Air source heat pump system with small temperature difference defrosting without shutdown

Abstract

The utility model relates to a kind of air source heat pump systems of small temperature difference defrosting exempt from shutdown.The system is additionally provided with first bypass branch and second bypass branch on refrigerant main circulation loop.System keeps running when defrosting, adjusts first bypass branch, distributes the refrigerant exhaust proportion of direct flow to evaporator and continues heat release in condenser, and mixed refrigerant medium-temperature superheated gas is obtained, enters evaporator and carries out small temperature difference defrosting;Second bypass branch is adjusted simultaneously, and compressor back gas is controlled, to ensure stable operation.Compared with prior art, the utility model realizes defrosting without shutdown by double bypass collaborative control;Without reversing four-way valve, system switches smoothly between heating and defrosting mode, reduces pressure fluctuation;System charging amount distribution changes little, and heating capacity can be quickly restored after defrosting;The defrosting heat source used is medium-low temperature refrigerant, reduces heat loss to environment, and defrosting efficiency is higher.

Description

Technical Field

[0001] This utility model relates to the field of heat pump defrosting technology, and in particular to an air source heat pump system that allows for defrosting with a small temperature difference without shutdown. Background Technology

[0002] Air source heat pump systems are highly efficient and energy-saving devices. Their basic principle is to utilize the phase change cycle of the refrigerant to "transfer" low-grade heat energy from outdoor air to indoor spaces for heating. Due to their high efficiency and environmental friendliness, they are widely used in building heating systems; however, their operation places extremely high demands on the system's stability and reliability.

[0003] In winter heating conditions, the surface temperature of the outdoor heat exchanger of an air source heat pump drops below 0°C, causing moisture in the air to condense into frost—an unavoidable physical phenomenon. This frost layer rapidly increases heat exchange resistance, blocks airflow channels, and leads to a sharp decline in the system's heating capacity and coefficient of performance (COP). If not removed promptly, a thick frost layer can also damage the heat exchanger, threatening the safe operation of the entire system.

[0004] To solve the frosting problem, the most widely used defrosting methods are reverse cycle defrosting and hot gas bypass defrosting. The principle of reverse cycle defrosting is to temporarily switch the system from heating mode to cooling mode, turning the outdoor unit into a high-temperature condenser for rapid defrosting. Hot gas bypass defrosting involves drawing a portion of high-temperature refrigerant vapor from the compressor's exhaust pipe and directly introducing it into the frosted outdoor unit to melt the refrigerant.

[0005] However, both of these mainstream defrosting methods have drawbacks. Reverse cycle defrosting requires frequent loop switching, causing drastic fluctuations in system pressure and temperature, affecting equipment stability and lifespan. Furthermore, its defrosting heat is essentially drawn from the original heating side (e.g., indoors), leading to fluctuations in the temperature of the fluid on the heating side. The main problem with hot gas bypass defrosting is that a large amount of liquid refrigerant accumulates in components such as the gas-liquid separator during defrosting. After defrosting, the system needs to wait for the refrigerant to migrate and rebalance, making rapid, continuous, and stable operation impossible, and it is prone to incomplete defrosting.

[0006] Furthermore, a common key issue is that both reverse cycle and hot gas bypass defrosting methods release heat to defrost by introducing high-temperature refrigerant into the frosted evaporator coils. However, during defrosting, a significant portion of this heat is directly dissipated into the surrounding low-temperature air through convection and other means. Studies have shown that the proportion of heat actually used for defrosting (i.e., defrosting efficiency) is generally only about 50%, resulting in significant energy waste.

[0007] In summary, the existing deficiencies constitute the key technical bottleneck restricting the efficient application of air source heat pumps in cold regions. Providing an air source heat pump system with a relatively simple structure, reliable control, and efficient defrosting without shutdown (continuous compressor operation) and without reversing the main refrigerant flow is a technical problem that urgently needs to be solved in this field. Utility Model Content

[0008] The purpose of this invention is to overcome the defects of the existing technology and provide an air source heat pump system with small temperature difference defrosting without shutdown. This system can perform defrosting operation without interrupting operation or switching flow direction, and ensures a smooth transition of system characteristics during the switching process between heating mode and defrosting mode.

[0009] Specifically: ① By setting a first regulating valve and coordinating it with a throttling element, the drastic fluctuations in the refrigerant charge distribution during the defrosting mode transition are effectively suppressed. This allows the system to quickly return to heating mode after exiting defrosting mode and rapidly rebuild effective heating capacity. ② By setting a second regulating valve, the superheat of the evaporator suction port is precisely controlled, ensuring stable operation of the system in defrosting mode for extended periods, thereby achieving thorough and complete melting of the frost layer on the evaporator surface. ③ The entire defrosting process uses medium-low temperature refrigerant for small-temperature-difference exothermic defrosting. Compared to existing high-temperature defrosting methods, this method significantly reduces the proportion of heat lost to the environment, allowing heat to be more concentrated on melting the frost layer, thus effectively improving the system's defrosting efficiency.

[0010] The objective of this utility model can be achieved through the following technical solutions:

[0011] This invention provides an air source heat pump system that allows for defrosting with a small temperature difference and no downtime, including a main refrigerant circulation loop and a bypass loop.

[0012] The refrigerant main circulation loop includes a compressor, a refrigerant passage for a condenser, a throttling element, a refrigerant passage for an evaporator, and a gas-liquid separator connected in sequence.

[0013] The bypass circuit includes a first bypass branch and a second bypass branch.

[0014] Furthermore, the evaporator is a refrigerant-air fluid heat exchanger, typically in the form of a finned tube heat exchanger or a microchannel heat exchanger.

[0015] Furthermore, an auxiliary liquid separation device is provided at the inlet of the evaporator.

[0016] Furthermore, the condenser is a refrigerant-external fluid heat exchanger. When the external fluid is a refrigerant such as water, the condenser is typically a plate heat exchanger, a shell-and-tube heat exchanger, or a tube-and-tube heat exchanger; when the external fluid is air, the condenser is typically a finned tube heat exchanger or a microchannel heat exchanger.

[0017] Furthermore, a four-way reversing valve can be installed in the main refrigerant circulation loop. The four ports of the four-way reversing valve are respectively connected to the compressor's suction port (via the gas-liquid separator), the compressor's discharge port, the refrigerant passage of the evaporator, and the refrigerant passage of the condenser. By switching and reversing the flow direction of the main refrigerant circulation loop through the four-way valve, the air source heat pump system can also perform a cooling function.

[0018] Furthermore, a first regulating valve is provided on the first bypass branch, one end of which is connected between the outlet of the compressor and the refrigerant passage inlet of the condenser, and the other end is connected between the outlet of the throttling element and the refrigerant passage inlet of the evaporator.

[0019] Furthermore, a second regulating valve is provided on the second bypass branch, with one end connected to the inlet of the evaporator refrigerant passage and the other end connected to the outlet of the evaporator refrigerant passage.

[0020] Furthermore, the throttling element, the first regulating valve, and the second regulating valve are preferably valves with electronic actuators (such as electronic expansion valves, electric ball valves, solenoid valves, etc.) to facilitate precise and rapid adjustment of the opening degree by the control unit.

[0021] This utility model discloses an air source heat pump system with a small temperature difference that allows for defrosting without shutdown, which has at least two operating modes: heating mode and defrosting mode.

[0022] In the heating mode, the workflow is as follows: In the evaporator, the low-temperature, low-pressure two-phase refrigerant in the refrigerant passage absorbs heat from the air flowing through the air passage, evaporating into superheated refrigerant gas. This gas is then drawn into the compressor via a gas-liquid separator and compressed into high-temperature, high-pressure refrigerant gas. Subsequently, it flows through the condenser's refrigerant passage, releasing heat to the external fluid in the other passage, and exits as subcooled refrigerant liquid. This refrigerant liquid is then throttled by a throttling element, transforming back into a low-temperature, low-pressure two-phase refrigerant, and returns to the evaporator's refrigerant passage, completing the refrigerant cycle. During this process, the external fluid in the condenser's external fluid passage is heated by the refrigerant on the other side, completing the heating function. The air in the evaporator's air passage is heated by the refrigerant on the other side, resulting in cooling, condensation, and frosting (under suitable conditions).

[0023] In the defrosting mode, the workflow is as follows: After being drawn into the compressor by the gas-liquid separator and compressed into high-temperature, high-pressure refrigerant gas, it splits into two at the condenser inlet: ① One part flows through the condenser's refrigerant channel, releasing heat to the external fluid in the other channel, and exits as subcooled refrigerant liquid, which is then throttled by a throttling element; ② The other part of the superheated gas bypasses the throttling element directly through the first regulating valve. The two parts of the refrigerant fluid mix to form a medium-temperature refrigerant gas. This medium-temperature refrigerant gas splits into two at the evaporator inlet: ① One part enters the evaporator through an auxiliary liquid separator, cools, and undergoes a phase change, releasing heat to the frost layer condensing in the other air channel; ② The other part bypasses the evaporator outlet directly through the second regulating valve. The two parts of the refrigerant fluid mix, and the resulting superheated refrigerant gas returns to the compressor inlet via the gas-liquid separator, completing the refrigerant cycle. During this process, the external fluid extracts heat from the other part of the refrigerant in the external fluid channel of the condenser, completing a partial heating function. The frost layer condensed in the air passage of the evaporator is melted by the refrigerant on the other side, and then discharged, completing the defrosting process.

[0024] In the heating mode, the compressor is turned on, external fluid flows through the condenser, and the fan driving the air flow on the evaporator side is turned on. The throttling element is open. The first regulating valve is closed, and the second regulating valve is closed. In the heating mode, the compressor's operating parameters are controlled to achieve the target heating demand, and the opening degree of the throttling element is controlled to adjust the suction superheat.

[0025] In the defrost mode, the compressor is on, external fluid flows through the condenser, and the fan driving the air flow on the evaporator side is off. The throttling element is on. The first regulating valve is on, and the second regulating valve is on. In the defrost mode, the opening of the first regulating valve is controlled to adjust the suction pressure, so that the evaporator coil temperature is higher than the set defrost threshold; the opening of the second regulating valve is controlled to adjust the suction superheat; and the opening of the throttling element is controlled to maintain the discharge pressure.

[0026] When the defrost entry condition is met, the system switches from the heating mode to the defrost mode; when the defrost exit condition is met, the system switches back from the defrost mode to the heating mode. An example of the defrost entry condition is that the detected compressor suction pressure corresponds to a saturation temperature below -15°C; an example of the defrost exit condition is that the detected compressor suction superheat is above 15K.

[0027] This utility model discloses an air source heat pump system that allows for defrosting with minimal temperature difference and no downtime, featuring the following characteristics and innovations:

[0028] 1. When the system switches from heating mode to defrost mode, or from defrost mode back to heating mode, the compressor always remains running. The overall circulation direction of the refrigerant in the main circuit consisting of the compressor, condenser, throttling element, and evaporator (e.g., from the compressor to the condenser to the throttling element to the evaporator and back to the compressor) does not need to be reversed through a four-way reversing valve or other devices. The smooth switching of the working mode is achieved by adjusting the opening of the throttling element, the first regulating valve, and the second regulating valve, thereby achieving defrosting without stopping the machine.

[0029] 2. In defrosting mode, the temperature of the refrigerant flowing through the evaporator coil (or the surface temperature of the coil) is maintained at a level slightly above the freezing point through the design and control of the bypass circuit. Compared with the traditional high-temperature hot gas defrosting method, the temperature difference is significantly reduced, hence the name "small temperature difference defrosting".

[0030] 3. In defrost mode, the throttling element maintains the discharge pressure (to prevent refrigerant from migrating significantly to the low-pressure side), the first bypass is set to provide heat and regulate the evaporation pressure / temperature (affecting the defrost temperature), and the second bypass is set to regulate the suction superheat and flow split (affecting the refrigerant flow / state entering the evaporator).

[0031] 4. In defrost mode, the distribution ratio can be adjusted by controlling the throttling element and the opening of the first regulating valve. While avoiding large changes in the high-pressure side state, the evaporator inlet state can be adjusted to ensure that the coil temperature is above the freezing point to achieve gentle defrosting (small temperature difference). At the same time, by adjusting the opening of the second regulating valve, the ratio of refrigerant flow into the evaporator to bypass flow is controlled, which ensures that there is enough refrigerant flowing through the evaporator to provide defrosting heat, and maintains a suitable suction superheat to ensure the safe operation of the compressor.

[0032] This utility model discloses an air source heat pump system that enables defrosting with minimal temperature difference and no downtime. Compared with existing technologies, it has the following advantages:

[0033] 1. Eliminates downtime and refrigerant flow switching, improving system stability. Compared to classic reverse-cycle defrosting technologies, this system requires no downtime and no refrigerant flow switching. When the system is used only for heating, the four-way reversing valve can even be omitted. The advantages are: ① The defrosting process effectively avoids system oscillations caused by flow switching, ensuring a smoother transition between heating and defrosting modes; ② During defrosting, the system does not absorb heat from external heating fluids; instead, it maintains some heating output.

[0034] 2. Significantly Reduces Refrigerant Migration and Simplifies the Rebalancing Process. Compared to hot gas bypass defrosting, this invention significantly reduces refrigerant migration, thereby simplifying the system rebalancing process. In conventional hot gas bypass defrosting mode, the exhaust bypass valve is fully open, causing a large amount of refrigerant to rush into the evaporator and migrate to the gas-liquid separator. After exiting defrosting mode, the system must undergo a lengthy refrigerant migration process back to the high-pressure side condenser before it can re-enter heating mode; during this process, due to the lack of refrigerant on the condenser side, the system cannot effectively provide heat. Conversely, in this invention, when entering defrosting mode, through the coordinated control of the throttling element and the first regulating valve, a certain proportion of refrigerant is ensured to continuously flow through the condenser, maintaining its outlet subcooled state, thus acting as a temporary "liquid storage" device. The high-pressure side therefore retains sufficient refrigerant, and an effective heating mode can be quickly re-established after defrosting.

[0035] 3. Enhanced defrosting stability and sustainability, achieving thorough defrosting. Compared to hot gas bypass defrosting, this invention significantly improves the stability and sustainability of the defrosting mode. In conventional hot gas bypass defrosting, the allowable defrosting time is limited because a large amount of refrigerant continuously migrates to the gas-liquid separator, making it difficult to maintain effective superheat at the compressor suction port after a period of time, forcing the system to prematurely exit the defrosting process; at this time, the frost layer on the evaporator surface often fails to completely melt. Therefore, this mode typically requires a large-capacity gas-liquid separator to barely extend the defrosting time. Conversely, this invention, by setting a bypass branch in parallel with the evaporator and adjusting its second regulating valve, controls the superheat of the outlet mixed refrigerant within a safe and effective range. This allows the system to operate stably in defrosting mode for extended periods, ensuring that the frost layer melts fully and completely.

[0036] 4. Improve defrosting efficiency and reduce ineffective heat loss. Whether it's reverse cycle defrosting or hot gas bypass defrosting, the essence is to introduce high-temperature refrigerant (temperature difference with the frost layer typically >50K) into the frosting evaporator coil for exothermic defrosting. However, a significant portion of this heat is lost to the surrounding low-temperature air environment through convection and other means. This invention uses medium-temperature refrigerant superheated gas (temperature difference with the frost layer approximately 25K) and its condensed two-phase refrigerant (temperature difference with the frost layer approximately 5K) for small-temperature-difference defrosting. The reduced temperature difference significantly decreases the proportion of heat lost to the environment, allowing heat to be more concentrated for melting the frost layer. Therefore, the defrosting efficiency of this invention system (i.e., the proportion of heat actually used to melt the frost layer out of the total heat provided by the system) is significantly improved. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of this utility model.

[0038] Figure 2This is a schematic diagram of the principle of Embodiment 1 of this utility model (heating mode).

[0039] Figure 3 This is a system state diagram (pressure-enthalpy diagram, pH diagram) of Embodiment 1 of this utility model in heating mode.

[0040] Figure 4 This is a schematic diagram of the principle of Embodiment 1 of this utility model (defrosting mode).

[0041] Figure 5 This is a system state diagram (pressure-enthalpy diagram, pH diagram) of Embodiment 1 of this utility model in defrosting mode.

[0042] Figure 6 This is a schematic diagram of the principle of Embodiment 2 of this utility model.

[0043] Figure 7 This is a schematic diagram of the principle of Embodiment 3 of this utility model.

[0044] In the diagram: 1-Compressor, 2-Condenser, 3-Throttling element, 4-First regulating valve, 5-Evaporator, 6-Second regulating valve, 7-Gas-liquid separator, 8-Auxiliary liquid distribution device, 10-Fan, 11-Frost layer, 13-Four-way reversing valve.

[0045] In the diagram, a ~ j represent refrigerant nodes. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0047] Example 1

[0048] This embodiment describes an air-source heat pump system that enables defrosting with minimal temperature difference and no downtime (see [link]). Figure 1 This includes the main refrigerant circulation loop and the bypass loop.

[0049] The refrigerant main circulation loop includes, in sequence, a compressor 1, a refrigerant passage for condenser 2, a throttling element 3, a refrigerant passage for evaporator 5, and a gas-liquid separator 7. Evaporator 5 is a refrigerant-air heat exchanger, typically a finned tube heat exchanger or a microchannel heat exchanger. An auxiliary liquid separator 8 is located at the evaporator inlet. Condenser 2 is a refrigerant-coolant heat exchanger. Water is a common form of coolant. Condenser 2 is typically a plate heat exchanger, a shell-and-tube heat exchanger, or a tube-and-tube heat exchanger. The throttling element 3 is preferably an electronically controlled valve, such as an electronic expansion valve or an electric ball valve.

[0050] The bypass circuit includes a first bypass branch and a second bypass branch. A first regulating valve 4 is installed on the first bypass branch, with one end connected between the outlet of the compressor 1 and the refrigerant inlet of the condenser 2, and the other end connected between the outlet of the throttling element 3 and the refrigerant inlet of the evaporator 5. The first regulating valve 4 is preferably an electrically controlled valve such as an electric ball valve or a solenoid valve. A second regulating valve 6 is installed on the second bypass branch, with one end connected to the inlet of the refrigerant passage of the evaporator 5, and the other end connected to the outlet of the refrigerant passage of the evaporator 5. The second regulating valve 6 is preferably an electrically controlled valve such as an electric ball valve or a solenoid valve.

[0051] This embodiment describes an air source heat pump system with a small temperature difference that allows for defrosting without shutdown, and it has at least two operating modes: heating mode and defrosting mode.

[0052] The workflow in heating mode is as follows (see...) Figure 2 and Figure 3 In the refrigerant passage of evaporator 5, the low-temperature, low-pressure two-phase refrigerant absorbs heat from the air flowing through the air passage and evaporates into superheated refrigerant gas (node ​​di). This gas is then drawn into compressor 1 by gas-liquid separator 7 (node ​​ia) and compressed into high-temperature, high-pressure refrigerant gas (node ​​ab). Subsequently, it flows through the refrigerant passage of condenser 2, releasing heat to the external fluid in the other passage, and exits as subcooled refrigerant liquid (node ​​bc). This refrigerant liquid is then throttled by throttling element 3, transforming back into low-temperature, low-pressure two-phase refrigerant (node ​​cd), and returns to the refrigerant passage of evaporator 5, completing the refrigerant cycle. During this process, the external fluid in the external fluid passage of condenser 2 is heated by the refrigerant on the other side, completing the heating function. The air in the air passage of evaporator 5 is heated by the refrigerant on the other side, resulting in cooling, condensation, and frosting (under suitable conditions), forming a frost layer 11 on the surface of evaporator 5.

[0053] The workflow in defrost mode is as follows (see...) Figure 4 and Figure 5The refrigerant gas, after being drawn into the compressor 1 by the gas-liquid separator 7 and compressed into high-temperature, high-pressure gas (node ​​ab), splits into two at the inlet of the condenser 2: ① One part flows through the refrigerant passage of the condenser 2, releasing heat to the external fluid in the other passage, and exits as subcooled refrigerant liquid (node ​​bc), and is throttled by the throttling element 3 (node ​​cd); ② The other part of the superheated gas bypasses directly to the outlet of the throttling element 3 via the first regulating valve 4 (node ​​be). The two parts of the refrigerant fluid mix to become medium-temperature refrigerant gas (nodes d and e mix to form f). This medium-temperature refrigerant gas splits into two at the inlet of the evaporator 5: ① One part enters the evaporator 5 via the auxiliary liquid separator 8, releasing heat to the frost layer condensing in the air passage on the other side (node ​​fg); ② The other part bypasses directly to the outlet of the evaporator 5 via the second regulating valve 6 (node ​​fj). The two refrigerant fluids mentioned above are mixed (nodes g and j are mixed as i), and the resulting superheated refrigerant gas returns to the compressor 1 suction port (node ​​ia) via the gas-liquid separator 7, completing the refrigerant cycle. During this process, the external fluid in the external fluid channel of the condenser 2 is heated by the refrigerant on the other side, completing a partial heating function. The frost layer condensed in the air channel of the evaporator 5 is melted and removed by the refrigerant on the other side, completing defrosting.

[0054] In this embodiment, in heating mode, compressor 1 is turned on, external fluid flows through condenser 2, and fan 10, which drives air flow through evaporator 5, is turned on. Throttling element 3 is turned on. First regulating valve 4 is closed, and second regulating valve 6 is closed. In heating mode, the operating parameters of compressor 1 are controlled to achieve the target heating demand, and the opening degree of throttling element 3 is controlled to adjust the suction superheat.

[0055] In this embodiment, under defrost mode, compressor 1 is turned on, external fluid flows through condenser 2, and fan 10, which drives the air flow on the evaporator 5, is turned off. Throttling element 3 is turned on. First regulating valve 4 is turned on, and second regulating valve 6 is turned on. In defrost mode, the opening degree of first regulating valve 4 is controlled to regulate suction pressure, so that the coil temperature of evaporator 5 is higher than the set defrost threshold; the opening degree of second regulating valve 6 is controlled to regulate suction superheat; and the opening degree of throttling element 3 is controlled to maintain discharge pressure.

[0056] When the defrosting entry conditions are met, the system switches from heating mode to defrosting mode; when the defrosting exit conditions are met, the system switches back from defrosting mode to heating mode. Defrosting entry conditions include suction pressure below a set threshold (e.g., corresponding evaporation temperature < -15°C). Defrosting exit conditions include suction superheat above a set threshold (e.g., 15K). Those skilled in the art can adjust these threshold settings according to specific application scenarios, climate conditions, or system configurations.

[0057] When the system switches from heating mode to defrosting mode, or from defrosting mode back to heating mode, compressor 1 continues to run, the system does not stop, and the refrigerant circuit flow does not need to be reversed. The mode switching is completed by adjusting the opening of throttling element 3, first regulating valve 4 and second regulating valve 6, thereby achieving defrosting without stopping the system.

[0058] like Figure 5 As shown, this system adopts a small temperature difference defrosting method. During the defrosting process (node ​​fg), the superheated gas of medium-temperature refrigerant (temperature difference of about 25K with the frost layer) and its condensed two-phase refrigerant (temperature difference of about 5K with the frost layer) release heat to the frost layer. The small temperature difference significantly reduces the proportion of heat lost to the environment, making the heat more concentrated for melting the frost layer, thereby improving the defrosting efficiency.

[0059] Example 2

[0060] The basic principle of this embodiment (see...) Figure 6 This is completely similar to Example 1, except that the external fluid of condenser 2 is not in the form of a refrigerant such as water, but in the form of air. Therefore, condenser 2 is a refrigerant-air heat exchanger, commonly in the form of a finned tube heat exchanger or a microchannel heat exchanger.

[0061] The typical application scenario for Example 2 is a household air conditioner. During winter operation, the condenser 2 is located in the indoor unit, and the evaporator 5 is located in the outdoor unit. The air conditioner extracts heat from the outdoor environment and releases heat to the indoor environment. When the outdoor temperature is low and the humidity is high, the evaporator 5 in the outdoor unit will frost up after running for a period of time. In this example, a defrosting method is adopted without stopping the unit, and no heat is extracted from the indoor side during defrosting. Instead, the condenser 2 maintains a small amount of heat supply to the indoor environment, thus preventing significant fluctuations in indoor temperature and improving overall comfort.

[0062] Example 3

[0063] The basic principle of this embodiment (see...) Figure 7 This embodiment is completely similar to Embodiments 1 and 2, except that a four-way reversing valve 13 is added. The four ports of the four-way reversing valve 13 are respectively connected to the suction port of the compressor 1 (via the gas-liquid separator 7), the discharge port of the compressor 1, the refrigerant passage of the evaporator 5, and the refrigerant passage of the condenser 2. By switching the flow direction of the main refrigerant circulation loop through the four-way reversing valve 13, the system can also perform refrigeration functions.

[0064] Note that in this embodiment, the four-way reversing valve 13 added to the system is only used for switching between heating and cooling modes. During the switching between heating and defrosting modes, the system does not need to be shut down, nor does it need to switch the four-way reversing valve 13. This ensures system stability while significantly reducing the switching frequency of the four-way reversing valve 13, which helps extend its service life and reduce the failure rate.

[0065] The above embodiments do not fully demonstrate all components of the refrigerant circulation, water flow path, and air flow path. During implementation, common refrigeration accessories such as high-pressure liquid receivers, oil separators, filters, and dryers are installed in the refrigerant circuit; accessories such as filters, power pumps, and control valves are installed in the water flow path; and accessories such as fans, air ducts, air valves, dampers, and filters are installed in the air flow path. Alternatively, heat exchangers may be added without departing from the spirit of the present utility model. These additions cannot be considered as substantial improvements to the present utility model and should fall within the protection scope of the present utility model.

[0066] The above description of the embodiments is provided to enable those skilled in the art to understand and use the utility model. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present utility model is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present utility model without departing from its scope should be within the protection scope of the present utility model.

Claims

1. An air source heat pump system, comprising a refrigerant main circulation loop and a bypass loop; The refrigerant main circulation loop includes a refrigerant passage of a compressor (1), a condenser (2), a throttling element (3), a refrigerant passage of an evaporator (5), and a gas-liquid separator (7) connected in sequence. Its features are, The bypass circuit includes: The first bypass branch has one end connected between the outlet of the compressor (1) and the refrigerant passage inlet of the condenser (2), and the other end connected between the outlet of the throttling element (3) and the refrigerant passage inlet of the evaporator (5). The second bypass branch is connected in parallel between the inlet and outlet of the refrigerant passage of the evaporator (5); The system is configured to enable mode switching by adjusting the opening of the first bypass branch, the second bypass branch and the throttling element (3) without changing the overall flow direction of the refrigerant in the main circuit from the compressor (1) through the condenser (2), the throttling element (3) and the evaporator (5) back to the compressor (1), and the compressor (1) continues to run during the switching process.

2. The system according to claim 1, characterized in that: A first regulating valve (4) is provided on the first bypass branch, and a second regulating valve (6) is provided on the second bypass branch.

3. The system according to claim 1, characterized in that: The system has a heating mode and a defrosting mode; In the heating mode, the refrigerant flows along the main circulation loop and the fan (10) on the evaporator side operates; In the defrosting mode, the ratio of refrigerant that bypasses directly to the low-pressure side and continues to release heat in the condenser (2) is adjusted by the first bypass branch and the throttling element (3). After mixing, the refrigerant enters the evaporator (5) for defrosting. At the same time, the evaporator side fan (10) stops, and the second bypass branch is adjusted to ensure that the compressor (1) returns gas. When the system switches between heating mode and defrosting mode, the compressor (1) continues to run.

4. The system according to claim 1, characterized in that: The system can be selectively configured with a four-way directional valve (13). The four ports of the four-way reversing valve (13) are respectively connected to: the exhaust port of the compressor (1), the inlet of the gas-liquid separator (7), one end of the refrigerant passage of the evaporator (5), and one end of the refrigerant passage of the condenser (2).

Images