable to effectively control the humidity of the air being circulated in a house, resulting in colder, but humid air. This not only affects the efficiency of the heat pump system, but also results in an unpleasant customer experience.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanying drawings. In some instances, the use of the same reference numerals may indicate similar or identical items. Various embodiments may utilize elements and/or components other than those illustrated in the drawings, and some elements and/or components may not be present in various embodiments. Throughout this disclosure, depending on the context, singular and plural terminology may be used interchangeably.

FIG. 1 illustrates a block diagram of a vapor compression cycle system with a reheat feature according to an embodiment of the present disclosure.

FIG. 2 illustrates a flow chart for a process of operating a vapor compression cycle system according to an embodiment of the present disclosure.

FIG. 3 illustrates a flow chart for a process of operating a vapor compression cycle system according to another embodiment of the present disclosure.

FIG. 4 illustrates a flow chart for a process of operating a vapor compression cycle system according to yet another embodiment of the present disclosure.

DETAILED DESCRIPTION

This disclosure relates generally to vapor compression cycle systems that include a de-humidification or a reheat feature. 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.

The present disclosure provides various systems and methods for using a reheat feature that can be enabled to remove or control humidity within an indoor space while at the same time keeping the ambient temperature in the indoor space cooler than the external ambient temperature. This improves the overall efficiency of the vapor compression cycle system while saving energy and increasing user comfort.

In regions where it may get extremely hot during some parts of the year, any climate control system operating in a facility, such as a house or a commercial building, often has difficulty maintaining a comfortable temperature within the facility. For example, in regions where the ambient outside temperature goes above 100° F., the climate control system may have difficulty in maintaining a comfortable temperature, such as 68° F., inside a facility. This large difference between the outside temperature and the indoor set point often leads to the climate control system operating for longer periods of time, resulting in more wear and tear on the system, and may even lead to failure in certain conditions. Further, if the hot outside air is coupled with high humidity, such as 90% or above, it becomes difficult to maintain dry conditions within a facility. If the climate control system is operating in a cooling mode, the air provided within the facility may be cooler but is also humid. This is undesirable as cold, humid air results in an unpleasant experience for the occupants of the facility.

In order to reduce the humidity of the air after the air is cooled, the present disclosure provides various systems and methods as described below. One of the techniques is to provide a mechanism for reheating the air after it is cooled using some of the existing refrigerant in the system. This technique of recovering heat from existing refrigerant in order to cool the air on-demand greatly increases the efficiency of the climate control system and also helps in reducing the humidity in the air, thereby providing better comfort to the occupants of the premises.

FIG. 1 illustrates a block diagram of a vapor compression cycle system 100 that includes a reheat feature according to an embodiment of the present disclosure. For example, the vapor compression cycle system 100 may be a heat pump or any other type of vapor compression cycle system described herein or otherwise. It is to be noted that not all components of a heat pump system are illustrated in FIG. 1. Only components for explaining the disclosure are shown. One skilled in the art will realize that a vapor compression cycle system can and does have many more components than what is shown in FIG. 1.

Vapor compression cycle system 100 includes a compressor 102. Compressor 102 has an intake port 130 and an outlet port 128. Compressor 102 operates to receive a fluid (for example, a refrigerant like R134a, R454B, or R410a or the like) and compress it into a high pressure, high temperature vapor. This high temperature, high pressure vapor is then output by compressor 102 via outlet port 128 to a reversing valve 104. Reversing valve 104 is in fluid communication with outlet port 128 and inlet port 130 of compressor 102. “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 and other types of gases. It should be noted that throughout the disclosure, ports/components described as being in “fluid communication” with each other have one or more refrigerant lines or other appropriate means of fluid communication that facilitate flow of a fluid between these ports/components.

In one embodiment, reversing valve 104 is in fluid communication with 3-way valve 106 and also a first port 114a of a first heat exchanger 114. In some embodiments, the first heat exchanger 114 can be an indoor heat exchanger that is located within the indoor space being heated or cooled or otherwise in thermal communication (e.g., via one or more air ducts) with an inside ambient environment. Reversing valve 104 operates in various modes. In one mode (e.g., a cooling mode), it can allow the fluid coming out of compressor 102 to flow to the 3-way valve 106. The fluid may then flow to a second heat exchanger 108, and then to a thermostatic expansion (TXV) valve 110 and the first heat exchanger 114 and onwards to compressor intake port 130. In one embodiment, the thermostatic expansion valve 110 can be a bi-directional thermostatic expansion valve (TXV), or in another embodiment, two TXVs can be arranged to provide bi-directional control the flow of fluid. The thermostatic expansion valve 110 expands the fluid passing through it, thereby lowering the pressure of the fluid and converting a small amount of the fluid to vapor form. The fluid that exits the thermostatic expansion valve 110 is in a liquid-vapor mix form.

While described in the example of FIG. 1 as a thermostatic expansion valve 110, any other expansion device may be used. For example, the thermostatic expansion valve 110 may be an electronic expansion valve (EXV), capillary tube, or any other refrigerant expansion device or combinations thereof.

The 3-way valve (also referred to herein as “reheat valve”) 106 is in fluid communication with the second heat exchanger 108. In an embodiment, the second heat exchanger 108 can be an outdoor heat exchanger that is located outside/external to a home/the indoor space or facility that uses vapor compression cycle system 100 or otherwise in thermal communication (e.g., via one or more air ducts) with an outside ambient environment. The 3-way valve 106 is also in fluid communication with a reheat coil 132. Details and operation of reheat coil 132 are described below. The 3-way valve 106 is also in fluid communication with reversing valve 104. In some embodiments, the 3-way valve 106 may direct the flow of fluid from compressor 102 to reheat coil 132.

A first port 108a of the second heat exchanger 108 is in fluid communication with the 3-way valve 106. The second port 108b of the second heat exchanger 108 is in fluid communication with thermostatic expansion valve 110. The thermostatic expansion valve 110 is in fluid communication with port 114b of the first heat exchanger 114. The second heat exchanger 108 may be any kind of heat exchanger known in the art or that may fit the purpose and function described below.

In an embodiment, the first heat exchanger 114 may be an indoor heat exchanger located within the facility that uses vapor compression cycle system 100 or otherwise in thermal communication (e.g., via one or more air ducts) with an indoor ambient environment. The first heat exchanger 114 may be any kind of heat exchanger known in the art or that may fit the purpose and function described below. The second port 114a of the first heat exchanger 114 may be in fluid communication with reversing valve 104. In addition to being in fluid communication with the thermostatic expansion valve 110, the port 114b of the first heat exchanger 114 is also in fluid communication with a solenoid valve 112.

Solenoid valve 112 is located between the port 114b of the first heat exchanger 114 and reheat coil 132. Solenoid valve 112 is in fluid communication with reheat coil 132 at a first end 124 of the reheat coil 132. Operation of solenoid valve 112 allows control of the flow of fluid between the first heat exchanger 114 and reheat coil 132 for use during the reheat operation, if needed. The same end 124 of reheat coil 132 is also in fluid communication with another solenoid valve 116. The other end of solenoid valve 116 is in fluid communication with a check valve 118. Check valve 118 allows flow of fluid in only one direction, i.e. from solenoid valve 116 towards the second heat exchanger 108. Check valve 118 is in fluid communication with the port 108a of the second heat exchanger 108 at a location 134 that is between the 3-way valve 106 and the second heat exchanger 108.

A first fan unit 120 may be coupled to the second heat exchanger 108. A second fan unit 122 may be coupled to the first heat exchanger 114. Both the first fan unit 120 and the second fan unit 122 are operable to blow a fluid, such as air, over their respective heat exchangers to either cool or warm the fluid. In one embodiment, reheat coil 132 and the first heat exchanger 114 are placed adjacent to each other such that the first heat exchanger 114 is closer to the second fan unit 122 and an air inlet of an air handler unit, which both the first heat exchanger 114 and reheat coil 132 may be a part of. In this embodiment, the second fan unit 122 is coupled to both the first heat exchanger 114 and reheat coil 132. Reheat coil 132 is placed adjacent to but after the first heat exchanger 114 such that when the second fan unit 122 is in operation, the return air first passes over the first heat exchanger 114 and then over (or otherwise comes in contact with) reheat coil 132. In this manner, especially in cooling mode with the reheat feature enabled, the air is first cooled by the first heat exchanger 114 and then heated slightly by reheat coil 132 to reduce moisture in the air. This cooler and reduced moisture air is then transported to the indoor space/facility via ducts and the like. After the air passes over reheat coil 132, it is provided to the premises being served by vapor compression cycle system 100. The second fan unit 122 then directs the cooler but drier/lower moisture air to its intended destination via the associated ductwork.

In an embodiment, the vapor compression cycle system 100 may include a controller unit 150. The controller unit 150 may include one or more processors, one or more memories, and instructions stored in the one or more memories. The instructions when executed by the one or more processors may allow the controller unit 150 to control various aspects of the operation of the vapor compression cycle system 100. In one embodiment, the controller unit 150 may communicate with one or more components (e.g., as illustrated in FIG. 1) of the vapor compression cycle system 100 via a wired or a wireless communication medium. The controller unit 150 may be a Direct Digital Control (DDC) type control unit or a non-DDC type control unit. In one embodiment, the controller unit 150 may receive input from and send instructions to the one or more of the components of the heat pump 100 illustrated in FIG. 1 in order to control the operation of the one or more components. In other embodiments, the controller unit 150 may be separate from the vapor compression cycle system 100.

Vapor compression cycle system 100 may operate in several modes. FIGS. 2-4 illustrate flow charts for the various modes of operation, such as of vapor compression cycle system 100 of FIG. 1. Each of the modes of operations are described in detail below with reference to the corresponding figures.

FIG. 2 illustrates a flow chart for a process 200 of operating a vapor compression cycle system in a first mode according to an embodiment of the present disclosure. For example, process 200 may be executed by the controller unit 150 during a heating mode of vapor compression cycle system 100 of FIG. 1. The details of the process 200 are explained below with reference to both FIGS. 1 and 2.

At the start of process 200, the solenoid valve 116 is closed at step 202. This prevents flow of fluid from reheat coil 132 to the second heat exchanger 108 via solenoid valve 116 and check valve 118. At step 204, the 3-way valve 106 is placed in a first state in which it prevents flow of the fluid (e.g., refrigerant) to/from reheat coil 132 to compressor 102, via the first end 126 of reheat coil 132. In the first state of the 3-way valve 106, the fluid is allowed to flow from the second heat exchanger 108 through the 3-way valve 106 and reversing valve 104 to the intake port 130 of the compressor 102.

At step 206, solenoid valve 112 is opened for a first period of time. In some embodiments, the first time period may be between 5 and 30 seconds depending on the operation and other parameters of vapor compression cycle system 100. This causes the superheated, high pressure fluid from compressor 102 to flow via reversing valve 104 to the first heat exchanger 114 (e.g., a condenser in the heating mode) and be condensed to a liquid. While the fluid exiting the first heat exchanger 114 is substantially liquid, some small remnant of vapor may be present, as understood by those of ordinary skill in the art. For example, the vapor content of the fluid exiting the first heat exchanger 114 may be less than 1%, less than 5%, less than 10%, or less than 25% of the fluid. Since solenoid valve 112 is open, a portion of the fluid (e.g., liquid refrigerant) flows from the first heat exchanger 114 into reheat coil 132 at step 208. Since solenoid valve 116 is closed and the 3-way valve 106 is in the first state, the portion of the fluid in reheat coil 132 has nowhere to go and stored in the reheat coil 132. In some embodiments, the portion of fluid in reheat coil 132 has a first temperature that is higher than the temperature of the portion of fluid in the second heat exchanger 108. In an embodiment, the temperature of the portion of the fluid in reheat coil 132 can be above 80° F. Also, the portion of the fluid in reheat coil 132 is at a higher pressure, such as 350 psi.

At step 210, the rest of the fluid output from compressor 102 flows through the first heat exchanger 114, the thermostatic expansion valve 110, the second heat exchanger 108, the 3-way valve 106, and the reversing valve 104, and enters compressor 102 at the intake 130. It should be noted that while the 3-way valve 106 prevents the flow of fluid from reheat coil 132 to compressor 102, it allows flow of fluid from the second heat exchanger 108 to compressor 102. At step 212, solenoid valve 112 is closed after expiration of the first time period. From then on, for the rest of the time that heat pump system is operating in the heating mode, solenoid valve 112 remains closed and the fluid circulation continues from compressor 102, to the first heat exchanger 114, to thermostatic expansion valve 110, to the second heat exchanger 108, via the 3-way valve 106 and reversing valve 104, back to compressor 102.

In some embodiments, the filling up of reheat coil 132 with fluid from compressor 102 in the manner described above is done once, during the winter season, when the vapor compression cycle system 100 is first put in a heating mode. Thereafter, the heat pump system can keep running in the heating mode. This extra fluid stored in reheat coil 132 reduces the amount of refrigerant flowing in the vapor compression cycle system 100 when it is operating in the heating mode. Thus, the reheat coil 132 is used to store refrigerant in the heating mode as the heat pump system can operate with less refrigerant in the heating mode than in the cooling mode.

FIG. 3 illustrates a process 300 that can occur during operation of vapor compression cycle system 100 of FIG. 1 in a second mode (e.g., a cooling mode) according to another embodiment of the present disclosure. In an embodiment, process 300 may be executed by the controller unit 150 illustrated in FIG. 1. For example, process 300 illustrates operation of the heat pump system in a cooling mode without the reheat feature enabled. For example, the cooling mode without reheat may be used when it is desired for a facility to be cooled and the humidity in the ambient air is low enough so that vapor compression cycle system 100 operates efficiently. For example, hotter, but drier climate regions would likely benefit more from this mode of operation. The details of the process 300 are explained below with reference to both FIGS. 1 and 3.

At step 302, solenoid valve 112 is opened. In instances where a prior mode of operation causes solenoid valve 112 to remain open, then valve 112 can be left open for the purposes of process 300. In other instances, even if solenoid valve 112 is open prior to the beginning of process 300, it can be closed and then reopened as part of step 302.

At step 304, solenoid valve 116 is closed. In instances where solenoid valve 116 is already closed prior to step 304, it is verified that the valve is indeed closed. At step 306, the 3-way valve 106 is placed in the first state such that it prevents flow of fluid to/from compressor 102 to reheat coil 132 via the second end 126 of reheat coil 132. However, in the first state, the 3-way valve 106 allows flow of fluid from compressor 102 to the second heat exchanger 108 (e.g., a condenser in the second mode).

At step 308, vapor compression cycle system 100 causes flow of fluid from compressor 102, via the 3-way valve 106, to the second heat exchanger 108 and onwards to the first heat exchanger 114 via thermostatic expansion valve 110. The fluid then continues to flow from the first heat exchanger 114 (e.g., an evaporator in the second mode) back to compressor via reversing valve 104.

At step 310, the portion of fluid stored in reheat coil 132 also flows to compressor via the first heat exchanger 114 to improve heat exchange capability. This occurs due to the following reasons. One, since solenoid valve 112 is open the fluid can flow from reheat coil 132 to the first heat exchanger 114 via the end 124 of the reheat coil 132. Second, the pressure inside the first heat exchanger 114 is lower than the pressure in the reheat coil 132. This pressure imbalance causes the fluid to flow into the first heat exchanger 114. In addition to the above, compressor 102 is also exerting a pull/suction force on the fluid. The vapor compression cycle system 100 then continues to run in this cooling mode until another change to its mode of operation is triggered.

In some embodiments, a portion of fluid may be stored in reheat coil 132 prior to the start of process 300, for example, using one or more actions described above in connection with process 200. For example, steps 202-208 may be executed prior to executing the steps of process 300.

In environments where the ambient air is hot and carries a lot of moisture, it is desirable to also lower/remove the amount of moisture in the air in addition to cooling the air so that the facility/premises being cooled has a pleasant environment and vapor compression cycle system 100 operates efficiently while not excessively cooling the moisture-laden air.

FIG. 4 illustrates a process 400 for operating vapor compression cycle system 100 of FIG. 1 in a third mode according to yet another embodiment of the present disclosure. In an embodiment, process 400 may be executed by the controller unit 150 illustrated in FIG. 1. For example, the third mode can be referred to as cooling mode with reheat feature enabled. At a high-level, this mode operates to both cool the air as well as remove the moisture from the cooled air by cooling air with the first heat exchanger 114 to a first temperature to remove a desired amount of moisture and subsequently slightly raising the air to a second temperature with the reheat coil 132 after it passes the first heat exchanger 114. The details of the process 400 are explained below with reference to both FIGS. 1 and 4.

In an embodiment, process 400 may be preceded by one or more steps of process 200. For example, one or more of steps 202, 204, 206, and 208 may occur before process 300 begins such that a portion of fluid is already stored in reheat coil 132 prior to the beginning of process 400. In other embodiments, other actions may occur that cause a portion of fluid from the compressor 102 to be stored in reheat coil 132.

At step 402, solenoid valve 112 is closed. This prevents fluid that is inside the reheat coil 132 from flowing to/from the first heat exchanger 114. At step 404, solenoid valve 116 is opened. This allows fluid stored in reheat coil 132 to flow via check valve 118 to the second heat exchanger 108.

At step 406, the 3-way valve 106 is placed in a second state such that it allows flow of fluid from compressor 102 to reheat coil 132 via the 3-way valve 106. Further, in the second state, the 3-way valve 106 prevents flow of fluid from the output of check valve 118 to compressor 102 via the 3-way valve 106.

At step 408, fluid from compressor 102 flows through the reversing valve 104 and to reheat coil 132 via the 3-way valve 106. It is to be noted that the fluid coming out of the compressor is superheated and at high pressure.

Concurrently, the second fan unit 122 is circulating/traversing a second fluid, such as air, over the first heat exchanger 114. The first heat exchanger 114 cools and dehumidifies the air, and reheat coil 132 slightly heats up the cooled and dehumidified air. The air is then collected after it is slightly heated by reheat coil 132 and provided to the facility/space that is coupled to vapor compression cycle system 100. For example, for a setting of 70° F., the air may be cooled to around 50-55° F. and dehumidified by the first heat exchanger 114 and then heated by reheat coil 132 to around 65-68° F., to get it closer to or about the setting/desired temperature. Thus, the temperature of air leaving the first heat exchanger 114 is lower than the temperature of air after it is heated by reheat coil 132.

At step 412, the fluid that is in the reheat coil 132 flows to the second heat exchanger 108 (e.g., a condenser in the third mode) via the valve 116. At step 414, the same first portion of the fluid flows from the second heat exchanger 108, via the thermostatic expansion valve 110, to the first heat exchanger first 114 (e.g., an evaporator in the third mode) and onwards back to compressor 102. This flow of the fluid continues in this fashion while the vapor compression cycle system 100 is operated in this cooling with reheat mode.

It should be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. References to a composition containing “a” constituent is intended to include other constituents in addition to the one named.

Also, in describing the disclosed technology, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

Ranges may be expressed herein as from “about” or “approximately” or “substantially” one particular value and/or to “about” or “approximately” or substantially” another particular value. When such a range is expressed, the disclosed technology can include from the one particular value and/or to the other particular value. Further, ranges described as being between a first value and a second value are inclusive of the first and second values. Likewise, ranges described as being from a first value and to a second value are inclusive of the first and second values.

Herein, the use of terms such as “having,” “has,” “including,” or “includes” are open-ended and are intended to have the same meaning as terms such as “comprising” or “comprises” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” are intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Moreover, although the term “step” can be used herein to connote different aspects of methods employed, the term should not be interpreted as implying any particular order among or between various steps herein disclosed unless and except when the order of individual steps is explicitly required. Further, the disclosed technology does not necessarily require all steps included in the methods and processes described herein. That is, the disclosed technology includes methods that omit one or more steps expressly discussed with respect to the methods described herein.

It should be apparent that the foregoing relates only to certain embodiments of the present disclosure and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the disclosure.

Although specific embodiments of the disclosure have been described, numerous other modifications and alternative embodiments are within the scope of the disclosure. For example, any of the functionality described with respect to a particular device or component may be performed by another device or component. Further, while specific device characteristics have been described, embodiments of the disclosure may relate to numerous other device characteristics. Further, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments. Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments could include, while other embodiments may not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.