Device and method for realizing multi-stage temperature control cooling

Abstract

The present invention belongs to the field of refrigeration technology, and specifically relates to a device and method for realizing multi-stage temperature control refrigeration. The device includes a regenerator, the regenerator is connected to an external three-stage evaporator, the refrigerant gas enters the regenerator from the external three-stage evaporator, the regenerator is connected to the condensing evaporator through an ethylene compressor, the condensing evaporator is connected to a propylene low-pressure compressor through a combiner 1, the propylene low-pressure compressor is connected to a propylene high-pressure compressor through a combiner 2, the propylene high-pressure compressor is connected to a liquid reservoir through a condenser, the liquid reservoir is connected to a throttle valve through a diverter 1, the throttle valve is connected to a combiner 2 through an economizer, the economizer is connected to a regulating valve through a diverter 2, and the regulating valve is connected to the condensing evaporator; a self-made nanofluid material is added to the device. A method for realizing multi-stage temperature control refrigeration, using the above-mentioned device, can realize three refrigeration temperatures. The present invention realizes multi-stage temperature control, reduces equipment, saves costs, and improves efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of refrigeration, and in particular relates to a device and a method for realizing multi-stage temperature-controlled refrigeration. Background Art

[0002] In recent years, with the continuous development of industry, refrigeration systems have been widely used in various industries. In some complex industrial production systems, there are demands for various refrigeration temperature ranges, which requires the simultaneous configuration of several different refrigeration units to correspond to the required refrigeration temperatures.

[0003] Each refrigeration unit requires an independent control and auxiliary system, which results in a large number of devices being put into use, complicated operation, large floor space and high cost for the overall project. Summary of the invention

[0004] The present invention aims at the deficiencies of the prior art and provides a device and a method for realizing multi-stage temperature controlled refrigeration.

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

[0006] In a first aspect, the present invention provides a device for realizing multi-stage temperature control refrigeration, comprising a regenerator, the regenerator is connected to an external three-stage evaporator, the refrigerant gas enters the regenerator from the external three-stage evaporator, the regenerator is also connected to a condenser evaporator through an ethylene compressor, the condenser evaporator is connected to a propylene low-pressure compressor through a combiner 1, the propylene low-pressure compressor is connected to a propylene high-pressure compressor through a combiner 2, the propylene high-pressure compressor is connected to a liquid reservoir through a condenser, the liquid reservoir is connected to a throttle valve through a diverter 1, the throttle valve is connected to a combiner 2 through an economizer, the economizer is also connected to a regulating valve through a diverter 2, and the regulating valve is connected to the condenser evaporator;

[0007] Nanofluid material is added to the regenerator and / or the condenser evaporator. The preparation method of the nanofluid material includes the following steps: making liquid metal indium tin alloy into liquid metal, mixing titanium carbide particles with SiO2 solution, adding APTES to obtain modified titanium carbide particles; mixing silicon nitride particles with PVA solution to obtain modified silicon nitride particles; adding modified titanium carbide particles and modified silicon nitride particles into liquid metal, dispersing, and applying electric field and magnetic field after dispersion to obtain nanofluid material.

[0008] It should be noted that, in the device of the present invention, homemade nanofluid materials can be added to the regenerator and / or the condenser evaporator. The reasons for the optimization of the present invention are: 1. During low-temperature evaporation and high-temperature condensation, the heat transfer performance of the fluid will be limited, especially when the heat exchange faces a large temperature difference, the use of nanofluids can accelerate the heat exchange. 2. When the operating temperature of the device is high or the condensation load is large, the addition of nanofluid materials can effectively increase the condensation rate to avoid insufficient condensation or the temperature cannot drop quickly. 3. If it is necessary to further increase the heat exchange speed of the present invention, it is also necessary to consider how to maintain the temperature stability of rapid heat exchange. The addition of nanofluid materials can accelerate the heat transfer process and improve the response speed of the overall system of the device. For example: when the system load changes or rapid cooling is required, the nanofluid can accelerate the transfer of heat in a shorter time by increasing the thermal conductivity, so that the refrigeration system can respond to temperature changes or cooling needs more quickly.

[0009] Preferably, the condenser evaporator is also connected to a regenerator, which discharges the refrigerant liquid after heat exchange into an external third-stage evaporator; the liquid storage device is also connected to an economizer, which is also connected to an external second-stage evaporator, and the economizer discharges the refrigerant liquid after heat exchange into an external second-stage evaporator.

[0010] Preferably, the diverter 1 is also connected to an external primary evaporator, and the diverter 1 discharges the refrigerant liquid after heat exchange into the external primary evaporator; the combiner 1 is also connected to an external secondary evaporator, and the external secondary evaporator discharges the refrigerant gas into the combiner 1.

[0011] Preferably, the second combiner is also connected to an external primary evaporator, and the external primary evaporator discharges the refrigerant gas into the second combiner.

[0012] Preferably, the particle size of the titanium carbide particles is 5-20 nm, the particle size of the silicon nitride particles is 15-50 nm, and the concentration of the SiO2 solution is 0.1 mol / L-1 mol / L.

[0013] Preferably, the magnetic field strength is 100 Gs-500 Gs; the electric field strength is 1 kV / cm-3 kV / cm.

[0014] In a second aspect, the present invention provides a method for realizing multi-stage temperature control refrigeration, wherein the method adopts the device for realizing multi-stage temperature control refrigeration, and the refrigerant gas includes propylene gas evaporated from an external first-stage evaporator, propylene gas evaporated from an external second-stage evaporator, and ethylene gas evaporated from an external third-stage evaporator;

[0015] The propylene gas evaporated from the external first-stage evaporator enters the second combiner.

[0016] The propylene gas evaporated from the external secondary evaporator enters the combiner 1, and is mixed with the propylene gas evaporated in the condenser evaporator in the combiner 1. After mixing, the gas enters the propylene low-pressure compressor for compression, and is compressed into medium-pressure and high-temperature propylene gas;

[0017] The medium-pressure and high-temperature propylene gas enters the second combiner; the propylene gas evaporated from the economizer also enters the second combiner; in the second combiner, the medium-pressure and high-temperature propylene gas is mixed with the propylene gas evaporated from the first evaporator and the propylene gas evaporated from the economizer, and the mixed gas enters the propylene high-pressure compressor and is compressed into high-temperature and high-pressure propylene gas;

[0018] The high-temperature and high-pressure propylene gas enters the condenser to be condensed into high-pressure propylene liquid, and then enters the liquid storage tank; the propylene liquid coming out of the liquid storage tank is divided into two paths, one path enters the economizer to become supercooled propylene liquid; the other path enters the splitter 1, and the splitter 1 discharges a part of the propylene liquid as refrigerant liquid into the external first-stage evaporator to achieve the first-stage refrigeration temperature;

[0019] The supercooled propylene liquid is also divided into two paths. One path enters the condenser evaporator after throttling and reducing the pressure through the regulating valve; the other path is discharged into the external secondary evaporator as refrigerant liquid to achieve the second-stage refrigeration temperature.

[0020] Preferably, the ethylene gas evaporated from the external three-stage evaporator enters the regenerator for heat exchange and temperature increase, and then enters the ethylene compressor for compression to obtain compressed high-temperature and high-pressure ethylene gas. The compressed high-temperature and high-pressure ethylene gas enters the condensing evaporator for heat exchange and condensation, and then enters the regenerator to increase the degree of supercooling to obtain supercooled ethylene liquid. The supercooled ethylene liquid is discharged into the external three-stage evaporator as a refrigerant liquid to achieve the refrigeration temperature of the third stage.

[0021] Preferably, the refrigeration temperature of the first stage can be set to 5°C ~ -5°C, and the refrigeration temperature of the second stage can be set to -45°C ~ -35°C.

[0022] Preferably, the refrigeration temperature of the third stage can be set to -90°C ~ -70°C.

[0023] Preferably, self-made nanofluid material can also be added into the regenerator and / or the condenser evaporator.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Multi-stage temperature control: The device of the present invention is actually divided into two systems, namely, a high-temperature refrigeration system and a low-temperature refrigeration system. The high-temperature refrigeration system is a propylene refrigeration system, and the refrigerant is propylene. The main components of the high-temperature refrigeration system are a propylene low-pressure compressor, a propylene high-pressure compressor, a condenser, a liquid storage tank, an economizer, a throttle valve, and a regulating valve. The low-temperature refrigeration system is an ethylene refrigeration system, and the refrigerant is ethylene. The main components of the low-temperature refrigeration system are an ethylene compressor, a condenser evaporator, and a regenerator.

[0026] The high temperature refrigeration system and the low temperature refrigeration system cooperate with each other to achieve three refrigeration temperatures, specifically the first stage refrigeration temperature, the second stage refrigeration temperature, and the third stage refrigeration temperature. The device of the present invention does not need to be configured with three sets of units at the same time, which saves investment costs and floor space, and improves the working efficiency of the unit. In addition, the device of the present invention is also very flexible, and the three refrigeration temperatures can also be achieved independently. The use of any one-stage refrigeration temperature does not affect the refrigeration temperature of the other two stages.

[0027] 2. The refrigerants used are propylene and ethylene, which are environmentally friendly refrigerants and will not cause environmental pollution or greenhouse effect.

[0028] 3. The present invention is further optimized by adding nanofluid materials to the device of the present invention, specifically, self-made nanofluid materials can be added to the regenerator and / or the condenser evaporator. Nanofluid is nanoparticles dispersed in the heat exchange medium to make a new heat exchange medium or heat transfer fluid. In the prior art, commonly used nanomaterial particles include copper, gold, and graphene nanoparticles. Traditional fluids, such as water, oil, etc., have low thermal conductivity, so their efficiency in heat exchange and cooling systems is limited. Although some enhanced fluids (such as fluids with added metal particles) have improved thermal conductivity to a certain extent, there is still a problem of insufficient heat transfer efficiency. Moreover, some fluid materials may decompose, corrode or precipitate particles during long-term use, affecting the heat exchange efficiency. In response to these problems, the present invention makes and improves existing nanofluids, modifies nanoparticles, improves the dispersibility and stability of particles in the base liquid, and constructs nanofluid materials with ordered structures.

[0029] It should be noted that the construction method and related mechanisms of the ordered structure are described in more detail in the examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 It is a schematic diagram of the device of the present invention.

[0032] The markings in the figure are: 1. Propylene low-pressure compressor; 2. Propylene high-pressure compressor; 3. Condenser; 4. Liquid receiver; 5. Throttle valve; 6. Economizer; 7. Condenser evaporator; 8. Ethylene compressor; 9. Regenerator; 10 Control valve; 11. Combiner 1; 12. Combiner 2; 13. Diverter 1; 14. Diverter 2. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] The experimental methods used below are conventional methods unless otherwise specified. The parts, equipment, materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified. The principles or mechanisms of the parts or equipment that can be purchased through commercial channels are well known, and the common names are given in the following, so they are not described in detail. Among them, the first combiner 11 and the second combiner 12 are both combiners, which can be combined valves, and the first divider 13 and the second divider 14 are both dividers, which can be divided valves.

[0035] Example 1

[0036] Reference Figure 1 , a device for realizing multi-stage temperature control cooling, including a regenerator 9, an external three-stage evaporator is pipeline-connected to the regenerator 9, the regenerator 9 is pipeline-connected to the ethylene compressor 8, the ethylene compressor 8 is pipeline-connected to the condensing evaporator 7, the condensing evaporator 7 is pipeline-connected to the combiner 11, the combiner 11 is pipeline-connected to the propylene low-pressure compressor 1, the propylene low-pressure compressor 1 is pipeline-connected to the combiner 2 12, the combiner 2 12 is pipeline-connected to the propylene high-pressure compressor 2, the propylene high-pressure compressor 2 is pipeline-connected to the condenser 3, the condenser 3 is pipeline-connected to the liquid storage 4, the liquid storage 4 is pipeline-connected to the diverter 13, the diverter 13 is pipeline-connected to the throttle valve 5, the throttle valve 5 is pipeline-connected to the economizer 6, and the economizer 6 is pipeline-connected to the combiner 2 12.

[0037] The flow divider 13 is connected to the external primary evaporator by pipeline. The liquid storage device 4 is connected to the economizer 6 by pipeline, the economizer 6 is connected to the flow divider 2 14 by pipeline, the flow divider 2 14 is connected to the regulating valve 10 by pipeline, the regulating valve 10 is connected to the condensing evaporator 7 by pipeline; the flow divider 2 14 is connected to the external secondary evaporator by pipeline.

[0038] It should be noted that the system of the present invention is actually divided into two systems, namely a high temperature refrigeration system and a low temperature refrigeration system. The high temperature refrigeration system is a propylene refrigeration system, and the low temperature refrigeration system is an ethylene refrigeration system.

[0039] The main components of the high-temperature refrigeration system are propylene low-pressure compressor 1, propylene high-pressure compressor 2, condenser 3, liquid storage tank 4, economizer 6, throttle valve 5, and regulating valve 10. The main components of the low-temperature refrigeration system are ethylene compressor 8, condenser evaporator 7, and regenerator 9. The connection relationship of these main components has been explained above. The purpose of dividing them into two systems is to better explain the role of this system. The role of each component is reflected by explaining the specific working process of this system.

[0040] Working process:

[0041] The refrigerant gas includes propylene gas evaporated from an external primary evaporator, propylene gas evaporated from an external secondary evaporator, and ethylene gas evaporated from an external tertiary evaporator.

[0042] The propylene gas evaporated from the external first-stage evaporator enters the second combiner 12.

[0043] The propylene gas evaporated from the external secondary evaporator enters the combiner 11, and is mixed with the propylene gas evaporated in the condenser evaporator 7 in the combiner 11. After mixing, the gas enters the propylene low-pressure compressor 1 for compression and is compressed into medium-pressure and high-temperature propylene gas. The medium-pressure and high-temperature propylene gas enters the combiner 2 12 from the propylene low-pressure compressor 1.

[0044] At the same time, the propylene gas evaporated from the economizer 6 enters the second combiner 12. Therefore, in the second combiner 12, the medium-pressure and high-temperature propylene gas is mixed with the propylene gas evaporated from the first-stage evaporator and the propylene gas evaporated from the economizer 6, and the mixed gas enters the propylene high-pressure compressor 2 and is compressed into high-temperature and high-pressure propylene gas.

[0045] High-temperature and high-pressure propylene gas enters the condenser 3 from the propylene high-pressure compressor 2, and after the gas is condensed into high-pressure propylene liquid, it enters the liquid storage tank 4. The propylene liquid coming out of the liquid storage tank 4 is divided into two paths. (1) One path enters the splitter 13, and the splitter 13 distributes a part of the propylene liquid to the external first-stage evaporator, that is, provides refrigerant liquid to the first-stage evaporator to achieve the first-stage refrigeration temperature.

[0046] The remaining part of the propylene liquid in the splitter 13 enters the economizer 6 after being throttled and depressurized by the throttle valve 5, evaporates into gas, and then enters the propylene high-pressure compressor 2 through the combiner 2 12. (2) Another way enters one side of the economizer 6, absorbs the cold energy on the other side of the economizer 6, and becomes supercooled propylene liquid.

[0047] The supercooled propylene liquid is divided into two paths, one of which is throttled and depressurized by the second splitter 14 and the regulating valve 10 and then enters the condenser evaporator 7. The other liquid is supplied to the external secondary evaporator through the second splitter 14, that is, the refrigerant liquid is provided to the secondary evaporator to achieve the second-stage refrigeration temperature.

[0048] The ethylene gas evaporated from the external three-stage evaporator enters the regenerator 9, and after the temperature is increased to the minimum allowable operating temperature of the ethylene compressor 8, it enters the ethylene compressor 8 for compression. The compressed high-temperature and high-pressure ethylene gas enters the condenser evaporator 7, and exchanges heat with the low-temperature propylene liquid on the other side of the condenser evaporator 7 in the condenser evaporator 7. After condensing the high-temperature and high-pressure ethylene liquid, it enters the regenerator 9 to increase the degree of supercooling and obtain the supercooled ethylene liquid. At the same time, the low-temperature propylene liquid evaporates into gas. It should be noted that the gas evaporated from the low-temperature propylene liquid can be passed into the propylene high-pressure compressor 2, and an additional pipeline can be connected between the propylene high-pressure compressor 2 and the regenerator 9 to facilitate the passage of gas.

[0049] The supercooled ethylene liquid is discharged from the regenerator 9 and supplied to the external three-stage evaporator, that is, the refrigerant liquid is supplied to the three-stage evaporator to achieve the third-stage refrigeration temperature.

[0050] It should be noted that the gas and liquid in the device of the present invention are routed through different pipelines to prevent the mixing of gas and liquid from affecting the working effect of the device. It should also be noted that the equipment and parts used in the device of the present invention can meet the flow of gas and / or liquid, such as: condenser 3, economizer 6, condenser evaporator 7, regenerator 9, these devices have a liquid side and a gas side, which can also be understood as the presence of liquid pipelines and gas pipelines. The basic principles or mechanisms of these devices are well known and can be clearly understood by those skilled in the art, so they are not elaborated.

[0051] Example 2

[0052] In this embodiment, the specific refrigeration temperature in Example 1 is given:

[0053] The first stage refrigeration temperature can be set to 5℃ to -5℃, the second stage refrigeration temperature can be set to -45℃ to -35℃, and the third stage refrigeration temperature can be set to -90℃ to -70℃. It should be noted that if necessary, any stage of evaporation temperature can be used according to the on-site usage.

[0054] The present invention is further optimized by adding nanofluid materials into the system of the present invention. Nanofluid is a new heat exchange medium or heat transfer fluid made by dispersing nanoparticles into a heat exchange medium. In the prior art, commonly used nanomaterial particles include copper, gold, and graphene nanoparticles. The present invention makes and improves existing nanofluids to obtain new nanofluid materials.

[0055] In the device of the present invention, self-made nanofluid material can be added into the regenerator 9 and / or the condenser evaporator 7 .

[0056] The reasons for such optimization of the present invention are: 1. During low-temperature evaporation and high-temperature condensation, the heat transfer performance of the fluid will be limited, especially when the heat exchange faces a large temperature difference, the use of nanofluids can accelerate the heat exchange.

[0057] 2. When the operating temperature of the device is high or the condensation load is large, the addition of nanofluid materials can effectively increase the condensation rate to avoid insufficient condensation or the temperature cannot drop quickly. 3. If it is necessary to further improve the heat exchange speed of the present invention, it is also necessary to consider how to maintain the temperature stability of rapid heat exchange. The addition of nanofluid materials can accelerate the heat transfer process and improve the response speed of the overall system of the device. For example, when the system load changes or rapid cooling is required, the nanofluid can accelerate the transfer of heat in a shorter time by increasing the thermal conductivity, so that the refrigeration system can respond to temperature changes or cooling needs more quickly.

[0058] Example 3

[0059] The preparation method of nanofluid material, the specific steps are as follows:

[0060] Prepare the base liquid: Mix 900g of liquid metal indium tin alloy and 100g of deionized water to obtain 90% liquid metal.

[0061] 10 g of 10 nm titanium carbide particles were mixed with 0.5 mol / L SiO2 solution, stirred for 60 minutes, and then 0.2 g of APTES (3-aminopropyltriethoxysilane) was added, and stirring was continued for 30 minutes to obtain modified titanium carbide particles.

[0062] 10 g of 20 nm silicon nitride particles were mixed with 3 g of 5% PVA (polyvinyl alcohol) solution, stirred for 90 minutes, and then the excess PVA was washed and removed to obtain modified silicon nitride particles.

[0063] 10 g of modified titanium carbide particles and 10 g of modified silicon nitride particles were added to 1000 g of liquid metal, and dispersed using an ultrasonic disperser with an ultrasonic power of 800 W, a frequency of 30 kHz, and a dispersion time of 90 minutes to obtain a dispersed liquid.

[0064] A 2 kV / cm electric field and a 300 Gs magnetic field were applied to the dispersed liquid for 15 minutes to induce the particles to self-assemble into an ordered structure to obtain a nanofluid material.

[0065] in,

[0066] Liquid metal indium tin alloy: 10% In, 90% Sn, available from Goodfellow.

[0067] Titanium carbide particles and silicon nitride particles can be purchased from Nanoshel.

[0068] PVA, SiO2 solution, and 3-aminopropyltriethoxysilane can all be purchased from Sigma-Aldrich.

[0069] Unless otherwise specified or limited by manufacturer model, the purity of raw materials is selected as 99%.

[0070] It should be noted that conventional titanium carbide is easy to agglomerate. The surface of titanium carbide is modified by using silicon dioxide. Silicon dioxide is introduced into the surface of titanium carbide particles, which is similar to covering the surface of titanium carbide with a layer of silicon dioxide coating. The layered structure and high surface area of ​​silicon dioxide can effectively prevent the agglomeration of titanium carbide particles in the liquid, while avoiding direct contact between particles, thereby maintaining stable dispersion of the particles.

[0071] PVA is used to modify the surface of silicon nitride. PVA molecules can cover the surface of silicon nitride particles to form a protective film, which can reduce the mutual attraction and adhesion between particles and effectively prevent particles from aggregating in liquid metal. At the same time, the hydrophilicity of PVA can also increase the hydrophilicity of silicon nitride particles and improve their dispersibility in aqueous solutions.

[0072] The nanoparticles are further induced to form an ordered structure through the combined induction of external electric and magnetic fields. The electric field is used to induce the symmetrical arrangement of the particles, and the magnetic field is used to cause the titanium carbide and silicon nitride particles to align along the magnetic lines, thereby enhancing the synergistic effect of the particles and forming a new highly ordered structure.

[0073] Dispersing the modified titanium carbide particles and silicon nitride particles into liquid metal can effectively improve the thermal conductivity of the liquid metal. Liquid metal indium tin alloy has good thermal conductivity as a heat transfer medium. After adding nanoparticles, the thermal conductivity of the particles is further optimized through the nanoscale thermal conduction effect. In particular, the modified particles can be evenly distributed and arranged in an orderly manner, which makes heat transfer more efficient.

[0074] Comparative Example 1

[0075] The preparation method of nanofluid material, the specific steps are as follows:

[0076] Prepare the base liquid: Mix 900g of liquid metal indium tin alloy and 100g of deionized water to obtain 90% liquid metal.

[0077] 10 g of 10 nm titanium carbide particles and 10 g of 20 nm silicon nitride particles were added to 1000 g of liquid metal and dispersed using an ultrasonic disperser with an ultrasonic power of 800 W, a frequency of 30 kHz, and a dispersion time of 90 minutes to obtain a dispersed liquid.

[0078] A 2 kV / cm electric field and a 300 Gs magnetic field were applied to the dispersed liquid for 15 minutes to induce the particles to self-assemble into an ordered structure to obtain a nanofluid material.

[0079] Wherein, the raw materials refer to Example 3.

[0080] Comparative Example 2

[0081] The preparation method of nanofluid material, the specific steps are as follows:

[0082] Prepare the base liquid: Mix 900g of ethylene glycol and 100g of deionized water to obtain a 90% base liquid.

[0083] 20 g of 20 nm aluminum oxide particles were added to 1000 g of the base liquid and dispersed using an ultrasonic disperser with an ultrasonic power of 800 W, a frequency of 30 kHz, and a dispersion time of 90 minutes to obtain a nanofluid material.

[0084] Alumina particles can be purchased from Nanoshel.

[0085] Test: Two refrigerants (propylene solution and ethylene solution) are added to a clean container, and then the nanofluid material (Example 3 or Comparative Example 1 or Comparative Example 2) is slowly added thereto. The nanofluid material is uniformly dispersed in the refrigerant using an ultrasonic disperser for 30-60 minutes to obtain a sample. The mass ratio of the refrigerant to the nanofluid material is 100:1, and the milliliters of the samples are the same.

[0086] Then put the sample into a centrifuge tube, put the centrifuge tube into a centrifuge, and set different centrifugal forces (2000g-4000g) and time for centrifugation.

[0087] After centrifugation, observe whether there is obvious particle precipitation, stratification or aggregation in the sample. If there is no obvious precipitation or stratification in the sample, it means that the nanofluid has good dispersion and high stability; if precipitation or stratification occurs, it means that the fluid has poor stability.

[0088] Experimental results: See Table 1 for the results.

[0089] Table 1

[0090]

[0091] Analysis: From the experimental results, it can be seen that Example 3 exhibits the best dispersibility and stability under the set centrifugal conditions, especially under the high centrifugal force of 4000g, it still remains clear and transparent without any precipitation. In contrast, under the condition of lower centrifugal force, the particle aggregation tendency of Comparative Example 1 appears, indicating that its stability is slightly inferior to that of Example 3. The nanofluid material of Comparative Example 2 exhibits poor stability and easily forms precipitation, indicating that its dispersibility is not as good as that of Example 3.

[0092] Comparative experiments and tests show that the nanofluid material prepared by the present invention has good dispersibility and stability, and good compatibility with refrigerants.

[0093] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A device for realizing multi-stage temperature controlled cooling, characterized in that: It includes a regenerator, the regenerator is connected to an external three-stage evaporator, the refrigerant gas enters the regenerator from the external three-stage evaporator, the regenerator is connected to the condenser evaporator through the ethylene compressor, the condenser evaporator is connected to the propylene low-pressure compressor through the combiner 1, the propylene low-pressure compressor is connected to the propylene high-pressure compressor through the combiner 2, the propylene high-pressure compressor is connected to the liquid receiver through the condenser, the liquid receiver is connected to the throttle valve through the diverter 1, the throttle valve is connected to the combiner 2 through the economizer, the economizer is connected to the regulating valve through the diverter 2, and the regulating valve is connected to the condenser evaporator; The splitter 1 is connected to the external primary evaporator, and the splitter 1 discharges the refrigerant liquid after heat exchange into the external primary evaporator; the combiner 1 is connected to the external secondary evaporator, and the external secondary evaporator discharges the refrigerant gas into the combiner 1; The second combiner is connected to an external primary evaporator, and the external primary evaporator discharges the refrigerant gas into the second combiner; Nanofluid material is added to the regenerator and / or condenser evaporator as a heat exchange medium or heat transfer fluid. The preparation method of the nanofluid material includes the following steps: making liquid metal indium tin alloy into liquid metal, mixing titanium carbide particles with SiO2 solution, adding APTES to obtain modified titanium carbide particles; mixing silicon nitride particles with PVA solution to obtain modified silicon nitride particles; adding modified titanium carbide particles and modified silicon nitride particles into liquid metal, dispersing, and applying electric field and magnetic field after dispersion to obtain nanofluid material.

2. The device for realizing multi-stage temperature control cooling according to claim 1, characterized in that: The condenser evaporator is connected to the regenerator, and the regenerator discharges the refrigerant liquid after heat exchange into the external third-stage evaporator; the liquid storage device is connected to the economizer, and the economizer is connected to the external second-stage evaporator, and the economizer discharges the refrigerant liquid after heat exchange into the external second-stage evaporator.

3. The device for realizing multi-stage temperature control cooling according to claim 1, characterized in that: The particle size of the titanium carbide particles is 5-20 nm, the particle size of the silicon nitride particles is 15-50 nm, and the concentration of the SiO2 solution is 0.1 mol / L-1 mol / L.

4. The device for realizing multi-stage temperature control cooling according to claim 1, characterized in that: The magnetic field strength is 100Gs-500Gs; the electric field strength is 1 kV / cm-3 kV / cm.

5. A method for realizing multi-stage temperature controlled cooling, the method adopting the device for realizing multi-stage temperature controlled cooling according to any one of claims 1 to 4, characterized in that: The refrigerant gas includes propylene gas evaporated from an external primary evaporator, propylene gas evaporated from an external secondary evaporator, and ethylene gas evaporated from an external tertiary evaporator; The propylene gas evaporated from the external first-stage evaporator enters the second combiner. The propylene gas evaporated from the external secondary evaporator enters the combiner 1, and is mixed with the propylene gas evaporated in the condenser evaporator in the combiner 1. After mixing, the gas enters the propylene low-pressure compressor for compression, and is compressed into medium-pressure and high-temperature propylene gas; The medium-pressure and high-temperature propylene gas enters the second combiner; the propylene gas evaporated from the economizer also enters the second combiner; in the second combiner, the medium-pressure and high-temperature propylene gas is mixed with the propylene gas evaporated from the first evaporator and the propylene gas evaporated from the economizer, and the mixed gas enters the propylene high-pressure compressor and is compressed into high-temperature and high-pressure propylene gas; The high-temperature and high-pressure propylene gas enters the condenser to be condensed into high-pressure propylene liquid, and then enters the liquid storage tank; the propylene liquid coming out of the liquid storage tank is divided into two paths, one path enters the economizer to become supercooled propylene liquid; the other path enters the splitter 1, and the splitter 1 discharges a part of the propylene liquid as refrigerant liquid into the external first-stage evaporator to achieve the first-stage refrigeration temperature; The supercooled propylene liquid is also divided into two paths. One path enters the condenser evaporator after throttling and reducing the pressure through the regulating valve; the other path is discharged into the external secondary evaporator as refrigerant liquid to achieve the second-stage refrigeration temperature.

6. The method for realizing multi-stage temperature control cooling according to claim 5, characterized in that: The ethylene gas evaporated from the external three-stage evaporator enters the regenerator for heat exchange and temperature increase, and then enters the ethylene compressor for compression to obtain compressed high-temperature and high-pressure ethylene gas. The compressed high-temperature and high-pressure ethylene gas enters the condensing evaporator for heat exchange and condensation, and then enters the regenerator to increase the supercooling degree to obtain supercooled ethylene liquid. The supercooled ethylene liquid is discharged into the external three-stage evaporator as a refrigerant liquid to achieve the third-stage refrigeration temperature.

7. The method for realizing multi-stage temperature control cooling according to claim 5, characterized in that: The first stage cooling temperature is set to 5℃~ -5℃, and the second stage cooling temperature is set to -45℃~ -35℃.

8. The method for realizing multi-stage temperature controlled cooling according to claim 6, characterized in that: The third stage cooling temperature is set to -90℃~ -70℃.

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