Heat pump device capable of conducting heating and defrosting simultaneously and operation method of heat pump device

Abstract

The invention discloses a heat pump device capable of simultaneously heating and defrosting. The heat pump device consists of an inner evaporator system and an outer evaporator system, the inner side evaporator system is connected with a gas-liquid separator, a compressor, an electric control valve, a condenser, a liquid storage tank, a filter, an economizer, an electronic expansion valve and an inner side system inlet; the outer side evaporator system is connected with a first electromagnetic valve, a gas-liquid separator, a compressor, an electric control valve, a condenser, a liquid storage tank, a filter, an economizer, an electronic expansion valve and a one-way valve and then is connected with an inlet of the outer side system. The operation method of the device comprises the steps that during defrosting, the bypass electromagnetic valve on the exhaust pipe is opened, meanwhile, the electric adjusting valve is closed according to a set proportion, part of high-temperature and high-pressure refrigerants enter an outer side system for heat dissipation, and then heat is absorbed through drainage of the draught fan so that the inner side finned evaporator can be defrosted. And after defrosting is finished, the two systems return to a common heat absorption state for heating. The tail end temperature is stable in the defrosting process, a four-way valve is omitted in the single heating unit, and the system is suitable for the extremely cold working condition.

Description

Technical Field

[0001] The present invention relates to the technical field of air source heat pumps, and particularly to a heat pump device capable of simultaneously heating and defrosting and an operation method thereof. Background Art

[0003] An air source heat pump extracts heat energy from the air for heating or cooling. It abandons the dependence on fossil fuels in traditional heating and cooling methods and realizes the low-impact utilization of natural resources through a thermodynamic cycle process. Specifically, based on the reverse Carnot cycle principle, through the coordinated operation of components such as an evaporator, a compressor, a condenser, and an expansion valve, the low-grade heat energy in the air is converted into high-grade heat energy to meet people's needs for indoor temperature adjustment.

[0004] The problems of frosting and defrosting of the outdoor evaporator of an air source heat pump lead to unstable operation and poor reliability of the unit. When an air source heat pump operates under meteorological conditions between -5°C and 5°C and with a relative humidity above 70%, its outdoor heat exchanger surface is most likely to frost. After the outdoor heat exchanger frosts, the frost layer continuously thickens, resulting in an increase in thermal resistance and an increase in air flow resistance, causing a decrease in heating capacity and the COP of the unit, resulting in energy waste. Reverse cycle defrosting is the most commonly used defrosting method at present. Reverse cycle defrosting is achieved by using a four-way reversing valve to change the refrigerant flow direction and convert the heating process into a cooling process. During defrosting, the superheated refrigerant vapor discharged from the compressor is sent to the outdoor coil for defrosting. When the defrosting is completed, the operation of the heat pump reverses again and heating restarts.

[0005] Reverse cycle defrosting will affect the water supply of an air source heat pump water heater, that is, during defrosting, hot water with an effective water temperature cannot be provided for users. At the same time, after defrosting, the original hot water temperature will decrease. In terms of energy, the loss during this defrosting process is equivalent to the shutdown for twice the defrosting time, and the frequent commutation of the four-way valve will affect its reliability and service life. Summary of the Invention

[0007] The purpose of the present invention is to provide a heat pump device capable of simultaneously heating and defrosting and an operation method thereof for the deficiencies of the prior art to solve the problems raised in the background art.

[0008] To achieve the above object, the present invention provides the following technical solutions: A heat pump device that can perform heating and defrosting simultaneously mainly includes an evaporator, a compressor, a condenser, and an expansion valve. The evaporator is a finned three-layer evaporative copper tube structure, where the inner two layers form the inner evaporator system and the outer layer forms the outer evaporator system. The inner system outlet of the inner evaporator system is sequentially connected to a gas-liquid separator, a compressor, an electric control valve, a condenser, a liquid storage tank, a filter, an economizer, an electronic expansion valve, and the inner system inlet to form a cycle. The outer system outlet of the outer evaporator system is sequentially connected to a first solenoid valve, a gas-liquid separator, a compressor, an electric control valve, a condenser, a liquid storage tank, a filter, an economizer, an electronic expansion valve, a check valve, and then connected to the outer system inlet to form a cycle. A bypass is provided at the outlet of the compressor, and this bypass is connected to the outer system inlet through a second solenoid valve. The outlet pipeline of the outer system is connected to the inlet of the condenser through a third solenoid valve, and a fourth solenoid valve is connected to the inlet of the liquid storage tank. A temperature sensor is provided near the outlet of the outer system.

[0009] The check valve is connected to the connecting pipe between the inner system inlet and the outer system inlet, and the direction is from the inner system inlet to the outer system inlet.

[0010] An operation method of a heat pump device that can perform heating and defrosting simultaneously. When the unit is operating in normal heating mode, its central control system controls the first solenoid valve to be in the open state and the electric control valve to be fully open by calculation and using the proportional-integral-derivative (PID) control law, while the second solenoid valve, the third solenoid valve, and the fourth solenoid valve are in the closed state. The compressor generates high-temperature and high-pressure gaseous refrigerant, which flows through the electric control valve and then enters the condenser to exchange heat with the medium at the user end. The medium-temperature and high-pressure gas-liquid mixed refrigerant after heat exchange enters the liquid storage tank, and the liquid refrigerant flowing out of the liquid storage tank enters the filter for filtration and then enters the economizer. If the ambient temperature is lower than 10°C, the unit's enthalpy-increasing electronic expansion valve opens and operates. At this time, the medium-temperature and high-pressure liquid refrigerant in the economizer exchanges heat crosswise with the low-temperature and low-pressure gaseous refrigerant expanded by the enthalpy-increasing electronic expansion valve, and the gaseous refrigerant after heat exchange enters the compressor for gas injection and enthalpy increase. If the ambient temperature is higher than 10°C, under the condition that the ambient temperature does not reach the opening condition of the enthalpy-increasing electronic expansion valve, the medium-temperature and high-pressure liquid refrigerant directly flows through the economizer without heat exchange. The main circuit refrigerant flows out of the economizer and enters the electronic expansion valve for expansion. The expanded low-temperature and low-pressure gaseous refrigerant is divided into two paths and enters the evaporator respectively. One path enters the inner evaporator system through the inner system inlet to absorb heat from the air, and the other path enters the outer evaporator system through the outer system inlet after passing through the check valve to absorb heat from the air. After absorbing heat, the refrigerant in the inner evaporator system enters the gas-liquid separator from the inner system outlet, and the refrigerant in the outer evaporator system enters the gas-liquid separator after passing through the first solenoid valve from the outer system outlet. Finally, the low-temperature and low-pressure gaseous refrigerant after passing through the gas-liquid separator enters the compressor to complete a cycle.

[0011] When the unit detects the need for defrosting, the central control system controls the second solenoid valve to open. At the same time, the electric control valve closes according to a set ratio of 70% - 75%, and the fourth solenoid valve opens, while the first solenoid valve and the third solenoid valve are in the closed state. At this time, the high-temperature and high-pressure gaseous refrigerant generated by the compressor is divided into two paths. One path enters the condenser through the electric control valve to continue heat exchange and completes the main cycle in sequence. The other path enters the outer evaporator system through the second solenoid valve (7) to release heat and melt the frost accumulated on the outer evaporator. At this time, since the refrigerant pressure at the inlet of the outer system is higher than that at the inlet of the inner system, the check valve is in the closed state. As the defrosting progresses, the refrigerant temperature in the outer evaporator system gradually rises. As the defrosting continues, the frost accumulated on the outer evaporator system has been preferentially removed. At this time, the inner evaporator system is drained by the fan and absorbs the heat released by the outer evaporator system, thereby melting and removing the frost. When the temperature sensor near the outlet of the outer system transmits a value higher than the outlet water temperature of the condenser, the central control system controls the unit to open the third solenoid valve and close the fourth solenoid valve, so that the refrigerant flows into the condenser to continue heat exchange, in order to better reduce the heat loss of the system. When the unit detects that the defrosting is completed, each valve returns to the above-mentioned common heating state and continues to operate in the heating mode.

[0012] Compared with the existing technology, the present invention has the following beneficial effects: 1. When the unit is defrosting, the present invention can avoid absorbing heat from the indoor heat dissipation terminal, solving the problem that the traditional defrosting method absorbs heat from the indoor heat dissipation terminal and causes room temperature fluctuations.

[0013] 2. When the unit uses a single heating machine, the present invention can omit the four-way valve, reducing production costs. At the same time, it reduces the unit failure caused by frequent commutation of the unit, and makes the electronic expansion valve always in the forward expansion state, without reverse expansion due to changing the refrigerant flow direction. This increases the service life of the expansion valve and also facilitates precise control of the opening degree.

[0014] 3. When defrosting, the present invention uses the form of the outer evaporator system transferring heat to the inner evaporator system for defrosting. This can not only stabilize the temperature of the use terminal, but also allow the inner evaporator system to absorb a part of the heat released by the outer evaporator system, reducing the overall heat loss of the system and achieving an energy-saving effect. At the same time, this feature can be used to maintain the normal operation of the entire unit when the unit cannot operate normally in an extremely cold environment by appropriately turning on this mode.

[0015] 4. During defrosting of the present invention, as defrosting progresses, the refrigerant temperature in the outer evaporator system gradually rises. When the temperature sensor near the outlet of the outer system transmits a value higher than the water outlet temperature of the condenser, the central control system controls the unit to open the third solenoid valve and close the fourth solenoid valve, so that the refrigerant flows into the condenser for further heat exchange, in order to better reduce the heat loss of the system and improve the system thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the system schematic diagram of the present invention; Figure 2 is the three-dimensional structure schematic diagram of the finned evaporator of the present invention; Figure 3 is the left view of the finned evaporator of the present invention; Figure 4 is the right view of the finned evaporator of the present invention; Reference numerals: 1, compressor; 2, electronic expansion valve; 3, check valve; 4, evaporator; 5, gas-liquid separator; 6, first solenoid valve; 7, second solenoid valve; 8, electric control valve; 9, third solenoid valve; 10, fourth solenoid valve; 11, condenser; 12, liquid storage tank; 13, filter; 14, economizer; 15, enhanced enthalpy electronic expansion valve; 41, inner system inlet; 42, inner system outlet; 43, outer system inlet; 44, outer system outlet; 45, temperature sensor; 46, inner evaporator system; 47, outer evaporator system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The technical solutions in the embodiments of the present invention will be described comprehensively, in detail and clearly below with reference to the drawings in the embodiments of the present invention.

[0019] See attached Figures 1-4As shown in the figure, a heat pump device that conducts heating and defrosting simultaneously mainly includes an evaporator, a compressor, a condenser, and an expansion valve. The evaporator 4 is a finned three-layer evaporative copper tube structure, where the inner two layers form the inner evaporator system 46, and the outer layer forms the outer evaporator system 47. The inner system outlet 42 of the inner evaporator system 46 is sequentially connected to a gas-liquid separator 5, a compressor 1, an electric control valve 8, a condenser 11, a liquid storage tank 12, a filter 13, an economizer 14, an electronic expansion valve 2, and the inner system inlet 41 to form a cycle. The outer system outlet 44 of the outer evaporator system 47 is sequentially connected to a first solenoid valve 6, a gas-liquid separator 5, a compressor 1, an electric control valve 8, a condenser 11, a liquid storage tank 12, a filter 13, an economizer 14, an electronic expansion valve 2, a check valve 3, and then connected to the outer system inlet 43 to form a cycle. A bypass is provided at the outlet of the compressor 1, and this bypass is connected to the outer system inlet 43 through a second solenoid valve 7. The pipeline of the outer system outlet 44 is connected to the inlet of the condenser 11 through a third solenoid valve 9, and a fourth solenoid valve 10 is connected to the inlet of the liquid storage tank 12. A temperature sensor 45 is provided near the outer system outlet 44.

[0020] The check valve 3 is connected to the connecting pipe between the inner system inlet 41 and the outer system inlet 43, and the direction is from the inner system inlet 41 to the outer system inlet 43.

[0021] A process flow of a heat pump that performs heating and defrosting simultaneously. When the unit is operating normally for heating, its central control system controls the first solenoid valve 6 to be in the open state and the electric control valve 8 to be fully open by calculation and using the proportional integral derivative (PID) law. The second solenoid valve 7, the third solenoid valve 9, and the fourth solenoid valve 10 are in the closed state. The compressor 1 generates high-temperature and high-pressure gaseous refrigerant, which flows through the electric control valve 8 and then enters the condenser 11 to exchange heat with the medium at the usage end. The medium-temperature and high-pressure gas-liquid mixed refrigerant after heat exchange enters the liquid storage tank 12, and the liquid refrigerant flowing out of the liquid storage tank 12 enters the filter 13 for filtration and then enters the economizer 14. If the ambient temperature is lower than 10°C, the unit's enthalpy-increasing electronic expansion valve 15 opens and operates. At this time, the medium-temperature and high-pressure liquid refrigerant in the economizer exchanges heat with the low-temperature and low-pressure gaseous refrigerant expanded by the enthalpy-increasing electronic expansion valve 15. The gaseous refrigerant after heat exchange enters the compressor 1 for air injection and enthalpy increase. If the ambient temperature is higher than 10°C, that is, under the ambient temperature condition where the enthalpy-increasing electronic expansion valve 15 has not reached the opening condition, the medium-temperature and high-pressure liquid refrigerant directly flows through the economizer without heat exchange. The main-circuit refrigerant flows out of the economizer 14 and enters the electronic expansion valve 2 for expansion. The low-temperature and low-pressure gaseous refrigerant after expansion is divided into two paths and enters the evaporator 4 respectively. One path enters the inner evaporator system through the inner system inlet 41 to absorb heat from the air, and the other path enters the outer evaporator system through the one-way valve 3 and the outer system inlet 43 to absorb heat from the air. After absorbing heat, the refrigerant in the inner evaporator system enters the gas-liquid separator 5 through the inner system outlet 42, and the refrigerant in the outer evaporator system enters the gas-liquid separator 5 through the outer system outlet 44 and the first solenoid valve 6. Finally, the low-temperature and low-pressure gaseous refrigerant after passing through the gas-liquid separator 5 enters the compressor 1 to complete a cycle.

[0022] When the unit detects that defrosting is required, the central control system controls the second solenoid valve 7 to open. At the same time, the electric regulating valve 8 closes at a set ratio of 70%-75%, and the fourth solenoid valve 10 opens, while the first solenoid valve 6 and the third solenoid valve 9 are in the closed state. At this time, the high-temperature and high-pressure gaseous refrigerant generated by the compressor 1 is divided into two paths. One path passes through the electric regulating valve 8 and enters the condenser 11 to continue heat exchange, and the main cycle is completed in sequence. The other path enters the outer evaporator system through the second solenoid valve 7 to release heat to melt the frost accumulated on the outer evaporator system. At this time, since the refrigerant pressure at the inlet 43 of the outer system is higher than the refrigerant pressure at the inlet 41 of the inner system, the check valve 3 is in the closed state. As the defrosting progresses, the refrigerant temperature in the outer evaporator system gradually rises. As the defrosting continues, the frost accumulated on the outer evaporator system has been preferentially removed. At this time, the inner evaporator system is drained by the fan and absorbs the heat released by the outer evaporator system, thereby melting and removing the accumulated frost. When the temperature sensor 45 near the outlet 44 of the outer system transmits a value higher than the outlet water temperature of the condenser 11, such as higher than 40°C, the central control system controls the unit to open the third solenoid valve 9 and close the fourth solenoid valve 10, so that the refrigerant flows into the condenser 11 to continue heat exchange to better reduce the heat loss of the system. When the unit detects that the defrosting is completed, each valve returns to the above-mentioned common heating state and continues to operate in the heating mode.

[0023] The above description is only a preferred embodiment of the present invention, and it is not a limitation of the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's solution still belong to the protection scope of the present invention.

Claims

1. A heat pump device that performs heating and defrosting simultaneously, mainly including an evaporator, a compressor, a condenser, and an expansion valve, characterized in that, The evaporator (4) is a finned three-layer evaporative copper tube structure, where the inner two layers form the inner evaporator system (46), and the outer layer forms the outer evaporator system (47); the inner system outlet (42) of the inner evaporator system (46) is sequentially connected to a gas-liquid separator (5), a compressor (1), an electric control valve (8), a condenser (11), a liquid storage tank (12), a filter (13), an economizer (14), an electronic expansion valve (2), and the inner system inlet (41) to form a cycle; the outer system outlet (44) of the outer evaporator system (47) is sequentially connected to a first solenoid valve (6), a gas-liquid separator (5), a compressor (1), an electric control valve (8), a condenser (11), a liquid storage tank (12), a filter (13), an economizer (14), an electronic expansion valve (2), a check valve (3), and then connected to the outer system inlet (43) to form a cycle; a bypass is provided at the outlet of the compressor (1), and this bypass is connected to the outer system inlet (43) through a second solenoid valve (7); the pipeline of the outer system outlet (44) is connected to the inlet of the condenser (11) through a third solenoid valve (9), and a fourth solenoid valve (10) is connected to the inlet of the liquid storage tank (12); a temperature sensor (45) is provided near the outer system outlet (44).

2. The heat pump device capable of performing heating and defrosting simultaneously according to claim 1, characterized in that: The check valve (3) is connected to the connecting pipe between the inner system inlet (41) and the outer system inlet (43), and the direction is from the inner system inlet (41) to the outer system inlet (43).

3. An operating method of a heat pump device that performs heating and defrosting simultaneously as described in claim 1, characterized in that: When the unit is operating normally for heating, its central control system controls the first solenoid valve (6) to be in the open state, the electric control valve (8) to be fully open, while the second solenoid valve (7), the third solenoid valve (9) and the fourth solenoid valve (10) are in the closed state through calculation and by adopting the proportional integral derivative (PID) control law; the compressor (1) generates high-temperature and high-pressure gaseous refrigerant, which flows through the electric control valve (8) and then enters the condenser (11) to exchange heat with the medium at the user end. After the heat exchange, the medium-temperature and high-pressure gas-liquid mixed refrigerant enters the liquid storage tank (12), and the liquid refrigerant flowing out of the liquid storage tank (12) enters the filter (13) for filtration and then enters the economizer (14); if the ambient temperature is lower than 10 °C, the unit's enthalpy-increasing electronic expansion valve (15) opens and operates. At this time, the medium-temperature and high-pressure liquid refrigerant in the economizer exchanges heat with the low-temperature and low-pressure gaseous refrigerant expanded by the enthalpy-increasing electronic expansion valve (15). After the heat exchange, the gaseous refrigerant enters the compressor (1) for gas replenishment and enthalpy increase; if the ambient temperature is higher than 10 °C, that is, under the ambient temperature condition where the enthalpy-increasing electronic expansion valve (15) has not reached the opening state, the medium-temperature and high-pressure liquid refrigerant directly flows through the economizer without heat exchange; the main-circuit refrigerant flows out of the economizer (14) and enters the electronic expansion valve (2) for expansion. The low-temperature and low-pressure gaseous refrigerant after expansion is divided into two paths and enters the evaporator (4) respectively. One path enters the inner evaporator system through the inner system inlet (41) to absorb heat from the air, and the other path enters the outer evaporator system through the check valve (3) and the outer system inlet (43) to absorb heat from the air; after absorbing heat, the refrigerant in the inner evaporator system enters the gas-liquid separator (5) through the inner system outlet (42), and the refrigerant in the outer evaporator system enters the gas-liquid separator (5) after passing through the first solenoid valve (6) from the outer system outlet (44); finally, the low-temperature and low-pressure gaseous refrigerant after passing through the gas-liquid separator (5) enters the compressor (1) to complete a cycle; When the unit detects the need for defrosting, the central control system controls the second solenoid valve (7) to open. At the same time, the electric regulating valve (8) closes by a set ratio of 70% - 75%, and the fourth solenoid valve (10) opens, while the first solenoid valve (6) and the third solenoid valve (9) are in the closed state. At this time, the high-temperature and high-pressure gaseous refrigerant generated by the compressor (1) is divided into two paths. One path enters the condenser (11) through the electric regulating valve (8) to continue heat exchange and completes the main cycle in sequence. The other path enters the outer evaporator system through the second solenoid valve (7) to release heat and melt the frost accumulated on the outer evaporator. At this time, since the refrigerant pressure at the outer system inlet (43) is higher than the refrigerant pressure at the inner system inlet (41), the check valve (3) is in the closed state. As the defrosting progresses, the refrigerant temperature in the outer evaporator system gradually increases. Then, as the defrosting continues, the frost accumulated on the outer evaporator system has been preferentially removed. At this time, the inner evaporator system is drained by the fan and absorbs the heat released by the outer evaporator system, thereby melting and removing the accumulated frost. When the temperature sensor (45) near the outer system outlet (44) transmits a value higher than the outlet water temperature of the condenser (11), the central control system controls the unit to open the third solenoid valve (9) and close the fourth solenoid valve (10) to make the refrigerant flow into the condenser (11) to continue heat exchange, so as to better reduce the heat loss of the system. When the unit detects that the defrosting is completed, each valve returns to the above-mentioned common heating state and continues to operate in the heating mode.

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