Large temperature span precise cooling and heating circulation system and control method thereof

Abstract

A large temperature span precise cold and hot circulation system and its control method, the system comprises a compressor, a condenser, a gas-liquid separator, a semiconductor refrigerator, a liquid storage tank, a gas storage tank, an ejector, an evaporator, etc. Through the coordinated control of the semiconductor refrigerator, the solenoid valve, the gas storage tank, the liquid storage tank, and the one-way valve, the separation, storage and reorganization of the mixed working fluid are realized, and the large temperature span operation is realized. The heat pipe heat exchanger is used to transfer the cold capacity at the evaporator outlet to the gas storage tank, thereby improving the liquefaction rate of the low-boiling-point working fluid and improving the energy utilization rate. The second gas-liquid separator and the third semiconductor refrigerator are coupled, and the proportion of the liquid phase components in the second gas-liquid separation is controlled by controlling the current of the semiconductor refrigerator, and the evaporation temperature of the system is accurately adjusted to achieve precise temperature control. The introduction of the ejector can reduce the irreversible loss of the system, increase the suction pressure, and reduce energy consumption. The present invention can realize precise temperature control over a large temperature span from high temperature to deep low temperature, and solve the problems of poor stability, low precision, and high energy consumption of the traditional temperature control system.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a large temperature span precise cold and hot cycle system and a control method thereof. Background Art

[0002] In recent years, with the rapid development of industrialization and urbanization, various products and industries with cooling and heating requirements have put forward higher requirements on the accuracy and range of temperature control systems. For example, in scenarios such as data centers, semiconductor manufacturing, aerospace, medical equipment, and precision processing, it is necessary to achieve precise temperature control over a large range, so the large temperature span precise temperature control technology has attracted much attention.

[0003] Traditional temperature control systems usually find it difficult to achieve rapid and precise adjustment over a wide range from deep freezing to high temperatures, and are prone to unstable temperature control and excessive energy consumption under large temperature spans. On the other hand, traditional temperature control targets of -70°C and below require single-fluid two-stage compressor refrigeration technology, which has problems such as high cost and high energy consumption. The use of mixed fluids can achieve -70°C deep low-temperature refrigeration, but the current mixed fluid technology has "temperature zone limitations". When the system uses a mixed fluid, it usually achieves good low-temperature or deep low-temperature refrigeration effects, but poor performance stability under medium or high temperature refrigeration, which cannot meet large temperature span regulation and control, and the system energy utilization efficiency is low. Summary of the invention

[0004] In view of the problems existing in the refrigeration technology and temperature control system in the above-mentioned prior art, the purpose of the present invention is to propose a large temperature span precise hot and cold circulation system and its control method. The present invention can realize the separation, storage and reorganization of the mixed working fluid through the coordinated cooperation of semiconductor refrigerators, solenoid valves, liquid storage tanks, gas storage tanks and one-way valves, overcome the limitations of the temperature zone of the mixed working fluid, and realize high temperature, medium temperature, low temperature and deep low temperature large temperature span control.

[0005] In order to achieve the above technical purpose, the present invention adopts the following technical solutions:

[0006] A large temperature span precision cold and hot circulation system, comprising a first gas-liquid separator 103, the first gas-liquid separator 103 is close to the cold end face of the first semiconductor refrigerator 104, the hot end face of the first semiconductor refrigerator 104 is connected in series with the hot end face of the second semiconductor refrigerator 111 through a refrigerant pipeline, the cold end face of the second semiconductor refrigerator 111 is close to the liquid storage tank 110, the liquid storage tank 110 is connected to the gas storage tank 108 through a one-way valve 107, and the liquid storage tank 110 can be further separated; the second gas-liquid separator 114 is close to the cold end face of the third semiconductor refrigerator 115, the hot end face of the third semiconductor refrigerator 115 is equipped with a cooling fan 116 for heat dissipation, and the second gas-liquid separator 114 separates the two-phase refrigerant at the outlet of the ejector 113 into The gas phase and liquid phase, wherein the gas phase refrigerant outlet of the second gas-liquid separator 114 is connected to the refrigerant pipelines of the hot end surface of the second semiconductor refrigerator 111, the hot end surface of the first semiconductor refrigerator 104, and the hot end surface of the third semiconductor refrigerator 115 in sequence through pipelines, and further superheating is achieved through step-by-step thermal effect. The hot end refrigerant outlet of the third semiconductor refrigerator 115 is connected to the inlet of the compressor 101, the outlet of the compressor 101 is connected to the inlet of the condenser 102, and the outlet of the condenser 102 is connected to the inlet of the first gas-liquid separator 103; the liquid phase refrigerant outlet of the second gas-liquid separator 114 is connected to the inlet of the electronic expansion valve 117, the outlet of the electronic expansion valve 117 is connected to the inlet of the evaporator 118, and the outlet of the evaporator 118 is connected to the ejector 113 The secondary flow inlet 1132 of the condenser 102 is connected to the secondary flow inlet 1132 and is ejected as a secondary flow; the outlet pipeline of the evaporator 118 is connected to the condensing section heat exchanger 1212 of the heat pipe heat exchanger 121, and the evaporating section heat exchanger 1211 of the heat pipe heat exchanger 121 is connected to the gas storage tank 108, and the cold at the outlet of the evaporator 118 is transferred to the gas storage tank 108 through the heat pipe heat exchanger 121, thereby realizing efficient utilization and conversion of energy; the first gas-liquid separator 103 separates the mixed refrigerant with different boiling points at the outlet of the condenser 102 into low-boiling point and high-boiling point refrigerants and stores them separately, wherein the low-boiling point refrigerant flows into the gas storage tank 108 through the first solenoid valve 105, and the outlet of the gas storage tank 108 is connected to the inlet of the third solenoid valve 109; the gas storage tank 108 is connected to the heat exchanger 1212 of the evaporating section of the heat pipe heat exchanger 121, and the evaporating section of the heat pipe heat exchanger 121 is connected to the gas storage tank 108. 11 is in close contact; the high boiling point refrigerant coming out of the first gas-liquid separator 103 flows into the liquid storage tank 110 through the second solenoid valve 106, the outlet of the liquid storage tank 110 is connected to the inlet of the fourth solenoid valve 112, and the refrigerant mixed with the outlet of the fourth solenoid valve 112 and the outlet of the third solenoid valve 109 enters the primary flow inlet 1131 of the ejector 113 as a primary fluid, and is mixed with the refrigerant at the outlet of the evaporator 118 to become a two-phase refrigerant and enter the second gas-liquid separator 114 for gas-liquid separation; the first temperature sensor T1 is arranged at the inlet of the compressor 101, the second temperature sensor T2 and the third temperature sensor T3 are arranged at the inlet and outlet of the evaporator 118 respectively, and the pressure sensor P1 detects the pressure of the second gas-liquid separator 114;The control module C1 is connected to the first semiconductor refrigerator 104, the second semiconductor refrigerator 111, the third semiconductor refrigerator 115, the first solenoid valve 105, the second solenoid valve 106, the third solenoid valve 109, the fourth solenoid valve 112, the check valve 107, the first temperature sensor T1, the second temperature sensor T2, the third temperature sensor T3, the pressure sensor P1, the cooling fan 116, the electronic expansion valve 117 and the asynchronous motor 119 connected to the nozzle 130. ;

[0007] The refrigerant used in the system is a ternary or quaternary or higher mixed refrigerant. In order to achieve temperature control and environmental adaptability in a large range, the mixed refrigerant is composed of a high-boiling point refrigerant and a low-boiling point refrigerant, wherein the high-boiling point refrigerant is one or more of R290, R744, R134a, and R1234ze(E), and the low-boiling point refrigerant is one or more of R1150, R14, R170, and R23; through the optimization control of the solenoid valve and the semiconductor refrigerator, the storage amount of the refrigerant in the gas storage tank 108 and the liquid storage tank 110 is controlled, and then the combination ratio of the high-boiling point refrigerant and the low-boiling point refrigerant is controlled, so as to achieve precise temperature control over a large temperature span under different combination modes and control methods.

[0008] The first gas-liquid separator 103 releases heat and cools down at the cold end of the first semiconductor refrigerator 104, the temperature in the first gas-liquid separator 103 decreases, and the mixed working fluid is cooled and liquefied, resulting in an increase in the content of high-boiling-point refrigerant in the liquid refrigerant, which is conducive to further regulating the content of high-boiling-point refrigerant in the liquid storage tank 110. Similarly, the high-boiling-point refrigerant in the liquid storage tank 110 releases heat and cools down at the cold end of the second semiconductor refrigerator 111, is further supercooled and liquefied, the temperature of the refrigerant in the liquid storage tank 110 is reduced, and at the same time, the content of high-boiling-point refrigerant in the liquid phase in the primary flow entering the ejector 113 is increased, thereby realizing the control of the mixed refrigerant components; the refrigerant in the second gas-liquid separator 114 releases heat and cools down at the cold end of the third semiconductor refrigerator 115, the content of liquid refrigerant in the second gas-liquid separator 114 increases, the amount of liquid flowing into the evaporator increases, and the refrigerant flow in the evaporator 118 is increased, which can effectively increase the cooling capacity of the circulation system.

[0009] The refrigerant at the gas phase outlet of the second gas-liquid separator 114 absorbs heat in the second semiconductor refrigerator 111 and the hot end of the first semiconductor refrigerator 104 to become superheated vapor with a certain degree of superheat, and then is further superheated by the third semiconductor refrigerator 115. The temperature of the refrigerant entering the compressor is further increased, and the hot end of the semiconductor refrigerator can accurately control the suction superheat. At the same time, the multi-stage thermal process can effectively prevent liquid hammer in the compressor 101, thereby improving the efficiency and safety of the compressor.

[0010] The gas storage tank 108 and the liquid storage tank 110 are arranged separately and side by side, which can realize the separation and storage of low-boiling point and high-boiling point refrigerants, and combined with the switching and opening adjustment of the first solenoid valve 105, the second solenoid valve 106, the third solenoid valve 109, the fourth solenoid valve 112 and the one-way valve 107, precise control of the mixed refrigerant components from separation to reorganization can be realized, and then the system temperature can be controlled by using mixed refrigerants of different components.

[0011] The evaporation section heat exchanger 1211 of the heat pipe heat exchanger 121 is wrapped around the wall of the gas tank 108 through the pipeline and is in close contact with the gas tank 108. The condensation section heat exchanger 1212 is wrapped around the outlet pipeline of the evaporator 118 and is in close contact with the outlet pipeline of the evaporator 118. The cold energy at the outlet of the evaporator 118 is transferred to the vicinity of the gas tank 108 through the heat pipe heat exchanger 121. In this process, the internal medium (water, ammonia, ethanol, etc.) of the heat pipe heat exchanger 121 exchanges heat with the cold source, and the liquid working medium in the heat pipe heat exchanger 121 is condensed by cooling, changing from gas to liquid, and then returns to the hot end to evaporate through capillary action; the working medium in the heat pipe heat exchanger 121 evaporates at the hot end, absorbs the heat around the gas tank 108, and liquefies as much low-boiling-point refrigerant as possible and stores it in the gas tank 108, thereby increasing the content of low-boiling-point refrigerant in the mixed working medium, and then regulating the system temperature.

[0012] The ejector 113 is an adjustable scalable ejector, comprising a nozzle 130, a suction chamber 131, a mixing chamber 132 and a diffusion chamber 133 which cover the nozzle 130 and are arranged in sequence from front to back. The distance from the nozzle 130 to the entrance of the mixing chamber 132 in the ejector is automatically adjusted by an asynchronous motor 119 connected to the nozzle 130, thereby adjusting the pressure at the ejector 1133 outlet; the pressure at the ejector 1133 outlet is between the pressure of the mixed refrigerant entering the primary inlet 1131 of the ejector 113 and the pressure of the refrigerant at the outlet of the evaporator 118. After the mixed refrigerant is accelerated and depressurized in the nozzle 130, it is mixed with the refrigerant from the outlet of the evaporator 118 in the mixing chamber 132, and then decelerated and pressurized in the diffusion chamber 133 before entering the second gas-liquid separator 114.

[0013] The control method of a large temperature span precise cold and hot cycle system is described, wherein the first temperature sensor T1 detects the refrigerant temperature at the inlet of the compressor 101, the second temperature sensor T2 detects the refrigerant temperature at the inlet of the evaporator 118, the third temperature sensor T3 detects the refrigerant temperature at the outlet of the evaporator 118, the pressure sensor P1 detects the pressure of the second gas-liquid separator 114, the control module C1 receives the temperature and pressure signals to control the start and stop of the asynchronous motor 119, the switch and input current of the first semiconductor refrigerator 104, the second semiconductor refrigerator 111, and the third semiconductor refrigerator 115, the opening of the electronic expansion valve 117, the input current of the cooling fan 116, the switch and opening of the first solenoid valve 105, the second solenoid valve 106, the third solenoid valve 109, and the fourth solenoid valve 112, and the switch of the one-way valve 107, thereby realizing the system large temperature span precise temperature control;

[0014] The control method is: T c Indicates the condensation temperature, T e represents the evaporation temperature, T e_set represents the set temperature, P1 represents the pressure in the second gas-liquid separator 114 detected by the pressure sensor P1, T m represents the saturation temperature corresponding to P1, k1 is the temperature value measured by the first temperature sensor T1, k2 is the temperature value measured by the second temperature sensor T2, k3 is the temperature value measured by the third temperature sensor T3, f1 is the opening of the electronic expansion valve 117, and the initial opening is 50% of the full opening;

[0015] a. When T e_set <-70℃, the system is in the ultra-low temperature refrigeration demand state, the control module C1 controls the first semiconductor refrigerator 104 to be powered off, the second semiconductor refrigerator 111 to be powered off, the first solenoid valve 105 is in a fully open state, the second solenoid valve 106 gradually increases the opening, the one-way valve 107 is opened, the third solenoid valve 109 is in a fully open state, and the fourth solenoid valve 112 is closed. At this time, the mixed refrigerant in the first gas-liquid separator 103 is separated into components, and most of the saturated gas rich in low boiling points enters the gas storage tank 108, and the rich A small amount of saturated liquid with a low boiling point enters the liquid storage tank 110, and the low boiling point refrigerant gas is then supplemented to the gas storage tank 108 through the one-way valve 107. The condensing section heat exchanger 1212 of the heat pipe heat exchanger 121 transfers the cold energy at the outlet of the evaporator 118 to the evaporating section heat exchanger 1211 around the gas storage tank 108, thereby reducing the temperature of the low boiling point working fluid in the gas storage tank 108, so that more of the low boiling point working fluid in the gas storage tank 108 becomes liquid, increasing the content of low boiling point components in the circulation system, and realizing ultra-low temperature refrigeration of the system under a single low boiling point working fluid;

[0016] b. When -70℃≤T e_set<-40℃, the system is in a low-temperature refrigeration demand state, the control module C1 receives the temperature signal, controls the first semiconductor refrigerator 104 to be powered on, the second semiconductor refrigerator 111 to be powered on, the first solenoid valve 105 and the second solenoid valve 106 to be fully open, the third solenoid valve 109 and the fourth solenoid valve 112 are initially closed, the one-way valve 107 is opened, the low-boiling-point working fluid is stored and liquefied in the gas storage tank 108, and the high-boiling-point working fluid is stored in the liquid storage tank 110. After the system is stable, the third solenoid valve 109 and the fourth solenoid valve 112 are controlled to be opened and kept at 50% opening. When T e_set >-55℃, the control module C1 controls the fourth solenoid valve 112 to increase its opening, so that the high boiling point components in the mixed working fluid increase. e_set When the temperature is ≤-55°C, the third solenoid valve 109 is controlled to increase its opening, and the low-boiling-point working fluid is increased in the mixed working fluid. The third solenoid valve 109 and the fourth solenoid valve 112 are controlled to cooperate with each other to achieve the reorganization of the mixed working fluid components. The opening of the third solenoid valve 109 and the opening of the fourth solenoid valve 112 can be adjusted to control the temperature in a wider range, so that the system can achieve low-temperature refrigeration under mixed working fluids.

[0017] c. When -40℃≤T e set <-10℃, the system is in a medium-temperature refrigeration demand state, the control module C1 receives the temperature signal, controls the first semiconductor refrigerator 104 to be powered off, the second semiconductor refrigerator 111 to be powered on, the first solenoid valve 105, the second solenoid valve 106 and the fourth solenoid valve 112 to be opened, the third solenoid valve 109 to be closed, the one-way valve 107 to be opened, the low-boiling-point working medium is liquefied and stored in the gas storage tank 108, and the low-boiling-point saturated gas in the liquid storage tank 110 is added to the gas storage tank 108 along the one-way valve 107, further realizing the effective separation of working mediums with different boiling points, the high-boiling-point saturated liquid enters the system from the liquid storage tank 110, the liquid storage tank 110 is cooled at the cold end of the second semiconductor refrigerator 111, and the liquid phase high-boiling-point liquid in the liquid storage tank 110 is further increased, realizing medium-temperature refrigeration of the system under a single high-boiling-point working medium;

[0018] d. When -10℃≤T e_setWhen the system is in a high-temperature refrigeration demand state, the control module C1 receives the temperature signal, controls the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 to be energized, the first solenoid valve 105 and the second solenoid valve 106 are in a fully open state, the one-way valve 107 is opened, the third solenoid valve 109 is closed, and the fourth solenoid valve 112 is opened. Only high-boiling-point working fluid runs in the system, and the first gas-liquid separator 103 and the liquid storage tank 110 gradually cool down the cold ends of the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 respectively, so as to further enrich the liquid component, and control the cold end temperature of the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 by increasing the current, but the maximum current is less than the current Imax of the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 under the maximum cooling capacity condition, thereby increasing the high-boiling-point component of the liquid phase of the system, realizing the operation of as many high-boiling-point refrigerants as possible, and realizing high-temperature refrigeration of the system under a single high-boiling-point working fluid;

[0019] Through the control method described in ad, the goal of large temperature cross-system circulation is achieved;

[0020] e. When the outlet temperature of the evaporator 118 is k3>k2+10, the second temperature sensor T2 and the third temperature sensor T3 transmit the temperature signal to the control module C1 and the control module C1 controls the third semiconductor refrigerator 115 to be powered on. When the third semiconductor refrigerator 115 is powered on, the cooling fan 116 is operated to dissipate heat. The input current of the cooling fan 116 is controlled by the temperature feedback signal of the first temperature sensor T1. When k1>T m +15, the compressor suction temperature is too high, which is not conducive to the stable operation of the system. At this time, the control module C1 controls the cooling fan 116 to increase the current and increase the heat dissipation of the hot end of the third semiconductor refrigerator 115. When k1<T m+5, the cooling fan 116 is turned off, so that the air intake port of the compressor 101 maintains an overheat of 5℃-15℃, which can protect the compressor; when the temperature difference between the second temperature sensor T2 and the third temperature sensor T3 increases, the control module C1 controls the third semiconductor refrigerator 115 to increase the input current, but the maximum current is less than the current Imax1 of the third semiconductor refrigerator 115 under the maximum cooling capacity condition; within this current range, the greater the input current of the third semiconductor refrigerator 115, the more cooling capacity its cold end surface generates, so the two-phase refrigeration in the second gas-liquid separator 114 The more liquid phase there is in the refrigerant, the greater the refrigerant flow through the electronic expansion valve 117 and the evaporator 118, the greater the cooling capacity, and the lower the outlet temperature of the evaporator 118. When k3<k2+5, the control module C1 controls the third semiconductor refrigerator 115 to cut off the power; when the evaporation temperature adjustment requirement cannot be met by adjusting the third semiconductor refrigerator 115, the control module C1 controls the opening f1 of the electronic expansion valve 117 to assist in adjusting the evaporator temperature, and the opening range of f1 is 20%-80% of the full opening; the inlet temperature of the compressor 101 is detected by the first temperature sensor T1, and when k1<T m +2, at this time, the refrigerant superheat at the suction port of the compressor 101 does not meet the operating requirements, the first temperature sensor T1 transmits the temperature signal to the control module C1 and the control module C1 controls the third semiconductor refrigerator 115 to increase the current, so that the refrigerant temperature at the inlet of the compressor 101 increases until k1>T m +5, so that the superheat of the compressor suction port is maintained at least 5°C. The superheat of the compressor suction port is controlled by the first semiconductor refrigerator 104, the second semiconductor refrigerator 111 and the third semiconductor refrigerator 115. The temperature of the hot end of the semiconductor refrigerator is controlled by controlling the current, thereby affecting the refrigerant temperature;

[0021] f. When the third semiconductor refrigerator 115 is not working, the pressure of the second gas-liquid separator 114 is a constant value P s When the third semiconductor refrigerator 115 is powered on, its cold end is close to the second gas-liquid separator 114 and absorbs the heat of the second gas-liquid separator 114, which will cause the pressure in the second gas-liquid separator 114 to decrease. <P s +0.1Mpa, the control module C1 controls the asynchronous motor 119 to adjust the position of the nozzle 130 of the injector 113; when the current of the third semiconductor refrigerator 115 increases, it absorbs more heat in the second gas-liquid separator 114, resulting in a decrease in the outlet pressure of the injector 113; at this time, the control module C1 controls the asynchronous motor 119 to make the nozzle 130 close to the mixing chamber 132, reducing the secondary flow rate of the injector 113, increasing the boost ratio of the injector 113, and keeping the outlet pressure of the injector 113 stable. When P1=P sWhen the current of the third semiconductor refrigerator 115 decreases, the asynchronous motor 119 is controlled by the control module C1 to move the nozzle 130 away from the mixing chamber 132. When the third semiconductor refrigerator 115 is not working, the nozzle 130 returns to the initial position.

[0022] The control method described in ad combined with the control method described in ef can achieve the goal of precise temperature control under a large temperature span system.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. Compared with the traditional vapor compression refrigeration temperature control cycle system, the present invention sets a solenoid valve, a liquid storage tank 110, and a gas storage tank 108 at the outlet of the first gas-liquid separator 103, and introduces a semiconductor refrigerator to cool the first gas-liquid separator 103 and the liquid storage tank 110. The semiconductor refrigerator, the solenoid valve, the liquid storage tank, the gas storage tank, and the one-way valve cooperate to achieve the separation, storage, and reorganization of the mixed working fluid, overcome the temperature zone limitation of the mixed working fluid, and achieve high temperature, medium temperature, low temperature, and deep low temperature wide temperature span control;

[0025] 2. The present invention adopts ternary or quaternary or higher mixed working fluids, and through the synergistic effect of multiple components, it can optimize the control system in a wider temperature and pressure range, and has good wide temperature range, adaptability, and high heat exchange efficiency;

[0026] 3. The present invention introduces three semiconductor refrigerators. The first semiconductor refrigerator 104 can cool the first gas-liquid separator 103, so that the high boiling point in the system mixed working fluid is stored in the liquid storage tank as much as possible. The second semiconductor refrigerator 111 can cool the liquid storage tank 110, so that the high boiling point working fluid is further cooled and liquefied. The third semiconductor refrigerator 115 can add additional cooling capacity to the second gas-liquid separator 114, thereby increasing the liquid phase refrigerant component in the gas-liquid separator, increasing the refrigerant flow rate flowing through the evaporator, and then increasing the cooling capacity to achieve the purpose of regulating the evaporation temperature. The refrigerant at the outlet of the second gas-liquid separator 114 absorbs heat at the hot ends of the second semiconductor refrigerator 111 and the first semiconductor refrigerator 104 and the third semiconductor refrigerator 115, so that the refrigerant in the compressor 101 maintains a certain degree of superheat to prevent liquid hammer. The cooling fan 116 can prevent the suction temperature of the compressor 101 from being too high.

[0027] 4. The present invention introduces a heat pipe heat exchanger 121, which utilizes the cold energy at the outlet of the evaporator 118 and efficiently transfers it to the gas storage tank 108 through the heat pipe heat exchanger 121. The evaporation section heat exchanger 1211 of the heat pipe heat exchanger 121 absorbs the heat around the gas storage tank 108, thereby promoting more low-boiling point refrigerants to liquefy, and significantly increasing the content of low-boiling point working fluids in the system. This design not only fully recovers and utilizes cold energy resources, improves the energy utilization rate of the system, but also optimizes the component ratio of the mixed refrigerant, providing a strong guarantee for achieving efficient large temperature span operation;

[0028] 5. The present invention introduces an ejector 113, which has the advantages of no moving parts, low cost, simple structure, low maintenance requirements, etc. It can effectively recover expansion work, increase the suction pressure of the compressor 101, and reduce the power consumption of the compressor 101;

[0029] 6. The present invention proposes a feasible and effective control method, which can realize efficient and stable operation of a large temperature span precise cold and hot circulation system through large temperature span regulation combined with precise temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of a large temperature span precise hot and cold circulation system according to an embodiment of the present invention.

[0031] Figure 2 Schematic diagram of the structure of the injector and the connection diagram of the injector and the asynchronous motor in the embodiment of the present invention.

[0032] Figure 3 This is a logic diagram of large temperature span regulation and control of a large temperature span precise cold and hot circulation system in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] The embodiment of the present invention proposes a large temperature span precise cold and hot circulation system and a control method thereof, which improves the traditional vapor compression refrigeration temperature control circulation system. The system adopts ternary or quaternary or higher mixed working fluids to participate in the circulation, and an electromagnetic valve, a liquid storage tank, and a gas storage tank are arranged at the outlet of the first gas-liquid separator. The first gas-liquid separator is adjacent to the cold end of the first semiconductor refrigerator, and the liquid storage tank is adjacent to the cold end of the second semiconductor refrigerator. The liquid storage tank is connected to the gas storage tank through a one-way valve, and the outlets of the liquid storage tank and the gas storage tank are provided with an electromagnetic valve. Through the coordinated control of the semiconductor refrigerator, the electromagnetic valve, the gas storage tank, the liquid storage tank, and the one-way valve, the mixed working fluid can be separated, stored, and then recombined, thereby realizing large temperature span operation. A heat pipe heat exchanger is introduced, and the cold energy at the outlet of the evaporator can be utilized, and the cold energy at the outlet of the evaporator can be transferred to the gas storage tank to absorb the heat around the gas storage tank, so that more low-boiling point refrigerant liquid The system increases the content of low-boiling-point working fluids and improves energy utilization. The ejector is introduced to recover the expansion work of the system and reduce the irreversible loss of the system, thereby improving the energy efficiency of the system. The semiconductor refrigerator is introduced. When the temperature of the system evaporator is high, the third semiconductor refrigerator is powered on. The third semiconductor refrigerator can provide additional cooling capacity to the gas-liquid separator, thereby increasing the proportion of liquid refrigerant in the second gas-liquid separator, increasing the refrigerant flow through the evaporator and thus increasing the cooling capacity, reducing the evaporator temperature, and achieving the effect of regulating the evaporation temperature. At the same time, the semiconductor refrigerator and the cooling fan are introduced. By controlling the current of the semiconductor refrigerator and the current of the cooling fan, the hot end of the semiconductor refrigerator can be used to keep the refrigerant at the compressor inlet at a certain degree of superheat to prevent liquid hammer, and it can also prevent excessive overheating, thereby improving the life of the compressor and the safety of the system.

[0035] See also Figure 1In an embodiment of the present invention, a large temperature span precision cold and hot circulation system includes: a compressor 101, a condenser 102, two gas-liquid separators, three semiconductor refrigerators, a liquid storage tank 110, a gas storage tank 108, four solenoid valves, a one-way valve 107, an ejector 113, a heat pipe heat exchanger 121, an evaporator 118, an electronic expansion valve 117, and a cooling fan 116; the first gas-liquid separator 103 is close to the cold end face of the first semiconductor refrigerator 104, the hot end face of the first semiconductor refrigerator 104 is connected in series with the hot end face of the second semiconductor refrigerator 111 through a refrigerant pipeline, the cold end face of the second semiconductor refrigerator 111 is close to the liquid storage tank 110, and the liquid storage tank 110 is connected to the gas storage tank 108 through the one-way valve 107, which can further 110 for separation; the second gas-liquid separator 114 is close to the cold end face of the third semiconductor refrigerator 115, and the hot end face of the third semiconductor refrigerator 115 is equipped with a cooling fan 116 for heat dissipation. The second gas-liquid separator 114 separates the two-phase refrigerant at the outlet of the ejector 113 into a gas phase and a liquid phase, wherein the gas phase refrigerant outlet of the second gas-liquid separator 114 is connected with the refrigerant pipelines of the hot end face of the second semiconductor refrigerator 111, the hot end face of the first semiconductor refrigerator 104, and the hot end face of the third semiconductor refrigerator 115 in sequence through pipelines, and further overheating is achieved through step-by-step thermal effect, the hot end refrigerant outlet of the third semiconductor refrigerator 115 is connected to the inlet of the compressor 101, the outlet of the compressor 101 is connected to the inlet of the condenser 102, and the condenser 102 The outlet is connected to the inlet of the first gas-liquid separator 103; the liquid-phase refrigerant outlet of the second gas-liquid separator 114 is connected to the inlet of the electronic expansion valve 117, the outlet of the electronic expansion valve 117 is connected to the inlet of the evaporator 118, and the outlet of the evaporator 118 is connected to the secondary flow inlet 1132 of the ejector 113, and is ejected as a secondary flow; the outlet pipeline of the evaporator 118 is connected to the condensing section heat exchanger 1212 of the heat pipe heat exchanger 121, and the evaporating section heat exchanger 1211 of the heat pipe heat exchanger 121 is connected to the gas storage tank 108, and the cold energy at the outlet of the evaporator 118 is transferred to the gas storage tank 108 through the heat pipe heat exchanger 121, thereby realizing efficient utilization and conversion of energy; the first gas-liquid separator 103 separates the mixed refrigerant with different boiling points at the outlet of the condenser 102 into a low The boiling point and high boiling point refrigerants are stored separately, wherein the low boiling point refrigerant flows into the gas storage tank 108 through the first solenoid valve 105, and the outlet of the gas storage tank 108 is connected to the inlet of the third solenoid valve 109; the wall of the gas storage tank 108 is in close contact with the evaporation section heat exchanger 1211 of the heat pipe heat exchanger 121; the high boiling point refrigerant coming out of the first gas-liquid separator 103 flows into the liquid storage tank 110 through the second solenoid valve 106, and the outlet of the liquid storage tank 110 is connected to the inlet of the fourth solenoid valve 112, and the refrigerant mixed with the outlet of the fourth solenoid valve 112 and the outlet of the third solenoid valve 109 enters the primary flow inlet 1131 of the ejector 113 as a primary fluid, and after mixing with the refrigerant at the outlet of the evaporator 118, it becomes a two-phase refrigerant and enters the second gas-liquid separator 114 for gas-liquid separation;The first temperature sensor T1 is arranged at the inlet of the compressor 101, the second temperature sensor T2 and the third temperature sensor T3 are arranged at the inlet and outlet of the evaporator 118 respectively, and the pressure sensor P1 detects the pressure of the second gas-liquid separator 114; the control module C1 is connected with the first semiconductor refrigerator 104, the second semiconductor refrigerator 111, the third semiconductor refrigerator 115, the first solenoid valve 105, the second solenoid valve 106, the third solenoid valve 109, the fourth solenoid valve 112, the one-way valve 107, the first temperature sensor T1, the second temperature sensor T2, the third temperature sensor T3, the pressure sensor P1, the cooling fan 116, the electronic expansion valve 117 and the asynchronous motor 119 connected to the nozzle 130.;

[0036] In the embodiment of the present invention, the refrigerant used in the system is a ternary or quaternary or higher mixed refrigerant. In order to achieve temperature control and environmental adaptability in a wide range, the mixed refrigerant is composed of a high-boiling point refrigerant and a low-boiling point refrigerant, wherein the high-boiling point refrigerant includes but is not limited to one or more of R290, R744, R134a, R1234ze(E), etc., and the low-boiling point refrigerant includes but is not limited to one or more of R1150, R14, R170, R23, etc. Through the optimization control of the solenoid valve and the semiconductor refrigerator, the storage amount of the refrigerant in the gas storage tank 108 and the liquid storage tank 110 is controlled, and then the combination ratio of the high-boiling point refrigerant and the low-boiling point refrigerant is controlled, so as to achieve precise temperature control over a large temperature span under different combination modes and control methods.

[0037] In the embodiment of the present invention, the first gas-liquid separator 103 releases heat and cools down at the cold end of the first semiconductor refrigerator 104, the temperature in the first gas-liquid separator 103 decreases, and the mixed working fluid is liquefied when cooled, resulting in an increase in the content of high-boiling-point refrigerant in the liquid refrigerant, which is beneficial to further control the proportion of high-boiling-point refrigerant in the liquid storage tank 110. Similarly, the high-boiling-point refrigerant in the liquid storage tank 110 releases heat and cools down at the cold end of the second semiconductor refrigerator 111 to achieve deep supercooling and liquefaction, the refrigerant temperature in the liquid storage tank 110 is reduced, and at the same time, the content of liquid high-boiling-point refrigerant in the primary flow entering the ejector 113 is increased, thereby achieving mixed refrigerant component control; the refrigerant in the second gas-liquid separator 114 releases heat and cools down at the cold end of the third semiconductor refrigerator 115, the content of liquid refrigerant in the second gas-liquid separator 114 increases, the amount of liquid flowing into the evaporator increases, and then the refrigerant flow in the evaporator 118 increases, thereby effectively increasing the refrigeration capacity of the circulation system, which can effectively enhance the refrigeration efficiency and system refrigeration capacity.

[0038] In the embodiment of the present invention, the refrigerant at the gas phase outlet of the second gas-liquid separator 114 absorbs heat at the second semiconductor refrigerator 111 and the hot end of the first semiconductor refrigerator 104, becomes superheated vapor with a certain degree of superheat, and then is further superheated by the third semiconductor refrigerator 115, and the temperature of the refrigerant entering the compressor is further increased, and the hot end of the semiconductor refrigerator can accurately control the suction superheat. At the same time, the multi-stage thermal process can effectively prevent the compressor 101 from liquid hammering, and improve the compressor efficiency and system safety.

[0039] In an embodiment of the present invention, the gas storage tank 108 and the liquid storage tank 110 are arranged separately and side by side to achieve effective separation and storage of low-boiling point and high-boiling point refrigerants. Through the coordinated control of the first solenoid valve 105, the second solenoid valve 106, the third solenoid valve 109, the fourth solenoid valve 112 and the one-way valve 107, the mixed refrigerant components can be accurately adjusted from separation, storage to reorganization to meet the flexible requirements of the refrigerant component ratio under different working conditions, and the system temperature is controlled by using mixed refrigerants of different components, thereby achieving efficient operation and precise temperature control of the system.

[0040] In the embodiment of the present invention, the evaporation section heat exchanger 1211 of the heat pipe heat exchanger 121 is wrapped around the wall of the gas tank 108 through the pipeline, and is in close contact with the gas tank 108. The condensation section heat exchanger 1212 is wrapped around the outlet pipeline of the evaporator 118, and is in close contact with the outlet pipeline of the evaporator 118. The cold capacity at the outlet of the evaporator 118 can be transferred to the surrounding of the gas tank 108 through the heat pipe heat exchanger 121. In this process, the internal medium (ethanol) of the heat pipe heat exchanger 121 exchanges heat with the cold source, and a phase change occurs. The liquid working medium in the heat pipe heat exchanger 121 is condensed by cooling, and changes from gas to liquid, and then flows back to the evaporation section through capillary action. In the evaporation section, the liquid working medium evaporates and absorbs the heat around the gas tank 108, thereby reducing the temperature of the gas tank and promoting the low-boiling point refrigerant to be fully liquefied and stored in the gas tank 108. In this way, the content of low-boiling-point refrigerant in the mixed working fluid can be significantly increased, the proportion of mixed refrigerant components can be optimized, the operating efficiency and large temperature span performance of the system can be improved, and the demand for precise temperature control can be met.

[0041] See also Figure 2In the embodiment of the present invention, the ejector 113 is an adjustable scalable ejector, including a nozzle 130, a suction chamber 131, a mixing chamber 132 and a diffusion chamber 133. The distance from the nozzle 130 to the entrance of the mixing chamber 132 in the ejector can be automatically adjusted by an asynchronous motor 119 connected to the nozzle 130, thereby regulating the system pressure boost ratio to achieve the purpose of adjusting the pressure at the ejector 113 outlet 1133; the outlet 1133 pressure of the ejector 113 is between the mixed refrigerant pressure at the primary inlet 1131 entering the ejector 113 and the refrigerant pressure at the outlet of the evaporator 118. The mixed refrigerant has a higher pressure. After being accelerated and depressurized in the nozzle 130, it is mixed with the refrigerant from the outlet of the evaporator 118 in the mixing chamber 132, and then decelerated and pressurized in the diffusion chamber 133 before entering the second gas-liquid separator 114.

[0042] In the embodiment of the present invention, the first temperature sensor T1 detects the refrigerant temperature at the inlet of the compressor 101, the second temperature sensor T2 detects the refrigerant temperature at the inlet of the evaporator 118, the third temperature sensor T3 detects the refrigerant temperature at the outlet of the evaporator 118, the pressure sensor P1 detects the pressure of the second gas-liquid separator 114, and the control module C1 receives the temperature and pressure signals to control the start and stop of the asynchronous motor 119, the switch and input current of the first semiconductor refrigerator 104, the second semiconductor refrigerator 111, and the third semiconductor refrigerator 115, the opening of the electronic expansion valve 117, the input current of the cooling fan 116, the switch and opening of the first solenoid valve 105, the second solenoid valve 106, the third solenoid valve 109, and the fourth solenoid valve 112, and the switch of the one-way valve 107, thereby realizing accurate temperature control under a large temperature span of the system;

[0043] The control method is: T c Indicates the condensation temperature, T e represents the evaporation temperature, T e_set represents the set temperature, P1 represents the pressure in the second gas-liquid separator 114 detected by the pressure sensor P1, T m represents the saturation temperature corresponding to P1, k1 is the temperature value measured by the first temperature sensor T1, k2 is the temperature value measured by the second temperature sensor T2, k3 is the temperature value measured by the third temperature sensor T3), f1 is the opening of the electronic expansion valve 117, and the initial opening is 50% of the full opening;

[0044] See also Figure 3 In the embodiment of the present invention, the control method described in ad below can achieve the goal of a large temperature span circulation system.

[0045] a. When T e_set<-70℃, the system is in the ultra-low temperature refrigeration demand state, the control module C1 controls the first semiconductor refrigerator 104 to be powered off, the second semiconductor refrigerator 111 to be powered off, the first solenoid valve 105 is in a fully open state, the second solenoid valve 106 gradually increases the opening, the one-way valve 107 is opened, the third solenoid valve 109 is in a fully open state, and the fourth solenoid valve 112 is closed. At this time, the mixed refrigerant in the first gas-liquid separator 103 is separated into components, and most of the saturated gas with low boiling point enters the gas storage tank 108. A small amount of saturated liquid rich in low boiling points enters the liquid storage tank 110, and the low boiling point refrigerant gas is then supplemented to the gas storage tank 108 through the one-way valve 107. The condensing section heat exchanger 1212 of the heat pipe heat exchanger 121 transfers the cold energy at the outlet of the evaporator 118 to the evaporating section heat exchanger 1211 around the gas storage tank 108, thereby reducing the temperature around the gas storage tank 108, so that more low boiling point working fluid in the gas storage tank 108 becomes liquid, increasing the content of low boiling point components in the circulation system, and realizing ultra-low temperature refrigeration of the system under single low boiling point working fluid;

[0046] b. When -70℃≤T e_set <-40℃, the system is in a low-temperature refrigeration demand state, the control module C1 receives the temperature signal, controls the first semiconductor refrigerator 104 to be powered on, the second semiconductor refrigerator 111 to be powered on, the first solenoid valve 105 and the second solenoid valve 106 to be fully open, the third solenoid valve 109 and the fourth solenoid valve 112 are initially closed, the one-way valve 107 is opened, the low-boiling-point working fluid is stored and liquefied in the gas storage tank 108, and the high-boiling-point working fluid is stored in the liquid storage tank 110. After the system is stable, the third solenoid valve 109 and the fourth solenoid valve 112 are controlled to be opened and kept at 50% opening. When T e_set >-55℃, the control module C1 controls the fourth solenoid valve 112 to increase its opening, so that the high boiling point components in the mixed working fluid increase. e_set When the temperature is ≤-55°C, the third solenoid valve 109 is controlled to increase its opening, and the low-boiling-point working fluid is increased in the mixed working fluid. The mixed working fluid components can be reorganized by controlling the third solenoid valve 109 and the fourth solenoid valve 112 to cooperate with each other. The temperature can be controlled in a wider range by regulating the opening of the third solenoid valve 109 and the fourth solenoid valve 112, so as to realize low-temperature refrigeration of the system under mixed working fluid.

[0047] c. When -40℃≤T e_set<-10℃, the system is in a medium-temperature refrigeration demand state, the control module C1 receives the temperature signal, controls the first semiconductor refrigerator 104 to be powered off, the second semiconductor refrigerator 111 to be powered on, the first solenoid valve 105, the second solenoid valve 106 and the fourth solenoid valve 112 to be opened, the third solenoid valve 109 to be closed, the one-way valve 107 to be opened, the low-boiling-point working medium is liquefied and stored in the gas storage tank 108, and the low-boiling-point saturated gas in the liquid storage tank 110 is added to the gas storage tank 108 along the one-way valve 107, further realizing the effective separation of working mediums with different boiling points, the high-boiling-point saturated liquid enters the system from the liquid storage tank 110, the liquid storage tank 110 is cooled at the cold end of the second semiconductor refrigerator 111, and the liquid phase high-boiling-point liquid in the liquid storage tank 110 is further increased, realizing medium-temperature refrigeration of the system under a single high-boiling-point working medium;

[0048] d. When -10℃≤T e_set When the system is in a high-temperature refrigeration demand state, the control module C1 receives the temperature signal, controls the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 to be energized, the first solenoid valve 105 and the second solenoid valve 106 are in a fully open state, the one-way valve 107 is opened, the third solenoid valve 109 is closed, and the fourth solenoid valve 112 is opened. Only high-boiling-point working fluid runs in the system, and the first gas-liquid separator 103 and the liquid storage tank 110 gradually cool down the cold ends of the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 respectively, so as to further enrich the liquid component, and control the cold end temperature of the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 by increasing the current, but the maximum current is less than the current Imax of the first semiconductor refrigerator 104 and the second semiconductor refrigerator 111 under the maximum cooling capacity condition, thereby increasing the high-boiling-point component of the liquid phase of the system, which is conducive to achieving a higher evaporation temperature, thereby achieving the operation of as many high-boiling-point refrigerants as possible, and realizing high-temperature refrigeration of the system under a single high-boiling-point working fluid;

[0049] The control method described in ad combined with the control method described in ef below can achieve the goal of accurate temperature control system under a large temperature span.

[0050] e. When the outlet temperature of the evaporator 118 is k3>k2+10, the second temperature sensor T2 and the third temperature sensor T3 transmit the temperature signal to the control module C1 and the control module C1 controls the third semiconductor refrigerator 115 to be powered on. When the third semiconductor refrigerator 115 is powered on, the cooling fan 116 is operated to dissipate heat. The input current of the cooling fan 116 is controlled by the temperature feedback signal of the first temperature sensor T1. When k1>T m +15, the compressor suction temperature is too high, which is not conducive to the stable operation of the system. At this time, the control module C1 controls the cooling fan 116 to increase the current and increase the heat dissipation of the hot end of the third semiconductor refrigerator 115. When k1<T m+5, the cooling fan 116 is turned off, so that the air intake port of the compressor 101 maintains an overheat of 5℃-15℃, which can protect the compressor; when the temperature difference between the second temperature sensor T2 and the third temperature sensor T3 increases, the control module C1 controls the third semiconductor refrigerator 115 to increase the input current, but the maximum current is less than the current Imax1 of the third semiconductor refrigerator 115 under the maximum cooling capacity condition; within this current range, the greater the input current of the third semiconductor refrigerator 115, the more cooling capacity its cold end surface generates, so the two-phase system in the second gas-liquid separator 114 The more liquid phase there is in the refrigerant, the greater the refrigerant flow through the electronic expansion valve 117 and the evaporator 118, the greater the cooling capacity, and the lower the outlet temperature of the evaporator 118. When k3<k2+5, the control module C1 controls the third semiconductor refrigerator 115 to cut off the power; when the evaporation temperature adjustment requirement cannot be met by adjusting the third semiconductor refrigerator 115, the control module C1 controls the opening of the electronic expansion valve 117 to assist in adjusting the evaporator temperature, and the f1 opening range is 20%-80% of the full opening; the inlet temperature of the compressor 101 is detected by the first temperature sensor T1. When k1<T m +2, at this time, the refrigerant superheat at the suction port of the compressor 101 is too small to meet the operating requirements, the first temperature sensor T1 transmits the temperature signal to the control module C1, and the control module C1 controls the third semiconductor refrigerator 115 to increase the current, so that the refrigerant temperature at the inlet of the compressor 101 increases until k1>T m +5, so that the superheat of the compressor suction port is maintained at least 5°C. The superheat of the compressor suction port is controlled by the first semiconductor refrigerator 104, the second semiconductor refrigerator 111 and the third semiconductor refrigerator 115. The temperature of the hot end of the semiconductor refrigerator is controlled by controlling the current, thereby affecting the refrigerant temperature;

[0051] f. When the third semiconductor refrigerator 115 is not working, the pressure of the second gas-liquid separator 114 is a constant value P s When the third semiconductor refrigerator 115 is powered on, its cold end is close to the second gas-liquid separator 114 and absorbs the heat of the second gas-liquid separator 114, which will cause the pressure in the second gas-liquid separator 114 to decrease. <P s +0.1Mpa, the control module C1 controls the asynchronous motor 119 to adjust the position of the nozzle 130 of the injector 113, thereby realizing the pressure increase ratio adjustment, and further achieving the control of the outlet 1133 pressure of the injector 113; when the current of the third semiconductor refrigerator 115 increases, it absorbs more heat in the second gas-liquid separator 114, resulting in a decrease in the outlet pressure of the injector 113; at this time, the control module C1 controls the asynchronous motor 119 to make the nozzle 130 position close to the mixing chamber 132, reduce the secondary flow rate of the injector 113, increase the pressure increase ratio of the injector 113, and keep the outlet pressure of the injector 113 basically stable. When P1=P sWhen the asynchronous motor 119 stops working, the position of the nozzle 130 remains unchanged; on the contrary, when the current of the third semiconductor refrigerator 115 decreases, the asynchronous motor 119 is controlled by the control module C1 to move the nozzle 130 away from the mixing chamber 132. When the third semiconductor refrigerator 115 is not working, the nozzle 130 returns to the initial position to maintain the outlet pressure of the injector 113 stable.

Claims

1. A large temperature span precise hot and cold circulation system, characterized by: The invention comprises a first gas-liquid separator (103), the first gas-liquid separator (103) is closely attached to the cold end surface of the first semiconductor refrigerator (104), the hot end surface of the first semiconductor refrigerator (104) is connected in series with the hot end surface of the second semiconductor refrigerator (111) through a refrigerant pipeline, the cold end surface of the second semiconductor refrigerator (111) is closely attached to a liquid storage tank (110), and the liquid storage tank (110) is connected to a gas storage tank (108) through a one-way valve (107); the second gas-liquid separator (114) is closely attached to the cold end surface of the third semiconductor refrigerator (115), a heat dissipation fan (116) is installed on the hot end surface of the third semiconductor refrigerator (115) for heat dissipation, and the second gas-liquid separator (114) connects the two outlets of the ejector (113) to the outlet of the ejector (113) The refrigerant is separated into a gas phase and a liquid phase, wherein the gas phase refrigerant outlet of the second gas-liquid separator (114) is connected to the refrigerant pipelines of the hot end surface of the second semiconductor refrigerator (111), the hot end surface of the first semiconductor refrigerator (104), and the hot end surface of the third semiconductor refrigerator (115) in sequence through pipelines, the hot end refrigerant outlet of the third semiconductor refrigerator (115) is connected to the inlet of the compressor (101), the outlet of the compressor (101) is connected to the inlet of the condenser (102), and the outlet of the condenser (102) is connected to the inlet of the first gas-liquid separator (103); the liquid phase refrigerant outlet of the second gas-liquid separator (114) is connected to the inlet of the electronic expansion valve (117), and the outlet of the electronic expansion valve (117) is connected to the evaporator (118) is connected to the inlet of the evaporator (118), the outlet of the evaporator (118) is connected to the secondary flow inlet (1132) of the ejector (113), and is ejected as a secondary flow; the outlet pipeline of the evaporator (118) is connected to the condensing section heat exchanger (1212) of the heat pipe heat exchanger (121), and the evaporating section heat exchanger (1211) of the heat pipe heat exchanger (121) is connected to the gas storage tank (108), so that the cold energy at the outlet end of the evaporator (118) is transferred to the gas storage tank (108) through the heat pipe heat exchanger (121); the first gas-liquid separator (103) separates the mixed refrigerant with different boiling points at the outlet of the condenser (102) into a low boiling point refrigerant and a high boiling point refrigerant, wherein the low boiling point refrigerant flows into the gas storage tank through the first solenoid valve (105). (108), the outlet of the gas storage tank (108) is connected to the inlet of the third solenoid valve (109); the gas storage tank (108) is in close contact with the heat exchanger (1211) of the evaporation section of the heat pipe; the high boiling point refrigerant coming out of the first gas-liquid separator (103) flows into the liquid storage tank (110) through the second solenoid valve (106), the outlet of the liquid storage tank (110) is connected to the inlet of the fourth solenoid valve (112), the refrigerant mixed with the outlet of the fourth solenoid valve (112) and the outlet of the third solenoid valve (109) enters the primary flow inlet (1131) of the ejector (113) as a primary fluid, and is mixed with the refrigerant at the outlet of the evaporator (118) to become a two-phase refrigerant and enter the second gas-liquid separator (114) for gas-liquid separation;The first temperature sensor (T1) is arranged at the inlet of the compressor (101), the second temperature sensor (T2) and the third temperature sensor (T3) are arranged at the inlet and outlet of the evaporator (118) respectively, and the pressure sensor (P1) detects the pressure of the second gas-liquid separator (114); the control module (C1) is connected to the first semiconductor refrigerator (104), the second semiconductor refrigerator (111), the third semiconductor refrigerator (115), the first solenoid valve (105), the second solenoid valve (106), the third solenoid valve (109), the fourth solenoid valve (112), the one-way valve (107), the first temperature sensor (T1), the second temperature sensor (T2), the third temperature sensor (T3), the pressure sensor (P1), the cooling fan (116), the electronic expansion valve (117), and the asynchronous motor (119) connected to the nozzle (130).

2. A large temperature span precise hot and cold cycle system according to claim 1, characterized in that: The refrigerant used in the system is a ternary or quaternary or higher mixed refrigerant, which is composed of a high-boiling point refrigerant and a low-boiling point refrigerant, wherein the high-boiling point refrigerant is one or more of R290, R744, R134a, and R1234ze(E), and the low-boiling point refrigerant is one or more of R1150, R14, R170, and R23; the solenoid valve and semiconductor refrigerator are optimized and controlled to control the combination ratio of the high-boiling point refrigerant and the low-boiling point refrigerant, thereby achieving precise temperature control over a large temperature span under different combination modes and control methods.

3. A large temperature span precise hot and cold cycle system according to claim 1, characterized in that: The first gas-liquid separator (103) releases heat and cools down at the cold end of the first semiconductor refrigerator (104), and the content of high-boiling-point refrigerant in the liquid phase refrigerant in the first gas-liquid separator (103) increases, which is conducive to further regulating the content of high-boiling-point refrigerant in the liquid storage tank (110). Similarly, the high-boiling-point refrigerant in the liquid storage tank (110) releases heat and cools down at the cold end of the second semiconductor refrigerator (111), is further supercooled and liquefied, and the refrigerant temperature is reduced. At the same time, the content of high-boiling-point refrigerant in the liquid phase in the primary flow entering the ejector (113) is increased, thereby realizing the control of the mixed refrigerant component; the refrigerant in the second gas-liquid separator (114) releases heat and cools down at the cold end of the third semiconductor refrigerator (115), and the content of liquid phase refrigerant in the second gas-liquid separator (114) increases, thereby increasing the refrigerant flow in the evaporator (118) and increasing the cooling capacity of the circulation system.

4. A large temperature span precise hot and cold cycle system according to claim 1, characterized in that: The refrigerant at the gas phase outlet of the second gas-liquid separator (114) absorbs heat at the hot ends of the second semiconductor refrigerator (111) and the first semiconductor refrigerator (104) to become superheated vapor with a certain degree of superheat, and then is further superheated by the third semiconductor refrigerator (115) to accurately control the suction superheat.

5. The large temperature span precise hot and cold cycle system according to claim 1, characterized in that: The gas storage tank (108) and the liquid storage tank (110) are arranged separately and side by side to achieve separation and storage of low-boiling point and high-boiling point refrigerants, and combined with the switching and opening adjustment of the first solenoid valve (105), the second solenoid valve (106), the third solenoid valve (109), the fourth solenoid valve (112) and the one-way valve (107), precise control of the mixed refrigerant components from separation to reorganization is achieved.

6. A large temperature span precise hot and cold cycle system according to claim 1, characterized in that: The evaporation section heat exchanger (1211) of the heat pipe heat exchanger (121) is wrapped around the wall of the gas storage tank (108) through a pipeline and is in close contact with the gas storage tank (108). The condensation section heat exchanger (1212) is wrapped around the outlet pipeline of the evaporator (118) and is in close contact with the outlet pipeline of the evaporator (118). The cold energy at the outlet of the evaporator (118) is transferred to the vicinity of the gas storage tank (108). During this process, the internal medium of the heat pipe heat exchanger (121) exchanges heat with the cold source. The liquid working medium in the heat pipe heat exchanger (121) is cooled and condensed, changing from gas to liquid, and then returns to the hot end to evaporate through capillary action. The working medium in the heat pipe heat exchanger (121) evaporates at the hot end and absorbs heat around the gas storage tank (108).

7. The large temperature span precise hot and cold cycle system according to claim 1, characterized in that: The ejector (113) is an adjustable zoom type ejector, comprising a nozzle (130), a suction chamber (131), a mixing chamber (132) and a diffusion chamber (133) which cover the nozzle (130) and are arranged in sequence from front to back. The distance from the nozzle (130) to the entrance of the mixing chamber (132) in the ejector is automatically adjusted by an asynchronous motor (119) connected to the nozzle (130); the pressure of the outlet (1133) of the ejector (113) is between the pressure of the mixed refrigerant at the primary inlet (1131) entering the ejector (113) and the pressure of the refrigerant at the outlet of the evaporator (118); the mixed refrigerant is accelerated and depressurized in the nozzle (130) and then mixed with the refrigerant from the outlet of the evaporator (118) in the mixing chamber (132), and then decelerated and pressurized in the diffusion chamber (133) and then enters the second gas-liquid separator (114).

8. A control method for a large temperature span precise cooling and heating cycle system according to any one of claims 1 to 7, characterized in that: The first temperature sensor (T1) detects the refrigerant temperature at the inlet of the compressor (101), the second temperature sensor (T2) detects the refrigerant temperature at the inlet of the evaporator (118), the third temperature sensor (T3) detects the refrigerant temperature at the outlet of the evaporator (118), the pressure sensor (P1) detects the pressure of the second gas-liquid separator (114), the control module (C1) receives the temperature and pressure signals to control the start and stop of the asynchronous motor (119), the switch and input current of the first semiconductor refrigerator (104), the second semiconductor refrigerator (111), and the third semiconductor refrigerator (115), the opening of the electronic expansion valve (117), the input current of the cooling fan (116), the switch of the first solenoid valve (105), the second solenoid valve (106), the third solenoid valve (109), and the fourth solenoid valve (112) and their opening, and the switch of the check valve (107); The control method is: T c Indicates the condensation temperature, T e represents the evaporation temperature, T e_set represents the set temperature, P1 represents the pressure in the second gas-liquid separator (114) detected by the pressure sensor (P1), T m represents the saturation temperature corresponding to P1, k1 is the temperature value measured by the first temperature sensor (T1), k2 is the temperature value measured by the second temperature sensor (T2), k3 is the temperature value measured by the third temperature sensor (T3), f1 is the opening of the electronic expansion valve (117), and the initial opening is 50% of the full opening; a. When T e_set When the temperature is less than -70°C, the system is in an ultra-low temperature refrigeration demand state, the control module (C1) controls the first semiconductor refrigerator (104) to be powered off, the second semiconductor refrigerator (111) to be powered off, the first solenoid valve (105) to be fully open, the second solenoid valve (106) to gradually increase its opening, the one-way valve (107) to be opened, the third solenoid valve (109) to be fully open, and the fourth solenoid valve (112) to be closed. At this time, the mixed refrigerant in the first gas-liquid separator (103) undergoes component separation, and most of the saturated gas rich in low boiling points enters the gas storage tank. (108), a small portion of saturated liquid rich in low boiling points enters the liquid storage tank (110), and the low boiling point refrigerant gas is then supplemented to the gas storage tank (108) through the one-way valve (107), and the condensing section heat exchanger (1212) of the heat pipe heat exchanger (121) transfers the cold energy at the outlet of the evaporator (118) to the evaporating section heat exchanger (1211) around the gas storage tank (108), thereby reducing the temperature of the low boiling point working fluid in the gas storage tank (108), so that more of the low boiling point working fluid in the gas storage tank (108) becomes liquid, thereby realizing ultra-low temperature refrigeration of the system under the condition of a single low boiling point working fluid; b. When -70℃≤T e_set <-40°C, the system is in a low-temperature refrigeration demand state, the control module (C1) receives the temperature signal, controls the first semiconductor refrigerator (104) to be powered on, the second semiconductor refrigerator (111) to be powered on, the first solenoid valve (105) and the second solenoid valve (106) to be in a fully open state, the third solenoid valve (109) and the fourth solenoid valve (112) are initially in a closed state, the one-way valve (107) is opened, the low-boiling-point working fluid is stored and liquefied in the gas storage tank (108), and the high-boiling-point working fluid is stored in the liquid storage tank (110). After the system is stable, the third solenoid valve (109) and the fourth solenoid valve (112) are controlled to be opened and maintained at 50% opening. When T e_set >-55°C, the control module (C1) controls the fourth solenoid valve (112) to increase its opening, so that the high boiling point components in the mixed working fluid increase. e_set When the temperature is ≤-55°C, the third solenoid valve (109) is controlled to increase its opening, thereby increasing the component of the low-boiling-point working fluid in the mixed working fluid, and the mixed working fluid components are reorganized by controlling the third solenoid valve (109) and the fourth solenoid valve (112) to coordinate with each other, thereby controlling the temperature in a wider range and realizing low-temperature refrigeration of the system under the mixed working fluid; c. When -40℃≤T e_set When the temperature is less than -10°C, the system is in a medium-temperature refrigeration demand state. The control module (C1) receives the temperature signal, controls the first semiconductor refrigerator (104) to be powered off, the second semiconductor refrigerator (111) to be powered on, the first solenoid valve (105), the second solenoid valve (106) and the fourth solenoid valve (112) to be opened, the third solenoid valve (109) to be closed, the one-way valve (107) to be opened, the low-boiling-point working fluid is liquefied and stored in the gas storage tank (108), and the low-boiling-point saturated gas in the liquid storage tank (110) is supplemented to the gas storage tank (108) along the one-way valve (107), the high-boiling-point saturated liquid enters the system from the liquid storage tank (110), the liquid storage tank (110) is cooled at the cold end of the second semiconductor refrigerator (111), and the liquid phase high-boiling-point liquid in the liquid storage tank (110) is further increased, so that the system realizes medium-temperature refrigeration under a single high-boiling-point working fluid; d. When -10℃≤T e_set When the system is in a high-temperature refrigeration demand state, the control module (C1) receives the temperature signal, controls the first semiconductor refrigerator (104) and the second semiconductor refrigerator (111) to be energized, the first solenoid valve (105) and the second solenoid valve (106) to be in a fully open state, the one-way valve (107) to be opened, the third solenoid valve (109) to be closed, and the fourth solenoid valve (112) to be opened. Only high-boiling-point working fluids are operated in the system. The first gas-liquid separator (103) and the liquid storage tank (110) gradually cool down the cold ends of the first semiconductor refrigerator (104) and the second semiconductor refrigerator (111), respectively. The cold end temperatures of the first semiconductor refrigerator (104) and the second semiconductor refrigerator (111) are controlled by increasing the current, but the maximum current is less than the current Imax of the first semiconductor refrigerator (104) and the second semiconductor refrigerator (111) under the maximum refrigeration capacity condition, thereby increasing the high-boiling-point components in the liquid phase of the system. Through the control method described in ad, the goal of large temperature cross-system circulation is achieved; e. When the outlet temperature of the evaporator (118) is k3>k2+10, the second temperature sensor (T2) and the third temperature sensor (T3) transmit the temperature signal to the control module (C1) and the control module (C1) controls the third semiconductor refrigerator (115) to be powered on. When the third semiconductor refrigerator (115) is powered on, the cooling fan (116) is operated to dissipate heat. The input current of the cooling fan (116) is controlled by the temperature feedback signal of the first temperature sensor (T1). When k1>T m +15, the compressor suction temperature is too high. At this time, the control module (C1) controls the cooling fan (116) to increase the current, thereby increasing the heat dissipation at the hot end of the third semiconductor refrigerator (115). When k1<T m +5, the cooling fan (116) is turned off so that the superheat of the air intake of the compressor (101) is maintained at 5°C-15°C; when the temperature difference between the second temperature sensor (T2) and the third temperature sensor (T3) increases, the control module (C1) controls the third semiconductor refrigerator (115) to increase the input current, but the maximum current is less than the current Imax1 of the third semiconductor refrigerator (115) under the maximum cooling capacity condition; within this current range, the greater the input current of the third semiconductor refrigerator (115), the greater the cooling capacity generated by its cold end face, and therefore the greater the liquid phase in the two-phase refrigerant in the second gas-liquid separator (114), The greater the refrigerant flow rate through the electronic expansion valve (117) and the evaporator (118), the greater the refrigeration capacity, and the lower the outlet temperature of the evaporator (118). When k3 < k2 + 5, the control module (C1) controls the third semiconductor refrigerator (115) to cut off the power supply. When the evaporation temperature adjustment requirement cannot be met by adjusting the third semiconductor refrigerator (115), the control module (C1) controls the opening f1 of the electronic expansion valve (117) to assist in adjusting the evaporator temperature, and the opening range of f1 is 20%-80% of the full opening. The inlet temperature of the compressor (101) is detected by the first temperature sensor (T1). When k1 < T m +2, at which time the refrigerant superheat at the suction port of the compressor (101) does not meet the operating requirements, the first temperature sensor (T1) transmits the temperature signal to the control module (C1), and the control module (C1) controls the third semiconductor refrigerator (115) to increase the current, so that the refrigerant temperature at the inlet of the compressor (101) increases until k1>T m +5, so that the superheat of the compressor suction port is maintained at least 5°C, and the superheat of the compressor suction port is controlled by the first semiconductor refrigerator (104), the second semiconductor refrigerator (111) and the third semiconductor refrigerator (115); f. When the third semiconductor refrigerator (115) is not working, the pressure of the second gas-liquid separator (114) is a constant value P s When the third semiconductor refrigerator (115) is powered on, its cold end is in close contact with the second gas-liquid separator (114) and absorbs the heat of the second gas-liquid separator (114), which will cause the pressure in the second gas-liquid separator (114) to decrease. When P1 <P s +0.1Mpa, the control module (C1) controls the asynchronous motor (119) to adjust the position of the nozzle (130) of the injector (113); when the current of the third semiconductor refrigerator (115) increases, it absorbs more heat in the second gas-liquid separator (114), resulting in a decrease in the outlet pressure of the injector (113); at this time, the control module (C1) controls the asynchronous motor (119) to make the nozzle (130) close to the mixing chamber (132), reduce the secondary flow rate of the injector (113), increase the boost ratio of the injector (113), and keep the outlet pressure of the injector (113) stable. When P1=P s When the third semiconductor refrigerator (115) is turned off, the asynchronous motor (119) stops working and the position of the nozzle (130) remains unchanged; conversely, when the current of the third semiconductor refrigerator (115) decreases, the asynchronous motor (119) is controlled by the control module (C1) to move the nozzle (130) away from the mixing chamber (132); when the third semiconductor refrigerator (115) is not working, the nozzle (130) returns to the initial position; The control method described in ad combined with the control method described in ef can achieve the goal of precise temperature control under a large temperature span system.

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