Air-cooled heat pump unit capable of never frosting during heating

Abstract

The air-cooled heat pump unit comprises a compressor and a four-way valve, a D-end pipeline of the four-way valve is connected with the exhaust end of the compressor, an E-end pipeline of the four-way valve is connected with an indoor heat exchanger, a C-end pipeline of the four-way valve is connected with an outdoor heat exchanger, and an S-end pipeline of the four-way valve is connected with a gas-liquid separator. The gas-liquid separator is in pipeline connection with the air suction end of the compressor, and the indoor heat exchanger is in pipeline connection with the outdoor heat exchanger. A three-way valve is arranged at the front end of the exhaust end pipeline of the compressor, the C end of the three-way valve is connected with the front end of the exhaust end pipeline of the compressor, the A end pipeline of the three-way valve is connected with the D end of the four-way valve, and the B end pipeline of the three-way valve is connected to the outdoor heat exchanger. The outdoor heat exchanger is provided with a temperature and humidity sensor and a first temperature sensor. The bypass proportion is dynamically adjusted, the three-way valve controls the flow of the high-temperature refrigerant entering the evaporator through opening adjustment, defrosting according to needs is achieved, and energy waste caused by excessive heating is avoided.

Description

Technical Field

[0001] This disclosure relates to the field of air-cooled heat pump units, and more particularly to a non-frost-forming air-cooled heat pump unit for heating. Background Technology

[0002] When an air-cooled heat pump unit is in heating mode, after the four-way valve switches, the high-temperature, high-pressure refrigerant discharged from the compressor directly enters the indoor condenser (responsible for supplying heat to the room). It then passes through a throttling device to reduce pressure and temperature before entering the outdoor evaporator to absorb heat. At this point, as the refrigerant flows through the outdoor evaporator (finned heat exchanger), the surface temperature of the finned heat exchanger becomes low. When the surface temperature is below the dew point temperature of water vapor in the air, frost will form on the surface of the heat exchanger fins. If defrosting is not done in time or the defrosting control logic is not properly handled, the frost on the fins will thicken or even freeze, affecting the heating performance of the heat pump. Currently, the defrosting technologies used to determine when an air-cooled heat pump unit has frost can be roughly divided into the following types: By switching the four-way valve to change the refrigerant flow, the system briefly enters a refrigeration cycle, using the high-temperature refrigerant discharged from the compressor to directly heat the outdoor evaporator and melt the frost. This method results in a decrease in indoor temperature, causing discomfort for users.

[0003] Using a solenoid valve for hot gas bypass defrosting, the four-way valve does not need to be switched during the hot gas bypass defrosting process, and the refrigerant flow maintains the heating cycle. The indoor condenser can still release some heat to maintain the heating function. However, traditional solenoid valves only support two states: open and closed. They cannot accurately adjust the bypass refrigerant flow, which may cause heat waste (excessive bypass) or insufficient defrosting (insufficient flow).

[0004] Electric defrosting involves embedding electric heating elements (such as electric heating tubes) in the evaporator fins or heat exchange tubes, converting electrical energy into heat to directly defrost. However, this method is energy-intensive (requiring 40-100W of electricity per square meter of heat exchange area) and poses a fire hazard.

[0005] Thermal storage defrosting utilizes phase change materials or thermal storage devices to store heat during the heating process, releasing the stored heat during defrosting to assist in the defrosting process. In this approach, the heat storage capacity and release rate of the thermal storage device (such as a thermal storage tank or phase change material) are limited by the material properties, which may lead to insufficient or delayed defrosting heat supply, especially in low-temperature environments where heat loss of the thermal storage medium is significant, affecting the defrosting effect. Furthermore, the thermal storage process requires additional energy from the compressor or electric heating device to maintain the temperature of the thermal storage medium, resulting in a decrease in overall system energy efficiency. For example, continuously heating the thermal storage device during non-defrosting phases leads to energy waste.

[0006] In conclusion, the technical solutions for heating and defrosting of air-cooled heat pump units need further optimization and improvement to address the defects and shortcomings of the aforementioned solutions. Summary of the Invention

[0007] In view of this, this disclosure proposes an air-cooled heat pump unit that never frosts during heating, which can perform heating and defrosting in parallel without affecting the indoor heating temperature. It can dynamically adjust the bypass ratio, precisely control the flow rate of high-temperature refrigerant entering the evaporator, realize defrosting on demand, avoid energy waste caused by overheating, simplify the pipeline structure and reduce pressure loss.

[0008] The technical solution of this invention is a wind-cooled heat pump unit that never frosts during heating, comprising a compressor and a four-way valve. The D-end of the four-way valve is connected to the discharge end of the compressor; the E-end of the four-way valve is connected to an indoor heat exchanger; the C-end of the four-way valve is connected to an outdoor heat exchanger; the S-end of the four-way valve is connected to a gas-liquid separator; the gas-liquid separator is connected to the suction end of the compressor; the indoor and outdoor heat exchangers are connected by pipes, and throttling devices are provided on the pipes. A high-pressure sensor is provided on the discharge end pipe of the compressor; a three-way valve is provided at the front end of the discharge end pipe of the compressor; the C-end of the three-way valve is connected to the front end of the discharge end pipe of the compressor; the A-end of the three-way valve is connected to the D-end of the four-way valve; and the B-end of the three-way valve is connected to the outdoor heat exchanger. The outdoor heat exchanger is equipped with a temperature and humidity sensor and a first temperature sensor.

[0009] When the air-cooled heat pump unit disclosed in this solution is in heating mode, the A and C ends of the three-way valve are open, while the B end is closed. The DE and CS ends of the four-way valve are open. The indoor heat exchanger performs condensation and heat dissipation, while the outdoor heat exchanger performs heat absorption and evaporation. The temperature and humidity sensor monitors the humidity and temperature of the air surrounding the outdoor heat exchanger, and the first temperature sensor monitors the surface temperature of the heat exchange element of the outdoor heat exchanger. When the surface temperature of the heat exchange element matches the humidity and temperature of the air surrounding the outdoor heat exchanger to reach the condensation condition, and the surface temperature of the heat exchange element is ≤0 degrees, the opening degree of the C and B ends of the three-way valve is controlled to allow the high-temperature and high-pressure gaseous refrigerant from the compressor to be partially input into the outdoor heat exchanger to increase the temperature of the heat exchange element and prevent frost formation.

[0010] Preferably, the indoor heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger, and the outdoor heat exchanger is a finned heat exchanger.

[0011] Preferably, the compressor's exhaust pipe is equipped with a second temperature sensor, the connection pipe between the B end of the three-way valve and the outdoor heat exchanger, and the connection pipe between the indoor heat exchanger and the outdoor heat exchanger converge into a single pipe, and a third temperature sensor is provided on the converged single pipe.

[0012] Preferably, a liquid receiver is provided on the pipeline connecting the outdoor heat exchanger and the outdoor heat exchanger. After passing through the liquid receiver, the pipeline is connected to the throttling device, and a first check valve is provided on the pipeline connecting the throttling device. The first check valve is used to ensure that the refrigerant can only flow into the throttling device.

[0013] Preferably, the pipeline between the first check valve and the throttling device is equipped with a filter. The throttling device includes an economizer and a main throttling valve pipeline and an auxiliary throttling valve pipeline connected to the economizer. The intermediate pressure gas generated in the economizer is transported to the compressor through the pipeline to supplement the intermediate gas supply during the compression process.

[0014] Preferably, the economizer has two separate pipelines at the front end of the output pipeline of the main throttle valve. One pipeline is connected to the pipeline connecting the indoor heat exchanger to the liquid storage tank, and a second check valve is provided on this pipeline to form the first circulation loop of the economizer. The other pipeline is provided with a third check valve, and the front end of the third check valve is divided into two branches. One pipeline is connected to the filter, and a fourth check valve is provided on this pipeline to form the second circulation loop of the economizer. The other pipeline is connected to the pipeline of the three-way valve connected to the outdoor heat exchanger via the B end.

[0015] Preferably, a fourth temperature sensor is provided at the inlet of the auxiliary throttle valve pipeline of the economizer, and a fifth temperature sensor is provided at the outlet of the auxiliary throttle valve pipeline after evaporation by the economizer.

[0016] Preferably, the S-end pipeline of the four-way valve is connected to the gas-liquid separator and a sixth temperature sensor and a low-pressure sensor are provided.

[0017] The beneficial effects of this invention are as follows: This technical solution incorporates a three-way valve in the pipeline connecting the compressor and the four-way valve. The C and A ends of the three-way valve are in a default connected state, while the B end of the three-way valve is connected to the outdoor heat exchanger. The B and C ends of the three-way valve can be controlled to shut off and their opening degree. Therefore, this solution can dynamically adjust the bypass ratio. By adjusting the opening degree of the three-way valve, the flow rate of the high-temperature refrigerant entering the evaporator can be controlled, achieving on-demand defrosting and avoiding energy waste caused by overheating. Furthermore, this solution uses a three-way valve to connect the compressor, indoor heat exchanger, and outdoor heat exchanger, directly switching the refrigerant path, simplifying the pipeline structure and reducing pressure loss. Attached Figure Description

[0018] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the air-cooled heat pump unit of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of a second embodiment of the air-cooled heat pump unit of the present invention.

[0021] Figure 3 This is a schematic diagram of the refrigerant flow direction in the heating mode of Embodiment 2 of the air-cooled heat pump unit of the present invention.

[0022] in, Figure 3 The direction of the middle arrow indicates the direction of refrigerant flow.

[0023] Explanation of reference numerals in the attached figures: 1-Compressor; 2-Three-way valve; 3-Four-way valve; 4-Indoor heat exchanger; 5-Outdoor heat exchanger; 6-Gas-liquid separator; 7-High pressure sensor; 8-Temperature and humidity sensor; 9-First temperature sensor; 10-Second temperature sensor; 11-Third temperature sensor; 12-Liquid receiver; 13-First check valve; 14-Filter; 15-Economizer; 16-Main throttle valve; 17-Auxiliary throttle valve; 18-Second check valve; 19-Third check valve; 20-Fourth check valve; 21-Fourth temperature sensor; 22-Fifth temperature sensor; 23-Sixth temperature sensor; 24-Low pressure sensor. Detailed Implementation

[0024] The technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this disclosure.

[0025] Example 1 Please refer to Figure 1 This is a specific embodiment of a non-frost-prone air-cooled heat pump unit disclosed in this solution, comprising a compressor 1, a four-way valve 3, a pipe connected to the discharge end of the compressor 1 at end D, a pipe connected to the indoor heat exchanger 4 at end E, a pipe connected to the outdoor heat exchanger at end C, a pipe connected to the gas-liquid separator 6 at end S, and a pipe connected to the suction end of the compressor 1 at end S. The indoor heat exchanger 4 and the outdoor heat exchanger are connected by pipes, and the pipes are equipped with throttling devices. A high-pressure sensor 7 is installed on the discharge end pipe of the compressor 1, and a three-way valve 2 is installed at the front end of the discharge end pipe of the compressor 1. The C end of the three-way valve 2 is connected to the front end of the discharge end pipe of the compressor 1, the A end of the three-way valve 2 is connected to the D end of the four-way valve 3, and the B end of the three-way valve 2 is connected to the outdoor heat exchanger. The outdoor heat exchanger is equipped with a temperature and humidity sensor 8 and a first temperature sensor 9. Preferably, the indoor heat exchanger 4 is a plate heat exchanger or a shell-and-tube heat exchanger, and the outdoor heat exchanger is a finned heat exchanger.

[0026] When the air-cooled heat pump unit disclosed in this solution is in heating mode, the A and C ends of the three-way valve 2 are open, and the B end is closed. The DE and CS ends of the four-way valve 3 are open. The indoor heat exchanger 4 performs condensation and heat dissipation, and the outdoor heat exchanger performs heat absorption and evaporation. The temperature and humidity sensor 8 monitors the humidity and temperature of the air surrounding the outdoor heat exchanger, and the first temperature sensor 9 monitors the surface temperature of the heat exchange element of the outdoor heat exchanger. When the surface temperature of the heat exchange element matches the humidity and temperature of the air surrounding the outdoor heat exchanger to reach the condensation condition, and the surface temperature of the heat exchange element is ≤0 degrees, the opening degree of the C and B ends of the three-way valve 2 is controlled so that the high-temperature and high-pressure gaseous refrigerant of the compressor 1 is partially input into the outdoor heat exchanger to increase the temperature of the heat exchange element and achieve frost prevention.

[0027] Example 2 Please refer to Figure 2 , Figure 3 This is another embodiment of a non-frost-prone air-cooled heat pump unit disclosed in this solution. It includes a compressor 1, a four-way valve 3, with the D-end of the four-way valve 3 connected to the discharge end of the compressor 1, the E-end of the four-way valve 3 connected to an indoor heat exchanger 4, the C-end of the four-way valve 3 connected to an outdoor heat exchanger, and the S-end of the four-way valve 3 connected to a gas-liquid separator 6. The gas-liquid separator 6 is connected to the suction end of the compressor 1. The indoor heat exchanger 4 and the outdoor heat exchanger are connected by pipes, and a throttling device is provided on the pipes. A high-pressure sensor 7 is provided on the discharge end pipe of the compressor 1. A three-way valve 2 is provided at the front end of the discharge end pipe of the compressor 1. The C-end of the three-way valve 2 is connected to the front end of the discharge end pipe of the compressor 1, the A-end of the three-way valve 2 is connected to the D-end of the four-way valve 3, and the B-end of the three-way valve 2 is connected to the outdoor heat exchanger. The outdoor heat exchanger is equipped with a temperature and humidity sensor 8 and a first temperature sensor 9.

[0028] Preferably, the indoor heat exchanger 4 is a plate heat exchanger or a shell-and-tube heat exchanger, and the outdoor heat exchanger is a finned heat exchanger.

[0029] Preferably, the discharge end pipe of the compressor 1 is equipped with a second temperature sensor 10. The connection pipe between the B end of the three-way valve 2 and the outdoor heat exchanger, and the connection pipe between the indoor heat exchanger 4 and the outdoor heat exchanger converge into a single pipe, and a third temperature sensor 11 is provided on this converged pipe. By designing the second temperature sensor 10, the third temperature sensor 11, and the high-pressure sensor 7, the flow rate of the high-temperature and high-pressure gaseous refrigerant required for defrosting can be controlled more precisely, and the opening degree of the three-way valve 2C end can be controlled more precisely.

[0030] Preferably, a liquid receiver 12 is provided on the pipeline connecting the outdoor heat exchanger and the outdoor heat exchanger. After passing through the liquid receiver 12, the pipeline is connected to the throttling device, and a first check valve 13 is provided on the pipeline connecting the throttling device. The first check valve 13 is used to ensure that the refrigerant can only flow into the end of the throttling device.

[0031] Preferably, a filter 14 is provided in the pipeline between the first check valve 13 and the throttling device. The throttling device includes an economizer 15 and a main throttling valve 16 pipeline and an auxiliary throttling valve 17 pipeline connected to the economizer 15. The intermediate pressure gas generated in the economizer 15 is transported to the compressor 1 through the pipeline to supplement the intermediate gas supply during the compression process.

[0032] Preferably, the economizer 15 has two separate pipelines at the front end of the output pipeline of the main throttling valve 16. One pipeline connects to the pipeline connecting the indoor heat exchanger 4 to the liquid receiver 12, and a second check valve 18 is installed on this pipeline, forming the first circulation loop of the economizer 15. The other pipeline has a third check valve 19, which splits into two branches. One branch connects to the filter 14, and a fourth check valve 20 is installed on this pipeline, forming the second circulation loop of the economizer 15. The other branch connects to the pipeline at end B of the three-way valve 2, which connects to the outdoor heat exchanger. In the design of the first and second circulation loops, the refrigerant in the main pipeline enters the evaporator to absorb heat after being depressurized by the main throttling valve 16, while the refrigerant in the auxiliary pipeline undergoes secondary throttling and evaporation through the economizer 15, absorbing heat from the main pipeline to increase the subcooling. The four check valves precisely control the flow direction, ensuring that the main and auxiliary pipelines operate independently and avoiding backflow interference.

[0033] Preferably, a fourth temperature sensor 21 is provided at the inlet of the auxiliary throttle valve 17 of the economizer 15, and a fifth temperature sensor 22 is provided at the outlet of the auxiliary throttle valve 17 after evaporation in the economizer 15. Based on the temperature difference feedback between the fourth and fifth temperature sensors 21 and 22, the control system can dynamically adjust the opening of the auxiliary throttle valve 17 to ensure that the refrigerant evaporation process in the auxiliary circuit is in an ideal superheated state (typically 3-8°C superheat), thus avoiding liquid slugging and improving gas injection efficiency.

[0034] Preferably, the pipeline connecting the S-end of the four-way valve 3 to the gas-liquid separator 6 is equipped with a sixth temperature sensor 23 and a low-pressure sensor 24. The sixth temperature sensor 23 monitors the return gas temperature to determine the separation efficiency of the gas-liquid separator 6. If the temperature drops abnormally (approaching the saturation temperature corresponding to the evaporation pressure), it indicates that the liquid refrigerant has not been completely separated, posing a risk of liquid slugging into the compressor 1. The low-pressure sensor 24 monitors the return gas pressure to prevent the compressor 1 from having excessively low suction pressure (leading to poor lubrication) or excessively high suction pressure (causing overload operation). Abnormal pressure will trigger a shutdown protection.

[0035] In heating mode, the high-temperature, high-pressure gaseous refrigerant compressed by compressor 1 is delivered to the indoor heat exchanger 4 via the DE terminals of the four-way valve 3. The indoor heat exchanger 4 condenses and dissipates heat, forming a high-pressure liquid refrigerant. This liquid refrigerant passes through a throttling device and then enters the outdoor heat exchanger for evaporation and heat absorption, forming a low-temperature, low-pressure gaseous refrigerant that returns to compressor 1 via the gas-liquid separator 6, forming a loop. During this heating process, the outdoor heat exchanger absorbs external heat and evaporates into a low-temperature, low-pressure gaseous refrigerant, causing its surface temperature to decrease. The humidity and temperature of the air surrounding the outdoor heat exchanger are monitored by temperature and humidity sensor 8, and the surface temperature of the heat exchanger elements is monitored by the first temperature sensor 9. When the surface temperature of the heat exchanger elements matches the humidity and temperature of the air surrounding the outdoor heat exchanger to reach condensation conditions, and the surface temperature of the heat exchanger elements is ≤0 degrees Celsius, the opening of terminals C and B of the three-way valve 2 is controlled. This allows a portion of the high-temperature, high-pressure gaseous refrigerant from compressor 1 to be input into the outdoor heat exchanger to increase the temperature of the heat exchanger elements and prevent frost formation. The dual-loop pipeline design, consisting of the economizer 15, main throttle valve 16, auxiliary throttle valve 17, fourth temperature sensor 21, fifth temperature sensor 22, first check valve 13, second check valve 18, third check valve 19, and fourth check valve 20, and the first temperature sensor 9, second temperature sensor 10, and sixth temperature sensor 23 in the air-cooled heat pump module, and it should be understood that this air-cooled heat pump module also includes a main control unit. This main control unit is a main control circuit and program that integrates the above-mentioned components. The main control unit is existing technology that is readily known to those skilled in the art of air-cooled heat pump modules. Therefore, the control unit is not described in detail. This solution aims to protect the connection arrangement structure of the relevant components and connecting pipelines, thereby forming a technical solution for defrosting by controlling the opening of the three-way valve 2 to regulate the bypass hot gas.

[0036] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A non-frost-prone air-cooled heat pump unit, comprising a compressor, a four-way valve, wherein the D-end pipe of the four-way valve is connected to the discharge end of the compressor, the E-end pipe of the four-way valve is connected to an indoor heat exchanger, the C-end pipe of the four-way valve is connected to an outdoor heat exchanger, the S-end pipe of the four-way valve is connected to a gas-liquid separator, the gas-liquid separator is connected to the suction end of the compressor, the indoor heat exchanger and the outdoor heat exchanger are connected by pipes, and the pipes are equipped with a throttling device, characterized in that, The compressor's exhaust pipe is equipped with a high-pressure sensor, and a three-way valve is installed at the front end of the compressor's exhaust pipe. The C end of the three-way valve is connected to the front end of the compressor's exhaust pipe, the A end of the three-way valve is connected to the D end of the four-way valve, and the B end of the three-way valve is connected to the outdoor heat exchanger. The outdoor heat exchanger is equipped with a temperature and humidity sensor and a first temperature sensor. In the case of the air-cooled heat pump unit, when the air-cooled heat pump unit is in heating mode, the A and C ends of the three-way valve are open, while the B end is closed. The DE and CS ends of the four-way valve are open. The indoor heat exchanger performs condensation and heat dissipation, while the outdoor heat exchanger performs heat absorption and evaporation. The temperature and humidity sensor monitors the humidity and temperature of the air surrounding the outdoor heat exchanger, and the first temperature sensor monitors the surface temperature of the heat exchange element of the outdoor heat exchanger. When the surface temperature of the heat exchange element matches the humidity and temperature of the air surrounding the outdoor heat exchanger to reach the condensation condition, and the surface temperature of the heat exchange element is ≤0 degrees, the opening degree of the C and B ends of the three-way valve is controlled to allow the high-temperature and high-pressure gaseous refrigerant from the compressor to be partially input into the outdoor heat exchanger to increase the temperature of the heat exchange element and prevent frost formation.

2. The air-cooled heat pump unit that never frosts during heating according to claim 1, characterized in that, The indoor heat exchanger is a plate heat exchanger or a shell-and-tube heat exchanger, and the outdoor heat exchanger is a finned heat exchanger.

3. The air-cooled heat pump unit that never frosts during heating according to claim 1, characterized in that, The compressor's exhaust pipe is equipped with a second temperature sensor. The connection pipe between the B end of the three-way valve and the outdoor heat exchanger, and the connection pipe between the indoor heat exchanger and the outdoor heat exchanger converge into a single pipe, and a third temperature sensor is provided on the converged single pipe.

4. The air-cooled heat pump unit that never frosts during heating according to claim 1, characterized in that, A liquid receiver is installed on the pipe connecting the outdoor heat exchanger and the outdoor heat exchanger. After passing through the liquid receiver, the pipe is connected to the throttling device. A first check valve is installed on the pipe connecting the throttling device. The first check valve is used to ensure that the refrigerant can only flow into the throttling device.

5. The air-cooled heat pump unit that never frosts during heating according to claim 4, characterized in that, A filter is provided in the pipeline between the first check valve and the throttling device. The throttling device includes an economizer and a main throttling valve pipeline and an auxiliary throttling valve pipeline connected to the economizer. The intermediate pressure gas generated in the economizer is transported to the compressor through the pipeline to supplement the intermediate gas supply during the compression process.

6. The air-cooled heat pump unit that never frosts during heating according to claim 5, characterized in that, The economizer has two separate pipelines at the front end of the main throttle valve's output pipeline. One pipeline is connected to the pipeline connecting the indoor heat exchanger to the liquid storage tank, and a second check valve is installed on this pipeline to form the first circulation loop of the economizer. The other pipeline is equipped with a third check valve, which splits into two branches at its front end. One branch is connected to the filter, and a fourth check valve is installed on this pipeline to form the second circulation loop of the economizer. The other branch is connected to the pipeline at the B end of the three-way valve, which is connected to the outdoor heat exchanger.

7. The air-cooled heat pump unit that never frosts during heating according to claim 5, characterized in that, A fourth temperature sensor is installed at the inlet of the auxiliary throttle valve pipeline of the economizer, and a fifth temperature sensor is installed at the outlet of the auxiliary throttle valve pipeline after evaporation in the economizer.

8. The air-cooled heat pump unit that never frosts during heating according to claim 1, characterized in that, The S-end pipeline of the four-way valve, which connects to the gas-liquid separator, is equipped with a sixth temperature sensor and a low-pressure sensor.

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