US20200166234A1

US20200166234A1 - Variable speed vapor compression systems and methods of controlling humidity with vapor compression systems

Info

Publication number: US20200166234A1
Application number: US16/698,100
Authority: US
Inventors: Derek A. Leman
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2018-11-28
Filing date: 2019-11-27
Publication date: 2020-05-28

Abstract

A variable speed vapor compression system includes a compressor, a first heat exchanger connected to the compressor, an expansion valve connected to the first heat exchanger, a second heat exchanger connecting the expansion valve to the compressor, a fan associated with the second heat exchanger, and a controller operatively connected to one or more of the compressor and the fan. The controller is responsive to instructions to receive a target humidity range for a conditioned space, receive a sensed humidity for the conditioned space, compare the sensed humidity to the target humidity range, and vary speed of one or more of the fan and the compressor based on the comparison of the sensed humidity and the target humidity range. Methods of controlling humidity in conditioned spaces and computer program products are also described.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Application No. 62/772,449 filed Nov. 28, 2018, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The subject matter disclosed herein generally relates to vapor compression systems, and more particularly to humidity control in spaces conditioned by variable speed vapor compression systems.
Environmental control systems, like air conditioners and heat pumps, are commonly used to control environmental conditions in structures such as buildings and vehicles. Air conditioners generally remove heat from air obtained from outside the structure, typically by cycling a working fluid through a closed working fluid loop. Heat pumps typically remove heat or add heat from air obtained from outside the structure, typically by altering the flow of a working fluid through a closed working fluid loop.
In some applications it can be desirable to provide humidity control within the structure interior. Humidity control is generally provided by changing the moisture content of the air obtained from inside or outside the structure, typically by altering the temperature change in the outside air prior to introduction to the structure or from air obtained from inside the structure. Since humidity control typically entails a tradeoff between the efficiency of the environmental control system and the degree of humidity of control provided to the structure interior, systems operating with higher latent heat removal levels for humidity control commonly providing lower efficiency than systems operating with lower or no latent heat removal, some air conditioners and heat pumps allow the user to turn humidity control off. This improves efficiency of the air conditioner or heat pump at the expense of the loss of humidity control in the structure interior.
Such conventional air conditioning systems and methods have generally been satisfactory for their intended purpose. However, there remains a need in the art for improved vapor compression systems and methods of controlling humidity using vapor compression systems. The present disclosure provides a solution to this need.

BRIEF SUMMARY

A variable speed vapor compression system includes a compressor, a first heat exchanger connected to the compressor, and expansion valve connected to the first heat exchanger. The variable speed vapor compression system also includes a second heat exchanger connecting the expansion valve to the compressor, a fan associated with the second heat exchanger, and a controller operatively connected to the compressor and the fan. The controller is responsive to instructions to receive a target humidity range for a conditioned space, receive a sensed humidity for the conditioned space, compare the sensed humidity to the target humidity range, and vary speed of at least one of the fan and the compressor based on the comparison of the sensed humidity and the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the first heat exchanger comprises a condenser, wherein the second heat exchanger comprises an evaporator.
In addition to the one or more features described above, or as an alternative, further embodiments may include a variable speed drive operably connected to the compressor.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the instructions cause the variable speed drive to reduce compressor speed when the sensed humidity is within the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the instructions cause the variable speed drive to increase compressor speed when the sensed humidity is outside of the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include further comprising a variable speed drive operably connected to the fan.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the instructions cause the variable speed drive to vary fan speed when the sensed humidity is within the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the instructions cause the variable speed drive to vary fan speed when the sensed humidity is outside the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the controller has a comfort mode and an efficiency mode.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the instructions cause the controller to vary speed of at least one of the fan and the compressor by toggling the vapor compression system between the comfort mode and the efficiency mode.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein toggling between the comfort mode and the efficiency mode includes automatically selecting between a first efficiency range and a second efficiency range, the first efficiency range having a higher peak efficiency than the second efficiency range.
In addition to the one or more features described above, or as an alternative, further embodiments may include a temperature sensor associated with an outlet side of the second heat exchanger and disposed in communication with the controller and a pressure sensor. The pressure sensor can be associated with an inlet side of the second heat exchanger and disposed in communication with the controller, and the instructions can cause the controller to vary speed of at least one of the fan and the compressor based on (a) temperature at the outlet end of the second heat exchanger, and (b) pressure at the inlet end of the second heat exchanger.
A method of controlling humidity in a conditioned space includes, at a variable speed vapor compression system as described above, receiving a target humidity range for a conditioned space, receiving a sensed humidity for the conditioned space, comparing the sensed humidity to the target humidity range, and varying speed of at least one of the fan and the compressor based on the comparison of the sensed humidity and the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include reducing compressor speed when the sensed humidity is within the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include increasing compressor speed when the sensed humidity is outside of the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include varying fan speed when the sensed humidity is within the target humidity range, and varying fan speed when the sensed humidity is outside the target humidity range.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein varying speed of at least one of the fan and the compressor includes toggling the vapor compression system between a comfort mode and an efficiency mode.
In addition to the one or more features described above, or as an alternative, further embodiments may include automatically toggling between a first efficiency range and a second efficiency range.
In addition to the one or more features described above, or as an alternative, further embodiments may include wherein the first efficiency range has a higher peak efficiency than the second efficiency range.
A computer program product tangibly embodied on a computer readable medium, the computer program product including instructions that, when executed by a processor, cause the processor to perform operations to receive a target humidity range for a conditioned space, receive a sensed humidity for the conditioned space, compare the sensed humidity to the target humidity range, and vary speed of at least one of a fan and a compressor based on the comparison of the sensed humidity and the target humidity range.
Technical effects of embodiments of the present disclosure include improved humidity control in conditioned spaces, such as residential structures. In certain embodiments improved humidity control is realized while operating the associated vapor compression system with the highest allowable efficiency.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting.

BRIEF DESCRIPTION

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a general schematic system diagram of a variable speed vapor compression system constructed in accordance with the present disclosure, showing an air conditioning system according to an embodiment;

FIG. 2 is a block diagram of a controller for the variable speed vapor compression systems of FIG. 1, showing program modules having instructions for varying speed of the variable speed vapor compression system; and

FIG. 3 is a flow diagram showing a method of controlling humidity in a conditioned space using the variable speed vapor compression system of FIG. 1.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
With reference to FIG. 1, a variable speed vapor compression system 100 is shown. The variable speed vapor compression system 100 includes a variable speed compressor 102, a first heat exchanger 104, and an expansion valve 106. The variable speed vapor compression system 100 also includes a second heat exchanger 108, a first fan 110, and a second fan 112. A fluid circuit 114 interconnect the variable speed compressor 102 with the first heat exchanger 104, the expansion valve 106, and the second heat exchanger 108. In this respect the variable speed compressor 102 is configured and adapted for compressing a fluid 10 and providing the compressed fluid 10 to the first heat exchanger 104. The first heat exchanger 104 is configured and adapted for cooling the compressed fluid 10 using a flow of air provided by the first fan 110, which is associated with the first heat exchanger 104. The expansion valve 106 is connected to the first heat exchanger 104, is arranged to receive therefrom cooled fluid 10, and is further arranged to expand the compressed and cooled fluid 10 for provision to second heat exchanger 108. The second heat exchanger 108 is connected to the expansion valve 106, is arranged to receive therefrom cooled and expanded fluid 10, and is further arranged to heat fluid 10 using a flow of air provided by the associated second fan 112.
Second heat exchanger 108 is in communication with a conditioned space 12, such as via connecting duct or through positioning within conditioned space 12. First heat exchanger 104 is located outside of conditioned space 12, e.g., in the external environment 14, and is configured and adapted to communicate heat from within conditioned space 12 to the external environment 14 through fluid circuit 114. In the illustrated environment variable speed vapor compression system 100 is arranged a residential HVAC system. This is for illustration purposes and is non-limiting. As will be appreciated by those of skill in the art in view of the present disclosure, types of HVAC systems can benefit from the present disclosure, such as heat pump systems as well as HVAC systems in both residential and non-residential settings.
First fan 110 is associated with the first heat exchanger 104 and includes a first fan variable speed motor 116. The first fan variable speed motor 116 is arranged to drive a flow of air across the first heat exchanger 104 from the external environment 14. A controller 118 is operatively connected with the first fan variable speed motor 116 to control the rate of heat exchange between the external environment 14 and the first heat exchanger 104. As shown in FIG. 1 the first heat exchanger 104 is configured as a condenser.
Second fan 112 is associated with the second heat exchanger 108 and includes a second fan variable speed motor 120. In this respect the second fan variable speed motor 120 is arranged to drive a flow of air, e.g., conditioned air from within the conditioned space 12 and/or makeup air from the external environment 14, across the second heat exchanger 108. Controller 118 is operatively connected with the second fan variable speed motor 120 to control the rate of heat removal from the flow of air drive across the second heat exchanger 108. As shown in FIG. 1 the second heat exchanger 108 is configured as an evaporator.
A variable speed drive 122 is operably connected to variable speed compressor 102. The controller 118 is operably connected to the variable speed drive 122 and configured to control the speed, and thereby pressure, of fluid 10 provided to the first heat exchanger 104. As will be appreciated by those of skill in the art in view of the present disclosure, operative connection of the controller 118 to each of the first fan variable speed motor 116, the second fan variable speed motor 120, and the variable speed compressor 102 provides control of the environment within the conditioned space 12. In this respect a humidity sensor 126 is disposed in communication with the conditioned space 12, e.g., located therein, and are further communicative with the controller 118 to provide information indicative of temperature and humidity within the conditioned space 12 to the controller 118. In the illustrated embodiment a suction-side temperature sensor 124 and a suction-side pressure sensor 125 are coupled to fluid circuit 114 on the suction side of the second heat exchanger 108, which provide additional granularity for humidity control within the conditioned space 12 and efficient operation of the variable speed vapor compression system 100.
With reference to FIG. 2, the controller 118 is shown. The controller 118 includes a processor 128, a device interface 130, and a user interface 132. The user interface 132 is configured and adapted to receive a user input 20, e.g., a target humidity range 22, as will be described, is disposed in communication with an internal communication link 134. The internal communication link 134 interconnects the user interface 132 with the device interface 130, the processor 128, and a memory 136. The memory 136 includes a non-transitory machine-readable medium with a plurality of program modules 138 recorded on it that, when read by the processor 128, cause the processor 128 to undertake certain actions. Among those actions are the steps of a method 200 (shown in FIG. 3) for controlling humidity in a conditioned space, as will be described.
Method 200 is implemented through an external communication link 140, connected to the controller 118 through the device interface 130, and through which the controller 118 is disposed in communication with the suction-side temperature sensor 124 and the humidity sensor 126, and through which the controller 118 is further operatively connected to the first fan variable speed motor 116, the second fan variable speed motor 120, and the compressor variable speed drive 122. It is contemplated that the external communications link 140 can be a wired or a wireless link, as suitable for an intended application.
Referring now to FIG. 3, the method 200 of controlling humidity within a conditioned space, e.g., conditioned space 12 (shown in FIG. 1), is shown. The method 200 includes receiving a target humidity range for a conditioned space, e.g., the target humidity range 22 (shown in FIG. 2) for the conditioned space 12 (shown in FIG. 1), as shown by box 210. A second humidity for the conditioned space is also received, e.g., humidity H (shown in FIG. 1), as shown by box 220. The sensed humidity is compared to the target humidity range, as shown with the box 230, and determination made as to whether the sensed humidity is within the target humidity range. The speed of at least one of a fan and a compressor, e.g., the second fan 112 (shown in FIG. 1) and the variable speed compressor 102 (shown in FIG. 1), is varied based on the comparison of the sensed humidity and the target humidity range, as shown with bracket 240.
In certain embodiments a variable speed compression system, e.g., the variable speed vapor compression system 100 (shown in FIG. 1), is toggled between an efficiency mode and a comfort mode to vary the speed of a compressor, e.g., the variable speed compressor 102 (shown in FIG. 1), and a fan, e.g., the second fan 112 (shown in FIG. 1), of the variable speed compression system. In this respect the variable speed vapor compression system is toggled into an efficiency mode when the comparison indicates that the sensed humidity is within the target humidity range, as shown with box 254. When the comparison indicates that the sensed humidity is outside of the target humidity range the variable speed vapor compression system is toggled into a comfort mode, as shown with box 264. Toggling to the efficiency mode toggles the variable speed vapor compression system to a first efficiency range, as shown with box 256. Toggling to the comfort mode toggles the variable speed vapor compression system to a second efficiency range, as shown with box 266, the first efficiency range having a higher peak efficiency than the second efficiency range.
In certain embodiments the speed of one or more of a compressor and a fan of a variable speed vapor compression system can be changed based on the comparison of the sensed humidity and the received humidity range. In this respect the speed of a compressor of the variable speed compression system, e.g., the variable speed compressor 102 (shown in FIG. 1) of the variable speed vapor compression system 100 (shown in FIG. 1), can be reduced when the sensed humidity is within the target humidity range and the sensed humidity is within the target humidity range, as shown with box 250. Speed of a fan of the variable speed compression system, e.g., the second fan 112 (shown in FIG. 1), can be varied when the sensed humidity is within the target humidity range, as shown with box 252. As will be appreciated by those of skill in the art, reducing compressor speed and controlling temperature in the conditioned space 12 (shown in FIG. 1) primarily with air flow moving across the second heat exchanger 108 (shown in FIG. 1) rather than the amount of compression imparted to the fluid 10 (shown in FIG. 1) can result in relatively high efficiency.
Oppositely, the speed of a compressor of the variable speed compression system, e.g., the variable speed compressor 102 (shown in FIG. 1) of the variable speed vapor compression system 100 (shown in FIG. 1), can be increased when the sensed humidity is outside the target humidity range, as shown with box 260. Speed of a fan of the variable speed compression system, e.g., the second fan 112 (shown in FIG. 1), can be varied when the sensed humidity is within the target humidity range and the sensed humidity is outside the target humidity range, as shown with box 262. As will be appreciated by those of skill in the art, increasing compressor speed and controlling temperature in the conditioned space 12 (shown in FIG. 1) primarily with the amount of compression imparted to the fluid 10 (shown in FIG. 1) can achieve humidity control at the expense of efficiency. For this reason, irrespective of whether the comparison indicates that the sensed humidity is within the target humidity range, the humidity and sensing operations continue, as indicated by the return to operation 220 subsequent to each of operations 250 and 260. It is contemplated that, in accordance with certain embodiments, toggling between the comfort mode and the efficiency can be done automatically, i.e., without user intervention.
Some variable speed vapor compression systems have an inverse relationship between latent removal (humidity control) and operational efficiency—especially at low speeds. I would define low speed as the state in which the variable speed compressor is operating at a lower speed and the system is operating at a lower capacity. When this happens, it is common for the indoor blower to blow air across the indoor coil at a high enough CFM that the indoor coil is warmer than the indoor air dew point. This provides higher operational efficiency in terms of system capacity versus system power consumed at the cost of not removing moisture or removing less moisture from the internal air. For that reason it can be necessary to allow a user to prioritize comfort (humidity) control over efficiency by manually selecting a mode of operation that prioritizes comfort, e.g., humidity control, over efficiency. While generally acceptable for its intended purpose, such control regimes can be relatively inefficient during intervals where the humidity in the conditioned space is well controlled, and during which the compression could otherwise be slowed.
To provide relatively high efficiency while controlling humidity variable speed vapor compression system 100 is configured and adapted to operate at its most efficient settings while still controlling humidity within conditioned space 12. In this respect controller 118 selects between a comfort mode, wherein humidity is controlled, and an efficiency mode, wherein operational efficiency is prioritized over humidity control, based on a target humidity range humidity (shown in FIG. 2) received at the controller 118 and input by a user. The target humidity range 22 allows the controller 118 to operate the variable speed vapor compression system 100 to operate at its most efficient that allow the conditioned space 12 to remain within the target humidity range 22. In certain embodiments the variable speed vapor compression system 100 includes a suction-side temperature sensor 124 and a suction-side pressure sensor 125 to control latent removal (humidity), providing granularity (e.g., fine steps) in the amount efficiency and humidity control provided by the variable speed vapor compression system 100.
Embodiments can also be in the form of computer program code containing instructions embodied in tangible media, such as network cloud storage, SD cards, flash drives, floppy diskettes, CD ROMs, hard drives, or any other computer-readable storage medium, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes a device for practicing the embodiments. Embodiments can also be in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into an executed by a computer, the computer becomes an device for practicing the embodiments. When implemented on a general-purpose microprocessor, the computer program code segments configure the microprocessor to create specific logic circuits.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

What is claimed is:

1. A variable speed vapor compression system, comprising:

a compressor;

a first heat exchanger connected to the compressor;

an expansion valve connected to the first heat exchanger;

a second heat exchanger connecting the expansion valve to the compressor;

a fan associated with the second heat exchanger; and

a controller operatively connected to the compressor and the fan, the controller responsive to instructions to:

receive a target humidity range for a conditioned space;

receive a sensed humidity for the conditioned space;

compare the sensed humidity to the target humidity range; and

vary speed of at least one of the fan and the compressor based on the comparison of the sensed humidity and the target humidity range.

2. The vapor compression system as recited in claim 1, wherein the first heat exchanger comprises a condenser, wherein the second heat exchanger comprises an evaporator.

3. The vapor compression system as recited in claim 1, further comprising a variable speed drive operably connected to the compressor.

4. The vapor compression system as recited in claim 3, wherein the instructions cause the variable speed drive to reduce compressor speed when the sensed humidity is within the target humidity range.

5. The vapor compression system as recited in claim 3, wherein the instructions cause the variable speed drive to increase compressor speed when the sensed humidity is outside of the target humidity range.

6. The vapor compression system as recited in claim 1, further comprising a variable speed drive operably connected to the fan.

7. The vapor compression system as recited in claim 6, wherein the instructions cause the variable speed drive to vary fan speed when the sensed humidity is within the target humidity range.

8. The vapor compression system as recited in claim 6, wherein the instructions cause the variable speed drive to vary fan speed when the sensed humidity is outside the target humidity range.

9. The vapor compression system as recited in claim 1, wherein the controller has a comfort mode and an efficiency mode,

10. The vapor compression system as recited in claim 9, wherein the instructions cause the controller to vary speed of at least one of the fan and the compressor by toggling the vapor compression system between the comfort mode and the efficiency mode.

11. The vapor compression system as recited in claim 10, wherein toggling between the comfort mode and the efficiency mode includes automatically selecting between a first efficiency range and a second efficiency range, the first efficiency range having a higher peak efficiency than the second efficiency range.

12. The vapor compression system as recited in claim 1, further comprising:

a temperature sensor associated with an outlet side of the second heat exchanger and disposed in communication with the controller; and

a pressure sensor associated with an inlet side of the second heat exchanger and disposed in communication with the controller, wherein the instructions cause the controller to vary speed of at least one of the fan and the compressor based on (a) temperature at the outlet end of the second heat exchanger, and (b) pressure at the inlet end of the second heat exchanger.

13. A method of controlling humidity in a conditioned space, comprising:

at a variable speed vapor compression system having a compressor, a first heat exchanger connected to the compressor, an expansion valve connected to the first heat exchanger, a second heat exchanger connecting the expansion valve to the compressor, a fan associated with the second heat exchanger, and a controller operatively connected to the compressor and the fan,

receiving a target humidity range for a conditioned space;

receiving a sensed humidity for the conditioned space;

comparing the sensed humidity to the target humidity range; and

varying speed of at least one of the fan and the compressor based on the comparison of the sensed humidity and the target humidity range.

14. The method as recited in claim 13, further comprising reducing compressor speed when the sensed humidity is within the target humidity range.

15. The method as recited in claim 13, further comprising increasing compressor speed when the sensed humidity is outside of the target humidity range.

16. The method as recited in claim 13, further comprising:

varying fan speed when the sensed humidity is within the target humidity range; and

varying fan speed when the sensed humidity is outside the target humidity range.

17. The method as recited in claim 13, wherein varying speed of at least one of the fan and the compressor includes toggling the vapor compression system between a comfort mode and an efficiency mode.

18. The method as recited in claim 13, further comprising automatically toggling between a first efficiency range and a second efficiency range.

19. The method as recited in claim 18, wherein the first efficiency range has a higher peak efficiency than the second efficiency range.

20. A computer program product tangibly embodied on a computer readable medium, the computer program product including instructions that, when executed by a processor, cause the processor to perform operations comprising:

receive a target humidity range for a conditioned space;

receive a sensed humidity for the conditioned space;

compare the sensed humidity to the target humidity range; and

vary speed of at least one of a fan and a compressor based on the comparison of the sensed humidity and the target humidity range.