Operation method of low-environment-temperature and high-water-temperature air energy heat pump

Abstract

The operation method of the low-environment-temperature and high-water-temperature air energy heat pump comprises the following steps that firstly, the heat pump is powered on to operate, and then the second step is executed; 2, when the central controller of the heat pump judges that the current environment temperature Ta is larger than the first set temperature t3 or the current water outlet temperature Tb is larger than the second set temperature t4, the step 12 is executed, and otherwise, the step 3 is executed; wherein the value range of the first set temperature t3 is-5 DEG C to-15 DEG C, and the value range of the second set temperature t4 is 30 DEG C to 40 DEG C; thirdly, the heat pump is started in a refrigeration mode, and the fourth step is executed; fourthly, the compressor operates at the first frequency F1, and the value range of the F1 is 30 Hz to 38 Hz; fifthly, the opening degree of the first electronic expansion valve is set to be 78%-98% of the full opening degree of the first electronic expansion valve, and the seventh step is executed; and step 6, first operation time T1 is passed. The invention has the characteristic of safe and reliable operation.

Description

Technical Field

[0001] The invention relates to an air energy heat pump, in particular to an operation method of an air energy heat pump with low ambient temperature and high water temperature. Background Art

[0002] Under the environmental protection policies of carbon neutrality and energy conservation and emission reduction, the sales of air energy products in the northern market are increasing, and they are gradually replacing wall-mounted boilers in extremely cold regions. In the extremely cold northern regions, the water temperature of the heat pump compressor is still relatively high after it stops running for a period of time due to the long downtime when the set temperature is reached, as well as reasons such as shutting down and going out, sudden power outages, etc. When the heat pump is started under such conditions, the compressor is very likely to be short of oil, which increases the risk of compressor damage.

[0003] In response to this situation, some manufacturers have made some improvements. For example, Chinese patent document number CN 212806136U disclosed on March 26, 2021 a super-low temperature environment high water temperature air source high efficiency heat exchange heat pump unit, including a compressor, a four-way valve, a condenser, an evaporator, an economizer and a first regenerator, the air inlet of the four-way valve is connected to the air outlet of the compressor, the first interface of the four-way valve is connected to the condenser, the condenser is connected to the first port of the economizer, the second port of the economizer is connected to the first regenerator, the second interface of the four-way valve is connected to the evaporator, the air outlet of the evaporator is connected to the superheat inlet of the first regenerator, the superheat outlet of the first regenerator is connected to the evaporator through a throttle, the outlet of the evaporator is connected to the subcooling inlet of the first regenerator through a four-way valve, and the subcooling outlet of the first regenerator is connected to the compression pump. However, the actual use effect of this super-low temperature environment high water temperature air source high efficiency heat exchange heat pump unit is not ideal and needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a method for operating an air energy heat pump with low ambient temperature and high water temperature which can run stably and reliably, so as to overcome the shortcomings of the prior art.

[0005] An operating method for a low ambient temperature and high water temperature air energy heat pump designed for this purpose is characterized in that the heat pump includes a compressor, an evaporator, a condenser, a four-way reversing valve and an economizer, the high-pressure outlet of the compressor is connected to the first interface of the four-way reversing valve, the second interface of the four-way reversing valve is connected to the refrigerant inlet of the evaporator, the refrigerant outlet of the evaporator is connected to the refrigerant inlet of the condenser through the first branch of the economizer, a first electronic expansion valve is connected in series between the refrigerant outlet of the evaporator and the first branch of the economizer, the refrigerant outlet of the condenser is connected to the fourth interface of the four-way reversing valve, and the third interface of the four-way reversing valve is connected to the The low-pressure inlet of the compressor is connected, one end of the second electronic expansion valve is connected in series between the first electronic expansion valve and the first branch of the economizer, the other end of the second electronic expansion valve is connected to the medium-pressure inlet of the compressor through the second branch of the economizer, an outlet water temperature sensor for detecting the current outlet water temperature Tb is provided on the outlet pipe of the condenser, an inlet water temperature sensor is provided on the inlet pipe of the condenser, an exhaust temperature sensor is provided at the high-pressure outlet of the compressor, a return air temperature sensor is provided at the low-pressure inlet of the compressor, and an ambient temperature sensor for detecting the current ambient temperature Ta is provided on the evaporator, and the operation includes the following steps:

[0006] Step 1: The heat pump is powered on and starts running, and then proceeds to step 2;

[0007] Step 2: When the central controller of the heat pump determines that the current ambient temperature Ta> the first set temperature t3 or the current outlet water temperature Tb> the second set temperature t4, the process proceeds to step 12; otherwise, the process proceeds to step 3;

[0008] The first set temperature t3 has a value range of -5°C to -15°C, and the second set temperature t4 has a value range of 30°C to 40°C;

[0009] Step 3: The heat pump is started in cooling mode, and then the process goes to step 4;

[0010] Step 4: The compressor operates at a first frequency F1, wherein the value range of F1 is 30 Hz to 38 Hz;

[0011] Step 5, setting the opening of the first electronic expansion valve to 78% to 98% of its full opening, and proceeding to step 7;

[0012] Step 6: After a first running time T1, the value range of T1 is 3 minutes to 5 minutes;

[0013] Step 7, the central controller determines whether the return air temperature of the compressor Tm≥Ta+5°C is established. If it is established, it goes to step 8, otherwise it goes to step 6;

[0014] Step 8: The heat pump operates in heating mode, and then proceeds to step 9;

[0015] Step nine, setting the opening of the second electronic expansion valve to 48% to 80% of its full opening, and proceeding to step ten;

[0016] Step 10, the central controller determines whether the current superheat Tc ≥ the third set temperature t5 is established. If it is yes, it goes to step 12, otherwise it goes to step 11;

[0017] Among them, the value range of t5 is 10℃~25℃;

[0018] Step 11: After the second running time T2, the value range of T2 is 8 minutes to 20 minutes; proceed to step 12;

[0019] Step 12: the opening of the second electronic expansion valve is controlled in a conventional mode;

[0020] Step 13: The heat pump operates in heating mode.

[0021] The present invention adopts the above-mentioned technical scheme, which can shorten the startup time of the heat pump with low ambient temperature and high water temperature, reduce the oil return loss, and improve the stability of the heat pump operation. At the same time, it solves the problem of insufficient exhaust superheat when the heat pump is started for heating, and the lubricating oil is carried out of the compressor by the refrigerant, resulting in oil shortage, thereby ensuring the safe and reliable operation of the heat pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an embodiment of the present invention.

[0023] Figure 2 It is a control flow chart of the present invention.

[0024] In the figure: 1 is an evaporator, 2 is an ambient temperature sensor, 3 is a gas-liquid separator, 4 is a first electronic expansion valve, 5 is a second electronic expansion valve, 6 is an economizer, 7 is an outlet water temperature sensor, 8 is an inlet water temperature sensor, 9 is a condenser, 10 is a compressor, 11 is an exhaust temperature sensor, 12 is a four-way reversing valve, and 13 is a return air temperature sensor. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] See also Figure 1-Figure 2, an operating method of an air energy heat pump with low ambient temperature and high water temperature, characterized in that the heat pump includes a compressor 10, an evaporator 1, a condenser 9, a four-way reversing valve 12 and an economizer 6, the high-pressure outlet of the compressor 10 is connected to the first interface of the four-way reversing valve 12, the second interface of the four-way reversing valve 12 is connected to the refrigerant inlet of the evaporator 1, the refrigerant outlet of the evaporator 1 is connected to the refrigerant inlet of the condenser 9 through the first branch of the economizer 6, the first electronic expansion valve 4 is connected in series between the refrigerant outlet of the evaporator 1 and the first branch of the economizer 6, the refrigerant outlet of the condenser 9 is connected to the fourth interface of the four-way reversing valve 12, and the third interface of the four-way reversing valve 12 is connected to the refrigerant inlet of the condenser 9. It is connected to the low-pressure inlet of the compressor 10, one end of the second electronic expansion valve 5 is serially connected between the first electronic expansion valve 4 and the first branch of the economizer 6, and the other end of the second electronic expansion valve 5 is connected to the medium-pressure inlet of the compressor 10 through the second branch of the economizer 6. A water outlet temperature sensor 7 for detecting the current water outlet temperature Tb is provided on the water outlet pipe of the condenser 9, a water inlet temperature sensor 8 is provided on the water inlet pipe of the condenser 9, an exhaust temperature sensor 11 is provided at the high-pressure outlet of the compressor 10, a return air temperature sensor 11 is provided at the low-pressure inlet of the compressor 10, and an ambient temperature sensor 2 for detecting the current ambient temperature Ta is provided on the evaporator 1.

[0027] The operation includes the following steps:

[0028] Step 1: The heat pump is powered on and starts running, and then proceeds to step 2;

[0029] Step 2: When the central controller of the heat pump determines that the current ambient temperature Ta> the first set temperature t3 or the current outlet water temperature Tb> the second set temperature t4, the process proceeds to step 12; otherwise, the process proceeds to step 3;

[0030] The first set temperature t3 has a value range of -5°C to -15°C, and the second set temperature t4 has a value range of 30°C to 40°C;

[0031] Step 3: The heat pump is started in cooling mode, and then the process goes to step 4;

[0032] Step 4: The compressor 10 operates at a first frequency F1, wherein the value range of F1 is 30 Hz to 38 Hz;

[0033] Step 5, setting the opening degree of the first electronic expansion valve 4 to 78% to 98% of its full opening degree, and entering step.

[0034] Example: When the full opening degree of the first electronic expansion valve 4 is 500, the forward opening degree of the first electronic expansion valve 4 can be set to 390-490.

[0035] Step 6: After a first running time T1, the value range of T1 is 3 minutes to 5 minutes;

[0036] Step 7, the central controller determines whether the return air temperature Tm≥Ta+5°C of the compressor 10 is established. If it is established, it goes to step 8, otherwise it goes to step 6;

[0037] Step 8: The heat pump operates in heating mode, and then proceeds to step 9;

[0038] Step nine, setting the opening of the second electronic expansion valve 5 to 48% to 80% of its full opening, and proceeding to step ten;

[0039] Example: When the full opening degree of the second electronic expansion valve 5 is 500, the forward opening degree of the second electronic expansion valve 5 can be set to 240-400.

[0040] Step 10, the central controller determines whether the current superheat Tc ≥ the third set temperature t5 is established. If it is yes, it goes to step 12, otherwise it goes to step 11;

[0041] Among them, the value range of t5 is 10℃~25℃;

[0042] Step 11: After the second running time T2, the value range of T2 is 8 minutes to 20 minutes; proceed to step 12;

[0043] Step 12: the opening of the second electronic expansion valve 5 is controlled in a conventional mode;

[0044] Step 13: The heat pump operates in heating mode.

[0045] In this embodiment, when entering the normal control mode, after the heat pump system has been running for 3 minutes, the superheat of the first electronic expansion valve 4 is controlled according to the exhaust gas superheat Tc of the heat pump system.

[0046] When Tc≤18℃, the opening of the first electronic expansion valve 4 is reduced every 30 seconds, 6 steps each time. When 18℃<Tc<32℃, the opening of the first electronic expansion valve 4 is adjusted according to the return air superheat of the heat pump system.

[0047] Return gas superheat Td = return gas temperature - condensing temperature.

[0048] The control of return air superheat is as follows: when Td≤1°C, the opening of the first electronic expansion valve 4 is reduced every 30 seconds, 6 steps each time; when 1°C<Td<3°C, the opening of the first electronic expansion valve 4 remains unchanged; when Td≥3, the opening of the first electronic expansion valve 4 is increased every 30 seconds, 8 steps each time.

[0049] When Tc≥32°C, the opening of the first electronic expansion valve 4 is increased every 30 seconds, 8 steps each time.

[0050] In this embodiment, when entering the normal control mode, after the heat pump system has been running for 3 minutes, the superheat of the second electronic expansion valve 5 is controlled according to the economizer superheat Tk.

[0051] The superheat of the economizer Tk = economizer outlet temperature - economizer inlet temperature.

[0052] When Tk≤0, the opening of the second electronic expansion valve is reduced every 10 seconds, 6 steps each time.

[0053] When 0<Tk≤2, the opening degree of the second electronic expansion valve maintains the current opening degree.

[0054] When Tk>2, the opening of the second electronic expansion valve is increased every 10 seconds, 8 steps each time.

[0055] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0056] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for operating an air energy heat pump with low ambient temperature and high water temperature, characterized in that The heat pump comprises a compressor (10), an evaporator (1), a condenser (9), a four-way reversing valve (12) and an economizer (6); the high-pressure outlet of the compressor (10) is connected to a first interface of the four-way reversing valve (12); the second interface of the four-way reversing valve (12) is connected to a refrigerant inlet of the evaporator (1); the refrigerant outlet of the evaporator (1) is connected to a refrigerant inlet of the condenser (9) through a first branch of the economizer (6); a first electronic expansion valve (4) is connected in series between the refrigerant outlet of the evaporator (1) and the first branch of the economizer (6); the refrigerant outlet of the condenser (9) is connected to a fourth interface of the four-way reversing valve (12); and the third interface of the four-way reversing valve (12) is connected to a low-pressure inlet of the compressor (10). One end of the second electronic expansion valve (5) is serially connected between the first electronic expansion valve (4) and the first branch of the economizer (6); the other end of the second electronic expansion valve (5) is connected to the medium-pressure inlet of the compressor (10) through the second branch of the economizer (6); an outlet water temperature sensor (7) for detecting the current outlet water temperature Tb is provided on the outlet water pipe of the condenser (9); an inlet water temperature sensor (8) is provided on the inlet water pipe of the condenser (9); an exhaust gas temperature sensor (11) is provided at the high-pressure outlet of the compressor (10); a return air temperature sensor (11) is provided at the low-pressure inlet of the compressor (10); and an ambient temperature sensor (2) for detecting the current ambient temperature Ta is provided on the evaporator (1). The operation includes the following steps: Step 1: The heat pump is powered on and starts running, and then proceeds to step 2; Step 2: When the central controller of the heat pump determines that the current ambient temperature Ta> the first set temperature t3 or the current outlet water temperature Tb> the second set temperature t4, the process proceeds to step 12; otherwise, the process proceeds to step 3; The first set temperature t3 has a value range of -5°C to -15°C, and the second set temperature t4 has a value range of 30°C to 40°C; Step 3: The heat pump is started in cooling mode, and then the process goes to step 4; Step 4: The compressor (10) operates at a first frequency F1, wherein the value range of F1 is 30 Hz to 38 Hz; Step 5, setting the opening of the first electronic expansion valve (4) to 78% to 98% of its full opening, and proceeding to step 7; Step 6: After a first running time T1, the value range of T1 is 3 minutes to 5 minutes; Step 7, the central controller determines whether the return air temperature Tm ≥ Ta + 5°C of the compressor (10) is established. If it is established, it proceeds to step 8, otherwise it proceeds to step 6; Step 8: The heat pump operates in heating mode, and then proceeds to step 9; Step nine, setting the opening of the second electronic expansion valve (5) to 48% to 80% of its full opening, and proceeding to step ten; Step 10, the central controller determines whether the current superheat Tc ≥ the third set temperature t5 is established. If it is yes, it goes to step 12, otherwise it goes to step 11; Among them, the value range of t5 is 10℃~25℃; Step 11: After the second running time T2, the value range of T2 is 8 minutes to 20 minutes; proceed to step 12; Step 12: the opening degree of the second electronic expansion valve (5) is controlled in a conventional mode; Step 13: The heat pump operates in heating mode.

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