US20150052914A1

US20150052914A1 - System and Method for Using an Electronic Expansion Valve to Control a Discharge Pressure in a Multi-Purpose HVAC System

Info

Publication number: US20150052914A1
Application number: US14/307,821
Authority: US
Inventors: Derek Leman; Aaron M. Bright; Matthew Austin
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2013-08-22
Filing date: 2014-06-18
Publication date: 2015-02-26

Abstract

A method for using an electronic expansion device in a system for heating water and conditioning an interior space by operating a first controller to monitor the operating discharge pressure from the compressor; and operating the first controller to produce a signal designating expansion of an orifice within the electronic expansion valve when the operating discharge pressure is greater than or equal to a predetermined pressure value.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to, and claims the priority benefit of, U.S. Provisional Patent Application Ser. No. 61/869,017 filed Aug. 22, 2013, the contents of which are hereby incorporated in their entirety into the present disclosure

TECHNICAL FIELD OF THE DISCLOSED EMBODIMENTS

The presently disclosed embodiments generally relate to systems for heating water and conditioning an interior space, and more particularly, to a system and method for using an electronic expansion valve to control a discharge pressure in a multi-purpose heating, ventilation, and air-conditioning (HVAC) system.

BACKGROUND OF THE DISCLOSED EMBODIMENTS

A typical water heater for residential hot water production and storage is an electrical resistance water heater and storage tank, although gas water heaters are also used to heat water in a storage tank. Water heaters typically include a storage tank defining a chamber for retention of water. A water inlet pipe is provided with a first connection for interconnection with a cold water supply line that conveys fresh, relatively cold water into the storage tank. In the case of electrical resistance water heaters, there are electrical resistance elements, within the storage tank, that heat the water.
An alternative method for heating water is an active desuperheater water heater. In one example of an active desuperheater water heater, the active desuperheater water heater uses a small pump to circulate water from a water storage tank, through a heat exchanger, and back into the water storage tank. The active desuperheater water heater intercepts the superheated hot gas that is rejected from an air conditioner or heat pump compressor, sitting outside the home, and transfers the heat to the water circulating through the heat exchanger. The active desuperheater water heater works only when the air conditioner or heat pump is operating in a cooling mode.
Another alternative method for heating water is a heat pump water heater. A heat pump water heater contains a fan, compressor, and an evaporator configured to sit on top of the water storage tank. The heat pump water heater circulates a refrigerant through an evaporator and compressor, and uses a fan and evaporator to pull heat from air surrounding the heat pump water heater in order to heat the refrigerant. The heated refrigerant runs through a condenser coil within the water storage tank, transferring heat to the water stored therein.
Yet another alternative method for heating water is a HVAC system coupled with a water heater module to form a multi-purpose system. This multi-purpose system utilizes a water heater module to divert a refrigerant to an indoor unit assembly when conditioning an interior space, or to the water heater module's heat exchanger when heating water. The outdoor heat pump circulates a refrigerant through an evaporator and compressor, and uses a fan and the evaporator to pull heat from air surrounding the heat pump in order to heat the refrigerant. The heated refrigerant runs through the water heater module heat exchanger, transferring heat to water also circulating through the water heater module heat exchanger.
During water heating operation, the operating discharge pressure within the outdoor heat pump may increase to levels that make the water heating cycle inefficient at a minimum, or may cease operation of the system. Generally, to control the discharge pressure, a thermostatic expansion valve is used to regulate the refrigerant flow into the evaporator. Generally, the function of the thermostatic expansion valve is to hold a constant evaporator superheat. When set and operating properly, the thermostatic expansion valve will keep the evaporator active throughout its entire length. However, use of a thermostatic expansion valve in a multi-purpose system requires use of additional valves to relieve pressure throughout the system for optimal performance. Therefore, there is a need for a method to use an expansion device to control the operating discharge pressure in a multi-purpose HVAC system to increase optimal performance.

SUMMARY OF THE DISCLOSED EMBODIMENTS

In one aspect, a method for using an electronic expansion device to control an operating discharge pressure in a multi-purpose HVAC system is provided. In one embodiment, the method includes the step of operating the multi-purpose HVAC system in a water heating mode. In one embodiment, the multi-purpose HVAC system includes an outdoor unit assembly including a compressor, a first controller and an electronic expansion device, operably coupled to a water heater module, the water heater module including at least one valve. In one embodiment, the at least one valve includes a pair of three way valves. In one embodiment, the multi-purpose HVAC system is configured to circulate a refrigerant from the outdoor unit assembly through the water heater module, and return to the outdoor unit assembly. In one embodiment, operating the multi-purpose HVAC system in a water heating mode generally includes operating one or more of the at least one valves to configure a refrigerant circuit. For example, a refrigerant circuit is generally configured by a second controller commanding one or more of the at least one valves to be placed in an open state, and commanding one or more of the at least one valves to be placed in a closed state.
The method includes the step of operating the first controller to monitor the operating discharge pressure from the compressor. The method includes the step of operating the first controller to produce a signal designating expansion of an orifice within the electronic expansion device when the operating discharge pressure is greater than or equal to a predetermined pressure value.
In one embodiment, the method includes the step of operating the first controller to remove the signal designating expansion of the orifice within the electronic expansion device when the operating discharge pressure is less than the predetermined pressure value. In another embodiment, the first controller removes the signal designating expansion of the orifice within the electronic expansion device when the multi-purpose HVAC system stops operating in the water heating mode. In another embodiment, the first controller removes the signal designating expansion of the orifice within the electronic expansion device when the orifice reaches a maximum opening size.
In one aspect, a multi-purpose HVAC system for heating water and conditioning an interior space is provided. In one embodiment, the multi-purpose HVAC system includes an outdoor unit assembly including a compressor, a first controller, and an electric expansion device, an indoor unit assembly, a water heater module including, at least one valve and a second controller, a plurality of conduits fluidically coupling the water heater module to the outdoor unit assembly and the indoor unit assembly. The second controller is configured to operate the outdoor unit assembly and the water heater module in a water heating mode. In one embodiment, the second controller is configured to operate the at least one valve to configure at least one refrigerant circuit. In one embodiment, the at least one valve includes a pair of three way valves.
In one embodiment, the at least one valve includes a first valve, a first conduit coupling the first valve to an inlet of the heat exchanger, a second valve, a second conduit coupling the second valve to an outlet of the heat exchanger, a third valve, a third conduit coupling the third valve to the first valve, a fourth valve, a fourth conduit coupling the fourth valve to the second valve, wherein the second controller is configured to open the first and second valves and close the third and fourth valves to configure the refrigerant circuit.
In one embodiment, the first controller is configured to monitor the operating discharge pressure from the compressor. In one embodiment, the first controller is configure to produce a signal designating expansion of an orifice within the electronic expansion valve when the operating discharge pressure is greater than or equal to a predetermined pressure value.
In one embodiment, the first controller is configured to remove the signal designating expansion of the orifice within the electronic expansion valve when the operating discharge pressure is less than the predetermined pressure value. In another embodiment, the first controller is configured to remove the signal designating expansion of the orifice within the electronic expansion device when the multi-purpose HVAC system stops operating in the water heating mode. In another embodiment, the first controller is configured to remove the signal designating expansion of the orifice within the electronic expansion device when the orifice reaches a maximum opening size.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments and other features, advantages and disclosures contained herein, and the manner of attaining them, will become apparent and the present disclosure will be better understood by reference to the following description of various exemplary embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a system for heating water and conditioning an interior space in one embodiment;

FIG. 2 is a method for using an electronic expansion device to control a discharge pressure in a system for heating water and conditioning an interior space in an exemplary embodiment;

FIG. 3 is a method for using an electronic expansion device to control a discharge pressure in a system for heating water and conditioning an interior space in an exemplary embodiment; and

FIG. 4 is a method for using an electronic expansion device to control a discharge pressure in a system for heating water and conditioning an interior space in an exemplary embodiment.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended.
FIG. 1 illustrates a multi-purpose system for heating water and conditioning an interior space, utilizing an embodiment of the present disclosure, and indicated generally at 10. Particularly, the multi-purpose system 10 includes a water heater module 12 operably coupled to an outdoor unit assembly 14 and an indoor unit assembly 16.
In one embodiment, outdoor unit assembly 14 includes a heat exchanger 18, a compressor 20, a fan 22, a first controller 24, and an electronic expansion device 26 including an orifice (not shown). The first controller 24 is in electrically coupled to the compressor 20, fan 224, and the electronic expansion device 26 for control thereof. The first controller 24 provides the outdoor unit assembly 14 with a variety of operation modes and control sequences to execute instructions during one of a heating mode and a cooling mode. Outdoor unit assemblies 14 include, but are not limited to air-to-air or ground source heat pumps. The electronic expansion device 26 is fluidically coupled to an outdoor unit assembly return connector 28 via a conduit 30. The electronic expansion device 26 generally controls the amount of refrigerant flow into the heat exchanger 18, thereby controlling the superheating at the outlet of the heat exchanger 18. Outdoor unit assembly 14 is fluidically coupled to the outdoor unit assembly supply connector 32 via a conduit 34.
In one embodiment, water heater module 12 includes a heat exchanger 36 configured to allow a refrigerant to circulate therethrough. It will be appreciated that the heat exchanger 36 may be external of the water heater module 12. The water heater module 12 includes a plurality of valves 38A-D configured to direct the flow of the refrigerant therethrough. The refrigerant supply side inlet of heat exchanger 36 is coupled to valve 38A via a conduit 40. The refrigerant return side outlet of heat exchanger 36 is coupled to valve 38C via a conduit 42. A valve 38B is coupled to valve 38A via a conduit 44. A valve 38D is coupled to valve 38C via a conduit 46. The valves 38A and 38B are further coupled to an outdoor unit assembly supply connector 48 via a conduit 50. Valve 38B is further coupled to an indoor unit assembly supply connector 52 via a conduit 54. It will be appreciated that the valves 38A and 38B, together with the conduits 44, 50 and 54, function as a first three-way valve. The valves 38C and 38D are further coupled to the outdoor unit assembly return connector 28 via a conduit 56. Valve 38D is further coupled to an indoor unit assembly return connector 58 via a conduit 60. It will be appreciated that the valves 38C and 38D, together with the conduits 46, 56, and 60 function as a second three-way valve.
In one embodiment, water heater module 12 further includes a water pump 62 to draw water therein. Water pump 62 is coupled to a water supply connector 64 via a conduit 66. Water pump 62 is further coupled to heat exchanger 36 via a conduit 68. The water heater module 12 includes a water return connector 70, which is coupled to heat exchanger 16 via a conduit 72.
A second controller 74 is in electrical communication with each of the plurality of valves 38A-D and the water pump 62 for control thereof. The second controller 74 provides the water heater module 12 with a variety of operation modes and control sequences to execute instructions during one of an interior space conditioning mode and water heating mode.
Indoor unit assembly 16 includes a heat exchanger 76, an expansion device 78, and an indoor fan 80. Indoor unit assemblies 16 include, but are not limited to air handlers. Indoor unit assembly 16 is fluidically coupled to the indoor unit assembly return connector 58 via a conduit 82 and fluidically coupled to the indoor unit assembly supply connector 52 via a conduit 84.
Water heater module 12 is in electrical communication with outdoor unit assembly 14 and indoor unit assembly 16 via a wired or wireless connection (not shown). Water heater module 12 generally operates to switch outdoor unit assembly 14 and indoor unit assembly 16 between an interior space conditioning mode and a water heating mode.
A water storage tank such as the tank 86 is configured to produce a signal to indicate when a water heating mode should be initiated. Water storage tank 86 is fluidically coupled to the water supply connector 64 via a conduit 88 and fluidically coupled to the water return connector 70 via a conduit 90. During a demand to heat water, water storage tank 86 is configured to send a signal to water heater module 12 to operate in a water heating mode. During use, water exits water storage tank 86 via domestic supply line 92, and returns via domestic return line 94.
FIG. 2 illustrates an exemplary method 100 for using an electronic expansion device 26 to control a discharge pressure in a multi-purpose system 10 for heating water and conditioning an interior space. Method 100 includes the step 102 of operating the multi-purpose system 10 in a water heating mode. In one embodiment, the multi-purpose system 10 generally operates in a water heating mode by operating one or more of the at least one valves 38A-D to configure at least one refrigerant circuit. For example, the at least one refrigerant circuit may be configured by the second controller 74 commanding valves 38A and 38C to be placed in an open state, and commanding valves 38B and 38D to be placed in a closed state. In one embodiment, outdoor unit assembly 14 is configured to circulate a refrigerant from the compressor 20 and into conduit 34. The refrigerant generally enters the water heater module 12 through outdoor unit assembly supply connector 48, wherein the refrigerant is directed through valve 38A and circulates through heat exchanger supply conduit 40. The refrigerant generally circulates through heat exchanger 36 and exits heat exchanger 36 via heat exchanger return conduit 42. The refrigerant is generally directed through valve 38C, and exits through outdoor unit assembly return connector 28. The refrigerant generally returns to outdoor unit assembly 14 via conduit 30 and through the electronic expansion device 26 and through heat exchanger 18. The refrigerant will continue to circulate through the at least one refrigerant circuit until the water heating demand is satisfied.
Step 104 includes operating the first controller 24 to monitor the operating discharge pressure from the compressor 20. The compressed refrigerant exits the compressor 20 at an operating discharge pressure. Over time, the operating discharge pressure may increase due to operating conditions. The first controller 24 determines the orifice (not shown) size setting of the electronic expansion device 26 based upon the outdoor ambient temperature and the orifice is held at that size until the operating discharge pressure reaches a predetermined pressure value set below a maximum safe pressure for the compressor 52.
If the operating discharge pressure is greater than or equal to the predetermined pressure value, as shown in step 106, the method continues to step 108, which comprises operating the first controller 24 to produce a signal designating expansion of the orifice within the electronic expansion device 26. Generally, to expand an orifice within the electronic expansion device 26, the first controller 24 produces a signal that is applied to a motor (not shown) within the electronic expansion device 26, wherein the motor is used to open and close the orifice In some embodiments, the motor rotates a fraction of a revolution for each signal sent by the first controller 24. Expanding the orifice within the electronic expansion device 26 allows more refrigerant to pass therethrough, thus, lowering the operating discharge pressure of the compressor 20.
In one embodiment, as shown in step 110, if the operating discharge pressure is less than the predetermined pressure value, the method continues to step 112, which comprises operating the first controller 24 to remove the signal designating expansion of the orifice within the electronic expansion device 26 so that the orifice size will be held at this position.
In another embodiment, as shown in FIG. 3, step 110 is replaced with step 110A, which determines if the multi-purpose HVAC system 10 has stopped operating in the water heating mode. If so, the first controller 24 removes the signal designating expansion of the orifice within the electronic expansion device 26 in step 112. When the multi-purpose HVAC system 10 stops operating in the water heating mode, the flow of refrigerant from the outdoor unit assembly 14 to the water heater module 12 is reduced, thus, lowering the operating discharge pressure of the compressor 20.
In another embodiment, as shown in FIG. 4, step 110 is replaced with step 110B, which determines whether the orifice has reached a maximum opening size. If so, the first controller 24 removes the signal designating expansion of the orifice within the electronic expansion device 26 in step 112. It will be appreciated that the first controller 24 and the second controller 74 may be combined into one controller.
It will be appreciated that the electronic expansion device 26 can expand the orifice therein to regulate the discharge pressure from the compressor 20 to keep the multi-purpose HVAC system 10 operating without the need for additional pressure relief devices.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.

Claims

What is claimed is:

1. A method for using an electronic expansion device to control an operating discharge pressure in a multi-purpose HVAC system including an outdoor unit assembly, the outdoor unit assembly including an electronic expansion valve, a compressor and a first controller, operably coupled to a water heater module, the water heater module including at least one valve, the multi-purpose HVAC system further, the method comprising the steps of:

(a) operating the multi-purpose HVAC system in a water heating mode;

(b) operating the first controller to monitor the operating discharge pressure from the compressor; and

(c) operating the first controller to produce a signal designating expansion of an orifice within the electronic expansion valve when the operating discharge pressure is greater than or equal to a predetermined pressure value.

2. The method of claim 1, further comprising:

(d) operating the first controller to remove the signal designating expansion of the orifice within the electronic expansion valve when the operating discharge pressure is less than the predetermined pressure value.

3. The method of claim 1, further comprising:

(d) operating the first controller to remove the signal designating expansion of the orifice within the electronic expansion valve when the multi-purpose HVAC system stops operating in a water heating mode.

4. The method of claim 1, further comprising:

(d) operating the first controller to remove the signal designating expansion of the orifice within the electronic expansion valve when the orifice reaches a maximum opening size.

5. The method of claim 1, wherein the at least one valve comprises a pair of three way valves.

6. The method of claim 1, wherein step (a) comprises a second controller operating one or more of the at least one valves to configure at least one refrigerant circuit.

7. The method of claim 6, wherein the at least one valve comprises:

a first valve coupled to an inlet of a heat exchanger via a first conduit;

a second valve coupled to an outlet of the heat exchanger via a second conduit;

a third valve coupled to the first valve via a third conduit;

a fourth valve coupled to the second valve via a fourth conduit;

wherein step (a) comprises opening the first and second valves and closing the third and fourth valves.

8. The method of claim 6, wherein the at least one refrigerant circuit circulates a refrigerant from the outdoor unit assembly, through the water heater module, and returns to the outdoor unit assembly.

9. A multi-purpose HVAC system comprising

an outdoor unit assembly including a first controller, a compressor, and an electronic expansion valve;

an indoor unit assembly;

a water heater module including at least one valve, a heat exchanger, and a second controller; and

a plurality of conduits operatively coupling the water heater module to the outdoor unit assembly and the indoor unit assembly;

wherein the first controller is configured to:

(a) operate the multi-purpose HVAC system in a water heating mode;

(b) monitor the operating discharge pressure from the compressor; and

(c) produce a signal designating expansion of an orifice within the electronic expansion valve when the operating discharge pressure is greater than or equal to a predetermined pressure value.

10. The multi-purpose HVAC system of claim 9, wherein the at least one valve comprises a pair of three way valves.

11. The multi-purpose HVAC system of claim 9, wherein step (a) comprises the second controller operating one or more of the at least one valves to configure at least one refrigerant circuit to circulate a refrigerant from the outdoor unit assembly through the water heater module, and returns to the outdoor unit assembly.

12. The multi-purpose HVAC system of claim 11, wherein the at least one valve comprises:

a first valve;

a first conduit coupling the first valve to an inlet of the heat exchanger;

a second valve;

a second conduit coupling the second valve to an outlet of the heat exchanger;

a third valve;

a third conduit coupling the third valve to the first valve;

a fourth valve;

a fourth conduit coupling the fourth valve to the second valve;

wherein the second controller is configured to open the first and second valves and close the third and fourth valves to configure the at least one refrigerant circuit.

13. The multi-purpose HVAC system of claim 9, wherein the first controller is configured to remove the signal designating expansion of the orifice within the electronic expansion valve when the operating discharge pressure is less than the predetermined pressure value.

14. The multi-purpose HVAC system of claim 9, wherein the first controller is configured to remove the signal designating expansion of the orifice within the electronic expansion valve when the multi-purpose HVAC system stops operating in a water heating mode.

15. The multi-purpose HVAC system of claim 9, wherein the first controller is configured to remove the signal designating expansion of the orifice within the electronic expansion valve when the orifice reaches its maximum opening size.