Variable-frequency high-temperature heat pump unit

Abstract

The utility model discloses a variable-frequency high-temperature heat pump unit which comprises a refrigerant pipeline and a waterway pipeline. A compressor, a condenser and an evaporator are mounted on the refrigerant pipeline, and a refrigerant can circularly flow in the refrigerant pipeline; the refrigerant pipeline and the waterway pipeline are both connected with the condenser, and heat exchange is conducted between the refrigerant pipeline and the waterway pipeline through the condenser; the water tank is connected with the waterway pipeline through the booster water pump, and the booster water pump can convey water in the water tank to the waterway pipeline for water and pressure supplementation. Through the arrangement, high-temperature hot water can be provided for the heat pump unit within the water temperature range of 90-130 DEG C through the booster water pump; water can be supplemented to the waterway pipeline in time through the booster water pump and the water tank, and the flow and the pressure in the waterway pipeline are controlled.

Description

Technical Field

[0001] This utility model relates to the field of heat pump water heaters, and in particular to a variable frequency high temperature heat pump unit. Background Technology

[0002] Existing heat pump water heaters provide hot water in the range of 40~55℃; they cannot provide hot water at high temperatures of 90~130℃; the water temperature variation range is 10~35℃; they are not suitable for high water temperature ranges of 35~70℃ under waste heat recovery conditions; the compressor uses a fixed frequency compressor and adopts traditional control technology, the control system is relatively simple, which is not conducive to quickly and reliably ensuring water temperature stability.

[0003] Furthermore, the PID control method used in existing heat pump water heaters has upper and lower output blind spots. For example, if the lower frequency limit is set to 20Hz, when the PID controller is in a frequency reduction state based on temperature comparison, although the lower frequency limit is set to 20Hz, the PID characteristic is continuous calculation. If the outlet water temperature is higher than the set temperature, it will remain in a frequency reduction state, and the PID's internal calculation result will reach 0Hz, at which point the actual control frequency is 20Hz. However, if the outlet water temperature is lower than the set temperature, the PID controller switches to a frequency increase state. At this time, the PID's internal calculation starts from 0Hz and increases the frequency upwards. If the internal calculation result is less than the lower limit of 20Hz, it will remain at 20Hz. This process from 0 to 20Hz can take 3 to 10 minutes. This is the existence of blind spots, which can lead to untimely frequency control, affecting the unit's operational stability and water temperature stability. Utility Model Content

[0004] To address the issues of low outlet water temperature and limited temperature adjustment range in existing heat pump units, this invention aims to provide a variable frequency high-temperature heat pump unit and its control method. This application can effectively improve the outlet water temperature and adjustment range of the heat pump unit, thereby better matching more working scenarios.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a variable frequency high-temperature heat pump unit, including a refrigerant pipeline and a water pipeline; a compressor, a condenser, and an evaporator are installed on the refrigerant pipeline, and the refrigerant can circulate in the refrigerant pipeline; both the refrigerant pipeline and the water pipeline are connected to the condenser, and the refrigerant pipeline and the water pipeline exchange heat through the condenser; the water tank is connected to the water pipeline through a booster pump, and the booster pump can send water in the water tank to the water pipeline for water replenishment and pressurization.

[0006] As a preferred option, a water supply valve is installed at the outlet of the booster pump, and a second safety valve for pressure relief is also installed on the water pipeline.

[0007] Preferably, a pressure sensor for controlling the start and stop of the booster pump is installed on the water pipeline, and the pressure sensor is located on the outlet side of the condenser.

[0008] Preferably, an inlet water temperature sensor and an outlet water temperature sensor are installed on the water pipeline. The inlet water temperature sensor is installed at the inlet of the condenser, and the outlet water temperature sensor is installed at the outlet of the condenser.

[0009] Preferably, an economizer, a liquid receiver, and a gas-liquid separator are also installed on the refrigerant pipeline. The economizer is located between the condenser and the evaporator, the liquid receiver is located between the condenser and the economizer, and the gas-liquid separator is located between the evaporator and the compressor.

[0010] As a preferred option, a main electronic expansion valve is also installed between the refrigerant line and the evaporator.

[0011] Preferably, a return gas temperature sensor and an evaporation pressure sensor are installed on the refrigerant line between the gas-liquid separator and the evaporator.

[0012] As a preferred option, the economizer is also equipped with an auxiliary pipeline. The inlet of the auxiliary pipeline is connected to the refrigerant pipeline between the economizer and the evaporator, and the outlet of the auxiliary pipeline is connected to the compressor's gas injection port. The refrigerant pipeline and the auxiliary pipeline exchange heat through the economizer.

[0013] Preferably, the gas-liquid separator is equipped with a heat tracing tape, and the compressor is equipped with a crankcase heating tape.

[0014] As a preferred option, an auxiliary electronic expansion valve is installed on the auxiliary pipeline, which is located between the economizer and the refrigerant pipeline.

[0015] The beneficial effects of the technical solution of this utility model are as follows: the above-mentioned mechanism can provide high-temperature hot water in the water temperature range of 35~70℃; the booster pump can provide high-temperature hot water in the water temperature range of 90~130℃ for the heat pump unit; the booster pump and water tank can replenish water to the water pipeline in a timely manner and control the flow and pressure in the water pipeline, thereby enabling the heat pump unit to operate stably.

[0016] The aforementioned units can also replace heating equipment such as gas-fired boilers, coal-fired boilers, and electric boilers, and can be widely used in electroplating plants, slaughterhouses, petrochemical plants, dairy farms, and other places with waste heat recovery needs. This can reduce emissions of air pollutants such as carbon dioxide and sulfur dioxide, thus benefiting environmental protection. Attached Figure Description

[0017] Figure 1 This is a system diagram of a variable frequency high-temperature heat pump unit;

[0018] Figure 2 This is the control flowchart for a variable frequency high-temperature heat pump unit.

[0019] Reference numerals: 1. Compressor; 2. High-pressure switch; 3. Exhaust temperature sensor; 4. Exhaust pipe needle valve; 5. Condenser; 6. First safety valve; 7. Condensing pressure sensor; 8. Liquid receiver; 9. Economizer; 10. Auxiliary electronic expansion valve; 11. Copper mesh filter; 12. Dryer filter; 13. Main electronic expansion valve; 14. Evaporator; 15. Evaporating pressure sensor; 16. Heating tape; 17. Gas-liquid separator; 18. Suction pipe needle valve; 19. Low-pressure switch ; 20. Crankcase heating belt; 21. Intermediate pressure sensor; 22. Air supply temperature sensor; 23. Condensate temperature sensor; 24. Water outlet temperature sensor; 25. Water inlet temperature sensor; 26. Economizer outlet temperature sensor; 27. Inlet temperature sensor; 28. Outlet temperature sensor; 29. ​​Return air temperature sensor; 30. Pressure sensor; 31. Second safety valve; 32. Water outlet valve; 33. Circulating water pump; 34. Water supply valve; 35. Booster water pump; 36. Water tank. Detailed Implementation

[0020] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0021] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined.

[0023] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. Example

[0025] like Figure 1 The variable frequency high-temperature heat pump unit shown includes refrigerant piping and water piping; a compressor 1, a condenser 5 and an evaporator 14 are installed on the refrigerant piping, and the refrigerant can circulate in the refrigerant piping; both the refrigerant piping and the water piping are connected to the condenser 5, and the refrigerant piping and the water piping exchange heat through the condenser 5;

[0026] The water tank is connected to the water pipeline via a booster pump 35, which can send water from the water tank 36 to the water pipeline for water replenishment and pressure replenishment.

[0027] With this configuration, the aforementioned mechanism can provide high-temperature hot water within a water temperature range of 35~70℃; the booster pump 35 can provide high-temperature hot water within a water temperature range of 90~130℃ for the heat pump unit; the booster pump 35 and the water tank 36 can replenish water to the water pipeline in a timely manner and control the flow and pressure in the water pipeline, thereby enabling the heat pump unit to operate stably.

[0028] The aforementioned units can also replace heating equipment such as gas-fired boilers, coal-fired boilers, and electric boilers, and can be widely used in electroplating plants, slaughterhouses, petrochemical plants, dairy farms, and other places with waste heat recovery needs. This can reduce emissions of air pollutants such as carbon dioxide and sulfur dioxide, thus benefiting environmental protection.

[0029] In this embodiment, a water supply valve 34 is installed at the outlet of the booster pump 35. By controlling the water supply valve 34, it is possible to control whether water in the water tank 36 flows into the water pipeline. A second safety valve 31, an inlet valve, and an outlet valve 32 are also installed on the water pipeline. The outlet valve is located at the outlet of the water pipeline, the inlet valve is located at the inlet of the water pipeline, and the second safety valve 31 is located between the condenser 5 and the outlet valve. This arrangement effectively controls the flow rate of the water pipeline; when the water pressure exceeds a predetermined value, the safety valve will perform a protective pressure relief.

[0030] In this embodiment, a pressure sensor 30 is installed on the water pipe to detect the pressure inside the water pipe; the pressure sensor 30 is installed on the outlet side of the condenser 5. Furthermore, an inlet water temperature sensor 25 and an outlet water temperature sensor 24 are installed on the water pipe. The inlet water temperature sensor 25 is located at the inlet of the condenser 5, and the outlet water temperature sensor 24 is located at the outlet of the condenser 5. This arrangement allows for effective detection and control of the heat pump unit's operating status by monitoring the pressure and temperature in the water pipe using these sensors.

[0031] In this embodiment, a circulating water pump 33 is installed on the water pipeline, and the circulating water pump 33 is located between the condenser 5 and the booster water pump 35.

[0032] In this embodiment, an economizer 9, a liquid receiver 8, and a gas-liquid separator 17 are also installed on the refrigerant pipeline. The economizer 9 is located between the condenser 5 and the evaporator 14, the liquid receiver 8 is located between the condenser 5 and the economizer 9, and the gas-liquid separator 17 is located between the evaporator 14 and the compressor 1. This configuration, with the economizer 9, ensures that the compressor 1 becomes a quasi-two-stage compression scroll compressor 1, expanding the operating range of the compressor 1. The liquid receiver ensures that the electronic expansion valve reliably regulates the refrigerant flow, preventing flashed refrigerant gas from affecting the throttling effect, and also ensures that the liquid refrigerant entering the electronic expansion valve contains only the minimum amount of gaseous refrigerant.

[0033] In a further preferred embodiment, a main electronic expansion valve 13 is also installed on the refrigerant line, and the main electronic expansion valve 13 is located between the economizer 9 and the evaporator 14; a dryer filter 12 is also installed on the refrigerant line, and the dryer filter 12 is located between the economizer 9 and the main electronic expansion valve 13.

[0034] A return gas temperature sensor 29 and an evaporation pressure sensor 15 are installed on the refrigerant line between the gas-liquid separator 17 and the evaporator 14.

[0035] A low-pressure switch 19 and a suction pipe needle valve 18 are installed on the refrigerant pipeline. The low-pressure switch 19 is located between the gas-liquid separator 17 and the compressor 1, and the suction pipe needle valve 18 is located between the low-pressure switch and the gas-liquid separator 17.

[0036] The refrigerant pipeline is equipped with a high-pressure switch 2, an exhaust temperature sensor 3, and an exhaust pipe needle valve 4. The high-pressure switch 2 is located between the compressor 1 and the condenser 5, the exhaust pipe needle valve 4 is located between the high-pressure switch and the condenser 5, and the exhaust temperature sensor 3 is located between the high-pressure switch and the condenser 5.

[0037] A first safety valve 6 is installed on the condenser 5, and a condensing pressure sensor 7 is installed between the condenser 5 and the liquid receiver 8.

[0038] An economizer outlet temperature sensor 26 is installed on the refrigerant line, and the economizer outlet temperature sensor is located at the outlet of the economizer.

[0039] A condensation temperature sensor 23 is installed between the liquid receiver 8 and the economizer 9; an inlet temperature sensor 27 and an outlet temperature sensor 28 are installed on the evaporator 9.

[0040] This setup, using the aforementioned sensors, enables the heat pump unit to operate reliably and accurately according to predetermined rules: electronic expansion valves are used for throttling in both the main and auxiliary circuits; simultaneously, condenser 5 outlet temperature and economizer 9 outlet temperature sensors are configured to monitor the condensing temperature and the cooling effect of economizer 9. This prevents excessively high condensing temperatures and allows for monitoring the cooling effect of economizer 9. The condenser 5 outlet temperature sensor monitors the condensing temperature to prevent it from becoming too high, which could cause the electronic expansion valve to malfunction; additionally, the condenser 5 outlet temperature and economizer 9 outlet temperature sensors are used to monitor the degree of subcooling generated by economizer 9.

[0041] In this embodiment, an auxiliary pipeline is also installed on the economizer 9. The inlet of the auxiliary pipeline is connected to the refrigerant pipeline between the economizer 9 and the evaporator 14, and the outlet of the auxiliary pipeline is connected to the gas supply port of the compressor 1. The refrigerant pipeline and the auxiliary pipeline exchange heat through the economizer 9.

[0042] In a further preferred embodiment, an auxiliary electronic expansion valve 10 is installed on the auxiliary pipeline, and the auxiliary electronic expansion valve 10 is located between the economizer 9 and the refrigerant pipeline; a copper mesh filter 11 is also installed on the auxiliary pipeline, and the copper mesh filter 11 is located between the auxiliary electronic expansion valve 10 and the refrigerant pipeline; an intermediate pressure sensor 21 and a gas supply temperature sensor 22 are installed on the auxiliary pipeline located between the compressor 1 and the economizer 9.

[0043] In this embodiment, a heating tape 16 is provided on the gas-liquid separator 17 to prevent refrigerant liquid from migrating into the gas-liquid separator 17 during long-term shutdown, which could cause the system to fail to start normally. A crankcase heating tape 20 is provided on the compressor 1.

[0044] In this embodiment, compressor 1 is a variable frequency scroll compressor 1, which makes the cooling capacity of compressor 1 adjustable. Example

[0045] A control method for controlling the above-mentioned variable frequency high-temperature heat pump unit includes two parts: frequency control and pressure boosting control.

[0046] like Figure 2 As shown, the compressor frequency is dynamically controlled by the temperature difference between the outlet water temperature and the user-set temperature. The compressor frequency adjustment amplitude is also dynamically adjusted within each frequency adjustment cycle by the temperature difference between the outlet water temperature and the user-set temperature. This solves the system problems caused by the large frequency increase and decrease caused by PID regulation, while giving full play to the advantages of PID regulation, ensuring stable outlet water temperature and more energy-efficient and reliable unit operation.

[0047] In the pressurization control, when the outlet water temperature of the water pipeline is lower than the user-set temperature, the booster pump is turned on to pressurize the water pipeline; when the outlet water temperature of the water pipeline is higher than the user-set temperature, the booster pump is turned off.

[0048] In this embodiment, during unit startup, the compressor starts after the circulating water pump and the main electronic expansion valve; the main electronic expansion valve maintains its initial opening for N seconds before adjustment; specifically, the compressor starts 10 seconds after the main electronic expansion valve opens; and the initial opening of the main electronic expansion valve is 50% of its full opening step, and the main electronic expansion valve maintains its initial opening for 90 seconds before adjustment.

[0049] Further preferably, before the unit is started for the first time, the water temperature on the evaporator side of the unit should be above 35°C, and the water temperature on the condenser side of the unit should be above 40°C before the compressor can be operated.

[0050] In a further preferred embodiment, the unit is powered on in advance before the compressor starts, so that the crankcase heater and heating tape of the unit can start working in advance; wherein, the crankcase heater and the heating tape of the gas-liquid separator should work for no less than 6 hours.

[0051] In this embodiment, after the compressor starts, it runs at its initial frequency for a duration of M before entering an automatic adjustment state. The initial frequency of the compressor is the lower limit of its operating frequency. Specifically, taking a compressor with an upper frequency limit of 130.0 Hz and a lower limit of 40.0 Hz as an example, the compressor starts at an initial frequency of 40 Hz and enters the automatic adjustment state after stabilizing for 3 minutes. This ensures that the unit operates under optimal conditions and safely.

[0052] In this embodiment, when adjusting the compressor operating frequency, it is first determined whether the operating frequency needs to be adjusted. If it needs to be changed, the compressor operating frequency is adjusted according to the difference between the user-set temperature and the outlet water temperature; otherwise, the compressor operates in its current state.

[0053] Further optimized, the compressor operating frequency is determined based on the user-set temperature and outlet water temperature to determine whether adjustment is needed. Specifically, when the unit is in the loading zone, the compressor operating frequency is increased; when the unit is in the holding zone, the current compressor operating frequency is maintained; and when the unit is in the unloading zone, the compressor operating frequency is decreased. Wherein, loading zone = outlet water temperature ≥ target temperature + upper limit of temperature difference; holding zone = target temperature + lower limit of temperature difference > outlet water temperature < target temperature + upper limit of temperature difference; unloading zone = outlet water temperature ≤ target temperature + lower limit of temperature difference; where the lower limit and upper limit of temperature difference are preset values.

[0054] In a further preferred embodiment, the unit has a built-in PID controller, which can calculate the PID output frequency based on the user-set temperature and the outlet water temperature; the calculation method of the PID output frequency can be found in the published documents such as CN113834187A, CN108954892A and CN104833102A.

[0055] Further preferably, when the compressor operating frequency needs to be changed, the compressor operating frequency is adjusted according to the difference between the user-set temperature and the outlet water temperature. Specifically, the compressor operating frequency is adjusted as follows: Frequency adjustment amplitude = (Temperature difference value - Lower limit of frequency adjustment temperature difference) / (Upper limit of frequency adjustment temperature difference - Lower limit of frequency adjustment temperature difference) * (Upper limit of frequency adjustment amplitude - Lower limit of frequency adjustment amplitude) + Lower limit of frequency adjustment amplitude; where the temperature difference value is the difference between the user-set temperature and the outlet water temperature, the upper and lower limits of frequency adjustment amplitude are both system settings, and the upper limit of frequency adjustment temperature difference is a preset value. Furthermore, when the temperature difference value is negative, it is multiplied by -1 to always keep the temperature difference value positive. Furthermore, when the temperature difference value is greater than the upper limit of the allowable temperature difference, the upper limit of the allowable temperature difference is used; where the upper limit of the allowable temperature difference is a preset value. Taking the calculated temperature difference value as 4.0℃, the set upper limit of the temperature difference value as 5.0℃, the set lower limit of the temperature difference value as 0.0℃, the upper limit of the frequency modulation amplitude as 5.0 Hz, the lower limit of the frequency modulation amplitude as 1.0 Hz, and the frequency modulation amplitude as X as an example, X = (4.0 - 0.0℃ / (5.0 - 0.0℃) * (5.0 Hz - 1.0 Hz) + 1.0 Hz, the calculated frequency modulation amplitude for each time period is 4.2 Hz.

[0056] Further preferably, when the compressor operating frequency needs to be changed, the compressor's frequency adjustment cycle is adjusted according to the difference between the user-set temperature and the outlet water temperature. Specifically, the frequency adjustment cycle = (temperature difference value - lower limit of frequency adjustment temperature difference) / (upper limit of frequency adjustment temperature difference - lower limit of frequency adjustment temperature difference) * (maximum frequency adjustment cycle - minimum frequency adjustment cycle) + minimum frequency adjustment cycle; where the maximum and minimum frequency adjustment cycles are preset values. Taking a temperature difference value = 3.0℃, a set upper limit of temperature difference value = 5.0℃, a set lower limit of temperature difference value = 0.0℃, a minimum frequency adjustment cycle = 5.0 s, a maximum frequency adjustment cycle = 20.0 s, and a frequency adjustment cycle = X as an example, X = (3.0 - 0.0℃ / (5.0 - 0.0℃) * (20.0 s - 5.0 s) + 1.0 Hz. The calculated frequency adjustment cycle is 11.0 s.

[0057] Taking the conditions of frequency adjustment amplitude = 4.2Hz and frequency adjustment period = 11.0S as an example: When the unit is in the loading zone, the PID output frequency – 2.0Hz > current frequency < frequency upper limit. The current frequency increases by 4.2Hz every 11.0S until it reaches the PID output frequency or the frequency upper limit, at which point the frequency increase stops. When the unit is in the holding zone: the current frequency = PID output frequency ± 2.0Hz, and the frequency is neither increased nor decreased. When the unit is in the unloading zone: the PID output frequency + 2.0Hz < current frequency > frequency lower limit. The current frequency decreases by 4.2Hz every 11.0S until it decreases to the PID output frequency or the frequency lower limit, at which point the frequency decrease stops.

[0058] To address the blind spot in PID control and ensure timely PID action, this embodiment incorporates a built-in timer instruction. When the compressor is in a frequency reduction state and the PID output frequency is lower than the compressor frequency lower limit, the timer instruction is triggered.

[0059] If the unit always meets the two conditions of the compressor being in a frequency reduction state and the PID output frequency being less than the compressor frequency lower limit during the execution of the timer instruction, then the manual intervention state will be triggered after the timer instruction ends, and the PID output frequency will be forcibly specified as the compressor frequency lower limit.

[0060] During the execution of the timer instruction, if the unit fails to meet either of the following two conditions—that the compressor is in a frequency reduction state and the PID output frequency is less than the lower limit of the compressor frequency—the timer instruction ends, and the unit resumes normal operation. This setting eliminates the compressor's dead zone of 0Hz to 20Hz, enabling the PID control to quickly adjust according to temperature changes.

[0061] To ensure stable unit operation and avoid operation under extreme conditions, in this embodiment, the compressor operating frequency is controlled based on the condensing pressure and evaporating pressure.

[0062] Specifically: when the system condensing pressure is detected to be greater than or equal to 25 bar, the compressor operating frequency remains unchanged; when the system condensing pressure is detected to exceed 25.1 bar, the compressor operating frequency is reduced by 0.5 Hz for every 0.1 bar increase, in order to prevent the unit from becoming unstable or triggering an alarm due to continuous pressure increase;

[0063] When the system evaporation pressure is detected to be less than or equal to 1 bar, the compressor operation frequency stops loading, and the compressor maintains the current operating frequency to prevent the compressor capacity from being loaded too quickly and causing a low-pressure alarm; when the evaporation pressure is greater than 1.5 bar, the compressor resumes normal loading.

[0064] In this embodiment, since the unit's heating outlet water temperature is as high as 130°C, the pressure in the corresponding water pipes must be guaranteed at each temperature point. If the pressure is too low, the hot water will boil and the set temperature cannot be reached.

[0065] Therefore, a corresponding pressure value needs to be set for each temperature point. A pressure sensor detects the pressure within the current water pipe and compares it with the pressure corresponding to the preset outlet water temperature. If the pressure corresponding to the current outlet water temperature is lower than the pressure corresponding to the preset outlet water temperature, the booster pump is activated to increase the pressure. If the pressure corresponding to the current outlet water temperature is higher than the pressure corresponding to the preset outlet water temperature + 500 Pa, the booster pump is deactivated. The corresponding values ​​for water temperature and pressure can be found in Table 1.

[0066] Table 1: Correspondence between boiling point of water and pressure

[0067] Temperature / °C Pressure / Pa Temperature / °C Pressure / Pa 90 70110.9 111 145690.5 91 72807.4 112 149840.3 92 75593.8 113 153990.7 93 78473.5 114 158140.6 94 81446.7 115 162290 95 84513.1 116 166440 96 87672.8 117 170590 97 90939.2 118 174740. 98 94298.9 119 186990 99 97752.0 119.6 208720 100 101320.5 121 216580 101 105340.7 122 224430 102 109360.9 123 232280 103 113390.1 124 240130 104 117410.3 125 247980 105 121430.5 126 255830 106 125450.7 127 263680 107 129470.9 128 271530 108 133500.1 129 279380 109 137520.3 130 287230 110 140520.3 131 295080

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A variable frequency high-temperature heat pump unit, characterized in that: It includes refrigerant piping and water piping; the refrigerant piping is equipped with a compressor (1), a condenser (5) and an evaporator (14), and the refrigerant can circulate in the refrigerant piping; the refrigerant piping and water piping are both connected to the condenser (5), and the refrigerant piping and water piping exchange heat through the condenser (5); The water tank is connected to the water pipeline via a booster pump (35). The booster pump (35) can send the water in the water tank (36) to the water pipeline for water replenishment and pressure replenishment.

2. The variable frequency high-temperature heat pump unit according to claim 1, characterized in that: A water supply valve (34) is installed at the outlet of the booster pump (35), and a second safety valve (31) for pressure relief is also installed on the water pipeline.

3. The variable frequency high-temperature heat pump unit according to claim 1, characterized in that: A pressure sensor (30) for controlling the start and stop of the booster pump (35) is installed on the water pipeline. The pressure sensor (30) is located on the outlet side of the condenser (5).

4. The variable frequency high-temperature heat pump unit according to claim 1, characterized in that: The water pipe is equipped with an inlet water temperature sensor (25) and an outlet water temperature sensor (24). The inlet water temperature sensor (25) is located at the inlet of the condenser (5), and the outlet water temperature sensor (24) is located at the outlet of the condenser (5).

5. A variable frequency high-temperature heat pump unit according to claim 1, characterized in that: An economizer (9), a liquid receiver (8), and a gas-liquid separator (17) are also installed on the refrigerant pipeline. The economizer (9) is located between the condenser (5) and the evaporator (14), the liquid receiver (8) is located between the condenser (5) and the economizer (9), and the gas-liquid separator (17) is located between the evaporator (14) and the compressor (1).

6. A variable frequency high-temperature heat pump unit according to claim 5, characterized in that: A main electronic expansion valve (13) is also installed on the refrigerant line. The main electronic expansion valve (13) is located between the economizer (9) and the evaporator (14).

7. A variable frequency high-temperature heat pump unit according to claim 5, characterized in that: A return gas temperature sensor (29) and an evaporation pressure sensor (15) are installed on the refrigerant line between the gas-liquid separator (17) and the evaporator (14).

8. A variable frequency high-temperature heat pump unit according to claim 1, characterized in that: An auxiliary pipeline is also installed on the economizer (9). The inlet of the auxiliary pipeline is connected to the refrigerant pipeline between the economizer (9) and the evaporator (14). The outlet of the auxiliary pipeline is connected to the gas supply port of the compressor (1). The refrigerant pipeline and the auxiliary pipeline exchange heat through the economizer (9).

9. A variable frequency high-temperature heat pump unit according to claim 8, characterized in that: An auxiliary electronic expansion valve (10) is installed on the auxiliary pipeline. The auxiliary electronic expansion valve (10) is located between the economizer (9) and the refrigerant pipeline.

10. A variable frequency high-temperature heat pump unit according to claim 1, characterized in that: A heating tape (16) is installed on the gas-liquid separator (17), and a crankcase heating tape (20) is installed on the compressor (1).

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