Patent Application
20200271364
The present disclosure relates generally to heat pump systems, and more particularly to the prevention of pressure spikes related to refrigerant from a charge compensator.
Some heat pump systems include low volume coils, such as microchannel coils, as indoor and outdoor coils. For example, microchannel coils can provide improved thermal performance and reduced refrigerant charge. Microchannel coils have relatively smaller volume that result in lower condenser refrigerant charge. However, in heat pump systems, such as packaged heat pump units, that utilize microchannel coils and a single, bidirectional thermal expansion device, a spike in the pressure of the refrigerant flow system can occur during the defrost cycle. In particular, the introduction of liquid refrigerant from the charge compensator to the refrigerant line downstream of the thermal expansion device (i.e., between the thermal expansion device and the indoor coil) can result in the thermal expansion device closing to compensate for a reduction of superheat in the indoor coil. The closing of the thermal expansion device can cause the pressure in the discharge line of the system to become excessively high, which can result in the heat pump system shutting down. Thus, a solution that prevents pressure spikes during defrost mode operations of heat pump systems that include low volume coils (e.g., microchannel coils) and a single bidirectional thermal expansion valve is desirable.
The present disclosure relates generally to heat pump systems, and more particularly to the prevention of pressure spikes related to refrigerant from a charge compensator. In some example embodiments, a pressure spike prevention assembly for use in a heat pump system includes a thermostatic expansion valve that includes a first port and a second port. The first port is designed to be fluidly coupled to an indoor coil, and the second port is designed to be coupled to an outdoor coil. The pressure spike prevention assembly further includes a multi-way valve that includes an inlet port, an output port, and a liquid line port. The inlet port is fluidly coupled to the first port. The output port is fluidly in communication with the second port. The liquid line port is configured to be fluidly coupled to a charge compensator of the heat pump system via a liquid line of the heat pump system.
In another example embodiment, a heat pump system includes a charge compensator and a thermostatic expansion valve that includes a first port and a second port. The heat pump system further includes a multi-way valve that includes an inlet port, an output port, and a liquid line port. The inlet port is fluidly coupled to the first port. The output port is fluidly in communication with the second port. The liquid line port is fluidly coupled to the charge compensator via a liquid line of the heat pump system.
In another example embodiment, a method of operating a heat pump system that includes a pressure spike prevention assembly includes controlling, by a control unit, a multi-way valve to provide a first flow path for a refrigerant to flow from an indoor coil to a charge compensator through an inlet port of the multi-way valve and a liquid line port of the multi-way valve during a heating mode operation of the heat pump system. The method further includes controlling, by the control unit, the multi-way valve to provide a second flow path for the refrigerant to flow from the charge compensator to a thermostatic expansion valve through the liquid line port of the multi-way valve and an outlet port of the multi-way valve during a cooling or defrost mode operation of the heat pump system.
These and other aspects, objects, features, and embodiments will be apparent from the following description and the appended claims.
Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The drawings illustrate only example embodiments and are therefore not to be considered limiting in scope. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or placements may be exaggerated to help visually convey such principles. In the drawings, the same reference numerals that are used in different drawings may designate like or corresponding, but not necessarily identical elements.
In the following paragraphs, example embodiments will be described in further detail with reference to the figures. In the description, well-known components, methods, and/or processing techniques are omitted or briefly described. Furthermore, reference to various feature(s) of the embodiments is not to suggest that all embodiments must include the referenced feature(s).
In some example embodiments, a 3-way solenoid type valve that operates in conjunction with the reversing valve of a heat pump system may be used to force liquid refrigerant that is displaced from the charge compensator back into the refrigerant line of the system upstream of the metering device when the system operating mode changes from heating to defrost (which is the same as cooling mode). The use of the 3-way solenoid type valve enables the metering device to control the amount of liquid refrigerant from the charge compensator, and thus can prevent large amounts of liquid refrigerant from flowing to the indoor coil during defrost mode.
Turning now to the figures, particular example embodiments are described.
In some example embodiments, the multi-way valve 104 may be a 3-way valve. For example, the multi-way valve 104 may be a 3-way solenoid valve. For example, the multi-way valve 104 may include an inlet port 110, an outlet port 112, and a liquid line port 114 that may each extend into and/or outside of the cavity of the multi-way valve 104. The first port 110 may be designed to be fluidly coupled to an indoor coil of a heat pump system. The second port 112 may be designed to be fluidly coupled to an outdoor coil of a heat pump system. The liquid line port 114 may be designed to be fluidly coupled to a charge compensator of a heat pump system. In
In some example embodiments, the first port 124 of the thermal expansion valve 102 may be in fluid communication with the inlet port 110 of the multi-way valve 104. To illustrate, a refrigerant pipe 108 may be connected to the first port 124 of the thermal expansion valve 102, and a refrigerant pipe 116 that is connected to the inlet port 110 of the multi-way valve 104 at one end may be connected to the pipe 108.
In some example embodiments, the second port 126 of the thermal expansion valve 102 may be in fluid communication with the outlet port 112 of the multi-way valve 104. To illustrate, a refrigerant pipe 106 may be connected to the second port 126 of the thermal expansion valve 102. A refrigerant pipe 118 that is connected to the outlet port 112 of the multi-way valve 104 may be connected to the pipe 106.
In some example embodiments, the multi-way valve 104 is configured as shown in
When the pressure spike prevention assembly 100 is configured for the defrost mode operation as shown in
In some example embodiments, the configuration of the pressure spike prevention assembly 100 shown in
By providing a mechanism that allows the thermal expansion valve 102 to control the flow of liquid refrigerant from a charge compensator to an evaporator/indoor coil, the pressure spike prevention assembly 100 can prevent pressure spikes in a heat pump and avoid system shutdown. As described below, the pressure spike prevention assembly 100 can prevent pressure spikes during defrost mode operations without disrupting system refrigerant flow during heating mode operations.
In some example embodiments, the pressure spike prevention assembly 100 may be included in a packaged heat pump system. In some alternative embodiments, the thermal expansion valve 102 and the multi-way valve 104 may be fluidly coupled using a different configuration of refrigerant pipes than shown in
In some example embodiments, when the pressure spike prevention assembly 100 is included in a heat pump system, the pipe 108 may be fluidly coupled to an indoor coil, and the pipe 106 may be fluidly coupled to an outdoor coil. In the configuration of the pressure spike prevention assembly 100 shown in
In some example embodiments, the refrigerant pipe 116 is fluidly coupled to the refrigerant pipe 108 such that some of the refrigerant in the pipe 108 can be diverted through the multi-way valve 104 to a charge compensator, for example, until the charge compensator is full. Such a configuration of the multi-way valve 104 allows a charge compensator of heat pump system to operate as intended by holding some of the system refrigerant during heating mode operations.
By allowing a flow of refrigerant through the thermal expansion valve 102 and some refrigerant to flow through the multi-way valve 104 during heating mode operations, the pressure spike prevention assembly 100 allows normal heating mode operations of a heat pump system while preventing pressure spikes during defrost mode operations as described with respect to
In some example embodiments, the heat pump system 300 may also include a compressor 306, a reversing valve 308, and a charge compensator 310. In the defrost mode configuration of the heat pump system 300 shown in
In some example embodiments, the charge compensator 310 is fluidly coupled to the multi-way valve 104 such that refrigerant that accumulated in the charge compensator 310 flows to the multi-way valve 104. For example, the liquid line port of the charge compensator 310 may be fluidly coupled to the liquid line port 114 of the multi-way valve 104 via the liquid line 312, and refrigerant may flow from the charge compensator 310 to the multi-way valve 104 via the liquid line 312. To illustrate, refrigerant may accumulate in the charge compensator 310 during heating mode operations of the heat pump system 300, and the accumulated liquid refrigerant may flow out of the charge compensator 310 during defrost mode operations. Because the multi-way valve 104 provides a flow path from the liquid line port 114 to the outlet port 112, the refrigerant that flows from the charge compensator 310 to the multi-way valve 104 through the liquid line port 114 flows out of the multi-way valve 104 through the outlet port 112. The refrigerant that flows out through the outlet port 112 flows into the thermal expansion valve 102 via the second port 126 of the thermal expansion valve 102.
In some example embodiments, the thermal expansion valve 102 is in fluid communication with the indoor coil 302 via a refrigerant pipe 318 that is downstream from the thermal expansion valve 102 based on the direction of refrigerant flow during the defrost mode operation of the heat pump system 300. The thermal expansion valve 102 is also in fluid communication with the outdoor coil 304 via a refrigerant pipe 314 that is upstream from thermal expansion valve 102. To illustrate, refrigerant from the outdoor coil 304 flows into the thermal expansion valve 102 via the second port 126 of the thermal expansion valve 102.
The thermal expansion valve 102 controls the flow of refrigerant from the outdoor coil 304 to the indoor coil 302 through the thermal expansion valve 102. The thermal expansion valve 102 also controls the flow of refrigerant from the charge compensator 310 to the indoor coil 302 through multi-way valve 104 and the thermal expansion valve 102. Because the inlet port 110 of the multi-way valve 104 is closed in the defrost mode configuration of the pressure spike prevention assembly 100, the refrigerant that flows out of the thermal expansion valve 102 flows to the indoor coil 302 without disruption by the multi-way valve 104. The thermal expansion valve 102 may adjust the refrigerant flow from the outdoor coil 304 and the charge compensator 310 to the indoor coil 302 based on superheat sensing, for example, by the sensing bulb 120.
In some example embodiments, a control unit 316 may control changes in the configuration of the heat pump system 300 between heating mode and defrost/cooling mode. For example, the control unit 316 may provide one or more electrical signals to the multi-way valve 104 and the reversing valve 308 to change the configurations of the multi-way valve 104 and the reversing valve 308. By changing the configurations of the multi-way valve 104 and the reversing valve 308, the control unit 316 may control the directions of refrigerant flow in the heat pump system 300. The control unit 316 may control the configuration changes based on indications from one or more thermostats as can be readily understood by those of ordinary skill in the art with the benefit of this disclosure. In some example embodiments, the control unit 316 may include a controller and components, such as a microcontroller and other supporting components (e.g., a memory device), to perform the operations of the control unit 316 described herein.
By routing the refrigerant from the charge compensator 310 to the upstream side of the thermal expansion valve 102 through the multi-way valve 104, the pressure spike prevention assembly 100 enables the thermal expansion valve 102 to control the flow of refrigerant from the charge compensator 310 to the indoor coil 302. Because the superheat in the suction line to the compressor 306 is dependent on the amount of refrigerant that flows through the thermal expansion valve 102 and because the refrigerant from the charge compensator 310 is routed through the thermal expansion valve 102 along with the refrigerant from the outdoor coil 304, the multi-way valve 104 enables the thermal expansion valve 102 to avoid pressure spikes that may otherwise result in the compressor 306 being shut down.
The same configuration of the heat pump system 300 shown in
In
By allowing the refrigerant from the indoor coil 302 to flow through the thermal expansion valve 102 to the outdoor coil 304 and by allowing some refrigerant to flow to the charge compensator 310 through the multi-way valve 104, the pressure spike prevention assembly 100 enables the heat pump system 300 to operate in normal heating mode.
At step 504, the method 500 may include controlling, by the control unit 316, the multi-way valve 104 to provide a second flow path for the refrigerant to flow from the charge compensator 310 to the thermostatic expansion valve 102 through the liquid line port 114 of the multi-way valve 104 and the outlet port 112 of the multi-way valve 104 during a cooling or defrost mode operation of the heat pump system 300.
In some example embodiments, the method 500 may include controlling, by the control unit 316, the reversing valve 308 such that a discharge port of the compressor 306 is fluidly coupled to the charge compensator 310 through the reversing valve 308 during the cooling or defrost mode operation of the heat pump system 300. To illustrate, during the cooling or defrost mode operation of the heat pump system 300, the refrigerant from the discharge port of the compressor 306 flows to the charge compensator 310 through the reversing valve 308.
In some example embodiments, the method 500 may also include controlling, by the control unit 316, the reversing valve 308 such that the discharge port of the compressor 306 is fluidly coupled to the indoor coil 302 through the reversing valve 308 during the heating mode operation of the heat pump system 300. To illustrate, during the heating mode operation of the heat pump system 300, the refrigerant from the discharge port of the compressor 306 flows to the indoor coil flows through the reversing valve 308.
In some alternative embodiments, the method 500 may include more or fewer steps than described above. In some example embodiments, some of the steps of the method 500 may be performed in a different order than described above.
Although particular embodiments have been described herein in detail, the descriptions are by way of example. The features of the embodiments described herein are representative and, in alternative embodiments, certain features, elements, and/or steps may be added or omitted. Additionally, modifications to aspects of the embodiments described herein may be made by those skilled in the art without departing from the spirit and scope of the following claims, the scope of which are to be accorded the broadest interpretation so as to encompass modifications and equivalent structures.
