Patent Application
20240247845
This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the presently described embodiments—to help facilitate a better understanding of various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In general, heating, ventilation, and air-conditioning (“HVAC”) systems circulate an indoor space's air over low-temperature (for cooling) or high-temperature (for heating) sources, thereby adjusting an indoor space's air temperature and humidity. HVAC systems generate these low- and high-temperature sources by, among other techniques, taking advantage of a well-known physical principle: a fluid transitioning from gas to liquid releases heat, while a fluid transitioning from liquid to gas absorbs heat.
Within a typical HVAC system, a fluid refrigerant circulates through a closed loop circuit of tubing that uses a compressor or compressors and other flow-control devices to manipulate the refrigerant's flow and pressure, causing the refrigerant to cycle between the liquid and gas phases. Generally, these phase transitions occur within the HVAC's heat exchangers, which are part of the closed loop and designed to transfer heat between the circulating refrigerant and flowing ambient air or another secondary fluid. As would be expected, the heat exchanger providing heating or cooling to the climate-controlled space or structure is described as being “indoor,” and the heat exchanger transferring heat with the surrounding outdoor environment is described as being “outdoor.”
Heat pump systems and electrification are the most recent fast-growing trends within the heating, ventilation, and air conditioning (“HVAC”) industry. A combination of factors including an increased emphasis on reducing combustion-based heating and reliance on fossil fuels, and the expansion of using heat pump (“HP”) systems in cold climates necessitates heat-pump systems with improved thermal performance at low temperatures.
A reversible heat pump is a refrigerant system where the flow of refrigerant in the circuit is reversible to operate in either a cooling mode or a heating mode. Reversible heat pump systems (generally referred to herein simply as “heat pumps”) work in either direction to provide heating or cooling to the internal space. In the cooling mode, the heat pump system operates like a typical air conditioner system, i.e., a refrigerant flows through an HVAC circuit where the refrigerant is compressed in a compressor and delivered to a condenser (or an outdoor heat exchanger). In the condenser, heat is exchanged between a medium such as outdoor air, water, or the like and the refrigerant. From the condenser, the refrigerant passes to an expansion valve, at which the refrigerant is expanded to a lower pressure and temperature, and then to an indoor heat exchanger. In the indoor heat exchanger, heat is exchanged between the refrigerant and the indoor air, to condition the indoor air and evaporate the refrigerant. When the refrigerant system is operating, the indoor heat exchanger cools the air that is being supplied to the indoor environment. In addition, as the temperature of the indoor air is lowered, moisture usually is also taken out of the air. In this manner, the humidity level of the indoor air can also be controlled.
When a heat pump is used for heating, the heat pump employs the same basic refrigeration-type cycle used by an air conditioner or a refrigerator, but refrigerant flows through the HVAC circuit in the opposite direction, releasing heat into the conditioned space rather than the surrounding environment. Reversible heat pumps employ a reversing, or four-way, valve to reverse the flow of refrigerant from the compressor through the indoor and outdoor heat exchangers. In a heating mode, the outdoor heat exchanger is an evaporator and the indoor heat exchanger is a condenser. The refrigerant flowing from the outdoor heat exchanger carries the thermal energy from outdoor air (or source such as water, soil, etc.) indoors.
The refrigerant used in any HVAC system can also affect the performance of the system. Restrictions on the use of certain refrigerants in HVAC and refrigeration systems has accelerated the effort of adapting moderate to low Global Warming Potential (GWP) refrigerants such as lower flammability (A2L) refrigerants—as classified by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) or ISO817—as the replacement of high GWP refrigerants. For example, refrigerant R410A with a GWP of 2088 may be replaced with refrigerant R32 with a GWP of 677. However, the R32 refrigerant has a higher discharge temperature, about 20° F. higher than its counterparts R454B and R410A. Higher discharge temperatures may limit a compressor operating envelope, especially at the extreme conditions such is high ambient cooling, low ambient heating, and defrost, when the operation of the HVAC systems is the most critical and needed the most. Therefore, it is desirable to provide a system level countermeasure to reduce a discharge temperature of the compressor and extend the system operating envelope, without significant cost impact and increased component design complexity.
Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
Embodiments of the present disclosure generally relate to a heating, ventilation, and air-conditioning (“HVAC”) system for use with a refrigerant, the HVAC system including: a closed loop circuit of tubing forming a refrigeration circuit; a compressor fluidly connected to the circuit and operable to compress the refrigerant and discharge the refrigerant at a compressor discharge temperature; an outdoor heat exchanger fluidly connected to the circuit downstream of the compressor while the HVAC system is in a cooling mode; a cooling expansion valve fluidly connected in the closed loop circuit downstream of the outdoor heat exchanger in the cooling mode, the cooling expansion valve configured to reduce a pressure of the refrigerant flowing therethrough; an indoor heat exchanger fluidly connected in the circuit downstream of the cooling expansion valve in the cooling mode; and a first bypass line fluidly connecting the circuit from a first location downstream of the outdoor heat exchanger and upstream of the cooling expansion valve to a second location downstream of the indoor heat exchanger and upstream of the compressor, in the cooling mode. Some of the refrigerant is flowable through the first bypass line at the first location to bypass the cooling expansion valve and the indoor heat exchanger and recombinable with the refrigerant in the circuit at the second location to lower the compressor discharge temperature as compared to not flowing the refrigerant through the first bypass line.
One or more embodiments relate to a method of operating a heating, cooling, and air conditioning (HVAC) system. The method includes: condensing high-pressure refrigerant in an outdoor heat exchanger of the HVAC system in a cooling mode of the HVAC system; separating the high-pressure refrigerant at a first location downstream of the outdoor heat exchanger and upstream of a cooling expansion valve such that a first portion of the refrigerant flows through a first bypass line and a second portion of the refrigerant flows to the cooling expansion valve, when the HVAC system is in the cooling mode; reducing the pressure of the second portion of the refrigerant exiting the condenser to a low-pressure refrigerant in the cooling expansion valve of the HVAC system, when the HVAC system is in the cooling mode; evaporating the second portion of the refrigerant in an indoor heat exchanger of the HVAC system; combining the second portion of the refrigerant from the indoor heat exchanger with the first portion of the refrigerant from the first bypass line at a second location downstream of the indoor heat exchanger and upstream of a compressor, in the cooling mode to form a combined refrigerant; compressing the combined refrigerant with the compressor of the HVAC system, the compressor comprising a discharge temperature; and lowering the discharge temperature of the compressor with the combined refrigerant as compared to not flowing the refrigerant through the first bypass line.
Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.
These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings.
One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
The present disclosure describes heating, ventilation, and air-conditioning (“HVAC”) systems having a refrigerant bypass. The refrigerant bypass lowers a temperature of refrigerant entering a compressor and, in turn, reduces a temperature of the refrigerant discharged from the compressor. The reduced temperature of the refrigerant discharged from the compressor increases compressor reliability and HVAC system performance envelope. The refrigerant bypass allows a portion of the refrigerant to bypass the expansion valve and indoor heat exchanger, in either a cooling mode or heating mode.
The HVAC system 100 includes an outdoor heat exchanger 102, which includes components for transferring heat with the environment external to the structure, an indoor heat exchanger 106, which mainly includes components for transferring heat with the air inside the structure, a cooling expansion valve 108, a compressor 104, and a bypass line 110. Refrigerant flows through the HVAC system 100 in a closed loop circuit of tubing connecting the components of the HVAC system 100. The HVAC system 100 may include fans (not shown) operable to blow air over the indoor heat exchanger 106 and/or the outdoor heat exchanger 102.
Using the compressor as a reference point for the beginning of the refrigeration cycle, the compressor 104 operates to increase the pressure of the refrigerant by compressing refrigerant into high temperature, high-pressure gas refrigerant. The compressor 104 then discharges the refrigerant to cycle through the rest of the closed loop circuit.
In a cooling mode, refrigerant flows from the compressor 104 to the outdoor heat exchanger 102 where the refrigerant is condensed, transitioning the refrigerant from a high-pressure gas to a high-pressure liquid by releasing heat to the environment external to the structure and lowering the temperature of the refrigerant. From the outdoor heat exchanger 102, the high-pressure liquid refrigerant then flows to the cooling expansion valve 108 where the refrigerant is expanded from high-pressure refrigerant to low-pressure refrigerant. The low-pressure refrigerant then flows to the indoor heat exchanger 106, where the refrigerant is evaporated by absorbing heat from the indoor environment. The indoor heat exchanger 106 thus acts as an evaporator, aiding transition of the refrigerant from a low-pressure liquid to a low-pressure gas. In doing so, the indoor heat exchanger 106 acts as a cooling element that removes heat from inside the structure. The low-pressure refrigerant then flows to the compressor 104 and the cycle repeats.
Heating may be provided independently by another source, such as, but not limited to, a gas furnace. Alternatively, the HVAC system could be configured as a reversible heat pump system to add or remove heat from inside the structure such as in the embodiments discussed below. In other embodiments, there may be no heating of any kind. HVAC systems that use refrigerant to both heat and cool the structure are often described as “heat pumps,” while systems that use refrigerant only for cooling are commonly described as “air conditioners.”
With reference to the direction of refrigerant flow in the cooling mode, the bypass line 110 extends from a first location 101 downstream of the outdoor heat exchanger 102 and upstream of the cooling expansion valve 108 to a second location 103 downstream of the indoor heat exchanger 106 and upstream of the compressor 104. In this manner, the bypass line 110 fluidly connects the closed loop circuit from the first location 101 to the second location 103. The bypass line 110 may be any suitable conduit for flowing refrigerant within the HVAC system 100. In one embodiment, the bypass line 110 is a capillary tube. The bypass line 110 may also be manufactured from a rigid material such as copper, steel or brass. Alternatively, the bypass line 110 may have an internal layer of a flexible material, such as rubberized or elastomeric material such as nylon or polytetrafluoroethylene (PTFE). Also alternatively, the bypass line 110 may be manufactured from a flexible material with a variable diameter based on a pressure differential across the bypass line 110.
Some of the liquid refrigerant is flowable through the bypass line 110 at the first location 101 to bypass the cooling expansion valve 108 and the indoor heat exchanger 106. By not flowing through the indoor heat exchanger 106, the refrigerant remains in the low-temperature liquid state after leaving the outdoor heat exchanger 102. The refrigerant is recombinable with the high-temperature gas refrigerant in the circuit from the indoor heat exchanger 106 at the second location 103 so as to reduce the overall temperature of the combined refrigerant flow. The lower temperature of the combined refrigerant flow allows for a lower temperature of the refrigerant entering the compressor, thus cooling the compressor and reducing the discharge temperature of the compressor 104 compared to not flowing the refrigerant through the bypass line 110. For example, the discharge temperature may be lowered from a range of 280° F. to 300° F. (138° C. to 149° C.) to a range of 260° F. to 270° F. (127° C. to 132° C.). The lower temperature of the combined refrigerant may also be used to maintain the discharge temperature of the compressor 104 below a maximum allowable threshold temperature, e.g., 275° F. (135° C.). At the same time, the bypass line 110 is sized to prevent “choking” the refrigerant flow in the bypass line 110 due to the refrigerant expanding in the bypass line 110. The bypass line 110 is also sized to bypass a minimum refrigerant flow when the compressor 104 is operating during normal operating conditions to avoid system performance degradation due to not flowing all the refrigerant through the indoor heat exchanger 106. System performance degradation could occur when less refrigerant flows through the indoor heat exchanger 106 as the overall capacity of the indoor heat exchanger 106 is diminished.
In one or more embodiments, an inner (or outer) diameter of the bypass line 110 may be predetermined, such that the bypass line 110 provides enough refrigerant during the high-pressure differential conditions to maintain a discharge temperature of the compressor 104 below an allowable limit set for the particular compressor and provides a minimum refrigerant flow during normal operating conditions. For example, during the normal operating conditions in the cooling mode, a suction pressure of the compressor 104 may be about 145 psi (1.00 kPa) and compressor discharge pressure may be about 400 psi (2,758 kPa), establishing a pressure differential of about 255 psi (1,758 kPa). However, at the high-pressure differential conditions such as high ambient temperature cooling, the discharge pressure of the compressor 104 may be about 630 psi (4,344 kPa), establishing the pressure differential of the compressor to be about 485 psi (3,344 kPa), or about 40% higher than during normal operations. The diameter of the bypass line 110 is sized to provide a minimum flow (or almost no flow) during normal operating conditions and a sufficient amount of flow during high-pressure differential conditions. In this way, the bypass line 110 enables the discharge temperature of the compressor 104 to be lowered and maintained within a desired operating range during all operating conditions. For example, the bypass line 110 may be sized in the range of 0.030 inches to 0.090 inches (0.762 mm to 2.286 mm).
The bypass line 110 thus provides a self-regulating mechanism to maintain the discharge temperature of the compressor 104 within the prescribed operating envelope by diverting a portion of liquid refrigerant from the indoor heat exchanger 106 and into the inlet of the compressor 104. Similar high-pressure differential conditions may be observed in a heating mode of operation when ambient temperatures external to the structure are low. Thus, sizing of the bypass line 110 should also be accounted for in reversible heat pump applications.
As shown, the HVAC system 200 includes a restriction 220 in the bypass line 210. The restriction 220 limits the flow rate of refrigerant through the bypass line 210, depending on the operating conditions (e.g., pressure differential) across the restriction 220. Thus, the restriction 220 reduces an amount of refrigerant flowing through the bypass line 210. The reduced diameter of the restriction 220 reduces the flow rate of refrigerant through the bypass line 210 and maintains the discharge temperature of the compressor 204 below the allowable limit set for the compressor. Controlling the amount of liquid refrigerant flowing through the bypass line 210 and the restriction 220 enables more precise control of the temperature of the refrigerant discharged by the compressor 204.
The diameters of the bypass line 210 and the restriction 220 depend on the size of the system and consequently the amount of refrigerant flowing through the bypass line 210. As an example, a diameter of the bypass line 210 may be in the range of 0.030 inches to 0.090 inches (0.762 mm to 2.286 mm) while the diameter of the restriction 220 may be in the range of 0.015 inches to 0.045 inches (0.381 mm to 1.143 mm). Including the restriction 220 with a precise diameter on the bypass line 210 also allows for a more forgiving diameter, diameter tolerance, and interior surface imperfection for the rest of the bypass line 210.
The flexible restriction 322 varies the flow rate of refrigerant through the flexible restriction 322. To do so, the flexible restriction 322 has a diameter which varies based on a pressure differential across the bypass line 310. The flexible restriction 322 may be fabricated from a material that expands when a fluid inside is pressurized. That is, the opening (e.g., internal diameter) of the flexible restriction 322 may increase relative to the pressure of the fluid. Thus, when the fluid is at a high pressure, the fluid may press against internal walls of the flexible restriction 322 and increase an opening or diameter of the flexible restriction 322 to allow more fluid to flow through the bypass line 310. When the pressure of the fluid is reduced, a force on the internal wall of the flexible restriction 322 may be reduced and thus the opening of the flexible restriction 322 may be reduced to allow less refrigerant to flow through the bypass line 310. Likewise, when the pressure of the fluid is increased, a force on the internal wall of the flexible restriction 322 may be increased and thus the opening of the flexible restriction 322 may be increased to allow less refrigerant to flow through the bypass line 310. Thus, the opening of the flexible restriction 322 is variable and proportionate to the pressure differential across the bypass line 310. Examples of suitable material for the flexible restriction include rubberized or elastomeric material such as nylon or polytetrafluoroethylene (PTFE).
The check valve 424 may be, for example, a mechanical check valve. In one or more embodiments, the check valve 424 is spring loaded. When a pressure differential across the check valve 424 exceeds a threshold, the pressure differential overcomes a spring force of the check valve 424 and the check valve 424 opens to allow refrigerant to flow through the bypass line 410. When the pressure differential across the check valve 424 is below the threshold, the check valve 424 closes. Thus, when the check valve 424 is open, refrigerant flows through the bypass line 410 to reduce the discharge temperature of the compressor 404. When the check valve 424 is closed, no refrigerant flows through the bypass line 410 and thus the discharge temperature of the compressor 404 is not reduced. Closing the check valve 424 enables the refrigerant to stay in the main closed-loop circuit when the compressor 404 is operating at lower demand conditions where the pressure differential across the check valve 424 is below the threshold. Further, when the check valve 424 is closed, no refrigerant can flow therethrough in from the second location 403.
The adjustable check valve 526 can be configured to allow an amount of refrigerant to flow therethrough in a manner proportional to the pressure differential across the adjustable check valve 526. To do so, the adjustable check valve 526 can have a variable spring force such that the amount of refrigerant flowing therethrough is proportional to the refrigerant pressure drop across the adjustable check valve 526. Like the mechanical check valve 424 of
The temperature sensor 632 may be installed to measure the temperature of the refrigerant being discharged from the compressor 604 and is thus located downstream of the compressor 604. Further, the temperature sensor 632 and the solenoid valve 630 may be connected to a relay 634. The relay 634 may control the solenoid valve 630 by sending a signal to open or close based on the temperature measured by the temperature sensor 632.
In at least one embodiment, the temperature sensor 632 is a temperature switch (e.g., a bi-metallic membrane). The solenoid valve 630 may open when the temperature at the bi-metallic membrane exceeds a pre-determined threshold. The solenoid valve 630 may close when the temperature at the bimetallic membrane is below the pre-determined threshold. In at least one embodiment, the solenoid valve 630 may be configured to open proportionally to the temperature measured by the sensor 632. For example, the higher the temperature measured by the sensor 632, the larger the opening of the solenoid valve 630. The solenoid valve thus allows more refrigerant through the bypass line 610 and reduces the discharge temperature of the compressor 604 when the discharge temperature of the compressor 604 is higher than the predetermined threshold. The solenoid valve 630 may be an ON/OFF solenoid valve, a proportional stepper motor solenoid valve, or a PWM (pulse width modulation) solenoid valve.
The temperature bulb 752 is positioned downstream of the compressor 704, e.g., connected to an output line of the compressor 704, to be affected based on the temperature of the refrigerant leaving the compressor 704. The temperature bulb 752 is in communication with the mechanical valve 750 and configured to communicate temperature-dependent pressure with mechanical valve 750. For example, as a temperature of the bulb 752 increases, a pressure within the bulb 752 increases. The mechanical valve 750 is controlled by the temperature bulb 752. For example, the temperature bulb 752 opens the mechanical valve 750 by exerting pressure on the valve 750 when the temperature of the bulb 752 is above a pre-determined threshold. The temperature bulb 752 closes the mechanical valve 750 when the temperature of the bulb 752 is at or below the pre-determined threshold. In at least one embodiment, the mechanical valve 750 can be adjusted to any position between open and closed based on the pressure communicated from the temperature bulb 752.
The mechanical valve 750 reduces the discharge temperature of the compressor 704 by allowing more refrigerant through the bypass line 710 when the discharge temperature of the compressor 704 increases and allowing less refrigerant through the bypass line 710 when the discharge temperature of the compressor 704 decreases. By adjusting the bulb 752 pressure charge, communication medium composition/formulation, and position (e.g., at the compressor 704 discharge or initial region of the outdoor heat exchanger 702 compared to at a later region of the outdoor heat exchanger 702), the degree of opening of the valve 750, and therefore the discharge temperature of the compressor 704, can be controlled.
The pressure tap 856 is connected to an output line (e.g., discharge) of the compressor 804. The pressure tap 856 is connected to the mechanical valve 854 and communicates pressure measured downstream of the compressor 804. The pressure tap 856 controls the opening of the mechanical valve 854 proportional to the pressure measured by the pressure tap 856. In at least one embodiment, the mechanical valve 854 can be adjusted to any position between open and closed based on the pressure communicated from the pressure tap 856. The mechanical valve 854 operates to allow more refrigerant through the bypass line 810 when the liquid refrigerant demand on the compressor 804 increases and the discharge pressure of the compressor 804 increases to further reduce the discharge temperature of the compressor 804.
The outdoor heat exchanger 902 is in the opposite state of the indoor heat exchanger 906 (e.g., absorbing or releasing heat). More specifically, in the heating mode, as shown in
The reversing valve 960 controls the direction of flow of the refrigerant within the system, allowing the system to both heat and cool the structure. The reversing valve 960 may be located, for example, within either the outdoor heat exchanger 902 or the indoor heat exchanger 906. The reversing valve 960 may be controlled by a control circuit to switch between cooling and heating modes of operation by changing the direction of the flow of refrigerant through the system 900.
In the cooling mode, the refrigerant flows from the outdoor heat exchanger 902 and splits upstream of the cooling expansion valve 964 at the first location 901. A first portion of the refrigerant flows through the bypass line 910 and a second portion of the refrigerant flows through the cooling expansion valve 964 and the indoor heat exchanger 906. The first and second portions of refrigerant are then recombined at the second location 903 to flow to the compressor 904. The combined refrigerant flow allows for a lower temperature of the refrigerant entering the compressor 904, thus cooling the compressor 904 and reducing the discharge temperature of the compressor 904 compared to not flowing the refrigerant through the bypass line 910. The compressor 904 then discharges the refrigerant to flow through the circuit again.
In one or more embodiments, any of the restriction 220 flexible restriction 322, mechanical check valve 424, adjustable check valve 526, solenoid valve 630, or mechanical valve 750 or 854 as discussed above may be disposed along the bypass line 910. Also, any of the temperature sensor 632, temperature bulb 752, or pressure tap 856 discussed above can be used to control the valves along the bypass line 910.
In the heating mode, the bypass line 910 extends from the first location 901 downstream of the indoor heat exchanger 906 and upstream of the heating expansion valve 962 to the second location 903 downstream of the outdoor heat exchanger 902 and upstream of the compressor 904. In this manner, the bypass line 910 fluidly connects the closed loop circuit from the first location 901 to the second location 903.
A first portion of the refrigerant is flowable through the bypass line 910 at the first location 901 to bypass the heating expansion valve 962 and the outdoor heat exchanger 902. A second portion of the refrigerant flows to the heating expansion valve 962 and then to the outdoor heat exchanger 902. The first portion and the second portion of the refrigerant flow to recombine at the second location 903 upstream of the compressor 904. The refrigerant discharged from the bypass line 910 is recombinable with the refrigerant in the circuit at the second location 903. Flowing the refrigerant through the bypass line 910 and recombining the refrigerant at the second location 903 lowers the discharge temperature of the compressor 904 compared to not flowing the refrigerant through the bypass line 910.
It should be understood that the reversible heat pump 900 depicted in
The second line 1072 fluidly connects the refrigerant circuit from a third location 1005 downstream of the outdoor heat exchanger 1002 and upstream of the cooling expansion valve 1064 to a fourth location 1007 downstream of the indoor heat exchanger 1006 and upstream of the compressor 1004.
Similar to
In one or more embodiments, any of the restriction 220 flexible restriction 322, mechanical check valve 424, adjustable check valve 526, solenoid valve 630, or mechanical valve 750 or 854 as discussed above may be disposed along the first bypass line 1070 or the second bypass line 1072. Also, any of the temperature sensor 632, temperature bulb 752, or pressure tap 856 discussed above can be used to control the valves along the first bypass line 1070 or the second bypass line 1072.
Further, the first bypass line 1070 and the second bypass line 1072 may include a mechanism (e.g., a valve) to prevent flow through the bypass line not being used for a current mode of operation. Consequently, each bypass line can be tuned to specific cooling or heating operating conditions. In the cooling mode, the refrigerant flows through the first bypass line 1070. Therefore, the second bypass line 1072 may include the mechanism to close the second bypass line 1072 to prevent the flow of refrigerant therethrough. A similar mechanism keeps the first bypass line 1070 open to allow the flow of refrigerant therethrough.
For the direction of refrigerant flow in the heating mode, the first bypass line 1070 extends from the first location 901 downstream of the indoor heat exchanger 1006 and upstream of the heating expansion valve 1062 to the second location 903 downstream of the outdoor heat exchanger 1002 and upstream of the compressor 1004. The second bypass line 1072 extends from the third location 905 downstream of the indoor heat exchanger 1006 and upstream of the heating expansion valve 1062 to the fourth location 907 downstream of the outdoor heat exchanger 1002 and upstream of the compressor 1004.
In the heating mode, a first portion of the refrigerant is flowable through the second bypass line 1072 at the third location 1005 to bypass the heating expansion valve 1062 and the outdoor heat exchanger 1002. A second portion of the refrigerant flows to the heating expansion valve 1062 and then to the outdoor heat exchanger 1002. The first portion and the second portion of the refrigerant flow recombine at the fourth location 1007 upstream of the compressor 1004. The refrigerant is recombinable with the refrigerant in the circuit at the second location 1003 to lower the discharge temperature of the compressor 1004 compared to not flowing the refrigerant through the second bypass line 1072. The compressor 1004 then discharges the refrigerant to flow through the circuit again.
In the heating mode, the refrigerant flows through the second bypass line 1072. Therefore, the first bypass line 1070 has the mechanism to close the first bypass line 1070 to prevent the flow of refrigerant through the first bypass line 1070. A similar mechanism keeps the second bypass line 1072 open to allow the flow of refrigerant through the second bypass line 1072.
The bi-flow expansion valve 1174 is configured to reduce a pressure of the refrigerant flowing through the valve in both cooling and heating modes of operation. The second bypass line 1172 is fluidically connected from a third location 1105 downstream of the bi-flow expansion valve 1174 and upstream of the indoor heat exchanger 1106 to a fourth location 1107 downstream of the indoor heat exchanger 1106 and upstream of the compressor 1104 in the cooling mode.
Similar to
In one or more embodiments, any of the restriction 220 flexible restriction 322, mechanical check valve 424, adjustable check valve 526, solenoid valve 630, or mechanical valve 750 or 854 as discussed above may be disposed along the first bypass line 1170 and the second bypass line 1172. Also, any of the temperature sensor 632, temperature bulb 752, or pressure tap 856 discussed above can be used to control the valves along the first bypass line 1170 and the second bypass line 1172.
The first bypass line 1170 and the second bypass line 1172 may also include a mechanism (e.g., a valve) to prevent flow through the bypass line not being used in either the cooling mode or the heating mode of operation. In another embodiment, a positive shutoff means is not required. For example, while one bypass line is being used, the opposite bypass line (the bypass line for the heating mode, when the system is operating in the cooling mode, and the bypass line for the cooling mode, when operating in the heating mode) would be at a low pressure. Under a low-pressure differential the refrigerant has a very low refrigerant mass flow rate through the opposite bypass line. Consequently, each bypass line can be tuned to specific cooling or heating operating conditions.
In the cooling mode, the refrigerant flows through the first bypass line 1170. Therefore, the second bypass line 1172 has the mechanism to keep it closed to prevent the flow of refrigerant through the second bypass line 1172. A similar mechanism keeps the first bypass line 1170 open to allow the flow of refrigerant through the first bypass line 1170. In another embodiment, the second bypass line 1172 is at a low-pressure differential, with very low refrigerant mass flow rate through the second bypass line 1172. Thus, the second tube bypass line 1172 does not require the shut-off mechanism described above. The opposite may be the case for the heating mode.
In the heating mode, the refrigerant flows through the second bypass line 1172. Therefore, the first bypass line 1170 has a mechanism to keep it closed to prevent the flow of refrigerant through the first bypass line 1170. A similar mechanism keeps the second bypass line 1172 open to allow the flow of refrigerant through the second bypass line 1172. In another embodiment, the first bypass line 1170 is at a low-pressure differential, with very low refrigerant mass flow rate through the first bypass line 1170. Thus, the second bypass line 1172 does not require the shut-off mechanism described above.
Similar to
In one or more embodiments, any of the restriction 220 flexible restriction 322, mechanical check valve 424, adjustable check valve 526, solenoid valve 630, or mechanical valve 750 or 854 as discussed above may be disposed along the first bypass line 1270 and the second bypass line 1272. Also, any of the temperature sensor 632, temperature bulb 752, or pressure tap 856 discussed above can be used to control the valves along the first bypass line 1270 and the bypass line 1272.
The first bypass line 1270 and the second bypass line 1272 may include a mechanism (e.g., a valve) to prevent flow through the bypass line not being used in either the cooling mode or the heating mode of operation. As shown in
In the cooling mode, the refrigerant flows through the first bypass line 1270. Therefore, the second bypass line 1272 has the mechanism to keep it closed to prevent the flow of refrigerant through the second bypass line 1272. A similar mechanism keeps the first bypass line 1270 open to allow the flow of refrigerant therethrough. In another embodiment, the second bypass line 1272 is at a low-pressure differential, with very low refrigerant mass flow rate through the second bypass line 1272. Thus, the second bypass line 1272 does not require the shut-off mechanism described above.
The second bypass line 1272 is disposed from the indoor heat exchanger 1206 outlet to the compressor 1204 inlet. For heating, the second bypass line 1270 extends from a third location 1205 downstream of the indoor heat exchanger 1206 and upstream of the cooling expansion valve 1264 to a fourth location 1207 downstream of the outdoor heat exchanger 1202 and upstream of the compressor 1204. In this manner, the second bypass line 1272 fluidly connects the closed loop circuit from the third location 1205 to the fourth location 1207.
A first portion of the refrigerant is flowable through the second bypass line 1272 at the third location 1205 to bypass the heating expansion valve 1262 and the outdoor heat exchanger 1202. A second portion of the refrigerant flows to the heating expansion valve 1262 and then to the outdoor heat exchanger 1202. The first portion and the second portion of the refrigerant flow to recombine at the fourth location 1207 upstream of the compressor 1204. The refrigerant is recombinable with the refrigerant in the circuit at the fourth location 1207 to lower the discharge temperature of the compressor 1204 compared to not flowing the refrigerant through the second bypass line 1272. The compressor 1204 then discharges the refrigerant to flow through the circuit again.
While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. For example, certain embodiments disclosed here envisage usage with a fan or no fan at all. Moreover, the rotating equipment (e.g., motors) and valves disclosed herein are envisaged as being operable at specified speeds or variable speeds through inverter circuitry, for example. Moreover, the internal and external control and communication with or among the components may be accomplished through wired and or wireless communications, including known communication protocols, Wi-Fi, 802.11(x), Bluetooth, to name just a few.
