A chiller and control method for controlling temperature using waste heat of compressor

Abstract

The present invention discloses a chiller and control method for controlling the temperature by using the waste heat of a compressor, comprising a compressor, wherein the exhaust passage of the compressor is connected to the air inlet of a plate heat exchanger through a heat dissipation component, and the air outlet of the plate heat exchanger is connected through a compressor return passage, and the plate heat exchanger is respectively connected to the water inlet passage and the drainage passage for heat exchange. The above technical scheme utilizes the waste heat of the compressor cylinder as a heat source for controlling the cold and hot balance, and a group of heat exchange coils are wound around the compressor cylinder for heat exchange with low-temperature and low-pressure refrigerant liquid, increasing the evaporation effect before the plate heat exchanger, ensuring that what returns to the compressor is gas, and there is no risk of liquid hammer, thereby improving the reliability of the unit, and at the same time, after heat exchange with water, a certain amount of sensible heat is reduced, and a certain amount of heating capacity is obtained, thereby achieving the purpose of cold and hot balance temperature control, and valve replacement is performed according to valve control requirements to reduce costs.

Description

Technical Field

[0001] The present invention relates to the technical field of cooling equipment, and in particular to a chiller using compressor waste heat for temperature control and a control method thereof. Background Art

[0002] In the industrial field, water chillers are widely used. At present, the temperature control of water chillers on the market is to reduce the cooling capacity by bypassing the exhaust gas to the evaporator. This method has relatively high requirements for control. If it is not controlled well, it is easy to cause liquid hammer to the compressor. In view of this problem, the present invention invents a water chiller and a control method that uses the waste heat of the compressor to control the temperature.

[0003] Chinese patent document CN106766295A discloses a "water chiller". It includes a compression device, a condensing device, a throttling device, and an evaporating device, which are connected in series to form a circulation loop, and also includes a control device and several temperature sensors with an inlet arranged between the compression device and the condensing device and an outlet arranged between the throttling device and the evaporating device; the above technical solution reduces the cooling capacity through the evaporator, and the risk of single control is high. Summary of the invention

[0004] The present invention mainly solves the technical problem that the technical solution reduces the refrigeration capacity through the evaporator and the single control risk is high. It provides a chiller and a control method for controlling the temperature by the waste heat of the compressor, and uses the waste heat of the compressor cylinder as the heat source for controlling the cold and hot balance. A group of heat exchange coils are wound around the compressor cylinder for exchanging heat with the low-temperature and low-pressure refrigerant liquid, thereby increasing the evaporation effect before the plate heat exchanger, ensuring that what returns to the compressor is gas, without the risk of liquid hammer, and improving the reliability of the unit. At the same time, after heat exchange with water, the sensible heat is reduced to a certain extent, and a certain heating capacity is obtained, thereby achieving the purpose of cold and hot balance temperature control, and the valve is replaced according to the valve control requirements to reduce costs.

[0005] The above technical problems of the present invention are mainly solved by the following technical solutions: The present invention includes a compressor, the exhaust passage of the compressor is connected to the air inlet of the plate heat exchanger through the heat dissipation component, the air outlet of the plate heat exchanger is connected through the compressor return passage, and the plate heat exchanger is respectively connected to the water inlet passage and the water discharge passage of the heat exchange. When the main engine is running, the low-temperature and low-pressure refrigerant vapor is converted into high-temperature and high-pressure superheated vapor by the work of the compressor for the fin heat exchanger. Through the forced convection of the fan, the air absorbs the heat of the high-temperature and high-pressure superheated vapor and blows out hot air. After the superheated vapor releases heat, it liquefies into a medium-temperature and high-pressure saturated liquid. After the electronic expansion valve throttles and reduces the pressure, it becomes a low-temperature and low-pressure saturated liquid and enters the plate heat exchanger. Through the unit's circulating water pump, it exchanges heat with water. The low-temperature and low-pressure saturated liquid absorbs the heat of the water and evaporates completely to become a low-temperature and low-pressure saturated vapor and is sucked into the compressor. The entire refrigeration cycle runs in this way over and over again.

[0006] Preferably, the compressor exhaust passage comprises a coil for heat exchange arranged at the compressor, and the coil is arranged between the heat dissipation component and the air inlet of the plate heat exchanger.

[0007] Preferably, the compressor exhaust passage is provided with a control branch connecting the coil input end and the coil output end, and the control branch is provided with a solenoid valve.

[0008] Preferably, the compressor exhaust passage is provided with a first electronic expansion valve for throttling and reducing pressure after passing through the heat dissipation component. After the superheated steam releases heat, it liquefies into a medium-temperature and high-pressure saturated liquid, and after passing through the electronic expansion valve for throttling and reducing pressure, it becomes a low-temperature and low-pressure saturated liquid and enters the plate heat exchanger to exchange heat with water.

[0009] Preferably, the compressor exhaust passage is provided with a shunt branch input before passing through the heat dissipation component, the first electronic expansion valve is provided with a shunt branch output after throttling and reducing the pressure, and a second electronic expansion valve is provided on the shunt branch.

[0010] Preferably, the heat dissipation assembly includes a fin heat exchanger and a fan arranged outside the fin heat exchanger. The low-temperature and low-pressure refrigerant vapor is converted into high-temperature and high-pressure superheated vapor by the compressor to pass through the fin heat exchanger. Through the forced convection of the fan, the air absorbs the heat of the high-temperature and high-pressure superheated vapor and blows out hot air.

[0011] Preferably, a high-pressure pressure sensor and an exhaust temperature sensor are provided on the exhaust passage between the compressor and the heat dissipation component.

[0012] Preferably, a low-pressure sensor and a return air temperature sensor are provided on the return air passage between the compressor and the plate heat exchanger.

[0013] Preferably, the water inlet passage is provided with a unit circulating water pump and a water flow switch, and a water inlet temperature sensor is provided between the water flow switch and the plate heat exchanger. The saturated liquid with low temperature and low pressure enters the plate heat exchanger and exchanges heat with water through the unit circulating water pump. The saturated liquid with low temperature and low pressure absorbs the heat of the water and evaporates completely to become saturated steam with low temperature and low pressure and is sucked into the compressor.

[0014] Preferably, a water outlet temperature sensor is provided on the drainage passage, and the heat exchange efficiency of the plate heat exchanger is detected in combination with the temperature collected by the water inlet temperature sensor.

[0015] The beneficial effects of the present invention are as follows: the waste heat of the compressor cylinder is used as a heat source for temperature control and hot and cold balance, a group of heat exchange coils are wound around the compressor cylinder to exchange heat with low-temperature and low-pressure refrigerant liquid, increase the evaporation effect before the plate heat exchanger, ensure that what returns to the compressor is gas, and there is no risk of liquid hammer, thereby improving the reliability of the unit. At the same time, after heat exchange with water, a certain amount of sensible heat is reduced and a certain amount of heating capacity is obtained, thereby achieving the purpose of hot and cold balance temperature control, and valve replacement is performed according to valve control requirements to reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a principle connection structure diagram of the present invention.

[0017] Figure 2 It is a control flow chart of the present invention.

[0018] Figure 3 It is another principle connection structure diagram of the present invention.

[0019] In the figure, 1 is a compressor, 2 is a fin heat exchanger, 3 is a fan, 4 is a first electronic expansion valve, 5 is a plate heat exchanger, 6 is a water flow switch, 7 is a unit circulating water pump, 8 is a second electronic expansion valve, 9 is a solenoid valve, 10 is a high-pressure pressure sensor, 11 is a low-pressure pressure sensor, 12 is an exhaust temperature sensor, 13 is a return air temperature sensor, 14 is a water inlet temperature sensor, and 15 is a water outlet temperature sensor. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the technical solution of the present invention is further described in detail below through embodiments and in combination with the accompanying drawings. It should be understood that the specific implementation method described here is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] As the main component of the chiller, the compressor can convert low-temperature and low-pressure gas into high-temperature and high-pressure gas, and plays a vital role in the refrigeration process. Ensuring the normal operation of the compressor is the premise for ensuring that the chiller can reflect the most basic functions. After confirming the various components and the cooling capacity of the general chiller, the superheat of the evaporator and the subcooling of the condenser in the chiller will change with the changes in the operating environment, especially when operating at high temperature (ambient temperature and water temperature) and low temperature (ambient temperature and water temperature), the superheat or subcooling in the chiller will be extremely negative or very high. If it cannot be adjusted in time, the excessive superheat will increase the operating temperature of the compressor, exceeding the safe operating range of the compressor and damaging the compressor, while the superheat that is too low or negative will cause the compressor to be compressed, directly damaging the compressor; and unreasonable subcooling will cause flashing or popping, affecting the normal operation of the chiller.

[0022] Traditional chillers generally mark the temperature operating range of the chiller and manually control the operating environment of the chiller to ensure the normal operation of the chiller. This traditional method requires manual guarantee that the operating environment of the chiller is within the allowable range to ensure the normal operation of the chiller. Although this method can effectively ensure that the operation of the chiller is not disturbed, it is very easy to have high and low temperatures when the operating environment is constantly changing, making it difficult to ensure the normal operation of the chiller.

[0023] When the main engine is running, the low-temperature and low-pressure refrigerant vapor is converted into high-temperature and high-pressure superheated steam through the compressor 1 and enters the fin heat exchanger 2. Through the forced convection of the fan 3, the air absorbs the heat of the high-temperature and high-pressure superheated steam and blows out hot air. After the superheated steam releases heat, it liquefies into medium-temperature and high-pressure saturated liquid. After throttling and reducing the pressure through the electronic expansion valve (1) 4, it becomes low-temperature and low-pressure saturated liquid and enters the plate heat exchanger 5. Through the unit circulating water pump 7, it exchanges heat with water. The low-temperature and low-pressure saturated liquid absorbs the heat of the water and evaporates completely to become low-temperature and low-pressure saturated steam and is sucked into the compressor 1. The entire refrigeration cycle operates in this way over and over again.

[0024] The technical problems to be solved by the present invention are: 1. The present invention utilizes the waste heat of the compressor cylinder as a heat source for temperature control and heat balance.

[0025] 2. A group of heat exchange coils are wound around the compressor cylinder to exchange heat with the low-temperature and low-pressure refrigerant liquid.

[0026] 3. Ensure that only gas is returned to the compressor, there is no risk of liquid hammer, and the reliability of the unit is improved.

[0027] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations (or steps) as sequential processes, many of the operations (or steps) therein can be implemented in parallel, concurrently, or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the drawings; the process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0028] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0029] Embodiment: A chiller and control method for controlling temperature by using waste heat from a compressor, such as Figure 1 As shown, it includes a compressor 1, the exhaust passage of the compressor 1 is connected to the air inlet of the plate heat exchanger 5 through the heat dissipation component, and a high-pressure pressure sensor 10 and an exhaust temperature sensor 12 are provided on the exhaust passage between the compressor 1 and the heat dissipation component. The high-pressure pressure sensor 10 and the exhaust temperature sensor 12 provided on the exhaust passage are used to collect the exhaust state of the compressor 1, and the low-pressure pressure sensor 11 and the return air temperature sensor 13 provided on the return air passage are used to collect the return air state of the compressor 1, and the exhaust state and the return air state are combined to judge the cooling and heat dissipation effect, thereby controlling the throttling and pressure reduction of the first electronic expansion valve 4 and the opening and switching time of the solenoid valve 9, and detecting the return air state at the same time, to prevent the occurrence of liquid hammer and affect the normal operation of the compressor. The heat dissipation component includes a fin heat exchanger 2 and a fan 3 arranged on the outside of the fin heat exchanger 2. The air outlet of the plate heat exchanger 5 is connected through the return air passage of the compressor 1, and a low-pressure pressure sensor 11 and a return air temperature sensor 13 are provided on the return air passage between the compressor 1 and the plate heat exchanger 5. The plate heat exchanger 5 is respectively connected to the water inlet passage and the drainage passage of the heat exchange. The water inlet passage is provided with a unit circulating water pump 7 and a water flow switch 6, and an inlet water temperature sensor 14 is provided between the water flow switch 6 and the plate heat exchanger 5. The water outlet temperature sensor 15 is provided on the drainage passage. The heat exchange efficiency of the plate heat exchanger is detected in combination with the temperature collected by the inlet water temperature sensor. The exhaust passage of the compressor 1 includes a coil for heat exchange arranged at the compressor 1, and the coil is arranged between the heat dissipation component and the air inlet of the plate heat exchanger 5. The exhaust passage of the compressor 1 is provided with a control branch connecting the coil input end and the coil output end, and the control branch is provided with a solenoid valve 9. The exhaust passage of the compressor 1 is provided with a first electronic expansion valve 4 for throttling and reducing pressure after passing through the heat dissipation component.

[0030] A control method of a chiller and a control method using compressor waste heat to control temperature, comprising the following steps: S1. Collect the refrigerant temperature before the coil and the refrigerant temperature before the plate heat exchanger 5; S2. Switch the solenoid valve 9 to determine the increase in heat Δ1 of the refrigerant after the solenoid valve 9 is opened per unit time; S3. Collect the temperature and pressure of the refrigerant in the return air passage of compressor 1 to set the liquid shock temperature threshold and the overheat temperature threshold; S4. Collect the actual heat exchange Δ2, and determine the heat exchange efficiency by combining the water temperature change and flow rate of the water inlet passage and the drainage passage of the plate heat exchanger 5;

[0031] S5. Control the switching time of the solenoid valve 9 and the water inlet flow rate to ensure the normal operation of the compressor 1.

[0032] When the compressor operates at normal power, the heat dissipation component operates normally, the temperature of the refrigerant in the return air passage of the compressor 1 does not exceed the liquid hammer temperature threshold and the overheating temperature threshold, the solenoid valve 9 is opened, and the water inlet volume of the water inlet passage of the plate heat exchanger 5 remains unchanged.

[0033] When the compressor is running at low power, the heat dissipation component is running normally, and the temperature of the refrigerant in the return air passage of compressor 1 exceeds the liquid hammer temperature threshold, the temperature gap of the refrigerant is collected, and the closing time of the solenoid valve 9 is controlled, so that the low-temperature and low-pressure saturated refrigerant after passing through the heat dissipation component first enters the coil and exchanges heat with the compressor cylinder, evaporates into gas in advance, and then enters the plate heat exchanger. After filling the heat gap, the temperature of the refrigerant in the return air passage of compressor 1 does not exceed the liquid hammer temperature threshold, and the water inlet volume of the water inlet passage remains unchanged; If the solenoid valve 9 is completely closed, all the refrigerant first enters the coil and exchanges heat with the compressor cylinder, but still cannot make up the heat gap. The water inlet flow rate is controlled to increase, and the flow demand is calculated by the heat exchange efficiency to ensure that after the heat gap is made up, the temperature of the refrigerant in the return air passage of the compressor 1 does not exceed the liquid shock temperature threshold.

[0034] When the compressor is running at high power, the heat dissipation component is running normally, and the temperature of the refrigerant in the return air passage of compressor 1 exceeds the overheating temperature threshold. The excess temperature of the refrigerant is collected, and the closing time of the solenoid valve 9 is controlled so that the low-temperature and low-pressure saturated refrigerant after passing through the heat dissipation component first enters the coil and exchanges heat with the compressor cylinder, evaporates into gas in advance, and then enters the plate heat exchanger, thereby reducing the temperature in the compressor and raising the overheating temperature threshold. The refrigerant evaporated in advance shall not exceed the overheating temperature threshold. At the same time, the water inlet volume of the water inlet passage is controlled to be reduced, and the flow demand is calculated by the heat exchange efficiency, so that the temperature of the refrigerant in the return air passage of compressor 1 does not exceed the overheating temperature threshold.

[0035] When the main engine is running, the low-temperature and low-pressure refrigerant vapor is converted into high-temperature and high-pressure superheated steam through the compressor 1 to enter the fin heat exchanger 2. Through the forced convection of the fan 3, the air absorbs the heat of the high-temperature and high-pressure superheated steam and blows out hot air. After the superheated steam releases heat, it liquefies into medium-temperature and high-pressure saturated liquid. After throttling and reducing the pressure through the first electronic expansion valve 4, it becomes low-temperature and low-pressure saturated liquid and enters the plate heat exchanger 5. Through the unit circulating water pump 7, the low-temperature and low-pressure saturated liquid absorbs the heat of the water and evaporates completely to become low-temperature and low-pressure saturated steam and is sucked into the compressor 1. The entire refrigeration cycle runs in this way over and over again.

[0036] When the load connected to the unit is small and the cooling capacity needs to be reduced. The solenoid valve 9 is usually closed and opened only when the maximum load is connected. The low-temperature and low-pressure saturated liquid after passing through the first electronic expansion valve 4 first enters the coil to exchange heat with the cylinder of the compressor 1, and then evaporates into gas in advance and enters the plate heat exchanger 5. The flow rate of the pre-evaporated gas can be adjusted according to the length of time the solenoid valve 9 is closed. Since the evaporation effect is not completed in the plate heat exchanger 5, the cooling capacity of the unit gradually decreases, and as long as the solenoid valve 9 is closed long enough, the gas entering the plate heat exchanger 5 may be superheated steam. After heat exchange with water, it reduces a certain amount of sensible heat and obtains a certain amount of heating capacity. Thereby achieving the purpose of cold and hot balance temperature control. Figure 1 As shown, this method is Figure 2 In comparison, the control method is relatively simple, and it ensures that the compressor will not be hit by liquid, which greatly improves the reliability of the unit. In addition, the price of the solenoid valve is lower than that of the electronic expansion valve, which reduces the cost of the whole machine.

[0037] Example 2 like Figure 2As shown, it includes a compressor 1, characterized in that the exhaust passage of the compressor 1 is connected to the air inlet of the plate heat exchanger 5 through the heat dissipation component, and a high-pressure pressure sensor 10 and an exhaust temperature sensor 12 are provided on the exhaust passage between the compressor 1 and the heat dissipation component. The high-pressure pressure sensor 10 and the exhaust temperature sensor 12 provided on the exhaust passage are used to collect the exhaust state of the compressor 1, and the low-pressure pressure sensor 11 and the return air temperature sensor 13 provided on the return air passage are used to collect the return air state of the compressor 1, and the exhaust state and the return air state are combined to judge the cooling and heat dissipation effect, thereby controlling the throttling and pressure reduction of the first electronic expansion valve 4 and the opening and switching time of the solenoid valve 9, and detecting the return air state at the same time, preventing the occurrence of liquid hammer and affecting the normal operation of the compressor. The heat dissipation component includes a fin heat exchanger 2 and a fan 3 arranged on the outside of the fin heat exchanger 2. The air outlet of the plate heat exchanger 5 is connected through the return air passage of the compressor 1, and a low-pressure pressure sensor 11 and a return air temperature sensor 13 are provided on the exhaust passage between the compressor 1 and the plate heat exchanger 5. The plate heat exchanger 5 is connected to the water inlet passage and the drainage passage for heat exchange respectively. The water inlet passage is provided with a unit circulating water pump 7 and a water flow switch 6, and an inlet water temperature sensor 14 is provided between the water flow switch 6 and the plate heat exchanger 5. The drainage passage is provided with an outlet water temperature sensor 15. Combined with the temperature collected by the inlet water temperature sensor, the heat exchange efficiency of the plate heat exchanger is detected. The exhaust passage of the compressor 1 is provided with a shunt branch input end before passing through the heat dissipation component, and the exhaust passage of the compressor 1 is provided with a first electronic expansion valve 4 for throttling and reducing pressure after passing through the heat dissipation component. The first electronic expansion valve 4 is provided with a shunt branch output end after throttling and reducing pressure, and a second electronic expansion valve 8 is provided on the shunt branch.

[0038] When the main engine is running, the low-temperature and low-pressure refrigerant vapor is converted into high-temperature and high-pressure superheated steam through the compressor 1 to enter the fin heat exchanger 2. Through the forced convection of the fan 3, the air absorbs the heat of the high-temperature and high-pressure superheated steam and blows out hot air. After the superheated steam releases heat, it liquefies into medium-temperature and high-pressure saturated liquid. After throttling and reducing the pressure through the first electronic expansion valve 4, it becomes low-temperature and low-pressure saturated liquid and enters the plate heat exchanger 5. Through the unit circulating water pump 7, the low-temperature and low-pressure saturated liquid absorbs the heat of the water and evaporates completely to become low-temperature and low-pressure saturated steam and is sucked into the compressor 1. The entire refrigeration cycle runs in this way over and over again.

[0039] When the load connected to the unit is small and the cooling capacity needs to be reduced, the first electronic expansion valve 4 is gradually opened, the second electronic expansion valve 8 is gradually opened, the refrigeration cycle flow of the main circuit is gradually reduced, and the flow of the exhaust bypass of the compressor 1 to the plate heat exchanger 5 is gradually increased, and the cooling capacity is gradually reduced. If the second electronic expansion valve 8 is opened too large, a condensation effect will be formed in the plate heat exchanger 5 instead of evaporation, and the high-temperature and high-pressure gas will be liquefied, which has a certain heating effect on water and is then sucked into the compressor 1, resulting in liquid hammer.

[0040] Example 3 In actual operation, a 10kW air-cooled single-channel machine is taken as an example. The exhaust passage of compressor 1 is connected to the air inlet of plate heat exchanger 5 through the heat dissipation component, and a high-pressure pressure sensor 10 and an exhaust temperature sensor 12 are provided on the exhaust passage between compressor 1 and the heat dissipation component. The heat dissipation component includes a fin heat exchanger 2 and a fan 3 arranged outside the fin heat exchanger 2. The air outlet of plate heat exchanger 5 is connected through the return air passage of compressor 1, and a low-pressure pressure sensor 11 and a return air temperature sensor 13 are provided on the exhaust passage between compressor 1 and plate heat exchanger 5. The plate heat exchanger 5 is respectively connected to the water inlet passage and the drainage passage for heat exchange. The water inlet passage is provided with a unit circulating water pump 7 and a water flow switch 6, and a water inlet temperature sensor 14 is provided between the water flow switch 6 and the plate heat exchanger 5. The drainage passage is provided with a water outlet temperature sensor 15. The exhaust passage of compressor 1 includes a coil for heat exchange arranged at compressor 1, and the coil is arranged between the heat dissipation component and the air inlet of plate heat exchanger 5. The exhaust passage of the compressor 1 is provided with a control branch connecting the coil input end and the coil output end, and the control branch is provided with a solenoid valve 9. The exhaust passage of the compressor 1 is provided with a first electronic expansion valve 4 for throttling and reducing pressure after passing through the heat dissipation component.

[0041] When the set temperature of the unit is 20℃ and the connected load is 5kW, the water in the pipeline gradually decreases from 30℃ to 20℃. The low-temperature and low-pressure refrigerant vapor is converted into high-temperature and high-pressure superheated steam through the work of compressor 1 and enters the fin heat exchanger 2. Through the forced convection of the fan 3, the air absorbs the heat of the high-temperature and high-pressure superheated steam and blows out hot air. In this process, the superheated steam releases heat and liquefies into medium-temperature and high-pressure saturated liquid. After the electronic expansion valve of DPF2.5 is opened at 20 pulses / second to throttle and reduce the pressure, a large amount of low-temperature and low-pressure refrigerant liquid enters the plate heat exchanger, exchanges heat with water through the unit's circulating water pump 7, and the low-temperature and low-pressure saturated liquid absorbs the heat of the water, and all evaporates into low-temperature and low-pressure saturated steam and is sucked into compressor 1, and the cooling capacity is continuously improved. When the outlet water temperature is about to drop to 20℃, the cooling capacity needs to be reduced. The electronic expansion valve of DPF2.5 is gradually closed at 10 pulses / second, the refrigeration cycle flow of the main line gradually decreases, and the closed FSF-6A solenoid valve begins to open. The low-temperature and low-pressure saturated liquid after passing through the first electronic expansion valve 4 first enters the coil and exchanges heat with the cylinder of the compressor 1, and then evaporates into gas in advance and enters the plate heat exchanger 5. The flow of the pre-evaporated gas can be adjusted according to the length of time the solenoid valve 9 is closed. Since the evaporation effect is not completed in the plate heat exchanger 5, the cooling capacity of the unit is gradually reduced, and as long as the solenoid valve 9 is closed for a long enough time, the gas entering the plate heat exchanger 5 may be superheated steam. After heat exchange with water, it reduces a certain amount of sensible heat and obtains a certain amount of heating. The purpose of cold and hot balance temperature control is achieved. The opening time of the FSF-6A solenoid valve is controlled by the temperature difference. The purpose of cold and hot balance temperature control is achieved. When the load connected to the unit is small and the cooling capacity needs to be reduced. For example Figure 1 As shown, this method is Figure 2 In comparison, the control method is relatively simple, and it ensures that the compressor will not be hit by liquid, which greatly improves the reliability of the unit. In addition, the price of the solenoid valve is lower than that of the electronic expansion valve, which reduces the cost of the whole machine.

[0042] The reliability requirements of industrial equipment are much higher than those of civil equipment. Even a few hours of shutdown will cause serious economic losses. Therefore, "low failure rate" and "durability" have become the primary requirements of many users for chillers, and the frequent start and stop of the compressor is one of the biggest killers that affect the life of the compressor. The high-temperature and high-pressure gas is liquefied, has a certain heating effect on water, and is then sucked into the compressor, resulting in liquid hammer, which affects the normal operation of the compressor and even affects the service life of the compressor. If the compressor stops immediately after operation, the lubricating oil flowing out with the refrigerant will easily not be able to return to the oil pool of the compressor. Frequent operation under oil shortage conditions will increase bearing wear, and eventually cause the compressor to stick. Secondly, the refrigeration compressor is at room temperature before operation, and the suction temperature after operation is often close to the freezing point or even below, while the exhaust side temperature is as high as 60°C or above. If the compressor is frequently started and stopped for temperature control, such reciprocating thermal shock is also one of the main causes of damage to metal parts. Finally, of course, there is the impact of the starting current on the motor. The starting current is large, so it will cause the high temperature of the coil for a short time. Frequent starting will cause the coil to continue to be high temperature and the insulating paint on the surface of the enameled wire will peel off and fail, causing the coil to burn. The low-temperature and low-pressure saturated liquid after passing through the first electronic expansion valve 4 first enters the coil to exchange heat with the cylinder of the compressor 1, and then evaporates into gas in advance and enters the plate heat exchanger. Since the evaporation effect is not completed in the plate heat exchanger 5, the cooling capacity of the unit gradually decreases, and as long as the solenoid valve 9 is closed for a long enough time, the gas entering the plate heat exchanger 5 may be superheated steam. After heat exchange with water, it reduces a certain amount of sensible heat and obtains a certain amount of heating. The purpose of cold and hot balance temperature control is achieved. This control method is relatively simple and ensures that the compressor will not be hit by liquid, which greatly improves the reliability of the unit. In addition, the price of the solenoid valve is lower than that of the electronic expansion valve, which reduces the cost of the whole machine, ensures that the compressor runs continuously at a speed lower than the maximum speed most of the time, and avoids frequent start and stop of the compressor.

[0043] The specific embodiments described herein are merely examples of the spirit of the present invention. The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that technicians in the technical field to which the present invention belongs can make various modifications or supplements to the described specific embodiments or replace them in a similar manner, but will not deviate from the spirit of the present invention or exceed the scope defined in the attached claims. For ordinary technicians in this field, multiple deformations and improvements can also be made without departing from the concept of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the attached claims.

Claims

1. A water chiller using compressor waste heat for temperature control, comprising a compressor (1), characterized in that: The exhaust passage of the compressor (1) is connected to the air inlet of the plate heat exchanger (5) through a heat dissipation component, and the air outlet of the plate heat exchanger (5) is connected to the return air passage of the compressor (1). The plate heat exchanger (5) is respectively connected to the water inlet passage and the water discharge passage for heat exchange.

2. A chiller using compressor waste heat to control temperature according to claim 1, characterized in that: The exhaust passage of the compressor (1) comprises a coil for heat exchange arranged at the compressor (1), wherein the coil is arranged between a heat dissipation component and an air inlet of a plate heat exchanger (5), and the exhaust passage of the compressor (1) is provided with a first electronic expansion valve (4) after passing through the heat dissipation component.

3. A chiller using compressor waste heat to control temperature according to claim 2, characterized in that: The exhaust passage of the compressor (1) is provided with a control branch connecting the coil input end and the coil output end, and the control branch is provided with a solenoid valve (9).

4. A chiller using compressor waste heat to control temperature according to claim 1, 2 or 3, characterized in that: The heat dissipation component comprises a fin heat exchanger (2) and a fan (3) arranged outside the fin heat exchanger (2).

5. A chiller using compressor waste heat to control temperature according to claim 1, 2 or 3, characterized in that: A high-pressure pressure sensor (10) and an exhaust temperature sensor (12) are provided on the exhaust passage between the compressor (1) and the heat dissipation component, and a low-pressure pressure sensor (11) and a return air temperature sensor (13) are provided on the return air passage between the compressor (1) and the plate heat exchanger (5).

6. A chiller using compressor waste heat to control temperature according to claim 1, 2 or 3, characterized in that: The water inlet passage is provided with a unit circulating water pump (7) and a water flow switch (6), an inlet water temperature sensor (14) is provided between the water flow switch (6) and the plate heat exchanger (5), and the drainage passage is provided with a water outlet temperature sensor (15).

7. A method for controlling a chiller using waste heat from a compressor for temperature control, characterized in that: The following steps are involved: S1. Collect the refrigerant temperature before the coil and the refrigerant temperature before the plate heat exchanger (5); S2. Switch the solenoid valve (9) to determine the increase in heat Δ1 of the refrigerant after the solenoid valve (9) is opened per unit time; S3. Collect the temperature and pressure of the refrigerant in the return air passage of the compressor (1) to set the liquid shock temperature threshold and the overheat temperature threshold; S4. Collect the actual heat exchange Δ2, and determine the heat exchange efficiency by combining the water temperature change and flow rate of the water inlet passage and the drainage passage of the plate heat exchanger (5); S5. Control the switching time of the solenoid valve (9) and the water inlet flow rate to ensure the normal operation of the compressor (1).

8. A chiller using compressor waste heat for temperature control according to claim 7, characterized in that: When the compressor operates at normal power, the heat dissipation component operates normally, the temperature of the refrigerant in the return air passage of the compressor (1) does not exceed the liquid hammer temperature threshold and the overheating temperature threshold, the solenoid valve (9) is opened, and the water inlet volume of the water inlet passage of the plate heat exchanger (5) remains unchanged.

9. A chiller using compressor waste heat for temperature control according to claim 7, characterized in that: When the compressor is running at low power, the heat dissipation component is running normally, the temperature of the refrigerant in the return air passage of the compressor (1) exceeds the liquid hammer temperature threshold, the temperature gap of the refrigerant is collected, and the closing time of the solenoid valve (9) is controlled so that the low-temperature and low-pressure saturated refrigerant after passing through the heat dissipation component first enters the coil and the compressor cylinder for heat exchange, evaporates into gas in advance, and then enters the plate heat exchanger. After the heat gap is filled, the temperature of the refrigerant in the return air passage of the compressor (1) does not exceed the liquid hammer temperature threshold, and the water inlet volume of the water inlet passage remains unchanged at this time; if the solenoid valve (9) is completely closed, all the refrigerant first enters the coil and the compressor cylinder for heat exchange and still cannot fill the heat gap, then the water inlet volume of the water inlet passage is controlled to increase, and the flow demand is calculated by the heat exchange efficiency to ensure that after the heat gap is filled, the temperature of the refrigerant in the return air passage of the compressor (1) does not exceed the liquid hammer temperature threshold.

10. A chiller using compressor waste heat for temperature control according to claim 7, characterized in that: When the compressor is running at high power, the heat dissipation component is running normally, the temperature of the refrigerant in the return air passage of the compressor (1) exceeds the overheating temperature threshold, the excess temperature of the refrigerant is collected, and the closing time of the solenoid valve (9) is controlled so that the low-temperature and low-pressure saturated refrigerant after passing through the heat dissipation component first enters the coil to exchange heat with the compressor cylinder, evaporates into gas in advance, and then enters the plate heat exchanger, thereby reducing the temperature in the compressor and raising the overheating temperature threshold. The refrigerant that evaporates in advance must not exceed the overheating temperature threshold. At the same time, the water inlet volume of the water inlet passage is controlled to be reduced, and the flow demand is calculated by the heat exchange efficiency so that the temperature of the refrigerant in the return air passage of the compressor (1) does not exceed the overheating temperature threshold.

Images