A water source heat pump system and control method thereof

Abstract

The present invention discloses a water source heat pump system and a control method thereof. The water source heat pump system includes: a hot water tank, a hot water circulation pump, a refrigeration unit, a liquid supply pipeline, a return air pipeline equipped with a low-pressure sensor, an evaporator heat exchange ice-melting device, a constant pressure water source, a water inlet main pipe equipped with a temperature sensor, a water outlet pipeline, etc.; the control method of the system includes: a dynamic setting of the increase and decrease pressure and a control method of the variable output of the refrigeration load of the refrigeration unit and a control method of the continuous heating of the evaporator alternating ice-melting system and the critical freezing point state of the outlet water. Through the above system and control method, the purpose of saving water resources, automatic ice melting and continuous heating is achieved, and the water source heat pump can be applied to different working conditions.

Description

Technical Field

[0001] The invention relates to a water source heat pump system and a control method thereof. Background Art

[0002] The existing water source heat pump is mainly divided into two refrigeration modes: dry refrigeration system and full liquid refrigeration system. 1. Dry water source heat pump: The evaporator of a general dry water source heat pump is a shell and tube evaporator, with the tube side as refrigerant and the shell side as water. The return air superheat of a dry refrigeration system is generally greater than 1K, and in actual use the superheat is generally greater than 5K. For example, when the evaporator inlet water temperature is 5°C, the outlet water temperature is 0°C, the superheat is 5K, and the evaporation temperature is -5°C, the outside of the evaporator tubes will be severely frozen, resulting in a decrease in heat exchange efficiency. If the spacing between the evaporator tubes is small, ice outside the tubes will cause the tubes to frost and bulge and damage. When the evaporator inlet water temperature is low and close to the freezing point, the existing water source heat pump cannot operate normally, and the ice must be continuously melted to ensure the heating effect, but the heating cannot be continued normally when the ice is melted. 2. Full liquid (wet) water source heat pump: The evaporator of a general full liquid water source heat pump is a shell and tube evaporator, with water on the tube side and refrigerant on the shell side. The return air superheat of the wet refrigeration system is generally ≥ 0K. In actual use, the superheat is generally slightly greater than 0K. For example, when the evaporator inlet water temperature is 5℃, the outlet water temperature is 0℃, the superheat is 0K, and the evaporator has a corresponding heat exchange area, the evaporation temperature is -3℃, and the evaporator tubes will also freeze at this time, resulting in a decrease in heat exchange efficiency. Ice in the tubes will cause the tubes to frost and bulge. When the evaporator inlet water temperature is low and close to the freezing point, the existing full-liquid water source heat pump cannot operate normally. It is necessary to continuously melt the ice to ensure the heating effect, but it is also impossible to continue heating normally during ice melting. In addition, the previous water source heat pump generally has a temperature difference of 5℃ between the inlet and outlet water. The evaporator mainly absorbs heat from the sensible heat of the inlet water. Since the liquid specific heat capacity of water is 1Kcal / kg.℃, the water consumption is large. Therefore, water source heat pumps cannot be used in some cases where water resources are not sufficient.

[0003] On the other hand, the existing water source heat pump refrigeration system is generally suitable for a single working condition and cannot automatically adjust under different working conditions to meet various working conditions. For example, when the water source temperature changes due to the ambient temperature, the water source heat pump works according to the fixed set working condition, which cannot make the water source heat pump achieve the best working efficiency. In addition, the evaporator de-icing of the existing low-temperature water source heat pump refrigeration system usually adopts the scraper method, which is not only complex in structure, but also has a high failure rate and high maintenance cost. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a water source heat pump system and a control method thereof. First, the system realizes continuous heating function by alternating ice melting, and has the characteristics of significant water saving; second, the heat exchange and ice melting device of the system has automatic ice melting and ice discharge functions; third, the system has the function of automatically adjusting the working load output of the water source heat pump according to the water source temperature.

[0005] The technical solution of the present invention is as follows:

[0006] 14. The heat exchange and de-icing device as claimed in claim 13, wherein the heat exchange and de-icing device comprises an evaporator water tank with an evaporator installed therein, the evaporator being respectively connected to a refrigerant return pipe and a refrigerant supply pipe; the evaporator water tank being respectively connected to a water inlet pipe and a water outlet pipe; the refrigerant supply pipe being provided with a refrigerant supply automatic valve, the refrigerant return pipe being provided with a refrigerant return automatic valve; the water inlet pipe being provided with a water inlet regulating automatic valve; the water outlet pipe and the water outlet of the evaporator water tank being connected to each other through a water outlet positioning pipe; the bottom end of the water outlet positioning pipe being connected to the water outlet of the evaporator water tank, and the top end being connected to the water outlet pipe; the evaporator water tank is also provided with an ice-melting drain outlet in the form of an overflow port, the lower edge position of the ice-melting drain outlet being higher than the top position of the water outlet positioning pipe; the evaporator An ice-melting drainage box for receiving water and ice overflowing from the ice-melting drainage outlet is also installed on one side of the evaporator water tank; the ice-melting drainage box is connected to an ice-melting drainage pipe; the heat exchange and ice-melting device also includes a first temperature sensor for detecting the water temperature at the water outlet of the evaporator water tank and a second temperature sensor for detecting the water temperature in the evaporator water tank; wherein a pressure sensor is installed on the refrigerant return main pipe; the system also includes a water inlet main pipe installed with a third temperature sensor, and the water inlet main pipe is respectively connected to the water inlet pipe of each heat exchange and ice-melting device; the system also includes a drainage main pipe, and the drainage main pipe is respectively connected to the evaporator water tank outlet pipe and the ice-melting drainage pipe of each heat exchange and ice-melting device; the refrigeration unit is respectively connected to the refrigerant return pipe and the refrigerant supply pipe of each heat exchange and ice-melting device through the refrigerant supply main pipe and the refrigerant return main pipe.

[0007] Preferably, the heat exchange and ice melting device further comprises a water outlet drain pipe, the bottom end of which is connected to the top end of the water outlet positioning pipe, and the top end of which is higher than the top of the evaporator water tank.

[0008] The control method of the system is characterized in that: after the water source heat pump has been running for a period of time, if the duration of the evaporation temperature of the evaporator of a certain heat exchange and ice-melting device being lower than the freezing point temperature reaches a set value, it is determined that the evaporator of the heat exchange and ice-melting device needs to be defrosted; at this time, the refrigerant supply automatic valve and the refrigerant return automatic valve are closed, the evaporator of the heat exchange and ice-melting device stops heat exchange, and starts to defrost and discharge ice; when the outlet water temperature of the evaporator of the heat exchange and ice-melting device is greater than or equal to the inlet water temperature for a duration that reaches a set ice-melting stop time value, it is determined that the evaporator has completed ice-melting, at this time, the water inlet automatic regulating valve is closed, and the heat exchange and ice-melting device enters a standby state; at this time, if another heat exchange and ice-melting device stops heat exchange, the heat exchange and ice-melting device that has entered the standby state is started to enter the heat exchange program; according to the above process, automatic ice melting is performed alternately in sequence to achieve continuous heating of the system.

[0009] The control method of the system is characterized by: monitoring the water temperature in each evaporator water tank in real time through a second temperature sensor, controlling the water inlet flow rate regulated by the water inlet automatic regulating valve, so that part of the water in the evaporator water tank is maintained at a critical freezing point state.

[0010] The control method of the system is characterized in that: when the water source heat pump is working, the third temperature sensor monitors the water source temperature t1 in real time, and compares the water source temperature t1 with the set temperature difference value ∆t to generate an increase and unload evaporation temperature control value t0=t1-∆, and converts the increase and unload evaporation temperature control value t0 into a corresponding evaporation pressure control value according to the refrigerant saturation pressure temperature characteristic curve or function formula pre-implanted in the controller; and automatically adjusts the variable load output of the refrigeration unit (3) by comparing the evaporation pressure value detected by the pressure sensor (6) with the evaporation pressure control value.

[0011] Further, when the control value t0>10°C, t0 is calculated as 10°C to prevent the compressor from overloading.

[0012] The positive effects of the present invention are:

[0013] 1. The heat exchange and ice melting device of the present invention has the functions of automatic ice melting and ice discharge: when the evaporator needs to melt ice, the refrigerant supply and return automatic valves of the heat exchange and ice melting device are automatically closed, and the water inlet flow rate is increased by adjusting the water inlet automatic valve. At this time, the low-temperature water at the critical freezing point of the lower part of the water tank is discharged from the water tank through the water outlet pipe. The water temperature in the water tank is higher than the freezing point, the pressure in the evaporator rises, and the refrigerant temperature is higher than the freezing point temperature, so that the ice on the evaporator is quickly detached. Since the density of ice is less than the density of water, the ice that has fallen off but not melted floats to the water surface. When the water inlet automatic valve automatically adjusts to increase the water volume, since the water outlet pipe can only meet the water outlet flow rate during refrigeration and heat exchange, the water level will rise to the position of the ice melting drain port, and the water will be discharged from the water tank from the ice melting drain port, and the ice floating on the water surface will be taken out of the water tank to complete the ice discharge.

[0014] 2. Automatic alternating ice melting and continuous heating: The system of the present invention adopts more than two sets of heat exchange ice melting devices with automatic ice melting and ice discharge functions. After one set of heat exchange ice melting devices has finished melting ice, its water inlet automatic valve is adjusted to reduce the water inlet flow rate so that the water level is lower than the ice melting outlet, and the refrigerant supply and return automatic valves are automatically opened, and the heat exchange ice melting device restarts heat exchange. When one of the heat exchange ice melting devices is melting ice, the other heat exchange ice melting devices are working normally and the heat exchange amount can meet the refrigeration load demand of the refrigeration unit. When the heat exchange ice melting device has finished melting ice, the next set of heat exchange ice melting devices will be melted. The heat exchange ice melting devices melt ice alternately in sequence, so that the water source heat pump can achieve the purpose of continuous heating.

[0015] 3. Reduce water consumption: The present invention can control the output load of the refrigeration unit by comparing the evaporation pressure value detected by the pressure sensor 6 with the set evaporation pressure control value, and adjust the water inlet flow of the evaporator by real-time monitoring the outlet water temperature of the evaporator water tank and the water temperature in the water tank, so that part of the water in the evaporator water tank is kept at the critical freezing point state. The evaporator absorbs a large amount of latent heat of water at the critical freezing point, achieving the technical goal of significantly reducing the water consumption of the evaporator. Due to the unique structure and control method of the heat exchange ice melting device in the present invention (controlling the evaporation temperature to keep part of the water in the water tank at the critical freezing point state), the latent heat released by the conversion of water at the freezing point temperature into ice at the freezing point temperature is 80 times the sensible heat released by liquid water for every 1°C decrease. The device can utilize 50% of the critical freezing point latent heat, so only 1 / 40 of the previous water volume is needed to make the water source heat pump work normally, thereby meeting the needs of using water source heat pumps in areas with insufficient water sources or too low water temperatures.

[0016] 4. The control method of the present invention realizes variable output of the unit's refrigeration load, so that the water source heat pump is suitable for different working conditions: the present invention automatically calculates and generates increase and unload evaporation pressure control parameters based on real-time monitoring of changes in water source temperature, and automatically adjusts the variable load output of the refrigeration unit according to the evaporation pressure detected by the pressure sensor (variable load output means include: increase and unload of compressors and increase and decrease of the number of compressors, frequency conversion control of compressor load output, etc.) to meet the refrigeration load required by the refrigeration unit, thereby achieving the best working efficiency of the water source heat pump.

[0017] The present invention is applicable to a water source heat pump system with low water temperature, insufficient water volume or large water temperature variations at different periods. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure and working principle of an embodiment of a water source heat pump refrigeration system of the present invention;

[0019] 1. Hot water tank, 2. Hot water pump, 3. Refrigeration unit, 4. Refrigerant return main pipe, 5. Refrigerant supply main pipe, 6. Pressure sensor, 7. A heat exchange and ice-melting device, 7-1. Refrigerant return automatic valve, 7-2. Refrigerant supply automatic valve, 7-3. Refrigerant return pipe, 7-4. Refrigerant supply pipe, 7-5. Water outlet drain pipe, 7-6. First temperature sensor, 7-7. Water outlet positioning pipe, 7-8. Water outlet pipe, 7-9. Ice-melting drain outlet, 7-10. Water inlet regulating automatic valve, 7-11. Ice-melting drain box, 7-12. Water inlet pipe, 7-13. Ice-melting drain pipe, 7-14. Evaporator, 7-15. Evaporator water tank, 7-16. Second temperature sensor, 8. B heat exchange and ice-melting device, 9. C heat exchange and ice-melting device, 10. Constant pressure water supply source, 11. Drain main pipe, 12. Water inlet main pipe, 13. Third temperature sensor. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the embodiments and the accompanying drawings.

[0021] like Figure 1 The embodiment of the system of the present invention includes a refrigeration unit 3 and three heat exchange ice-melting devices with the same structure, and the three heat exchange ice-melting devices are heat exchange ice-melting device A 7, heat exchange ice-melting device B 8 and heat exchange ice-melting device C 9.

[0022] Taking A heat exchange ice melting device as an example, the heat exchange ice melting device includes an evaporator water tank 7-15 in which an evaporator 7-14 is installed. The evaporator 7-14 is respectively connected to a refrigerant return pipe 7-3 and a refrigerant supply pipe 7-4, and the refrigerant return pipe 7-3 and the refrigerant supply pipe 7-4 are used to connect a refrigeration unit. The evaporator water tank 7-15 is respectively connected to a water inlet pipe 7-12 and a water outlet pipe 7-8.

[0023] The refrigerant supply pipe 7-4 is equipped with a refrigerant supply automatic valve 7-2, and the refrigerant return pipe 7-3 is equipped with a refrigerant return automatic valve 7-1. The water inlet pipe 7-12 is equipped with a water inlet regulating automatic valve 7-10. The water outlet pipe 7-8 and the water outlet of the evaporator water tank 7-15 are connected to each other through a water outlet positioning pipe 7-7. The bottom end of the water outlet positioning pipe 7-7 is connected to the water outlet of the evaporator water tank 7-15, and the top end is connected to the water outlet pipe 7-8. The heat exchange and ice melting device also includes a water outlet drain pipe 7-5, the bottom end of which is connected to the top end of the water outlet positioning pipe 7-7, and the top end of the water outlet drain pipe 7-5 is higher than the top end of the evaporator water tank 7-15.

[0024] The evaporator water tank 7-15 is also provided with an ice-melting drain outlet 7-9 in the form of an overflow port, and the lower edge position of the ice-melting drain outlet 7-9 is higher than the top position of the water outlet positioning pipe 7-7.

[0025] An ice-melt drainage box 7-11 for receiving water and ice overflowing from the ice-melt drainage port 7-9 is also installed on one side of the evaporator water tank 7-15, and the ice-melt drainage box 7-11 is connected to an ice-melt drainage pipe 7-13.

[0026] This embodiment also includes a first temperature sensor 7-6 for detecting the water temperature at the water outlet of the evaporator water tank 7-15. The first temperature sensor 7-6 can be installed on the water outlet positioning pipe 7-7.

[0027] This embodiment further includes a second temperature sensor 7-16 for detecting the water temperature in the evaporator water tank 7-15. The second temperature sensor 7-16 can be installed in the evaporator water tank 7-15 and can be adjusted in height.

[0028] The refrigeration unit 3 is connected to the hot water tank 1 through a pipeline and a hot water pump 2. The refrigeration unit 3 is also connected to the refrigerant inlet and outlet pipelines of the three heat exchange and ice-melting devices through a refrigerant supply main pipe 5 and a refrigerant return main pipe 4, such as the refrigerant supply pipe 7-4 and the refrigerant return pipe 7-3 of the A heat exchange and ice-melting device 7. A pressure sensor 6 is installed on the refrigerant return main pipe 4. This embodiment also includes a constant pressure water supply source 10, and the constant pressure water supply source 10 is connected to a water inlet main pipe 12. The water inlet main pipe 12 is connected to the water tank water inlet pipes of the three heat exchange and ice-melting devices, such as the water inlet pipe 7-12 of the A heat exchange and ice-melting device 7. A third temperature sensor 13 is installed on the water inlet main pipe 12. This embodiment also includes a drainage main pipe 11, and the drainage main pipe 11 is connected to the drainage pipelines and ice discharge pipelines of the three heat exchange and ice-melting devices, such as the water outlet pipe 7-8 and the ice melting drainage pipe 7-13 of the A heat exchange and ice-melting device 7.

[0029] When the water source heat pump is working, the controller monitors the water source temperature t1 in real time according to the third temperature sensor 13, and compares the water source temperature t1 with the set temperature difference ∆t to generate the increase and unload evaporation temperature control value t0=t1-∆, and converts the increase and unload evaporation temperature control value t0 into the corresponding evaporation pressure control value according to the saturated pressure temperature characteristic curve or function formula of the refrigerant implanted in the controller in advance. By comparing the evaporation pressure value detected by the pressure sensor 6 with the evaporation pressure control value, the variable load output of the refrigeration unit 3 is automatically adjusted. The adjustment means of the variable load output include: increase and unload of the compressor and increase and decrease of the number of compressors, variable frequency control of the load output of the compressor, etc., to meet the refrigeration load required by the refrigeration unit. For example: when the water source temperature t1=12℃, the temperature difference ∆t=5℃ set by the controller, the increase and unload evaporation temperature control value t0=t1-∆t=12-5=7℃ is calculated, and the increase and unload evaporation temperature control value t0 is converted into the corresponding evaporation pressure control value according to the saturated pressure temperature characteristic curve or function formula of the refrigerant implanted in advance in the controller, and the load variable output of the refrigeration unit is controlled. When the control value t0>10℃, it is calculated as 10℃ (to prevent the compressor from overloading).

[0030] The refrigeration unit 3 automatically starts according to the set value, opens the water inlet regulating automatic valve 7-10, and the water in the constant pressure water supply source 10 flows to the evaporator water tank 7-15 through the water inlet main pipe 12 and the water inlet pipe 7-12 in turn, and then flows to the drainage main pipe 11 through the water outlet positioning pipe 7-7 and the water outlet pipe 7-8 in turn after heat exchange with the refrigerant in the evaporator 7-14; at the same time, the refrigerant supply automatic valve 7-2 and the refrigerant return automatic valve 7-1 are opened, and the refrigerant of the refrigeration unit 3 enters the evaporator 7-14 through the refrigerant supply main pipe 5 and the refrigerant supply pipe 7-4 in turn, and then returns to the refrigeration unit 3 through the refrigerant return pipe 7-3 and the refrigerant return main pipe 4 in turn after heat exchange with the water in the evaporator water tank 7-15. The working principle of the heat exchange ice melting device B 8 and the heat exchange ice melting device C 9 is the same as that of the heat exchange ice melting device A 7.

[0031] When the water temperature provided by the constant pressure water supply source 10 is low, after the water source heat pump runs for a period of time, if the evaporation temperature (the evaporation temperature is obtained by calculating and converting the evaporation pressure value detected by the pressure sensor 6 and the saturated pressure-temperature characteristic curve or function formula of the refrigerant implanted in the controller) of the evaporator of the heat exchange and ice-melting device A is less than the freezing point temperature for a duration that reaches a set value (the set value is set according to the debugging experimental data), it is determined that the evaporator 7-14 of the heat exchange and ice-melting device A needs to be thawed; at this time, the refrigerant supply automatic valve 7-2 and the refrigerant return automatic valve 7-1 are automatically closed, and the evaporator 7-14 stops heat exchange. The water inlet automatic regulating valve 7-10 is automatically adjusted to increase the water inlet. Water at the critical freezing point is discharged from the evaporator water tank 7-15 through the water outlet positioning pipe 7-7 and the water outlet pipe 7-8 in turn, and then leaves the system through the drainage main pipe 11; when the water temperature in the evaporator water tank 7-1 exceeds the freezing point temperature, the pressure in the evaporator 7-14 rises, and the refrigerant temperature rises. When the evaporation temperature exceeds the freezing point temperature, the ice layer falls off from the evaporator 7-14 quickly, and because the flow of the water outlet pipe 7-8 can only meet the smaller water inlet flow of the evaporator during refrigeration, the water inlet automatic regulating valve 7-10 automatically adjusts to increase the water inlet, so the water level in the evaporator water tank 7-15 continues to rise. When it rises to the position of the ice melt drain port 7-9, the detached ice layer overflows into the ice melt drain tank 7-11 through the ice melt drain port 7-9, and then is discharged to the drainage main pipe 11 through the thicker ice melt drain pipe 7-13 and discharged from the system.

[0032] When the water temperature detected by the first temperature sensor 7-6 is greater than or equal to the inlet water temperature detected by the third temperature sensor 13 for a period of time that reaches the set ice-melting stop time value (the set value is set based on the debugging experimental data), it is determined that the evaporator 7-14 has completed ice melting. At this time, the water inlet automatic regulating valve 7-10 is closed, and the A heat exchange and ice-melting device 7 enters the standby state.

[0033] At this time, if the evaporator of the heat exchange and ice melting device B 8 or the heat exchange and ice melting device C 9 stops exchanging heat, the heat exchange and ice melting device A 7 is started to enter the heat exchange program, the refrigerant supply automatic valve 7-2 and the refrigerant return automatic valve 7-1 are automatically opened, and the water inlet automatic regulating valve 7-10 restores the water inlet flow to the heat exchange state flow, and the evaporator 7-14 exchanges heat again. The ice is automatically melted alternately in sequence according to the above process. Since only one evaporator melts the ice at a time, the heat exchange capacity of the other evaporators can meet the refrigeration load requirements of the water source heat pump system, so the water source heat pump can continue to heat while melting the ice.

[0034] When the water temperature provided by the constant pressure water supply source 10 is low, the water in the evaporator water tank of each ice melting heat exchange device enters through the water inlet main pipe 12, and is cooled by the evaporator, and the critical freezing point low temperature water is in the lower middle part of the evaporator water tank 15. The evaporation pressure of the evaporator is monitored in real time by the pressure sensor 6 to control the output load of the refrigeration unit. The water temperature in each evaporator water tank is monitored in real time by the second temperature sensor 7-16, and the water inlet flow rate adjusted by the water inlet automatic regulating valve is controlled to keep part of the water in the evaporator water tank at the critical freezing point. The evaporator absorbs a large amount of latent heat of the water at the critical freezing point, which greatly reduces the water consumption of the evaporator. Because water has a large amount of latent heat in the critical freezing point state, only a small amount of low temperature water is needed to make the water source heat pump work normally.

[0035] The system absorbs both sensible heat and latent heat in low-temperature water through various heat exchange and ice-melting devices, and releases them into the hot water pool through the condenser of the refrigeration unit to achieve the efficiency of the heat pump.

[0036] In summary, this system can not only provide uninterrupted heating when the evaporator melts ice, but also achieve the purpose of normal use of the water source heat pump under different working conditions.

Claims

1. A water source heat pump system, comprising a refrigeration unit (3) and at least two heat exchange and ice melting devices, characterized in that: The heat exchange and ice-melting device comprises an evaporator water tank with an evaporator installed inside, and the evaporator is respectively connected to a refrigerant return pipe and a refrigerant supply pipe; the refrigeration unit (3) is respectively connected to the refrigerant return pipe and the refrigerant supply pipe of each heat exchange and ice-melting device through a refrigerant supply main pipe (5) and a refrigerant return main pipe (4); the evaporator water tank is respectively connected to a water inlet pipe and a water outlet pipe; a refrigerant supply automatic valve is installed on the refrigerant supply pipe, and a refrigerant return automatic valve is installed on the refrigerant return pipe; an inlet regulating automatic valve is installed on the water inlet pipe; the water outlet pipe and the water outlet of the evaporator water tank are connected to each other through a water outlet positioning pipe; the bottom end of the water outlet positioning pipe is connected to the water outlet of the evaporator water tank, and the top end is connected to the water outlet pipe; the evaporator water tank is also provided with an ice-melting drain in the form of an overflow port, and the ice-melting drain is provided with an overflow port. The lower edge position is higher than the top position of the water outlet positioning pipe; an ice-melting drainage box for receiving water and ice overflowing from the ice-melting drainage outlet is also installed on one side of the evaporator water tank; the ice-melting drainage box is connected to the ice-melting drainage pipe; the heat exchange ice-melting device also includes a first temperature sensor for detecting the water temperature at the water outlet of the evaporator water tank and a second temperature sensor for detecting the water temperature in the evaporator water tank; wherein a pressure sensor (6) is installed on the refrigerant return main pipe (4); the system also includes a water inlet main pipe (12) installed with a third temperature sensor (13), and the water inlet main pipe (12) is respectively connected to the water inlet pipes of the water tanks of each heat exchange ice-melting device; the system also includes a drainage main pipe (11), and the drainage main pipe (11) is respectively connected to the evaporator water tank outlet pipes and ice-melting drainage pipes of each heat exchange ice-melting device.

2. The water source heat pump system according to claim 1, characterized in that: The heat exchange and ice melting device also includes a water outlet drain pipe, the bottom end of which is connected to the top end of the water outlet positioning pipe, and the top end of which is higher than the top of the evaporator water tank.

3. A control method for a water source heat pump system as claimed in claim 1 or 2, characterized in that: After the water source heat pump has been running for a period of time, if the duration of the evaporation temperature of the evaporator of a certain heat exchange and ice-melting device being lower than the freezing point temperature reaches a set value, it is determined that the evaporator of the heat exchange and ice-melting device needs to be defrosted; at this time, the refrigerant supply automatic valve and the refrigerant return automatic valve are closed, the evaporator of the heat exchange and ice-melting device stops heat exchange, and starts to defrost and discharge ice; when the outlet water temperature of the evaporator of the heat exchange and ice-melting device is greater than or equal to the inlet water temperature for a duration that reaches the set ice-melting stop time value, it is determined that the evaporator has completed ice-melting, at this time, the water inlet automatic regulating valve is closed, and the heat exchange and ice-melting device enters a standby state; at this time, if another heat exchange and ice-melting device stops heat exchange, the heat exchange and ice-melting device that has entered the standby state is started to enter the heat exchange program; according to the above process, the ice is automatically melted alternately in sequence to achieve continuous heating of the system.

4. The control method of the system according to claim 1 or 2, characterized in that: The water temperature in each evaporator water tank is monitored in real time by the second temperature sensor, and the water inlet automatic regulating valve is controlled to adjust the water inlet flow of the evaporator water tank, so that part of the water in the evaporator water tank is maintained at a critical freezing point state.

5. The control method of the system according to claim 1 or 2, characterized in that: When the water source heat pump is working, the third temperature sensor monitors the water source temperature t1 in real time and compares the water source temperature t1 with the set temperature difference. Δ t comparison operation generates the increase and unload evaporation temperature control value t0 = t1- Δ t, converting the increase / unload evaporation temperature control value t0 into a corresponding evaporation pressure control value according to the refrigerant saturation pressure-temperature characteristic curve or function formula pre-implanted in the controller; and automatically adjusting the variable load output of the refrigeration unit (3) by comparing the evaporation pressure value detected by the pressure sensor (6) with the evaporation pressure control value.

6. The control method of the system according to claim 5, characterized in that: When the control value t0>10°C, t0 is calculated as 10°C to prevent the compressor from overloading.

Images