Refrigerating system for reducing suction and exhaust temperatures of compressor and control method

Abstract

A refrigerating system for reducing suction and exhaust temperature of a compressor comprises the compressor, an oil separator, a condenser, a liquid storage device, a filter and an evaporator which are sequentially connected through a pipeline to form a refrigerating circulation loop. A second temperature sensor is arranged at the inlet end of the compressor, a first temperature sensor is arranged at the outlet end of the evaporator, and a third temperature sensor is arranged in the space where the evaporator is located. A refrigerant flowing out of the outlet end of the filter is divided into four paths through a pipeline a, a pipeline b, a pipeline c and a pipeline d; a is communicated with a cooling pipeline on a compressor shell; b is communicated with an inlet pipeline of the compressor; c and d are respectively connected with an inlet end of the evaporator, and a refrigerant flowing out of an outlet of the evaporator is connected with an inlet pipeline of the compressor through a pipeline e or f. The invention further discloses a control method of the refrigerating system for reducing the suction and exhaust temperatures of the compressor, and the connection of the pipelines a, b, c, d, e and f is controlled by detecting the temperatures of the first temperature sensor, the second temperature sensor and the third temperature sensor so as to reduce the suction and exhaust temperatures of the compressor.

Description

Technical Field

[0001] The present invention relates to the field of compressor suction and exhaust temperature control, and in particular to a refrigeration system and a control method for reducing the suction and exhaust temperature of a compressor. Background Art

[0002] In the modern society with rapid economic development, air conditioning has gradually become an indispensable part of human life, which has greatly improved people's quality of life and work efficiency. At the same time, in order to further improve the performance of air conditioning, the air conditioning industry is constantly innovating technology. As the core component of air conditioning, the safe and efficient operation of the compressor is crucial to air conditioning. The high suction and exhaust temperature of the compressor is an important factor affecting the normal operation of the air conditioner. Therefore, the effective control of the suction and exhaust temperature of the compressor is particularly critical.

[0003] For air conditioners and general small refrigeration equipment, the suction temperature of the compressor is mostly required to be between 5°C and 15°C, and the exhaust temperature usually cannot exceed 120°C. When the exhaust temperature of the compressor is too high, the power consumption of the compressor increases, the refrigeration efficiency decreases, and the high temperature may cause the lubricating oil to decompose, reducing its lubrication and cooling effects, accelerating the wear of the compressor. The internal materials of the compressor will also accelerate aging due to high temperature, such as seals and insulating materials, shortening the life of the equipment. In addition, continuous high temperature may cause the compressor motor to overload, increase the risk of failure, and even affect the circulation of the refrigerant, resulting in unstable refrigerant flow and affecting the refrigeration effect of the unit.

[0004] There are many factors that may cause the compressor's suction and exhaust temperatures to be too high, such as insufficient refrigerant in the evaporator, component blockage, excessively high ambient temperature, or inadequate pipe insulation measures.

[0005] At present, the main ways to control the suction and exhaust temperatures of compressors are liquid spray cooling and hot gas bypass cooling. Among them, when using liquid spray cooling, it uses a part of low-temperature and high-pressure liquid refrigerant to spray liquid at the suction port of the compressor. Although it can effectively reduce the suction temperature of the compressor, it is difficult to accurately grasp the spraying amount of liquid refrigerant. Too much liquid refrigerant sprayed may cause "liquid hammer" in the compressor; too little liquid refrigerant sprayed will make it difficult to reduce the suction temperature of the compressor, affecting the system performance. Hot gas bypass cooling is to return part of the high-pressure hot gas directly to the evaporator through the bypass pipeline to reduce the exhaust temperature. Although it reduces the refrigerant flow through the condenser and evaporator, it will reduce the refrigeration efficiency of the system, thereby requiring more energy consumption to maintain the same refrigeration effect and increasing the load on the compressor. Although the above two methods can effectively reduce the suction and exhaust temperatures of the compressor and protect the compressor in some cases, there are many problems such as high control difficulty, loss of system heat exchange area and reduced refrigeration effect.

[0006] Therefore, it is urgent to propose a system and control strategy that can effectively and quickly reduce the suction and exhaust temperatures of the compressor. Summary of the invention

[0007] In view of the problems and shortcomings in the prior art, the present invention provides a refrigeration system and a control method for reducing the suction and exhaust temperatures of a compressor.

[0008] The technical solution of the present invention is as follows:

[0009] A refrigeration system for reducing the suction and exhaust temperatures of a compressor comprises a compressor, an oil separator, a condenser, a liquid storage device, a filter and an evaporator which are sequentially connected through pipelines to form a refrigeration cycle.

[0010] A second temperature sensor is provided at the inlet end of the compressor, a first temperature sensor is provided at the outlet end of the evaporator, and a third temperature sensor for detecting the ambient temperature is provided in the space where the evaporator is located.

[0011] The refrigerant flowing out of the outlet end of the filter is divided into four paths through pipeline a, pipeline b, pipeline c, and pipeline d; wherein pipeline a is connected to the cooling pipeline on the compressor casing, and is connected to a first capillary tube and a first solenoid valve; pipeline b is connected to the inlet pipeline of the compressor, and its outlet end is located upstream of the second temperature sensor, and pipeline b is connected to a second solenoid valve and a first expansion valve; pipeline c and pipeline d are respectively connected to the inlet end of the evaporator, pipeline c is connected to a third solenoid valve and a second expansion valve, and pipeline d is connected to a fourth solenoid valve and a second capillary tube.

[0012] The refrigerant flowing out of the evaporator outlet is connected to the compressor inlet pipeline through pipeline e or f, a fifth solenoid valve is provided on pipeline f, an evaporation pressure regulating valve is provided on pipeline e, and the fifth solenoid valve and the evaporation pressure regulating valve are located upstream of the intersection of pipeline b and the compressor inlet pipeline.

[0013] Specifically, the first solenoid valve and the first capillary tube on the pipeline a are arranged in sequence along the flow direction of the refrigerant. The second solenoid valve and the first expansion valve on the pipeline b are arranged in sequence along the flow direction of the refrigerant. The third solenoid valve and the second expansion valve on the pipeline c are arranged in sequence along the flow direction of the refrigerant. The fourth solenoid valve and the second capillary tube on the pipeline d are arranged in sequence along the flow direction of the refrigerant.

[0014] A refrigeration control method for reducing the suction and exhaust temperatures of a compressor is applicable to controlling the above-mentioned refrigeration system for reducing the suction and exhaust temperatures of the compressor, comprising the following steps:

[0015] Compare the command temperature with the design temperature. If the command temperature is equal to the design temperature, connect pipeline d and determine whether the temperature of the first temperature sensor is lower than the maximum suction temperature of the compressor. If so, connect pipeline f. If not, connect pipelines e and b in sequence and determine whether the temperature of the second temperature sensor is lower than the maximum suction temperature of the compressor. If not, connect pipeline a.

[0016] If the command temperature is higher than the design temperature, connect pipeline c and determine whether the temperature of the first temperature sensor is lower than the maximum suction temperature of the compressor: if it is, connect pipeline f; if it is not, connect pipelines e and b in sequence and determine whether the temperature of the second temperature sensor is lower than the maximum suction temperature of the compressor: if it is not, connect pipeline a;

[0017] If the command temperature is lower than the design temperature, pipeline d is connected, and it is determined whether the temperature of the first temperature sensor is lower than the maximum suction temperature of the compressor: if it is lower, pipeline f is connected, the refrigeration system is operated, and pipeline c is connected after the temperature of the third temperature sensor reaches the design temperature; if it is not lower than, pipelines e and b are connected in sequence, and it is determined whether the temperature of the second sensor is lower than the maximum suction temperature of the compressor: if it is lower, pipeline c is connected after the temperature of the third temperature sensor reaches the design temperature; if it is not lower than, pipeline a is connected, the refrigeration system is operated, and pipeline c is connected after the temperature of the third temperature sensor reaches the design temperature.

[0018] Specifically, the operation of connecting pipeline a, pipeline b, pipeline c, and pipeline d is achieved by closing the first solenoid valve, the second solenoid valve, the third solenoid valve, and the fourth solenoid valve respectively.

[0019] The step of connecting the pipeline f is achieved by closing the fifth solenoid valve, and the operation of connecting the pipeline e is achieved by disconnecting the fifth solenoid valve while opening the steam pressure regulating valve.

[0020] The beneficial effects of the present invention are:

[0021] The refrigerant flowing out of the filter outlet is divided into four routes through pipeline a, pipeline b, pipeline c, and pipeline d, among which a is connected to the cooling pipeline on the compressor housing, b is connected to the compressor inlet pipeline, and c and d are arranged in parallel and connected to the inlet of the evaporator. The first temperature sensor, the second temperature sensor, and the third temperature sensor are respectively installed at the outlet of the evaporator, the inlet of the compressor, and the space where the evaporator is located, so that the temperature of each sensor can be detected in real time. When the system is working, different cooling control strategies can be flexibly selected through the indications of each temperature sensor, and the corresponding pipeline is connected by controlling the opening and closing of the solenoid valve on the corresponding pipeline.

[0022] Among them, the refrigerant condensed by the condenser is passed through the pipeline b to the inlet pipeline of the compressor after throttling, depressurizing and cooling by the first expansion valve, and mixed with the refrigerant coming out of the evaporator to reduce the suction temperature of the compressor, thereby reducing the exhaust temperature of the compressor at the same time. The refrigerant condensed by the condenser is passed through the pipeline a to the cooling pipeline of the compressor after throttling, depressurizing and cooling by the first capillary tube to cool the compressor and further reduce the suction temperature and exhaust temperature of the compressor. Thereby achieving the effect of quickly and effectively controlling the suction and exhaust temperatures of the compressor, and ensuring the normal and stable operation of the refrigeration system.

[0023] In the prior art, hot gas bypass reduces the suction and exhaust temperatures of the compressor by directly returning part of the high-temperature and high-pressure refrigerant vapor to the evaporator, which will cause the refrigerant temperature and pressure in the evaporator to increase, the heat exchange temperature difference to decrease, and the heat exchange efficiency to decrease. If the same refrigeration effect as the present invention is to be achieved, it may be necessary to increase the heat exchanger area. In the system of the present invention, the refrigerant temperature passing through the evaporator is within the normal range under any operating condition, thereby ensuring the refrigeration efficiency without losing the heat exchange area of ​​the heat exchanger, while ensuring the stable operation of the refrigeration system under design conditions and non-design conditions, thereby improving the reliability and service life of the compressor operation.

[0024] In addition, when controlling the suction and exhaust temperatures of the compressor, the present invention does not need to set up a refrigeration system outside the system, but uses the temperature conditions of the refrigerant itself in the system to control the opening and disconnection of the valve through the outlet of the evaporator, the inlet of the compressor and the ambient temperature of the evaporator, thereby realizing the switching of different refrigerant operation pipelines, thereby reducing the suction and exhaust temperatures of the compressor and ensuring the reliable operation of the refrigeration system under various working conditions. Moreover, the system cost of the present invention is low, the control logic is simple and reliable, and the maintenance is convenient, which greatly reduces the initial investment and operating costs of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the refrigeration system of the present invention;

[0026] Figure 2 for Figure 1 Flow chart of a method for controlling a refrigeration system;

[0027] 1. Compressor; 2. Oil separator; 3. Condenser; 4. Liquid storage tank; 5. Filter; 6. Evaporator; 7. Evaporation pressure regulating valve; 81. First capillary tube; 82. Second capillary tube; 91. First solenoid valve; 92. Second solenoid valve; 93. Third solenoid valve; 94. Fourth solenoid valve; 95. Fifth solenoid valve; 101. First expansion valve; 102. Second expansion valve; 111. First temperature sensor; 112. Second temperature sensor; 113. Third temperature sensor. DETAILED DESCRIPTION

[0028] Example 1

[0029] See also Figure 1 As shown, a refrigeration system for reducing the suction and exhaust temperatures of a compressor 1 comprises a compressor 1, an oil separator 2, a condenser 3, a liquid storage device 4, a filter 5, and an evaporator 6 which are sequentially connected through pipelines to form a refrigeration cycle. A second temperature sensor 112 is provided at the inlet end of the compressor 1, a first temperature sensor 111 is provided at the outlet end of the evaporator 6, and a third temperature sensor 113 for detecting the ambient temperature is provided in the space where the evaporator 6 is located.

[0030] The refrigerant flowing out of the outlet of the filter 5 is divided into four routes through pipeline a, pipeline b, pipeline c, and pipeline d; among them, pipeline a is connected to the cooling pipeline on the shell of the compressor 1, and is connected to the first capillary 81 and the first electromagnetic valve 91; pipeline b is connected to the inlet pipeline of the compressor 1, and its outlet end is located upstream of the second temperature sensor, and pipeline b is connected to the second electromagnetic valve 92 and the first expansion valve 101; pipeline c and pipeline d are respectively connected to the inlet end of the evaporator 6, and pipeline c is connected to the third electromagnetic valve 93 and the second expansion valve 102, and pipeline d is connected to the fourth electromagnetic valve 94 and the second capillary 82. Pipeline b is used to pass the refrigerant condensed by the condenser 3 into the inlet pipeline of the compressor 1 after throttling, depressurization and temperature reduction by the first expansion valve 101, and mix with the refrigerant coming out of the evaporator 6 to reduce the suction temperature of the compressor 1, thereby reducing the exhaust temperature of the compressor 1 at the same time. Pipeline a is used to pass the refrigerant flowing out of the condenser 3 into the cooling pipeline of the compressor 1 after throttling, reducing pressure and temperature through the first capillary tube 81, so as to cool the compressor 1 and further reduce the suction temperature and exhaust temperature of the compressor 1.

[0031] The refrigerant flowing out of the outlet of the evaporator 6 is connected to the inlet pipeline of the compressor 1 through pipeline e or f. A fifth solenoid valve 95 is provided on pipeline f, and an evaporation pressure regulating valve 7 is provided on pipeline e. The fifth solenoid valve 95 and the evaporation pressure regulating valve 7 are located upstream of the intersection of pipeline b and the inlet pipeline of the compressor 1.

[0032] See Figure 1In this embodiment, the outlet of compressor 1 is connected to the inlet of oil separator 2, the outlet of oil separator 2 is connected to the inlet of condenser 3, the outlet of condenser 3 is connected to the inlet of liquid storage 4, the outlet of liquid storage 4 is connected to the inlet of filter 5, and the refrigerant flowing out of the outlet of filter 5 is divided into four paths, the first path is connected to the inlet of first capillary tube 81 through the first solenoid valve 91, the outlet of first capillary tube 81 is directly connected to compressor 1, the second path is connected to the inlet of first expansion valve 101 through the second solenoid valve 92, the outlet of first expansion valve 101 is connected to the inlet of compressor 1 The third route is connected to the inlet of the second expansion valve 102 through the third solenoid valve 93, and the outlet of the second expansion valve 102 is connected to the inlet pipeline of the evaporator 6. The fourth route is connected to the inlet of the second capillary 82 through the fourth solenoid valve 94, and the outlet of the second capillary 82 is connected to the inlet of the evaporator 6. The refrigerant flowing out of the outlet of the evaporator 6 is divided into two routes, the first route is connected to the inlet pipeline of the compressor 1 through the fifth solenoid valve 95, and the second route is connected to the inlet of the evaporation pressure regulating valve 7, and the outlet of the evaporation pressure regulating valve 7 is connected to the inlet pipeline of the compressor 1. The first temperature sensor 111 is installed at the outlet of the evaporator 6, the second temperature sensor 112 is installed at the inlet of the compressor 1, and the third temperature sensor 113 is installed in the warehouse where the evaporator 6 is located, for detecting the ambient temperature.

[0033] Further, see Figure 1 , the first solenoid valve 91 and the first capillary tube 81 on the pipeline a are arranged in sequence along the flow direction of the refrigerant. The second solenoid valve 92 and the first expansion valve 101 on the pipeline b are arranged in sequence along the flow direction of the refrigerant. The third solenoid valve 93 and the second expansion valve 102 on the pipeline c are arranged in sequence along the flow direction of the refrigerant. The fourth solenoid valve 94 and the second capillary tube 82 on the pipeline d are arranged in sequence along the flow direction of the refrigerant. The first expansion valve and the second expansion valve are electromagnetic expansion valves or thermal expansion valves.

[0034] Example 2

[0035] See also Figure 2 A refrigeration system control method for reducing the suction and exhaust temperatures of a compressor 1 is used to control the above-mentioned refrigeration system for reducing the suction and exhaust temperatures of a compressor 1.

[0036] The technical concept of the present invention is:

[0037] (I): When the outlet temperature of the evaporator is greater than the maximum suction temperature of the compressor, the second solenoid valve 92 is closed, the pipeline b is connected, and the refrigerant flowing out of the filter 5 is throttled, depressurized and cooled by the first expansion valve 101, and then merged into the inlet pipeline of the compressor 1, and merged with the refrigerant from the evaporator 6 to reduce the suction temperature of the compressor 1.

[0038] (ii) If the suction temperature of the compressor is still very high after connecting to pipeline b, and the suction temperature cannot be controlled between 5°C and 15°C, and the exhaust temperature usually cannot be controlled below 120°C, pipeline a is connected by closing the first solenoid valve, and the refrigerant liquid flowing out of the filter 5 is throttled, depressurized and cooled through the first capillary tube 81, and directly enters the cooling pipeline in the casing of the compressor 1 at a fixed design flow rate, so as to further cool the compressor and realize the final protection against overheating of the suction and exhaust gases of the compressor 1.

[0039] (III): An evaporation pressure regulating valve and a solenoid valve are connected in parallel on the pipeline connecting the outlet of the evaporator and the inlet of the compressor. When the outlet temperature of the evaporator is higher than the maximum suction temperature of the compressor, the fifth solenoid valve 95 is disconnected and the evaporation pressure regulating valve 7 is opened. At this time, the pressure in the evaporator is reduced by the evaporation pressure regulating valve 7, thereby reducing the temperature of the refrigerant entering the compressor 1. In combination with the connection state of pipeline b and pipeline a, the suction temperature and exhaust temperature of the compressor are jointly reduced to meet the rated working temperature requirements of the compressor.

[0040] The control method of the present invention comprises the following steps:

[0041] The command temperature is compared with the design temperature. If the command temperature is equal to the design temperature, the pipeline d is connected to allow the refrigerant to flow into the evaporator, and it is determined whether the temperature of the first temperature sensor 111 is lower than the maximum suction temperature of the compressor 1:

[0042] If the temperature of the first temperature sensor 111 is lower than the maximum suction temperature of the compressor 1, the pipeline f is connected to execute the refrigeration cycle;

[0043] If the temperature of the first temperature sensor 111 is not lower than the maximum suction temperature of the compressor 1, the pipelines e and b are connected in sequence, and the refrigerant flowing from the evaporator to the compressor inlet pipeline is cooled through the pipeline b while executing the refrigeration cycle, and it is determined whether the temperature of the second temperature sensor 112 is lower than the maximum suction temperature of the compressor 1:

[0044] If the temperature of the second temperature sensor 112 is not lower than the maximum intake temperature of the compressor 1, the pipeline a is connected to cool the compressor through the pipeline a to reduce the intake and exhaust temperatures of the compressor and ensure the normal operation of the compressor; if the temperature of the second temperature sensor 112 is lower than the maximum intake temperature of the compressor 1, the pipeline a is disconnected.

[0045] The command temperature refers to the temperature that the system needs to reach as specified by the user, and the design temperature refers to the design temperature of the refrigeration system.

[0046] Specifically, the operations of connecting pipeline a, pipeline b, pipeline c, and pipeline d are realized by respectively closing the first electromagnetic valve 91, the second electromagnetic valve 92, the third electromagnetic valve 93, and the fourth electromagnetic valve 94. The step of connecting pipeline f is realized by closing the fifth electromagnetic valve 95, and the operation of connecting pipeline e is realized by disconnecting the fifth electromagnetic valve 95 while opening the steam pressure regulating valve.

[0047] In this embodiment, when the command temperature is equal to the design temperature, the following three operating conditions are included:

[0048] Working condition 1, when the command temperature is the system design temperature, pipeline d is opened, pipeline a, pipeline b, and pipeline c are closed, and the high-temperature and high-pressure refrigerant flows out of the compressor 1, passes through the oil separator 2, and the refrigerant from which the lubricating oil is separated is passed into the condenser 3 to release heat and condense. The condensed refrigerant enters the liquid storage tank 4, and then enters the filter 5 to remove impurities. The refrigerant flowing out of the filter 5 passes through the fourth solenoid valve 94, through the second capillary tube 82, and is passed into the evaporator 6 at a fixed design flow rate so that the evaporator 6 reaches the system design temperature.

[0049] When the temperature indicated by the first temperature sensor 111 arranged at the outlet end of the evaporator 6 is lower than the maximum suction temperature of the compressor 1, the fifth solenoid valve 95 is opened, the evaporation pressure regulating valve 7 is closed, the pipeline f is connected, and the refrigerant that meets the suction and exhaust temperature requirements of the compressor 1 is introduced into the compressor 1 and continues to complete the refrigeration cycle, so that the system works according to the command temperature.

[0050] Working condition two, when the command temperature is the system design temperature, pipeline d is opened, pipelines a, b, and c are closed, and the high-temperature and high-pressure refrigerant flows out of the compressor 1, passes through the oil separator 2, and the refrigerant from which the lubricating oil is separated is introduced into the condenser 3 for heat release and condensation. The condensed refrigerant enters the liquid storage tank 4, and then enters the filter 5 to remove impurities. The refrigerant flowing out of the filter 5 passes through the fourth solenoid valve 94, through the second capillary tube 82, and is introduced into the evaporator 6 at a fixed design flow rate so that the evaporator 6 reaches the system design temperature.

[0051] When the temperature indicated by the first temperature sensor 111 disposed at the outlet of the evaporator 6 is not lower than the highest suction temperature of the compressor 1, the evaporation pressure regulating valve 7 is opened, the fifth solenoid valve 95 is closed, and the pipeline e is connected, and the pressure in the evaporator 6 is reduced through the evaporation pressure regulating valve 7, thereby reducing the temperature of the refrigerant entering the compressor 1. Subsequently, the pipeline b is opened, and the refrigerant flowing out of the filter 5 passes through the second solenoid valve 92, and then passes through the first expansion valve 101 for throttling, pressure reduction and temperature reduction, and the opening of the first expansion valve 101 is adjusted by the difference between the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 and the highest suction temperature of the compressor 1, and then the refrigerant merges with the refrigerant from the evaporator 6 in the inlet pipeline of the compressor 1 to reduce the suction temperature of the compressor 1, and at the same time, it can avoid the refrigerant entering the compressor with liquid to cause liquid hammer in the compressor.

[0052] When the temperature indicated by the second temperature sensor 112 arranged at the inlet end of the compressor 1 is lower than the maximum suction temperature of the compressor 1, the refrigerant meeting the suction and exhaust temperature requirements of the compressor 1 is introduced into the compressor 1 and continues to complete the refrigeration cycle, so that the system works according to the command temperature.

[0053] Working condition three, when the command temperature is the system design temperature, pipeline d is opened, pipelines a, b, and c are closed, and the high-temperature and high-pressure refrigerant flows out of the compressor 1, passes through the oil separator 2, and the refrigerant from which the lubricating oil is separated is introduced into the condenser 3 for heat release and condensation. The condensed refrigerant enters the liquid storage tank 4, and then enters the filter 5 to remove impurities. The refrigerant flowing out of the filter 5 passes through the fourth solenoid valve 94, through the second capillary tube 82, and is introduced into the evaporator 6 at a fixed design flow rate so that the evaporator 6 reaches the system design temperature.

[0054] When the temperature indicated by the first temperature sensor 111 disposed at the outlet of the evaporator 6 is not lower than the highest suction temperature of the compressor 1, the evaporation pressure regulating valve 7 is opened, the fifth solenoid valve 95 is closed, and the pipeline e is connected. The pressure in the evaporator 6 is reduced through the evaporation pressure regulating valve 7, thereby reducing the temperature of the refrigerant entering the compressor 1. Subsequently, the pipeline b is opened, and the refrigerant flowing out of the filter 5 passes through the second solenoid valve 92, and is throttled and depressurized and cooled by the first expansion valve 101. The opening of the first expansion valve 101 is adjusted by the difference between the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 and the highest suction temperature of the compressor 1. Subsequently, the refrigerant is combined with the refrigerant from the evaporator 6 in the inlet pipeline of the compressor 1 to reduce the suction temperature of the compressor 1, and at the same time, it can be avoided that the refrigerant entering the compressor is liquid-carrying and causes liquid hammer in the compressor.

[0055] If the temperature indicated by the second temperature sensor 112 arranged at the inlet end of the compressor 1 is not lower than the maximum suction temperature of the compressor 1, the pipeline a is opened, and the refrigerant flowing out of the filter 5 passes through the first solenoid valve 91, and is throttled, reduced in pressure and temperature through the first capillary tube 81, and is directly passed into the cooling pipeline in the casing of the compressor 1 at a fixed design flow rate, thereby achieving the final protection against overheating of the suction and exhaust of the compressor 1, and realizing that the system works according to the command temperature or the system is shut down.

[0056] If the command temperature is higher than the design temperature, the pipeline c is connected to allow the refrigerant to enter the evaporator. At the same time, the flow rate of the refrigerant entering the evaporator is controlled by the second expansion valve 102, and it is determined whether the temperature of the first temperature sensor 111 is lower than the maximum suction temperature of the compressor 1:

[0057] If the temperature of the first temperature sensor 111 is lower than the maximum suction temperature of the compressor 1, the pipeline f is connected to execute the refrigeration cycle;

[0058] If the temperature of the first temperature sensor 111 is not lower than the maximum suction temperature of the compressor 1, the pipeline e and the pipeline b are connected in sequence, and the refrigerant flowing from the evaporator into the compressor inlet pipeline is cooled through the pipeline b while executing the refrigeration cycle, and it is determined whether the temperature of the second temperature sensor 112 is lower than the maximum suction temperature of the compressor 1:

[0059] If the temperature of the second temperature sensor 112 is not lower than the maximum intake temperature of the compressor 1, the pipeline a is connected to cool the compressor through the pipeline a to reduce the intake and exhaust temperatures of the compressor and ensure the normal operation of the compressor; if the temperature of the second temperature sensor 112 is lower than the maximum intake temperature of the compressor 1, the pipeline a is disconnected.

[0060] In this embodiment, when the command temperature is higher than the design temperature, the following three operating conditions are included:

[0061] Working condition four, when the command temperature is higher than the system design temperature, the c passage is opened, and the a, b, and d passages are closed. The refrigerant flowing out of the filter 5 passes through the third solenoid valve 93, and is throttled, depressurized, and cooled by the second expansion valve 102. The opening of the second expansion valve 102 is adjusted according to the superheat of the refrigerant at the outlet of the evaporator 6 to meet the refrigeration requirements of the evaporator 6.

[0062] When the temperature indicated by the first temperature sensor 111 arranged at the outlet end of the evaporator 6 is lower than the maximum suction temperature of the compressor 1, the fifth solenoid valve 95 is opened, the evaporation pressure regulating valve 7 is closed, the pipeline f is connected, and the refrigerant that meets the suction and exhaust temperature requirements of the compressor 1 is introduced into the compressor 1 and continues to complete the cycle, so that the system works according to the command temperature.

[0063] Working condition five, when the command temperature is higher than the system design temperature, the c passage is opened, and the a, b, and d passages are closed. The refrigerant flowing out of the filter 5 passes through the third solenoid valve 93, and is throttled, depressurized, and cooled by the second expansion valve 102. The opening of the second expansion valve 102 is adjusted according to the superheat of the refrigerant at the outlet of the evaporator 6 to meet the refrigeration requirements of the evaporator 6.

[0064] When the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 is not lower than the highest suction temperature of the compressor 1, the evaporation pressure regulating valve 7 is opened, the fifth solenoid valve 95 is closed, and the pipeline e is connected. The pressure in the evaporator is reduced through the evaporation pressure regulating valve 7, thereby reducing the temperature of the refrigerant entering the compressor 1. Subsequently, the b passage is opened, and the refrigerant flowing out of the filter 5 passes through the second solenoid valve 92, and is throttled and depressurized and cooled by the first expansion valve 101. The opening of the first expansion valve 101 is adjusted by the difference between the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 and the highest suction temperature of the compressor 1. Subsequently, the refrigerant is combined with the refrigerant from the evaporator 6 in the inlet pipeline of the compressor 1 to reduce the suction temperature of the compressor 1, and at the same time, it can be avoided that the refrigerant entering the compressor is liquid-carrying and causes liquid hammer in the compressor.

[0065] When the temperature indicated by the second temperature sensor 112 arranged at the inlet end of the compressor 1 is lower than the maximum suction temperature of the compressor 1, the refrigerant meeting the suction and exhaust temperature requirements of the compressor 1 is introduced into the compressor 1 and continues to complete the cycle, so that the system works according to the command temperature.

[0066] Working condition six, when the command temperature is higher than the system design temperature, the c passage is opened, the a, b, d passages are closed, and the refrigerant flowing out of the filter 5 passes through the third solenoid valve 93, and the second expansion valve 102 is throttled to reduce the pressure and temperature, and the opening of the second expansion valve 102 is adjusted according to the superheat of the refrigerant at the outlet of the evaporator 6, so as to meet the refrigeration requirements of the evaporator 6.

[0067] When the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 is not lower than the highest suction temperature of the compressor 1, the evaporation pressure regulating valve 7 is opened, the fifth solenoid valve 95 is closed, and the pipeline e is connected. The pressure in the evaporator is reduced through the evaporation pressure regulating valve 7, thereby reducing the temperature of the refrigerant entering the compressor 1. Subsequently, the b passage is opened, and the refrigerant flowing out of the filter 5 passes through the second solenoid valve 92, and is throttled and depressurized and cooled by the first expansion valve 101. The opening of the first expansion valve 101 is adjusted by the difference between the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 and the highest suction temperature of the compressor 1. Subsequently, the refrigerant is combined with the refrigerant from the evaporator 6 in the inlet pipeline of the compressor 1 to reduce the suction temperature of the compressor 1, and at the same time, it can be avoided that the refrigerant entering the compressor is liquid-carrying and causes liquid hammer in the compressor.

[0068] If the temperature indicated by the second temperature sensor 112 arranged at the inlet end of the compressor 1 is not lower than the maximum suction temperature of the compressor 1, the a passage is opened, and the refrigerant flowing out of the filter 5 passes through the first solenoid valve 91, and is throttled, depressurized and cooled by the first capillary tube 81, and is directly passed into the casing of the compressor 1 at a fixed design flow rate, thereby achieving the final protection against overheating of the suction and exhaust of the compressor 1, and realizing that the system works according to the command temperature or the system is shut down.

[0069] If the command temperature is lower than the design temperature, the pipeline d is connected, and it is determined whether the temperature of the first temperature sensor 111 is lower than the maximum suction temperature of the compressor 1:

[0070] If the temperature of the first temperature sensor 111 is lower than the maximum suction temperature of the compressor 1, the pipeline f is connected, and the refrigeration system is operated for a period of time to make the refrigeration temperature reach the design temperature. At the same time, the ambient temperature is detected by the third temperature sensor. Then, after the temperature of the third temperature sensor 113 reaches the design temperature, the pipeline c is connected, and the refrigerant entering the evaporator is controlled by the second expansion valve 102 in the pipeline c to make the ambient temperature reach the command temperature.

[0071] If the temperature of the first temperature sensor 111 is not lower than the maximum suction temperature of the compressor 1, the pipelines e and b are connected in sequence. The function of connecting the pipeline b is to reduce the compressor suction temperature by throttling, depressurizing and cooling the refrigerant through the first expansion valve 101 and then entering the compressor inlet pipeline. It is also determined whether the temperature of the second sensor is lower than the maximum suction temperature of the compressor 1:

[0072] If the temperature of the second sensor is lower than the maximum suction temperature of the compressor 1, the temperature of the third temperature sensor is detected, and after the temperature of the third temperature sensor 113 reaches the design temperature, the pipeline c is connected, and the refrigerant flow is controlled through the pipeline c to cool the system until the refrigeration temperature of the system reaches the command temperature;

[0073] If the temperature of the second sensor is not lower than the maximum intake temperature of the compressor 1, the pipeline a is connected to cool the compressor to further reduce the intake and exhaust temperatures of the compressor, and the ambient temperature is detected by the third temperature sensor. Then, the pipeline c is connected after the temperature of the third temperature sensor 113 reaches the design temperature. The ambient temperature reaches the command temperature by connecting the pipeline c and controlling the flow rate.

[0074] In this embodiment, when the command temperature is lower than the design temperature, the following three operating conditions are included:

[0075] Working condition seven, when the command temperature is lower than the system design temperature, passage d is opened, passages a, b, and c are closed, and the refrigerant flowing out of the filter 5 passes through the fourth solenoid valve 94, through the second capillary tube 82, and enters the evaporator 6 at a fixed design flow rate, so that the evaporator 6 reaches the system design temperature.

[0076] When the temperature indicated by the first temperature sensor 111 disposed at the outlet of the evaporator 6 is lower than the highest suction temperature of the compressor 1, the fifth solenoid valve 95 is opened, the evaporation pressure regulating valve 7 is closed, and the pipeline f is connected to allow the refrigeration system to operate normally, and the ambient temperature is detected by the third temperature sensor 113. When the ambient temperature is equal to the design temperature, the c passage is opened, and the refrigerant flowing out of the filter 5 passes through the third solenoid valve 93, and then enters the evaporator 6 after throttling, reducing pressure and cooling through the second expansion valve 102. At the same time, the opening of the second expansion valve 102 is adjusted according to the superheat of the refrigerant at the outlet of the evaporator 6 to meet the refrigeration requirements of the evaporator 6. After that, the refrigerant that meets the suction and exhaust temperature requirements of the compressor 1 flows from the evaporator into the compressor 1 to complete the refrigeration cycle, and the system refrigeration temperature reaches the command temperature through the connection of the pipeline c and flow control.

[0077] Working condition eight, when the command temperature is lower than the system design temperature, passage d is opened, passages a, b, and c are closed, and the refrigerant flowing out of the filter 5 passes through the fourth solenoid valve 94, through the second capillary tube 82, and enters the evaporator 6 at a fixed design flow rate, so that the evaporator 6 reaches the system design temperature.

[0078] When the temperature indicated by the first temperature sensor 111 disposed at the outlet of the evaporator 6 is not lower than the highest suction temperature of the compressor 1, the evaporation pressure regulating valve 7 is opened, the fifth solenoid valve 95 is closed, and the pipeline e is connected. The pressure in the evaporator is reduced through the evaporation pressure regulating valve 7, thereby reducing the temperature of the refrigerant entering the compressor 1. Subsequently, the b passage is opened, and the refrigerant flowing out of the filter 5 passes through the second solenoid valve 92, and then passes through the first expansion valve 101 for throttling, pressure reduction and temperature reduction. The opening of the first expansion valve 101 is adjusted by the difference between the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 and the highest suction temperature of the compressor 1. Subsequently, the refrigerant merges with the refrigerant from the evaporator 6 in the inlet pipeline of the compressor 1 to reduce the suction temperature of the compressor 1, and at the same time, it can prevent the refrigerant entering the compressor from carrying liquid and causing liquid hammer in the compressor.

[0079] When the temperature indicated by the second temperature sensor 112 disposed at the inlet end of the compressor 1 is lower than the maximum suction temperature of the compressor 1, the compressor is at a normal suction and exhaust operating temperature. At this time, it is only necessary to detect the ambient temperature through the third temperature sensor 113 according to the command temperature control system. When the ambient temperature is equal to the design temperature, the c passage is opened, and the refrigerant flowing out of the filter 5 passes through the third solenoid valve 93, and then flows into the evaporator 6 after throttling, reducing pressure and cooling through the second expansion valve 102. At the same time, the opening of the second expansion valve 102 is adjusted according to the superheat of the refrigerant at the outlet of the evaporator 6, so as to meet the refrigeration requirements of the evaporator 6. Afterwards, the refrigerant flowing out of the evaporator 6 that meets the suction and exhaust temperature requirements of the compressor 1 is introduced into the compressor 1 and the refrigeration cycle is continued to be completed, so that the ambient temperature reaches the command temperature.

[0080] Working condition nine, when the command temperature is lower than the system design temperature, passage d is opened, passages a, b, and c are closed, and the refrigerant flowing out of the filter 5 passes through the fourth solenoid valve 94, through the second capillary tube 82, and enters the evaporator 6 at a fixed design flow rate, so that the evaporator 6 reaches the system design temperature.

[0081] When the temperature indicated by the first temperature sensor 111 disposed at the outlet of the evaporator 6 is not lower than the highest suction temperature of the compressor 1, the evaporation pressure regulating valve 7 is opened, the fifth solenoid valve 95 is closed, and the pipeline e is connected. The pressure in the evaporator is reduced through the evaporation pressure regulating valve 7, thereby reducing the temperature of the refrigerant entering the compressor 1. Subsequently, the b passage is opened, and the refrigerant flowing out of the filter 5 passes through the second solenoid valve 92, and then passes through the first expansion valve 101 for throttling, pressure reduction and temperature reduction. The opening of the first expansion valve 101 is adjusted by the difference between the temperature indicated by the first temperature sensor 111 at the outlet of the evaporator 6 and the highest suction temperature of the compressor 1. After that, the refrigerant merges with the refrigerant from the evaporator 6 in the inlet pipeline of the compressor 1 to reduce the suction temperature of the compressor 1, and at the same time, it can avoid the refrigerant entering the compressor with liquid, which causes liquid hammer in the compressor.

[0082] When the temperature indicated by the second temperature sensor 112 disposed at the inlet end of the compressor 1 is not lower than the highest suction temperature of the compressor 1, the a passage is opened, and the refrigerant flowing out of the filter 5 passes through the first solenoid valve 91, and then throttles and reduces pressure and temperature through the first capillary 81, and directly enters the cooling pipeline in the shell of the compressor 1 at a fixed design flow rate to reduce the suction and exhaust temperature of the compressor, so as to achieve the final protection of the suction and exhaust overheating of the compressor 1. If the suction temperature of the compressor 1 is lower than its highest suction temperature. The system runs for a period of time, and the ambient temperature is detected by the third temperature sensor 113. When the ambient temperature is equal to the design temperature, the c passage is opened, and the refrigerant flowing out of the filter 5 passes through the third solenoid valve 93, and then throttles and reduces pressure and temperature through the second expansion valve 102 to flow into the evaporator 6, and adjusts the opening of the second expansion valve 102 according to the superheat of the refrigerant at the outlet of the evaporator 6, so as to meet the refrigeration requirements of the evaporator 6. After that, the refrigerant flowing out of the evaporator that meets the suction and exhaust temperature requirements of the compressor 1 is passed into the compressor 1 and continues to complete the refrigeration cycle, so that the ambient temperature reaches the command temperature.

Claims

1. A refrigeration system for reducing the suction and exhaust temperatures of a compressor, comprising a compressor (1), an oil separator (2), a condenser (3), a liquid storage device (4), a filter (5), and an evaporator (6) which are sequentially connected through pipelines to form a refrigeration cycle, characterized in that: The inlet end of the compressor (1) is provided with a second temperature sensor (112), the outlet end of the evaporator (6) is provided with a first temperature sensor (111), and the space where the evaporator (6) is located is provided with a third temperature sensor (113) for detecting the ambient temperature; The refrigerant flowing out of the outlet end of the filter (5) is divided into four paths through pipeline a, pipeline b, pipeline c, and pipeline d; wherein pipeline a is connected to the cooling pipeline on the shell of the compressor (1), and is connected to a first capillary tube (81) and a first solenoid valve (91); pipeline b is connected to the inlet pipeline of the compressor (1), and its outlet end is located upstream of the second temperature sensor, and pipeline b is connected to a second solenoid valve (92) and a first expansion valve (101); pipeline c and pipeline d are respectively connected to the inlet end of the evaporator (6), pipeline c is connected to a third solenoid valve (93) and a second expansion valve (102), and pipeline d is connected to a fourth solenoid valve (94) and a second capillary tube (82); The refrigerant flowing out of the outlet of the evaporator (6) is connected to the inlet pipeline of the compressor (1) through the pipeline e or f, the pipeline f is provided with a fifth solenoid valve (95), the pipeline e is provided with an evaporation pressure regulating valve (7), and the fifth solenoid valve (95) and the evaporation pressure regulating valve (7) are located upstream of the intersection of the pipeline b and the inlet pipeline of the compressor (1).

2. The refrigeration system according to claim 1, characterized in that: The first solenoid valve (91) and the first capillary tube (81) on the pipeline a are arranged in sequence along the flow direction of the refrigerant.

3. The refrigeration system according to claim 1, characterized in that: The second solenoid valve (92) and the first expansion valve (101) on the pipeline b are arranged in sequence along the flow direction of the refrigerant.

4. The refrigeration system according to claim 1, characterized in that: The third solenoid valve (93) and the second expansion valve (102) on the pipeline c are arranged in sequence along the flow direction of the refrigerant.

5. The refrigeration system according to claim 1, characterized in that: The fourth solenoid valve (94) and the second capillary tube (82) on the pipeline d are arranged in sequence along the flow direction of the refrigerant.

6. A refrigeration control method for reducing the suction and exhaust temperatures of a compressor, characterized in that: A refrigeration system for reducing the suction and exhaust temperatures of a compressor according to any one of claims 1 to 5, comprising the following steps: The command temperature is compared with the design temperature. If the command temperature is equal to the design temperature, pipeline d is connected, and it is determined whether the temperature of the first temperature sensor (111) is lower than the maximum suction temperature of the compressor (1). If so, pipeline f is connected. If not, pipelines e and b are connected in sequence, and it is determined whether the temperature of the second temperature sensor (112) is lower than the maximum suction temperature of the compressor (1). If not, pipeline a is connected. If the command temperature is higher than the design temperature, pipeline c is connected, and it is determined whether the temperature of the first temperature sensor (111) is lower than the maximum suction temperature of the compressor (1); if it is lower, pipeline f is connected; if it is not lower, pipelines e and b are connected in sequence, and it is determined whether the temperature of the second temperature sensor (112) is lower than the maximum suction temperature of the compressor (1); if it is not lower, pipeline a is connected; If the command temperature is lower than the design temperature, pipeline d is connected, and it is determined whether the temperature of the first temperature sensor (111) is lower than the maximum suction temperature of the compressor (1). If it is lower, pipeline f is connected, the refrigeration system is operated, and pipeline c is connected after the temperature of the third temperature sensor (113) reaches the design temperature. If it is not lower, pipelines e and b are connected in sequence, and it is determined whether the temperature of the second sensor (112) is lower than the maximum suction temperature of the compressor (1). If it is lower, pipeline c is connected after the temperature of the third temperature sensor (113) reaches the design temperature. If it is not lower, pipeline a is connected, the refrigeration system is operated, and pipeline c is connected after the temperature of the third temperature sensor (113) reaches the design temperature.

7. The refrigeration system according to claim 6, characterized in that: The operation of connecting pipeline a, pipeline b, pipeline c, and pipeline d is achieved by closing the first solenoid valve (91), the second solenoid valve (92), the third solenoid valve (93), and the fourth solenoid valve (94) respectively.

8. The refrigeration system according to claim 6 or 7, characterized in that: The step of connecting the pipeline f is achieved by closing the fifth solenoid valve (95), and the operation of connecting the pipeline e is achieved by disconnecting the fifth solenoid valve (95) and opening the steam pressure regulating valve at the same time.

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