Environmental test box and control method thereof

Abstract

The embodiment of the invention discloses an environmental test box and a control method thereof. The environmental test box comprises a controller, a working medium conveying branch, a working medium separation branch, a working medium condensation branch and an evaporation refrigeration branch, the controller is used for controlling the working medium conveying branch to convey a set mixed working medium to the working medium separation branch, and controlling the working medium separation branch to perform working medium separation treatment on the set mixed working medium at set pressure based on a received target temperature signal; the working medium condensation branch is used for condensing the treated set mixed working medium; and the evaporation refrigeration branch is used for carrying out evaporation refrigeration by utilizing the condensed set mixed working medium to realize the corresponding target temperature. The set mixed working media with different boiling points are used as refrigerants, the working medium separation branch is used for separating the set mixed working media at the set pressure based on the target temperature signal, and the technical problem that in the prior art, an environment test box only uses a single-stage compression system, and an ultralow-temperature environment cannot be achieved is solved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of temperature control technology, and in particular to an environmental test chamber and a control method thereof. Background Art

[0002] With the development of science and technology, the requirements for the performance and reliability of various automotive parts and consumer electronic products are getting higher and higher. A large number of environmental performance tests are required before they leave the factory. Therefore, the reliability, energy efficiency and cost requirements of high and low temperature constant temperature and humidity test chambers that can perform high and low temperature tests and wet and hot alternating tests are also getting higher and higher.

[0003] At present, the low temperature range of high and low temperature constant temperature and humidity test chambers on the market is mostly -30℃ to -70℃, which can be specifically divided into -30℃, -40℃, -50℃, -60℃ and -70℃. Among them, the test chambers at -30℃ and -40℃ are the most, but the applications of -50℃ and -60℃ are more, while the applications of -70℃ are relatively less. The test chambers at -30℃ mainly achieve low temperature through a single-stage compression system, while the applications below -40℃ belong to the ultra-low temperature range, which is mainly achieved through a cascade compression system.

[0004] The cascade system is mainly a dual-machine cascade system, that is, two compressors are used to work in the high temperature zone and the low temperature zone respectively to achieve the target temperature. Its advantage is that the system is relatively stable and has high reliability, but its disadvantage is that the system has more components, higher cost and lower energy efficiency. Summary of the invention

[0005] The embodiment of the present invention provides an environmental test chamber and a control method thereof, which solves the technical problem that the environmental test chamber in the prior art cannot achieve an ultra-low temperature environment by using only a single-stage compression system.

[0006] In a first aspect, an embodiment of the present invention provides an environmental test chamber, the environmental test chamber comprising a controller (100), a working fluid delivery branch (200), a working fluid separation branch (300), a working fluid condensation branch (400), and an evaporative cooling branch (500);

[0007] The controller (100) is electrically connected to the working fluid delivery branch (200) and the working fluid separation branch (300) respectively, and is used to control the working fluid delivery branch (200) to deliver a set mixed working fluid to the working fluid separation branch (300), and control the working fluid separation branch (300) to perform working fluid separation processing on the set mixed working fluid at a set pressure based on a received target temperature signal, wherein the set mixed working fluid comprises at least one refrigerant having a boiling point higher than a first boiling point value and one refrigerant having a boiling point lower than a second boiling point value, and the first boiling point value is higher than the second boiling point value;

[0008] The working medium condensation branch (400) is connected to the working medium separation branch (300) and is used to supercool the processed set mixed working medium;

[0009] The evaporative cooling branch (500) is connected to the working medium condensation branch (400) and is used to perform evaporative cooling using the set mixed working medium after supercooling to achieve a corresponding target temperature.

[0010] In a second aspect, an embodiment of the present invention further provides a control method for an environmental test chamber, which is applied to a controller of the environmental test chamber described in any embodiment of the first aspect, and the control method includes:

[0011] Obtaining a target temperature signal;

[0012] Based on the target temperature signal, the working medium delivery branch is controlled to deliver a set mixed working medium to the working medium separation branch, wherein the set mixed working medium includes at least one refrigerant with a boiling point higher than a first boiling point value and one refrigerant with a boiling point lower than a second boiling point value, and the first boiling point value is higher than the second boiling point value;

[0013] Based on the target temperature signal, the working fluid separation branch is controlled to perform working fluid separation processing on the set mixed working fluid at a set pressure;

[0014] Sending the set mixed working fluid after separation treatment into the working fluid condensation branch for supercooling;

[0015] The set mixed working fluid after supercooling is sent to the evaporative refrigeration branch for evaporative refrigeration to achieve the corresponding target temperature.

[0016] The embodiment of the present invention discloses an environmental test chamber and a control method thereof, including a controller, a working fluid delivery branch, a working fluid separation branch, a working fluid condensation branch, and an evaporative refrigeration branch; the controller is used to control the working fluid delivery branch to deliver a set mixed working fluid to the working fluid separation branch, and control the working fluid separation branch to perform working fluid separation processing on the set mixed working fluid at a set pressure based on the received target temperature signal, wherein the set mixed working fluid includes at least one refrigerant with a boiling point higher than a first boiling point value and a refrigerant with a boiling point lower than a second boiling point value; the working fluid condensation branch is used to supercool the processed set mixed working fluid; the evaporative refrigeration branch is used to perform evaporative refrigeration using the supercooled set mixed working fluid to achieve the corresponding target temperature. The present application solves the technical problem that the environmental test chamber in the prior art cannot achieve an ultra-low temperature environment by using only a single-stage compression system, and achieves the technical effect of using a simple single-stage compression system to achieve ultra-low temperature regulation, and has a simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of an environmental test chamber provided by an embodiment of the present invention;

[0018] Figure 2 is a structural diagram of an environmental test chamber provided by an embodiment of the present invention;

[0019] Figure 3 The present invention provides a flow chart of a method for controlling an environmental test chamber. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0021] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish different objects, rather than to limit a specific order. The following embodiments of the present invention can be implemented separately, or in combination with each other, and the embodiments of the present invention do not impose specific limitations on this.

[0022] Figure 1 It is a schematic diagram of an environmental test chamber provided in an embodiment of the present invention.

[0023] like Figure 1 As shown, the environmental test box includes a controller 100 , a working fluid delivery branch 200 , a working fluid separation branch 300 , a working fluid condensation branch 400 and an evaporative cooling branch 500 .

[0024] The controller 100 is electrically connected to the working fluid delivery branch 200 and the working fluid separation branch 300, respectively, and is used to control the working fluid delivery branch 200 to deliver a set mixed working fluid to the working fluid separation branch 300, and control the working fluid separation branch 300 to perform working fluid separation processing on the set mixed working fluid at a set pressure based on the received target temperature signal, wherein the set mixed working fluid includes at least one refrigerant with a boiling point higher than a first boiling point value and a refrigerant with a boiling point lower than a second boiling point value, and the first boiling point value is higher than the second boiling point value.

[0025] The working fluid condensation branch 400 is connected to the working fluid separation branch 300, and is used to supercool the processed set mixed working fluid; the evaporative cooling branch 500 is connected to the working fluid condensation branch 400, and is used to perform evaporative cooling using the supercooled set mixed working fluid to achieve the corresponding target temperature.

[0026] Among them, the mixed working fluid needs to include at least two refrigerants with different boiling points to meet the refrigeration needs of different low temperatures. Preferably, the first boiling point value is -50°C and the second boiling point value is -80°C. Then, the mixed working fluid needs to include at least one refrigerant with a boiling point higher than -50°C and one refrigerant with a boiling point lower than -80°C.

[0027] Preferably, the refrigerant with a boiling point higher than -50°C is selected as refrigerant R404A, and the refrigerant with a boiling point lower than -80°C is selected as refrigerant R23. As an ultra-low temperature refrigerant, R23 has a high pressure, so the proportion of R23 must be controlled within a certain range to enable the entire system to work normally within the range of -60°C on the evaporation side and 30°C on the condensation side. In the embodiment of the present invention, it is determined experimentally that the mass proportion of R23 does not exceed 30% of the total mass of the entire set mixed working fluid. In the embodiment of the present invention, the mixed working fluids are set as R404A and R23 as examples.

[0028] Obviously, when the mixed working fluid is set to include both R404A and R23, an ultra-low temperature refrigeration environment of at least -60°C can be achieved. When a low temperature refrigeration environment such as -30°C needs to be achieved, the working fluid separation branch 300 can be used to separate the set mixed working fluid at a set pressure, separate part or all of the refrigerant R23, and only use the refrigerant R404A to achieve a low temperature refrigeration environment.

[0029] Specifically, the controller 100 will receive a target temperature signal, which represents the refrigeration temperature that the environmental test chamber needs to achieve. When the controller 100 receives the target temperature signal, it controls the environmental test chamber to adjust the temperature. First, the compressor 1 in the working fluid delivery branch 200 is used to inhale the set mixed working fluid in gaseous state, and after preliminary condensation by the condenser 3 in the working fluid delivery branch 200, the set mixed working fluid in gas and liquid phases is delivered to the working fluid separation branch 300. The first regenerator 5 in the working fluid separation branch 300 will separate the set mixed working fluid under the control of the controller 100. The set pressure is determined based on the target temperature signal. If the target temperature to be adjusted is higher, the set pressure will increase, and the proportion of separated R23 will be higher. If the target temperature to be adjusted is lower, the set pressure will decrease, and the proportion of separated R23 will be lower. The specific set pressure will be obtained based on experimental measurements and stored in the controller 100 for use.

[0030] After determining the corresponding set pressure, the controller 100 controls the working fluid separation branch 300 to separate the set mixed working fluid. The set mixed working fluid obtained after processing is sent to the working fluid condensation branch 400 for supercooling to obtain a liquid set mixed working fluid. Finally, the liquid set mixed working fluid is sent to the evaporative refrigeration branch 500 for evaporative refrigeration to finally achieve the required target temperature.

[0031] The present application solves the technical problem that the environmental test chamber in the prior art cannot achieve an ultra-low temperature environment by using only a single-stage compression system by using a set mixed working fluid with different boiling points as a refrigerant, and uses a working fluid separation branch to separate the set mixed working fluid at a set partial pressure based on a target temperature signal. This achieves the technical effect of achieving ultra-low temperature regulation by using a simple single-stage compression system, and has a simple structure and low cost.

[0032] Figure 2 It is a structural diagram of an environmental test box provided in an embodiment of the present invention.

[0033] Alternatively, see Figure 2 The working fluid separation branch 300 includes a first regenerator 5, an expansion tank inlet solenoid valve 21, an expansion tank 23 and an expansion tank outlet solenoid valve 25; the first regenerator 5, the expansion tank inlet solenoid valve 21, the expansion tank 23 and the expansion tank outlet solenoid valve 25 are all electrically connected to the controller 100; the first regenerator 5 is a regenerator with three-in-one functions of vapor-liquid separation, liquid storage and heat recovery.

[0034] The first inlet a1 of the first reheater 5 is connected to the working fluid delivery branch 200, and the first outlet b1 of the first reheater 5 is connected to the working fluid condensation branch 400. The first reheater 5 is used to receive the set mixed working fluid transmitted by the working fluid delivery branch 200, and perform working fluid separation processing on the set mixed working fluid under the control of the controller 100, and send the liquid set mixed working fluid after separation processing into the working fluid condensation branch 400 for subcooling.

[0035] The inlet of the expansion tank 23 is connected to the second outlet b2 of the first regenerator 5 through the expansion tank inlet solenoid valve 21, and the outlet of the expansion tank 23 is connected to the working fluid condensation branch 400 through the expansion tank outlet solenoid valve 25; the expansion tank inlet solenoid valve 21 and the expansion tank outlet solenoid valve 25 are opened or closed under the control of the controller 100, so that the expansion tank 23 stores or releases the working fluid separated by the first regenerator 5.

[0036] Specifically, when the set mixed working fluid reaches the working fluid separation branch 300, it will first enter the first regenerator 5. The first regenerator 5 is a multifunctional regenerator with three functions of vapor-liquid separation, liquid storage and heat recovery. When all R23 is required to participate in refrigeration, the controller 100 controls the expansion tank inlet solenoid valve 21 to close, so that the set mixed working fluid cannot enter the expansion tank 23. All the set mixed working fluids are further condensed by the return air above in the first regenerator 5 and then directly sent to the working fluid condensation branch 400 for final condensation, and finally sent to the evaporative refrigeration branch 500 for refrigeration.

[0037] When part of R23 is needed to participate in refrigeration, or when R23 is not needed to participate in refrigeration, the controller 100 controls the expansion tank inlet solenoid valve 21 to open, and adjusts the pressure in the expansion tank 23 according to the target temperature to be regulated (i.e., adjusts the pressure in the tank to the above-mentioned set pressure), so that part of the R23 or all of the R23 in the set mixed working fluid enters the expansion tank 23 for storage, and then closes the expansion tank inlet solenoid valve 21 to complete the separation process of the set mixed working fluid, and the remaining set mixed working fluid in the first regenerator 5 is sent to the working fluid condensation branch 400 for condensation, and finally sent to the evaporative refrigeration branch 500 for refrigeration to achieve the target temperature. Among them, the corresponding relationship between the pressure in the expansion tank 23 and the target temperature is obtained according to experimental measurement, and is pre-stored in the controller 100 for standby use. Obviously, the corresponding relationship between the pressure in the tank and the target temperature is related to the component type, component setting ratio, etc. of the set mixed working fluid, which will not be repeated here.

[0038] Alternatively, if Figure 2 As shown, the working fluid separation branch 300 also includes an expansion tank pressure sensor 24; the controller 100 is electrically connected to the expansion tank pressure sensor 24

[0039] The controller 100 is further configured to control the internal pressure of the expansion tank 23 based on the target temperature signal, and monitor the internal pressure of the expansion tank 23 through the expansion tank pressure sensor 24 .

[0040] Specifically, an expansion tank pressure sensor 24 is further provided in the expansion tank 23 , and the controller 100 can monitor the pressure in the expansion tank 23 through the expansion tank pressure sensor 24 , so as to assist in regulating the set pressure.

[0041] Alternatively, see Figure 2 A one-way valve 22 is also provided between the expansion tank inlet solenoid valve 21 and the expansion tank 23 to prevent the separated set mixed working fluid from flowing back; a temperature sensor TT-5 for monitoring the temperature is also provided in the first regenerator 5.

[0042] Alternatively, see Figure 2 An air supply capillary 26 is also provided between the expansion tank outlet solenoid valve 25 and the working fluid condensation branch 400, which is used to compensate the working fluid in the working fluid condensation branch 400 with the gaseous working fluid stored in the expansion tank 23 under the control of the controller 100 according to the condensation needs, so as to improve the condensation effect of the working fluid condensation branch 400.

[0043] Alternatively, if Figure 2 As shown, the working medium delivery branch 200 includes a compressor 1 , an oil separator 2 and a condenser 3 .

[0044] The control end of the compressor 1 is electrically connected to the controller 100 , the outlet b4 of the compressor 1 is connected to the first inlet a1 of the first regenerator 5 through the oil separator 2 and the condenser 3 in sequence, and the first inlet a3 of the compressor 1 is connected to the third outlet b3 of the first regenerator 5 .

[0045] The compressor 1 is used to convert the set mixed working fluid whose suction pressure is lower than the first pressure value into the set mixed working fluid whose pressure is higher than the second pressure value under the control of the controller 100; the oil separator 2 is used to separate the lubricating oil in the set mixed working fluid; the condenser 3 is used to condense the set mixed working fluid and send the condensed set mixed working fluid to the first reheater 5.

[0046] Specifically, when the temperature of the environmental test chamber needs to be controlled, the controller 100 controls the gaseous lower-pressure set mixed working fluid to be sucked into the compressor 1, and is converted into a high-pressure set mixed working fluid and sent to the oil separator 2. After oil separation, in the condenser 3, all the R404A in the set mixed working fluid is condensed into a liquid state, and a very small amount of R23 is condensed into a liquid state. Therefore, the set mixed working fluid in a gas-liquid coexistence state is sent to the first regenerator 5 with a three-in-one function. In the first regenerator 5, the R23 gas will continue to be further condensed by the return air from above, and another part of it will become a liquid. At this time, R404A is in a liquid state, a part of R23 is in a liquid state, and a part of R23 is in a gas state. If there is no need to separate the R23 in the set mixed working fluid, the set mixed working fluid in a gas-liquid mixed state will be sent to the working fluid condensation branch 400.

[0047] Optionally, a condensation pressure sensor 4 is also provided between the condenser 3 and the first inlet a1 of the first reheater 5, for real-time monitoring of the condensation pressure at the condenser 3; a document sensor TT-1 for monitoring the compressor intake temperature is also provided at the first inlet a3 of the compressor 1; and a temperature sensor TT-2 for monitoring the compressor exhaust temperature is also provided at the outlet b4 of the compressor 1.

[0048] Alternatively, if Figure 2 As shown, the working medium condensation branch 400 includes a second regenerator 8 .

[0049] The first inlet a5 of the second heat regenerator 8 is connected to the first outlet b1 of the first heat regenerator 5; the first inlet a5 of the second heat regenerator 8 is directly connected to the first outlet b5 of the second heat regenerator 8; the second inlet a6 of the second heat regenerator 8 is directly connected to the second outlet b6 of the second heat regenerator 8.

[0050] The first outlet b5 of the second regenerator 8 is connected to the second inlet a6 of the second regenerator 8 through the evaporative refrigeration branch 500; the second inlet a6 of the second regenerator 8 is also connected to the expansion tank outlet solenoid valve 25; the second outlet b6 of the second regenerator 8 is connected to the second inlet a2 of the first regenerator 5.

[0051] The second regenerator 8 uses the working medium with a temperature lower than the first temperature value sent by the evaporative refrigeration branch 500 to subcool the set mixed working medium sent by the first regenerator 5 .

[0052] Specifically, since the set mixed working fluid sent to the second regenerator 8 in the working fluid condensation branch 400 may contain gaseous working fluid, in order to ensure the refrigeration effect, the set mixed working fluid needs to be further condensed in the second regenerator 8 so that it all becomes liquid, and there may even be a certain degree of supercooling, and then sent to the evaporative refrigeration branch 500 for final evaporative refrigeration.

[0053] Alternatively, if Figure 2 As shown, the working medium condensation branch 400 further includes a drying filter 6 and a sight glass 7 which are sequentially connected between the first outlet b1 of the first regenerator 5 and the first inlet a5 of the second regenerator 8 .

[0054] The drying filter 6 is used to dry the set mixed working medium discharged from the first outlet b1 of the first regenerator 5; the sight glass 7 is used to set the current status of the mixed working medium.

[0055] Specifically, since part of the set mixed working fluid coming out of the first outlet b1 of the first regenerator 5 is in liquid state and part is in gaseous state, a drying filter 6 is provided at the first outlet b1 of the first regenerator 5 where there may be a dry filter 6 for drying the entire set mixed working fluid, and a sight glass 7 is used to monitor the current status of the set mixed working fluid, and the dried set mixed working fluid is then sent to the second regenerator 8 for final condensation.

[0056] Alternatively, if Figure 2 As shown, the evaporative refrigeration branch 500 includes an evaporator 11 .

[0057] The inlet a7 of the evaporator 11 is connected to the first outlet b5 of the second regenerator 8, and the outlet b7 of the evaporator 11 is connected to the second inlet a6 of the second regenerator 8; the evaporator is used to perform evaporative cooling using the set mixed working fluid sent into the second regenerator 8 to achieve the target temperature.

[0058] Specifically, see Figure 2 A pulse width solenoid valve 9, an expansion valve 10 and a temperature sensor TT-3 for monitoring the temperature are also provided between the first outlet b5 of the second regenerator 8 and the inlet a7 of the evaporator 11. The pulse width solenoid valve 9 and the expansion valve 10 can be used to control the flow rate and flow velocity of the set mixed working medium entering the evaporator 11, so as to achieve precise temperature control. After the set liquid mixed working medium enters the evaporator 11, evaporative cooling is achieved to obtain the target temperature.

[0059] It should be noted that in the actual temperature control process, the liquid set mixed working fluid has a large temperature slip in the evaporator 11. Under the same evaporation pressure, the inlet a7 of the evaporator 11 may have a lower temperature. Therefore, the environmental test chamber can achieve a target temperature lower than the theoretical -60°C as a whole.

[0060] See also Figure 2 A temperature sensor TT-4 and an evaporation pressure regulating valve 13 are also provided between the outlet b7 of the evaporator 11 and the second outlet b6 of the second reheater 8, which are respectively used to realize the pressure monitoring and pressure regulation of the evaporator 11; an evaporator outlet solenoid valve 12 is also connected in parallel at both ends of the evaporation pressure regulating valve 13, which is used to control the flow of the set mixed working fluid at the outlet b7 of the evaporator 11.

[0061] Alternatively, if Figure 2 As shown, the environmental test chamber further includes a first liquid spraying branch 600 and a second liquid spraying branch 700 .

[0062] The first liquid injection branch 600 includes a liquid injection solenoid valve 31 and a liquid injection throttle valve 32; the liquid injection solenoid valve 31 and the liquid injection throttle valve 32 are sequentially connected between the sight glass 7 and the second inlet a4 of the compressor 1; the first liquid injection branch 600 is used to control the exhaust temperature of the compressor 1.

[0063] The second liquid injection branch 700 includes a two-way liquid injection solenoid valve 33 and a liquid injection expansion valve 34; the two-way liquid injection solenoid valve 33 and the liquid injection expansion valve 34 are sequentially connected between the sight glass 7 and the second outlet a2 of the first regenerator 5; the second liquid injection branch 700 is used to control the suction temperature of the compressor 1.

[0064] Specifically, see Figure 2 An exhaust temperature sensor 16 is also provided at the second inlet a4 of the compressor 1. According to the measurement of the exhaust temperature of the compressor 1 by the exhaust temperature sensor 16, the on-off of the injection solenoid valve 31 can be adjusted in real time to realize the use of the injection throttle valve 32 to send part of the set mixed working fluid into the compressor 1 to adjust the exhaust temperature, thereby ensuring the reliability of the system exhaust.

[0065] See also Figure 2 An intake temperature sensor 14 and an intake pressure sensor 15 are also provided at the first inlet a3 of the compressor 1. The intake temperature sensor 14 and the intake pressure sensor 15 are respectively used to monitor the intake temperature and the intake pressure at the first inlet a3 of the compressor 1 in real time. The intake temperature sensor 14 also includes a temperature bag 141. The feedback of the intake temperature of the intake temperature sensor 14 can control the on-off of the two-way liquid injection solenoid valve 33. The setting of the temperature bag 141 can realize the opening adjustment of the liquid injection expansion valve 34 to realize the regulation of the intake temperature.

[0066] Alternatively, if Figure 2 As shown, the environmental test chamber also includes a hot gas bypass solenoid valve 35 and a hot gas bypass regulating valve 36; the hot gas bypass solenoid valve 35 and the hot gas bypass regulating valve 36 are connected in sequence between the oil separator 2 and the first inlet a3 of the compressor 1; the hot gas bypass solenoid valve 35 and the hot gas bypass regulating valve 36 cooperate to control the amount of the set mixed working fluid discharged by the compressor 1.

[0067] The specific working principle of the environmental test chamber provided by the embodiment of the present invention is introduced below with reference to a specific embodiment.

[0068] Exemplarily, when the target temperature represented by the target temperature signal is -60°C, a set mixed working fluid in a gaseous state with a mass proportion of no more than 30% is sucked into the compressor 1 under the action of the controller 100, and a set mixed working fluid with a higher pressure gas comes out of the compressor 1. After passing through the oil separator 2, in the condenser 3, all the R404A in the set mixed working fluid is condensed into a liquid state, and only a very small amount of R23 is condensed into a liquid state. Therefore, the set mixed working fluid in a gas-liquid coexistence state enters the first regenerator 5 with a three-in-one function.

[0069] The first regenerator 5 is a customized pressure vessel that integrates the steam separation function of the set mixed working fluid, the liquid storage function and the heat recovery function for the refrigerant. It has liquid storage at the bottom, steam separation in the middle and heat recovery at the top.

[0070] At this time, since the target temperature is an ultra-low temperature of -60°C, all R23 needs to participate in the refrigeration cycle. The controller 100 controls the expansion tank inlet solenoid valve 21 on the side of the first regenerator 5 to be in a closed state, and R23 cannot enter the expansion tank 23. In the first regenerator 5, the R23 gas will continue to be further condensed by the return air from above, and another part of it will become liquid. The bottom of the first regenerator 5 is the working medium outlet (i.e., the first outlet b1). At this time, the state of the mixed working medium is set to be R404A in liquid state, and a part of R23 is gas. The whole passes through the first outlet b1, the drying filter 6 and the sight glass 7, and then reaches the second regenerator 8. In the second regenerator 8, the mixed working medium is set to be further condensed by the low-temperature working medium from the outlet b7 of the evaporator 11, and then all becomes liquid, and there is a certain degree of supercooling.

[0071] The set mixed working medium that becomes liquid in the second regenerator 8 passes through the pulse width solenoid valve 9 and the expansion valve 10 and enters the evaporator 11, finally realizing evaporative cooling to reach the target temperature.

[0072] In the evaporator 11, R23 evaporates first and becomes gas. Since the temperature inside and outside the evaporator 11 is very low, R404A does not evaporate completely. Therefore, there is still a certain amount of R404A liquid at the outlet b7 of the evaporator 11. At this time, the set mixed working fluid at the outlet b7 exchanges heat with the set mixed working fluid that has not been completely condensed in the second regenerator 8, so that the unevaporated R404A is basically completely evaporated. This is the first heat recovery, and then enters the first regenerator 5 for secondary heat recovery, and finally forms a gas set mixed working fluid with a certain superheat degree and enters the suction port of the compressor 1 (i.e., the first inlet a3), forming a cycle.

[0073] When the target temperature represented by the target temperature signal is -40°C, although the set mixed working fluid is used to achieve the target temperature of -40°C, the set mixed working fluid has an extremely high pressure, which will cause high power consumption of the compressor 1. Therefore, when the temperature is controlled at -40°C or above in the environmental test chamber, the R23 in the set mixed working fluid can be gradually separated, and only R404A can be retained to achieve the control of the target temperature with lower energy consumption.

[0074] Specifically, when the mixed working medium is set to leave the condenser 3 and enter the first regenerator 5, the R404A in the mixed working medium is set to be liquid, and a large amount of R23 is set to be gas. At this time, R23 needs to be separated, so the controller 100 controls the expansion tank inlet solenoid valve 21 to be turned on, and the gaseous R23 gradually enters the expansion tank 23 from the upper part of the first regenerator 5 under the action of the steam separation function of the first regenerator 5. The controller 100 controls the expansion tank outlet solenoid valve 25 to be closed to ensure that the R23 entering the expansion tank 23 can be stored therein. The volume of the expansion tank 23 is based on the total R23 in the mixed working medium, that is, when the volume of the expansion tank 23 is filled with all the gas R23, the pressure P2 in the tank is slightly less than the condensation pressure P1 measured by the condensation pressure sensor 4 at this time, so that all the R23 can enter the expansion tank 23.

[0075] After a certain cycle time, the pressure of the expansion tank 23 reaches the calibrated tank pressure P2, and the controller 100 controls the expansion tank inlet solenoid valve 21 to close. At this time, the first regenerator 5 is mainly R404A (there is also a trace amount of liquid R23 which can be ignored). Subsequently, the set mixed working fluid separated and processed in the first regenerator 5 is condensed and cooled through the second regenerator 8, evaporator 11, etc., to achieve the control of the target temperature of -40°C.

[0076] On the contrary, when there is only R404A in the first regenerator 5, but an ultra-low temperature of -60°C is required, the controller 100 will control the expansion tank outlet solenoid valve 21 to open. Since the pressure inside the expansion tank 23 is significantly higher than the suction pressure, the R23 in the expansion tank 23 will be gradually sucked into the first regenerator 5, so that the first regenerator 5 will be converted into a set mixed working fluid containing both R404A and R23 for subsequent refrigeration.

[0077] When it is necessary to achieve, for example, -50°C, the controller 100 can adjust the tank pressure of the expansion tank 23 (i.e., the above-mentioned set pressure). According to the size of the calibrated tank pressure of -50°C, when the expansion tank 23 is reduced or increased to the calibrated tank pressure, the expansion tank inlet and outlet solenoid valves 21 and 25 before and after the expansion tank 23 are closed to ensure that the R23 ratio therein is appropriate, that is, the above-mentioned regulation of the set pressure allows the first regenerator 5 to achieve the target temperature of -50°C with the most reasonable set pressure and maintain optimal energy consumption.

[0078] In the embodiment of the present invention, by changing the proportion of ultra-low temperature working fluid in the set mixed working fluid according to the target temperature, when the target temperature above -40°C is achieved, the ultra-low temperature working fluid in the set mixed working fluid can be reduced to almost 0, and when -40°C to -60°C is achieved, the proportion of ultra-low temperature working fluid in the set mixed working fluid can be adjusted according to the target temperature, so that the entire refrigeration system works within the most suitable pressure range, which can ensure the realization of the target temperature and the speed of achieving the target temperature, and can also make the energy consumption of the compressor relatively minimum. Therefore, from the overall point of view, the optimal design of reducing the cost in the system structure and reducing the energy consumption in operation is achieved.

[0079] At the same time, since the set mixed working fluid has a lower evaporator inlet temperature, it has certain advantages in cooling speed. When some situations require rapid cooling without paying much attention to energy consumption, such as rapid cooling to -40℃, a certain proportion of R23 can be added to meet the cooling speed of the system.

[0080] Therefore, on the whole, the refrigeration system with an adjustable ratio of set mixed working fluid can not only give full play to the advantages of the set mixed working fluid in achieving ultra-low temperature and cooling speed, making the method of achieving ultra-low temperature simpler and low cost, but also adjust the ratio of the mixed working fluid according to the required target temperature and cooling speed, thereby making the operation of the system more energy efficient and safer.

[0081] It should be noted that the lowest temperature of -60°C indicated in the embodiment of the present invention is only an example. In actual use, the proportion of the ultra-low temperature working fluid in the mixed working fluid can be increased according to the pressure range of the compressor (that is, it is not limited to the limitation of R23 not exceeding 30% by mass in the above embodiment of the present invention), so that the achievable target temperature can be further reduced to -70°C or even lower. It will not be repeated here.

[0082] Figure 3 The present invention provides a flow chart of a method for controlling an environmental test chamber.

[0083] The control method of the environmental test chamber is applied to the controller of the environmental test chamber in any of the above embodiments, such as Figure 3 As shown, the control method of the environmental test chamber specifically includes the following steps:

[0084] S101, obtaining a target temperature signal;

[0085] S102, based on the target temperature signal, controlling the working medium delivery branch to deliver a set mixed working medium to the working medium separation branch, wherein the set mixed working medium includes at least one refrigerant with a boiling point higher than a first boiling point value and one refrigerant with a boiling point lower than a second boiling point value, and the first boiling point value is higher than the second boiling point value;

[0086] S103, controlling the working fluid separation branch to perform working fluid separation processing on the set mixed working fluid at a set pressure based on the target temperature signal;

[0087] S104, sending the set mixed working fluid after separation into the working fluid condensation branch for subcooling;

[0088] S105, sending the supercooled set mixed working fluid into the evaporative refrigeration branch for evaporative refrigeration to achieve the corresponding target temperature.

[0089] The present application solves the technical problem that the environmental test chamber in the prior art cannot achieve an ultra-low temperature environment by using only a single-stage compression system by using a set mixed working fluid with different boiling points as a refrigerant, and uses a working fluid separation branch to separate the set mixed working fluid at a set pressure based on a target temperature signal. This achieves the technical effect of achieving ultra-low temperature regulation by using a simple single-stage compression system, and has a simple structure and low cost.

[0090] Optionally, S103, controlling the working fluid separation branch to perform working fluid separation processing on the set mixed working fluid at a set pressure based on the target temperature signal includes:

[0091] The set pressure of the expansion tank on the working fluid separation branch is determined based on the target temperature signal; the pressure inside the expansion tank is adjusted based on the determined set pressure; based on the target temperature signal, the first regenerator on the working fluid separation branch is controlled to separate the set mixed working fluid by opening or closing the expansion tank with the adjusted pressure inside the tank.

[0092] The control method of the environmental test chamber provided in the embodiment of the present invention is executed by the controller in the environmental test chamber in the above embodiment. Therefore, the control method of the environmental test chamber provided in the embodiment of the present invention also has the beneficial effects described in the above embodiment, which will not be described again here.

[0093] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0094] Finally, it should be noted that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An environmental test chamber, characterized in that: The environmental test box comprises a controller (100), a working fluid delivery branch (200), a working fluid separation branch (300), a working fluid condensation branch (400) and an evaporative cooling branch (500); The controller (100) is electrically connected to the working fluid delivery branch (200) and the working fluid separation branch (300) respectively, and is used to control the working fluid delivery branch (200) to deliver a set mixed working fluid to the working fluid separation branch (300), and control the working fluid separation branch (300) to perform working fluid separation processing on the set mixed working fluid at a set pressure based on a received target temperature signal, wherein the set mixed working fluid comprises at least one refrigerant having a boiling point higher than a first boiling point value and one refrigerant having a boiling point lower than a second boiling point value, and the first boiling point value is higher than the second boiling point value; The working medium condensation branch (400) is connected to the working medium separation branch (300) and is used to supercool the processed set mixed working medium; The evaporative cooling branch (500) is connected to the working medium condensation branch (400) and is used to perform evaporative cooling using the set mixed working medium after supercooling to achieve a corresponding target temperature.

2. The environmental test chamber according to claim 1, characterized in that: The working fluid separation branch (300) comprises a first regenerator (5), an expansion tank inlet solenoid valve (21), an expansion tank (23), and an expansion tank outlet solenoid valve (25); The first regenerator (5), the expansion tank inlet electromagnetic valve (21), the expansion tank (23) and the expansion tank outlet electromagnetic valve (25) are all electrically connected to the controller (100); the first regenerator (5) is a regenerator having three-in-one functions of vapor-liquid separation, liquid storage and heat recovery; The first inlet (a1) of the first heat regenerator (5) is connected to the working medium conveying branch (200), and the first outlet (b1) of the first heat regenerator (5) is connected to the working medium condensing branch (400). The first heat regenerator (5) is used to receive the set mixed working medium transmitted by the working medium conveying branch (200), and to perform working medium separation processing on the set mixed working medium under the control of the controller (100), and to send the set mixed working medium in liquid state after separation processing into the working medium condensing branch (400) for subcooling; The inlet of the expansion tank (23) is connected to the second outlet (b2) of the first regenerator (5) through the expansion tank inlet solenoid valve (21), and the outlet of the expansion tank (23) is connected to the working fluid condensation branch (400) through the expansion tank outlet solenoid valve (25); the expansion tank inlet solenoid valve (21) and the expansion tank outlet solenoid valve (25) are opened or closed under the control of the controller (100) so that the expansion tank (23) stores or releases the working fluid separated by the first regenerator (5).

3. The environmental test chamber according to claim 2, characterized in that: The working fluid separation branch (300) further includes an expansion tank pressure sensor (24); The controller (100) is electrically connected to the expansion tank pressure sensor (24); The controller (100) is also used to control the pressure inside the expansion tank (23) based on the target temperature signal, and to monitor the pressure inside the tank through the expansion tank pressure sensor (24).

4. The environmental test chamber according to claim 2, characterized in that: The working medium conveying branch (200) comprises a compressor (1), an oil separator (2) and a condenser (3); The control end of the compressor (1) is electrically connected to the controller (100); the outlet (b4) of the compressor (1) is connected to the first inlet (a1) of the first regenerator (5) in sequence through the oil separator (2) and the condenser (3); and the first inlet (a3) ​​of the compressor (1) is connected to the third outlet (b3) of the first regenerator (5); The compressor (1) is used to convert the set mixed working fluid having a suction pressure lower than a first pressure value into the set mixed working fluid having a pressure higher than a second pressure value under the control of the controller (100); The oil separator (2) is used to separate the lubricating oil in the set mixed working medium; The condenser (3) is used to condense the set mixed working fluid and send the condensed set mixed working fluid into the first regenerator (5).

5. The environmental test chamber according to claim 4, characterized in that: The working medium condensation branch (400) comprises a second regenerator (8); The first inlet (a5) of the second heat regenerator (8) is connected to the first outlet (b1) of the first heat regenerator (5); the first inlet (a5) of the second heat regenerator (8) is directly connected to the first outlet (b5) of the second heat regenerator (8); the second inlet (a6) of the second heat regenerator (8) is directly connected to the second outlet (b6) of the second heat regenerator (8); The first outlet (b5) of the second regenerator (8) is connected to the second inlet (a6) of the second regenerator (8) through the evaporative cooling branch (500); the second inlet (a6) of the second regenerator (8) is also connected to the expansion tank outlet solenoid valve (25); the second outlet (b6) of the second regenerator (8) is connected to the second inlet (a2) of the first regenerator (5); The second regenerator (8) uses the working fluid with a temperature lower than the first temperature value sent by the evaporative refrigeration branch (500) to subcool the set mixed working fluid sent by the first regenerator (5).

6. The environmental test chamber according to claim 5, characterized in that: The working medium condensation branch (400) further comprises a drying filter (6) and a sight glass (7) which are sequentially connected between the first outlet (b1) of the first heat regenerator (5) and the first inlet (a5) of the second heat regenerator (8); The drying filter (6) is used to dry the set mixed working medium discharged from the first outlet (b1) of the first regenerator (5); The sight glass (7) is used to set the current status of the mixed working medium.

7. The environmental test chamber according to claim 5, characterized in that: The evaporative refrigeration branch (500) comprises an evaporator (11); The inlet (a7) of the evaporator (11) is connected to the first outlet (b5) of the second regenerator (8), and the outlet (b7) of the evaporator (11) is connected to the second inlet (a6) of the second regenerator (8); The evaporator is used to utilize the set mixed working fluid sent by the second regenerator (8) to perform evaporative cooling to achieve the target temperature.

8. The environmental test chamber according to claim 6, characterized in that: The environmental test chamber further comprises a first liquid spraying branch (600) and a second liquid spraying branch (700); The first liquid injection branch (600) comprises a liquid injection solenoid valve (31) and a liquid injection throttle valve (32); the liquid injection solenoid valve (31) and the liquid injection throttle valve (32) are connected in sequence between the sight glass (7) and the second inlet (a4) of the compressor (1); The first liquid injection branch (600) is used to control the exhaust temperature of the compressor (1); The second liquid spraying branch (700) comprises a two-way liquid spraying electromagnetic valve (33) and a liquid spraying expansion valve (34); the two-way liquid spraying electromagnetic valve (33) and the liquid spraying expansion valve (34) are connected in sequence between the sight glass (7) and the second outlet (a2) of the first regenerator (5); The second liquid injection branch (700) is used to control the suction temperature of the compressor (1).

9. The environmental test chamber according to claim 4, characterized in that: The environmental test box further comprises a hot gas bypass solenoid valve (35) and a hot gas bypass regulating valve (36); The hot gas bypass solenoid valve (35) and the hot gas bypass regulating valve (36) are connected in sequence between the oil separator (2) and the first inlet (a3) ​​of the compressor (1); The hot gas bypass solenoid valve (35) and the hot gas bypass regulating valve (36) cooperate to control the amount of the set mixed working fluid discharged by the compressor (1).

10. The environmental test chamber according to claim 1, characterized in that: The first boiling point value is -50°C, and the second boiling point value is -80°C.

11. A method for controlling an environmental test chamber, characterized in that: The controller applied to the environmental test chamber according to any one of claims 1 to 10, wherein the control method comprises: Obtaining a target temperature signal; Based on the target temperature signal, the working medium delivery branch is controlled to deliver a set mixed working medium to the working medium separation branch, wherein the set mixed working medium includes at least one refrigerant with a boiling point higher than a first boiling point value and one refrigerant with a boiling point lower than a second boiling point value, and the first boiling point value is higher than the second boiling point value; Based on the target temperature signal, the working fluid separation branch is controlled to perform working fluid separation processing on the set mixed working fluid at a set pressure; Sending the set mixed working fluid after separation treatment into the working fluid condensation branch for supercooling; The set mixed working fluid after supercooling is sent to the evaporative refrigeration branch for evaporative refrigeration to achieve the corresponding target temperature.

12. The control method of the environmental test chamber according to claim 11, characterized in that: Controlling the working medium separation branch to perform working medium separation processing on the set mixed working medium at a set pressure based on the target temperature signal includes: Determining a set pressure of an expansion tank on the working fluid separation branch based on the target temperature signal; adjusting the pressure in the expansion tank based on the determined set pressure; Based on the target temperature signal, the expansion tank whose internal pressure is adjusted is opened or closed to control the first regenerator on the working medium separation branch to separate the set mixed working medium.

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