A cryogenic gas generating device and a method of controlling the temperature of a cryogenic gas and the characteristics of bubbles formed by the gas

Abstract

The application discloses a low-temperature gas generating device and a low-temperature gas temperature and bubble characteristic control method, and belongs to the technical field of low-temperature gas generating devices. The low-temperature gas generating device comprises a gas supply device, a gas cooling device, a gas heat preservation device, a water tank, a measuring device, a gas temperature control module and a bubble control module. The gas cooling device comprises a cooler and a heat exchange pipe. The gas heat preservation device comprises a cooling interlayer and a nozzle. The heat exchange pipe is arranged in the cooler and is communicated with the cooling interlayer. The cooler is internally provided with a cooling medium. The gas flowing through the heat exchange pipe is cooled by the cooling medium and low-temperature gas is obtained. The low-temperature gas in the cooling interlayer is cooled and preserved by the cooling medium. The low-temperature gas is sprayed out through the nozzle and forms bubbles in the water tank. The gas temperature control module is used for controlling the temperature of the low-temperature gas. The bubble control module is used for controlling the size of the bubbles. The gas cooling device is arranged to cool the gas, and the cooled gas is preserved by the gas heat preservation device, so that the low-temperature state of the gas in the pipeline is further maintained, and the lowest gas phase temperature at the nozzle outlet can be maintained at -196 DEG C.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of submerged injection two-phase flow experiment, and relates to a low-temperature gas generating device and a control method for low-temperature gas temperature and bubble characteristics formed by the gas. BACKGROUND

[0002] The submerged injection smelting technology has been widely applied in the fields of traditional smelting of metals such as lead, zinc, antimony and copper, and recycling of solid wastes such as waste lead-acid batteries, waste electronic circuit boards, non-ferrous smelting slag and industrial sludge. In recent years, domestic and foreign scholars have carried out a large number of experimental studies on the gas-liquid two-phase flow process based on water solution experimental devices. However, the boiling point of water under normal pressure is low, and the highest gas-liquid temperature difference formed by the experimental device is only about 50℃ without affecting the observation of bubbles. The boiling point of water can be increased by pressurization, but the high pressure condition affects the bubble generation and migration process.

[0003] Meanwhile, the gas-liquid temperature difference designed by the above experimental system is the difference between the gas temperature at the nozzle inlet and the liquid temperature, and the heat transfer process of the gas in the nozzle and the inner wall of the nozzle and the backflow liquid is not considered. The heat exchange between the gas in the nozzle and the inner wall surface leads to a significant increase in the temperature of the gas along the flow direction, and the actual gas-liquid temperature difference at the nozzle outlet is less than the designed value. The smaller gas-liquid temperature difference leads to that the influence of the bubble density change on the bubble generation, detachment and migration process is not significant. Especially under small flow conditions, the bubble waiting time is long, and the heat exchange between the gas and the inner wall of the nozzle and the backflow liquid leads to that the bubble is heated to a high temperature state at the generation moment.

[0004] The existing experimental device cannot avoid the convection heat transfer process of the gas in the nozzle, and the bubble is heated to a high temperature state at the generation moment, which leads to that the experimental research on the influence of the change of the gas phase density on the bubble generation, detachment, migration process and liquid phase flow characteristics cannot be carried out. In addition, the water solution experimental system usually shoots the image of the bubble generated at the nozzle outlet by a high-speed camera to obtain the bubble diameter, aspect ratio, migration trajectory and liquid phase flow field information and other characteristics. The existing experimental equipment cannot control the size of the bubble, and cannot consistently control the size of the bubble in multiple experiments, which easily affects the quality of the image shot by the high-speed camera and affects the judgment of the characteristics. SUMMARY

[0005] The application is provided to overcome at least one deficiency of the prior art, and provides a low-temperature gas generating device and a control method for low-temperature gas temperature and bubble characteristics formed by the gas.

[0006] In order to achieve the above object, the application adopts the following technical scheme: a low-temperature gas generating device, a gas supply device, a gas cooling device, a gas heat preservation device, a water tank, a measuring device, a gas temperature control module and a bubble control module, the gas cooling device comprises a cooler and a heat exchange pipe, the gas heat preservation device comprises a cooling interlayer and a nozzle, the heat exchange pipe is arranged in the cooler, the heat exchange pipe is communicated with the cooling interlayer, the cooler is internally provided with a cooling medium, the gas flowing through the heat exchange pipe is cooled by the cooling medium to obtain low-temperature gas, the low-temperature gas in the cooling interlayer is cooled and preserved by the cooling medium, the preserved low-temperature gas is sprayed from the nozzle and forms bubbles in the water tank, the gas temperature control module is used for controlling the temperature of the low-temperature gas, and the bubble control module is used for controlling the size of the bubbles.

[0007] Further, the gas supply device comprises a nitrogen tank, a pressure reducing valve and a flow controller which are connected in sequence, the nitrogen tank is connected with the pressure reducing valve, the pressure reducing valve is connected with the flow controller, the flow controller is connected with the heat exchange pipe, one end of the heat exchange pipe is connected with the cooler, the other end of the heat exchange pipe is connected with the cooling interlayer, the cooling interlayer is connected with the nozzle, and the nozzle is arranged in the water tank.

[0008] Further, the top of the cooler is provided with a heat preservation cover, the cooler is provided with a double-layer steel plate structure, and the double-layer steel plates are vacuumized. The cooler is externally coated with heat preservation material.

[0009] Further, the heat exchange pipe is installed at the bottom of the cooler; the material of the heat exchange pipe is high-thermal-conductivity material, the outside of the heat exchange pipe is the cooling medium, the inside of the heat exchange pipe is the cooled gas, and the gas exchanges heat with the cooling medium through the wall surface of the heat exchange pipe.

[0010] Further, the cooling interlayer is connected with the heat exchange pipe and the water tank, the cooler is arranged adjacent to the water tank, the cooling interlayer is provided with a double-layer pipe structure and comprises a first pipe, a second pipe and a circular ring piece, the first pipe and the second pipe are coaxially arranged inside and outside, a cooling gap is arranged between the inner pipe wall of the first pipe and the outer pipe wall of the second pipe, the side wall of the cooler is provided with an outlet end, the heat exchange pipe is located inside the outlet end, and a gap is arranged between the heat exchange pipe and the outlet end; one end of the first pipe is fixedly connected with the outlet end, the other end of the first pipe is fixedly connected with the water tank, the second pipe is fixedly connected with the outlet end of the heat exchange pipe, and the other end of the second pipe is fixedly connected with the nozzle; the gap and the cooling gap are communicated, the cooling gap of the first pipe and the second pipe close to the water tank is sealingly connected through the circular ring piece, the cooling medium flows into the cooling gap through the gap, and the cooled gas flows out from the heat exchange pipe and then enters the second pipe of the cooling interlayer.

[0011] Further, the measuring device comprises a high-speed camera and a computer, the image acquisition end of the high-speed camera faces the water tank to collect the bubble image sprayed from the nozzle, the high-speed camera is communicatively connected with the computer, the high-speed camera transmits the collected bubble image to the computer, and the computer measures the gas-liquid two-phase flow characteristics through the bubble image.

[0012] A control method of low-temperature gas temperature and bubble characteristics formed by the gas, which controls the low-temperature gas temperature generated by the low-temperature gas generation device and the bubble size formed by the gas, and specifically comprises the following steps:

[0013] Step S1: calculating the heat exchange area of the heat exchange pipe, and obtaining the target length of the heat exchange pipe according to the heat exchange area;

[0014] Step S2: establishing a bubble detachment volume calculation model, and calculating the bubble size according to the model;

[0015] The bubble detachment volume calculation model is:

[0016]

[0017] In formula (1), We m is a dimensionless modified We number; is a dimensionless bubble diameter, V b is the bubble volume, with the unit of m 3 , which is a parameter to be solved; V0 is the initial volume of the bubble detachment stage, with the unit of m 3 ; and is calculated by the following formula:

[0018]

[0019] In formula (2), ρ g and ρ l are the densities of gas and liquid phases respectively, with the unit of kg / m 3 , which are known values; g is the acceleration of gravity; the coefficient C1=1, σ is the surface tension coefficient, with the unit of mN / m, which is a known value; d0 is the nozzle diameter, with the unit of m, which is a set value; u0 is the gas flow rate at the nozzle, with the unit of m / s, which is a known value; A0 is the nozzle cross-sectional area, with the unit of m 2 , which is a set value, and V0 is calculated according to the above formula;

[0020] The modified We number We m is calculated by the following formula:

[0021]

[0022] In formula (3), ρ g and ρ l are the densities of gas and liquid phases respectively, with the unit of kg / m 3 , which are known values;

[0023] u0 is the gas flow rate at the nozzle, with the unit of m / s, which is a known value; A0 is the nozzle cross-sectional area, with the unit of m 2, which is the set value; σ surface tension coefficient, unit is mN / m, which is a known value; d0 is the nozzle diameter, unit is m, which is the set value; coefficient C1 = 1, coefficient C2 = 0.5; According to the above, We m ;

[0024] We m , V0 is substituted into formula (1) to obtain V b ;

[0025] Step S3: End step.

[0026] Furthermore, the specific steps of calculating the heat exchange area of ​​the heat exchange tube in step S1 are:

[0027] Step S11: The outer wall temperature of the heat exchange tube is obtained through the heat exchange process between the cooling medium and the outer wall of the heat exchange tube.

[0028] Degree T t,o ;

[0029] Regarding the heat exchange process between the cooling medium and the outer wall of the heat exchange tube, the heat exchange tube is immersed in the cooling medium. It is assumed that the outer wall temperature of the heat exchange tube is T t,o Consistent with the cooling medium temperature, when the cooling medium is selected, the outer wall temperature T t,o is a known value;

[0030] Step S12: Establish the heat transfer Q of the outer wall of the heat exchange tube during the heat transfer process from the outside to the inside t The heat transfer equation 1;

[0031] Step S13: Establishing the convective heat transfer quantity Q during the convective heat transfer process between the inner wall of the heat exchange tube and the cooled gas c The heat transfer equation 2:

[0032] Step S14: Establish the heat absorption Q of the cooled gas per second g The heat transfer equation 3;

[0033] Step S15: Establish Q t , Q c , Q g Constraints;

[0034] Step S16: Calculate the heat absorption Q of the cooled gas according to the heat transfer equation 3 g ;

[0035] Step S17: Calculate the heat transfer Q of the outer wall of the heat exchange tube from outside to inside according to the constraint conditions. t ;

[0036] Step S18: Initialize the temperature range of the inner wall of the heat exchange tube [T low , T high ], where T is taken in the first iterationlow T is the temperature of the cooling medium high T is the temperature after being cooled

[0037] Step S19, the midpoint T of the temperature interval is taken as the current heat exchange tube inner wall temperature m As the current heat exchange tube inner wall temperature, the heat exchange area A of the current cycle is obtained according to the heat transfer equation 1;

[0038] In this step, the inner diameter and the outer diameter of the heat exchange tube are set values;

[0039] Step S20, the heat exchange area A of the current cycle and the inner wall temperature T m are brought into the heat transfer equation 2 to obtain the convective heat transfer quantity Q c between the heat exchange tube inner wall and the cooled gas

[0040] Step S21, whether the difference between Q c and Q g is less than a set value is compared, if yes, T m is the heat exchange tube inner wall temperature, the cycle is ended, the heat exchange area A at the required temperature is obtained, and step S23 is entered; if not, step S22 is entered;

[0041] Step S22, if Q c > Q g , it indicates that the heat exchange tube inner wall temperature is too high, the lower limit T low of the temperature interval of step S18 is close to the inner wall temperature, T m is replaced by T high , the temperature interval [T low , T m ] is taken as the current heat exchange tube inner wall temperature interval, and the cycle is continued by returning to step S18; if Q c < Q g , it indicates that the inner wall temperature is too low, the upper limit of the temperature interval of step S18 is close to the inner wall temperature, T m is replaced by T low , the temperature interval [T m , T high ] is taken as the current heat exchange tube inner wall temperature interval, and the cycle is continued by returning to step S18;

[0042] Step S23, the target length of the heat exchange tube under the condition of the target temperature of the low-temperature gas and the set inner diameter and outer diameter of the heat exchange tube is obtained according to the heat exchange area A.

[0043] Further, the heat transfer equation 1 is specifically:

[0044]

[0045] In the formula, Q tQ is the heat transfer quantity of the heat exchange pipe, unit is W, which is the parameter to be solved; λ t is the heat transfer coefficient of the heat exchange pipe, which is related to the average temperature of the heat exchange pipe, the average temperature is the arithmetic average of the inner wall temperature and the outer wall temperature of the heat exchange pipe, unit is W / (m·K), which is unknown value, when the inner wall temperature of the heat exchange pipe is known, then λ t is known value; l t is the length of the heat exchange pipe, unit is m, which is the parameter to be solved; T t,i is the inner wall temperature of the heat exchange pipe, unit is ℃, which is the parameter to be solved; T t,o is the outer wall temperature of the heat exchange pipe, unit is ℃; r t,o is the outer diameter of the heat exchange pipe, unit is m; r t,i is the inner diameter of the heat exchange pipe, unit is m;

[0046] The heat transfer equation 2 is specifically:

[0047] Q c = hA△T m

[0048] In the formula, Q c is the convective heat transfer quantity between the inner wall of the heat exchange pipe and the cooled gas, unit is W, which is the parameter to be solved; A is the heat exchange area of the heat exchange pipe, A = 2 × π × r t,i × l t , unit is m 2 , which is the parameter to be solved; ΔT m is the logarithmic mean temperature difference between the cooled gas and the inner wall of the heat exchange pipe, unit is ℃, which is calculated by the following formula:

[0049]

[0050] In the formula, T g,i is the temperature of the gas before being cooled, unit is ℃, which is known value; T t,i is the inner wall temperature of the heat exchange pipe, unit is ℃, which is the parameter to be solved; T g,o is the temperature of the gas after being cooled, unit is ℃, which is the set value;

[0051] h is the convective heat transfer coefficient in the pipe, unit is W / (m 2 ·K), which is calculated by the following formula:

[0052]

[0053] In the formula, λ g is the heat transfer coefficient of the cooled gas, which is related to the type of the cooled gas, the temperature before the gas is cooled, the temperature after the gas is cooled, unit is W / (m·K), which is known value; r t,im is the inner diameter of the heat exchange pipe, Nu is the Nusselt number, and is calculated by the following formula;

[0054]

[0055] Re f is the Reynolds number, and the calculation formula is Re f = ur t,i / v, u is the gas velocity, in m / s, which is a set value; r t,i is the inner diameter of the heat exchange pipe, in m; v is the gas viscosity, in m 2 / s, which is a known value; Pr f is the gas Prandtl number, which is obtained by consulting a gas property parameter table, and h is a known value; the heat transfer equation 3 is specifically as follows:

[0056] Q g = mc△T g

[0057] Q g is the heat absorption amount of the cooled gas per second, in W, which is a to-be-solved parameter; m is the mass of the cooled gas, in kg, which is a known value; c is the specific heat of the gas, in J / (kg·K), which is a known value; ΔT g is the temperature difference before and after the gas is cooled, ΔT g =T g,i -T g,o , in ℃, which is a known value.

[0058] Further, the constraint condition is Q t = Q c = Q g .

[0059] In summary, the present application has the advantages that:

[0060] The gas cooling device is arranged to cool the gas, and the gas heat preservation device is arranged to heat preserve the cooled gas, so that the low-temperature state of the gas in the pipeline is further maintained, the minimum gas phase temperature at the nozzle outlet can be maintained at -196 DEG C, the device can generate low-temperature gas at the nozzle outlet under a wide range of flow conditions, high gas-liquid temperature difference at the nozzle outlet is met, and new technical support is provided for the research on the immersion type jetting gas-liquid two-phase flow heat transfer process under the condition of high gas-liquid temperature difference.

[0061] The gas temperature control module is arranged to accurately control the temperature of the low-temperature gas, and the bubble control module is arranged to accurately control the size of the gas bubbles. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 is a schematic diagram of the low-temperature gas generating device.

[0063] Figure 2 The flow chart for calculating the heat exchange area of the present application. DETAILED DESCRIPTION

[0064] The present application can be implemented or applied in other different embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following examples and features in the examples can be combined with each other without conflict.

[0065] It should be noted that the diagrams provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and only the components related to the present application are shown in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component can be a random change, and the component layout pattern can be more complex.

[0066] All directional indications (such as up, down, left, right, front, back, transverse, longitudinal, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications will also change accordingly.

[0067] Due to installation errors and other reasons, the parallel relationship referred to in the embodiments of the present application may actually be an approximate parallel relationship, and the vertical relationship may actually be an approximate vertical relationship.

[0068] Embodiment one:

[0069] As shown in Figure 1 A low-temperature gas generating device includes a gas supply device, a gas cooling device, a gas heat preservation device, a water tank 8, a measuring device, a gas temperature control module, and a bubble control module. The gas cooling device includes a cooler 4 and a heat exchange pipe 5. The gas heat preservation device includes a cooling interlayer 6 and a nozzle 7. The heat exchange pipe 5 is arranged in the cooler 4, and the heat exchange pipe 5 is in communication with the cooling interlayer 6. The cooler 4 is internally provided with a cooling medium. The gas flowing through the heat exchange pipe 5 is cooled by the cooling medium to obtain low-temperature gas. The low-temperature gas in the cooling interlayer 6 is cooled and preserved by the cooling medium. The preserved low-temperature gas is sprayed from the nozzle 7 and forms bubbles in the water tank 8. The gas temperature control module is used to control the temperature of the low-temperature gas, and the bubble control module is used to control the size of the bubbles.

[0070] The gas supply device includes a nitrogen tank 1, a pressure reducing valve 2, and a flow controller 3 connected in sequence. As shown in Figure 1As shown, the nitrogen tank 1 is horizontally placed on the ground, the outlet end of which is connected with the inlet end of the pressure reducing valve 2, the outlet end of the pressure reducing valve 2 is connected with the inlet end of the flow controller 3 through a pipeline, the flow controller 3 can stably generate gas, the outlet end of the flow controller 3 is connected with the heat exchange pipe 5 through a pipeline, the outlet end of the heat exchange pipe 5 is connected with the inlet end of the cooling layer 6, the outlet end of the cooling layer 6 is connected with the inlet end of the nozzle 7, the heat exchange pipe 5 is connected with the cooler 4, and the outlet end of the nozzle 7 is arranged in the water tank 8. The gas flows through the nitrogen tank 1, the pressure reducing valve 2, the flow controller 3, the heat exchange pipe 5, the cooling layer 6 and the nozzle 7 in sequence, and is sprayed out of the outlet end of the nozzle 7 into the water tank 8.

[0071] The cooler 4 contains cooling medium, which includes but is not limited to liquid nitrogen, liquid helium, liquid hydrogen, liquid neon, liquid argon and liquid oxygen and other low-boiling materials. The top of the cooler 4 is provided with a heat preservation cover, which is made of low thermal conductivity materials such as polytetrafluoroethylene. The cooler 4 is provided with a double-layer steel plate structure, and the double-layer steel plate is vacuumized. The cooler 4 is externally coated with silica aerogel, thermal insulation cotton and other thermal insulation materials to avoid heat transfer and reduce the loss of cooling medium.

[0072] The heat exchange pipe 5 is preferably horizontally installed at the bottom of the cooler 4, and is threadedly connected with the side wall inlet of the cooler 4 and provided with a sealing ring or other sealing material therebetween to avoid leakage of the cooling medium. The heat exchange pipe 5 is made of high thermal conductivity materials such as copper, which is used for rapid cooling of the gas in the pipe. The gas flows from the outlet of the flow controller 3 into the heat exchange pipe 5 in the cooler 4, the outside of the heat exchange pipe 5 is the cooling medium, and the inside of the heat exchange pipe 5 is the cooled gas. The gas exchanges heat with the cooling medium through the wall of the heat exchange pipe 5. Preferably, the cooling medium is liquid nitrogen, and the gas can be cooled to -196℃.

[0073] In this embodiment, the temperature of the cooling medium increases after heat exchange, and the cooling medium becomes gas and escapes from the cooler 4 when the temperature exceeds the boiling point, so that the problem of affecting the cooling of the subsequent gas due to the long-time heat exchange of the cooling medium does not occur. In addition, in this embodiment, the heat exchange pipe 5 is installed at the bottom of the cooler 4, so that when there is enough cooling medium, even if the cooling medium becomes gas and escapes from the cooler 4, the heat exchange pipe 5 is always immersed in the cooling medium, and the cooling of the subsequent gas is not affected.

[0074] In the existing device, the gas flowing through the connecting pipeline and the nozzle is heated to a high temperature at the moment of bubble generation due to the convection heat exchange process. To solve this problem, the cooling layer 6 is arranged in the present application to further maintain the low temperature state of the low-temperature gas cooled by the heat exchange pipe 5, and reduce the heat loss of the low-temperature gas in the nozzle 7.

[0075] The cooling interlayer 6 connects the heat exchange pipe 5 and the water tank 8, and the cooler 4 is arranged adjacent to the water tank 8. Specifically, the cooling interlayer 6 is arranged in a double-pipe structure and includes a first pipe 12, a second pipe 13 and a circular ring sheet (not shown in the figure). The first pipe 12 and the second pipe 13 have different diameters, and the diameter of the first pipe 12 is greater than that of the second pipe 13. The first pipe 12 and the second pipe 13 are coaxially arranged inside and outside. A cooling gap is arranged between the inner pipe wall of the first pipe 12 and the outer pipe wall of the second pipe 13. The side wall of the cooler 4 is provided with an outlet end (not shown in the figure), and the heat exchange pipe 5 is arranged inside the outlet end. The heat exchange pipe 5 and the outlet end have a gap therebetween, and a cooling medium can flow out of the gap. One end of the first pipe 12 is fixedly connected to the outlet end, and the other end is fixedly connected to the water tank 8. The second pipe 13 is fixedly connected to the outlet end of the heat exchange pipe 5, and the other end is fixedly connected to the nozzle 7. The cooling gap of the first pipe 12 and the second pipe 13 close to the water tank 8 is sealingly connected through the circular ring sheet, so as to ensure the sealing state between the pipe sections of the cooling interlayer 6. The low-temperature cooling medium in the cooler 4 can flow into the cooling gap through the gap, and is blocked by the circular ring sheet welded at the outlet of the interlayer. The cooled gas flows out of the heat exchange pipe 5 and enters the second pipe 13 of the cooling interlayer 6, and is further cooled by the cooling interlayer 6 to maintain the low-temperature state of the gas.

[0076] Preferably, the material of the circular ring sheet is stainless steel.

[0077] Preferably, the nozzle 7 is located in the water tank 8. The material of the nozzle 7 includes but is not limited to polytetrafluoroethylene and other low-thermal-conductivity thermal insulation materials, which reduces the heat loss of the low-temperature gas.

[0078] Preferably, the first pipe 12 is connected to the water tank 8 through threads, and part of the cooling interlayer is immersed in the transparent solution in the water tank 8. Through the cooling and heat preservation of the cooling interlayer 6, the lowest gas phase temperature at the outlet of the nozzle 7 is still-196℃ (measured at 10mm inside the nozzle).

[0079] The embodiment can further widen the flow range of the sprayed gas through the cooler 4 and the cooling interlayer 6. Under large flow conditions, the length of the heat exchange pipe 5 and the cooling interlayer 6 is increased to realize the low-temperature state of the gas at the outlet of the nozzle 7. Under small flow conditions, the cooling and heat preservation of the cooling interlayer 6 are realized. The minimum flow rate of the system at which the gas-liquid temperature difference is formed at the outlet of the nozzle is 10mL / min (at room temperature).

[0080] The water tank 8 is filled with a transparent solution which is a liquid phase material, when the low-temperature gas is sprayed out of the nozzle 7 into the water tank 8, the low-temperature gas contacts with the liquid phase material to form bubbles, that is, the bubbles are formed at the outlet of the nozzle 7, the water tank 8 is provided with a heater 11, the heater 11 heats the liquid phase material to maintain the temperature of the liquid phase material constant, and the liquid phase material can be heated to a maximum of 200 DEG C. The liquid phase material includes but is not limited to glycerol-water solution, silicone oil, anhydrous ethanol and other heat-conducting oil and alcohol materials. Such materials have the characteristics of high boiling point, high transmittance and the like.

[0081] The measuring device adopts a high-speed camera 9 and a computer 10, the image acquisition end of the high-speed camera 9 is directed to the water tank 8 to collect the bubble image sprayed out of the nozzle 7, the high-speed camera 9 is in communication connection with the computer 10, the high-speed camera 9 transmits the collected bubble image to the computer 10, and the computer 10 accurately measures the gas-liquid two-phase flow characteristics through the bubble image.

[0082] The existing experimental system is difficult to simultaneously satisfy the high gas-liquid temperature difference at the outlet of the nozzle and the accurate control of the bubble size, while the experimental system of the present application realizes the low-temperature state of the gas at the outlet of the nozzle 7 through the cooling of the cooler 4 and the cooling and heat preservation of the cooling sandwich layer 6 (the temperature measured at 10 mm in the nozzle is-196 DEG C), and the liquid phase material can be heated to a maximum of 200 DEG C, so that the gas-liquid temperature difference at the outlet of the nozzle 7 is up to 396 DEG C, and the liquid phase material is a transparent solution, so that the bubble characteristics in the water tank 8 are accurately measured through the high-speed camera 9 and the computer 10.

[0083] The gas temperature control module is used for controlling the temperature of the low-temperature gas, which is based on the heat exchange area of the heat exchange pipe 5 connected with the cooler 4 and the cooling sandwich layer 6, so as to control the temperature of the low-temperature gas at the outlet of the nozzle 7.

[0084] The bubble control module is used for controlling the bubble size sprayed out of the nozzle 7 at the outlet.

[0085] As shown in Figure 2 The present application also provides a control method for the temperature of the low-temperature gas and the bubble characteristics of the gas formed by the low-temperature gas, which controls the temperature of the low-temperature gas generated by the low-temperature gas generating device and the bubble size of the gas, and specifically includes the following steps:

[0086] Step S1: calculating the heat exchange area of the heat exchange pipe 5, and obtaining the target length of the heat exchange pipe 5 according to the heat exchange area;

[0087] Step S2: establishing a bubble detachment volume calculation model, and calculating the bubble size according to the model;

[0088] Step S3: ending the step;

[0089] During the calculation of the heat exchange area of ​​the heat exchange tube 5 in step S1, the inner wall temperature and heat exchange area of ​​the heat exchange tube 5 are unknown during the heat exchange calculation process. At the same time, when calculating the thermal conductivity of the heat exchange tube 5 according to the average temperature of the tube wall, the inner wall temperature of the heat exchange tube 5 needs to be known. However, the inner wall temperature of the heat exchange tube 5 is unknown, so it is necessary to calculate it through the following iterative method.

[0090] Considering the various heat transfer processes between the cooling medium and the cooled gas outside the heat exchange tube 5, a heat transfer equation is established for each heat transfer process. Constraints are established based on the principle of energy conservation, and corresponding data is obtained. This data is then incorporated into each heat transfer equation, and the heat exchange area is calculated through iterative calculation.

[0091] The heat transfer process of this embodiment includes: heat exchange between the cooling medium and the outer wall of the heat exchange tube 5, heat conduction from the outer wall of the heat exchange tube 5 to the inside, and convection heat exchange between the inner wall of the heat exchange tube 5 and the cooled gas, specifically including the following steps:

[0092] Step S11: Obtain the outer wall temperature T of the heat exchange tube 5 through the heat exchange process between the cooling medium and the outer wall of the heat exchange tube 5 t,o ;

[0093] Regarding the heat exchange process between the cooling medium and the outer wall of the heat exchange tube 5, since the heat exchange tube 5 is immersed in the cooling medium for a long time, it can be considered that the outer wall temperature T t,o The same as the cooling medium temperature, when the cooling medium is liquid nitrogen, T t,o =-196℃, when the cooling medium is other materials, the outer wall temperature T t,o It can also be other temperatures, that is, when the cooling medium is selected, the outer wall temperature T t,o is a known value;

[0094] Step S12: establishing a heat transfer equation 1 for the heat transfer process from the outside to the inside of the outer wall of the heat exchange tube 5;

[0095] The heat transfer equation 1 is specifically:

[0096]

[0097] Where Q t is the heat transfer from the outer wall of the heat exchange tube 5 from the outside to the inside, in W, which is the parameter to be solved; t is the thermal conductivity of the heat exchange tube 5, which is related to the average temperature of the heat exchange tube 5. The average temperature is the arithmetic mean of the inner and outer wall temperatures of the heat exchange tube 5. The unit is W / (m·K). It is an unknown value. When the inner wall temperature of the heat exchange tube 5 is known, then λ t is a known value; l t is the length of the heat exchange tube 5, in m, which is the parameter to be solved; T t,i is the inner wall temperature of the heat exchange tube 5, in °C, which is the parameter to be solved; Tt,o T is the temperature of the outer wall of the heat exchange pipe 5, in ℃; t,o r is the outer diameter of the heat exchange pipe 5, in m; t,i r is the inner diameter of the heat exchange pipe 5, in m.

[0098] Step S13: establishing the heat transfer equation 2 of the convective heat transfer amount Q c between the inner wall of the heat exchange pipe 5 and the cooled gas:

[0099] The heat transfer equation 2 is specifically:

[0100] Q c = hA△T m

[0101] In the formula, Q c is the convective heat transfer amount between the inner wall of the heat exchange pipe 5 and the cooled gas, in W, which is a parameter to be solved; A is the inner heat exchange area of the heat exchange pipe 5, A = 2 x π x r t,i x l t , in m 2 , which is a parameter to be solved; ΔT m is the logarithmic mean temperature difference between the cooled gas and the inner wall of the heat exchange pipe 5, in ℃, which is calculated by the following formula:

[0102]

[0103] In the formula, T g,i is the temperature of the gas before being cooled, in ℃, which is a known value; T t,i is the temperature of the inner wall of the heat exchange pipe 5, in ℃, which is a parameter to be solved; T g,o is the temperature of the gas after being cooled, in ℃, which is a set value;

[0104] h is the convective heat transfer coefficient inside the pipe, in W / (m 2 ·K), which is calculated by the following formula:

[0105]

[0106] In the formula, λ g is the thermal conductivity of the cooled gas, which is related to the type of the cooled gas, the temperature of the gas before being cooled, and the temperature of the gas after being cooled, in W / (m·K), which is a known value; r t,i is the inner diameter of the heat exchange pipe 5, in m; Nu is the Nusselt number, which is calculated by the following formula:

[0107]

[0108] In the formula, Re f is the Reynolds number, and the calculation formula is Re f = ur t,iv, u is the gas velocity, unit: m / s, which is a set value; r t,i r is the inner diameter of the heat exchange tube 5, unit: m; v is the gas viscosity, unit: m 2 / s, which is a known value; Pr f Pr is the gas Prandtl number, which is obtained by consulting the gas property parameter table, so h is a known value.

[0109] Step S14: Establish the heat absorption amount Q of the cooled gas per second g of the heat transfer equation 3;

[0110] The heat transfer equation 3 is as follows:

[0111] Q g = mc△T g

[0112] In the formula, Q g is the heat absorption amount of the cooled gas per second, unit: W, which is a to-be-solved parameter; m is the mass of the cooled gas, unit: kg, which is a known value; c is the specific heat of the gas, unit: J / (kg·K), which is a known value; ΔT g is the temperature difference before and after the gas is cooled, ΔT g =T g,i -T g,o , unit: ℃, which is a known value.

[0113] Step S15: Establish the constraint condition of Q t , Q c , Q g

[0114] Q t = Q c = Q g

[0115] Step S16: Directly calculate the heat absorption amount Q g of the cooled gas according to the heat transfer equation 3;

[0116] When calculating the thermal conductivity according to the average temperature of the inner and outer tube walls of the heat exchange tube 5, the inner wall temperature of the heat exchange tube 5 needs to be known, and the inner wall temperature of the heat exchange tube 5 is unknown, so it needs to be calculated through the iteration method described below. The iteration method needs to estimate a value of the to-be-solved quantity for calculation, and then correct the estimated value with the calculation result, and gradually approach until the error between the estimated value and the calculation result is within a certain range. In this calculation example, the inner diameter and the outer diameter of the heat exchange tube 5 are given in advance, so only the length of the heat exchange tube 5 needs to be calculated to obtain the corresponding heat exchange area. The specific process is as follows:

[0117] Step S17, calculate the heat conduction amount Q t of the outer wall of the heat exchange tube 5 from the outside to the inside according to the constraint condition; ​

[0118] Step S18, initialize the temperature interval [T low , T high ] of the inner wall of the heat exchange pipe 5, wherein T low is the temperature of the cooling medium and T high is the temperature after being cooled in the first iteration process;

[0119] Step S19, take T m , the midpoint of the temperature interval, as the current inner wall temperature of the heat exchange pipe 5 to perform calculation, and obtain the heat exchange area A of the current cycle according to the heat transfer equation 1;

[0120] Step S20, bring the heat exchange area A of the current cycle and the inner wall temperature T m into the heat transfer equation 2 to calculate the convective heat transfer quantity Q c between the inner wall of the heat exchange pipe 5 and the cooled gas;

[0121] Step S21, compare whether the difference between Q c and Q g is less than a set value, if yes, T m is the inner wall temperature of the heat exchange pipe 5, end the cycle, obtain the heat exchange area at the required temperature, and enter step S23; if no, enter step S22;

[0122] Step S22, if Q c > Q g , it indicates that the inner wall temperature of the heat exchange pipe 5 is too high, the lower limit T low of the temperature interval of step S18 is close to the inner wall temperature, T m is replaced by T high , the temperature interval [T low , T m ] is taken as the current inner wall temperature interval of the heat exchange pipe 5, and the cycle returns to step S18; if Q c < Q g , it indicates that the inner wall temperature is too low, the upper limit of the temperature interval of step S18 is close to the inner wall temperature, T m is replaced by T low , the temperature interval [T m , T high ] is taken as the current inner wall temperature interval of the heat exchange pipe 5, and the cycle returns to step S18;

[0123] Step S23, obtain the target length of the heat exchange pipe 5 at the target temperature of the low-temperature gas and under the condition that the inner diameter and the outer diameter of the heat exchange pipe 5 are set according to the heat exchange area.

[0124] That is, under the condition that other conditions, such as gas flow rate, gas temperature parameter before cooling, etc. remain unchanged, the inner diameter and outer diameter of the heat exchange pipe 5, the target temperature of the low-temperature gas are known, and the heat exchange pipe 5 of the target length is selected, so that the gas can be cooled to the target temperature in the heat exchange pipe 5.

[0125] The calculation process is described by specific examples:

[0126] Suppose the gas flow rate is 50 L / min, the gas temperature before cooling is 25°C, and the gas temperature after cooling is -100°C. The relevant physical property parameters are obtained by looking up the table. The cycle termination condition is that the relative error of the heat exchange amount is less than 0.05%. The calculation process is as follows.

[0127]

[0128] 1 -196 -100 -148 117.02 1 x 10 -4 ]] No 2 -196 -148 -172 117.02 3 x 10 -4 ]]> No 3 -196 -172 -184 117.02 6 x 10 -4 ]]> No 4 -196 -184 -190 117.02 1 x 10 -3 ]]> No 5 -196 -190 -193 117.02 2.9 x 10 -3 ]] No 6 -196 -193 -194.5 117.02 5.8 x 10 -3 ]]> No 7 -196 -194.5 -195.25 117.02 1.2 x 10 -2 ]]> No 8 -196 -195.25 -195.625 117.02 2.3 x 10 -2 ]]> No 9 -196 -195.625 -195.81 117.02 4.7 x 10 -2 ]]> No 10 -196 -195.81 -195.91 117.02 9.3 x 10 -2 ]]> No … Final result -196 -195.85 -195.925 117.02 117.06 Yes

[0129] The bubble detachment volume calculation model established in step S2 is:

[0130]

[0131] In formula (1), We m is a dimensionless modified We number; is a dimensionless bubble diameter, V b is the bubble volume, with the unit of m 3 , which is a parameter to be solved; V0 is the bubble detachment stage starting volume, with the unit of m 3 ; which is calculated by the following formula:

[0132]

[0133] In formula (2), ρ g and ρ l are the gas-liquid two-phase densities, with the unit of kg / m 3 , which are known values; g is the gravitational acceleration; the coefficient C1=1, σ is the surface tension coefficient, with the unit of mN / m, which is a known value; d0 is the nozzle diameter, with the unit of m, which is a set value; u0 is the gas flow rate at the nozzle 7, with the unit of m / s, which is a known value; A0 is the nozzle cross-sectional area, with the unit of m 2 , which is a set value, and V0 can be calculated according to the above formula;

[0134] The modified We number We m can also be calculated by the following formula:

[0135]

[0136] In formula (3), ρ g and ρ lρl, ρg are gas-liquid two-phase densities, unit: kg / m 3 , which is a known value; u0 is the gas flow rate at the nozzle 7, unit: m / s, which is a known value; A0 is the nozzle cross-sectional area, unit: m 2 , which is a set value; σ is the surface tension coefficient, unit: mN / m, which is a known value; d0 is the nozzle diameter, unit: m, which is a set value; the coefficient C1=1, the coefficient C2=0.5; We m ;

[0137] The gas-liquid two-phase densities, the gas flow rate at the nozzle 7, the nozzle diameter, the nozzle cross-sectional area, the surface tension coefficient, etc. are the blowing parameters. In general and in this embodiment, the blowing parameters are the known values or the set values by default. Based on the known blowing parameters, We m , V0 is obtained. We m , V0 is substituted into formula (1) to obtain V b , the bubble is regarded as spherical, the bubble diameter is obtained according to the volume formula of the sphere, and the bubble diameter of this embodiment is the bubble size.

[0138] This embodiment adjusts the blowing parameters to control the bubble size, thereby realizing the accurate control of the bubble size.

[0139] Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

Claims

1. A method of controlling the temperature of a cryogenic gas and the characteristics of bubbles formed by the gas, based on the temperature of a cryogenic gas generated by a cryogenic gas generating device and the size of bubbles formed by the gas, characterized by: The low-temperature gas generating device comprises a gas supply device, a gas cooling device, a gas heat preservation device, a water tank, a measuring device, a gas temperature control module and a bubble control module, the gas cooling device comprises a cooler and a heat exchange pipe, the gas heat preservation device comprises a cooling interlayer and a nozzle, the heat exchange pipe is arranged in the cooler, the heat exchange pipe is communicated with the cooling interlayer, the cooler is internally provided with a cooling medium, the gas flowing through the heat exchange pipe is cooled by the cooling medium to obtain low-temperature gas, the low-temperature gas in the cooling interlayer is cooled and preserved by the cooling medium, the preserved low-temperature gas is sprayed from the nozzle and forms bubbles in the water tank, the gas temperature control module is used for controlling the temperature of the low-temperature gas, and the bubble control module is used for controlling the size of the bubbles; The control method specifically comprises the following steps: Step S1: calculating the heat exchange area of the heat exchange pipe, and obtaining the target length of the heat exchange pipe according to the heat exchange area; Step S2: establishing a bubble detachment volume calculation model, and calculating the bubble size according to the model; The bubble detachment volume calculation model is as follows: ；（1） In formula (1), We m is a dimensionless modified Weber number; is a dimensionless bubble diameter, , V b is the bubble volume in m 3 , which is the parameter to be solved; V 0 is the initial volume of the bubble detachment stage in m 3 ; calculated by the following formula: （2） in formula (2), ρ g and ρ l respectively the gas-liquid two-phase density, in kg / m 3 , which is a known value; g is the gravitational acceleration; the coefficient C 1 = 1, σ is the surface tension coefficient, in mN / m, which is a known value; d 0 is the nozzle diameter, in m, which is a set value; u 0 is the gas flow rate at the nozzle, in m / s, which is a known value; A 0 is the nozzle cross-sectional area, in m 2 , which is a set value, calculated according to the above formula V 0; modified weber number We m calculated by the formula: （3） in formula (3), ρ g and ρ l are the gas-liquid two-phase densities, in kg / m 3 , which are known values; u 0 is the gas flow rate at the nozzle, in m / s, which is a known value; A 0 is the nozzle cross-sectional area, in m 2 , which is a set value; σ is the surface tension coefficient, in mN / m, which is a known value; d 0 is the nozzle diameter, in m, which is a set value; coefficients C 1 = 1, coefficients C 2 = 0.5; according to the above, it is possible to obtain We m ; Substitute We m , V 0 into equation (1) to obtain V b ; Step S3: ending the step.

2. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas according to claim 1, characterized in that: The specific steps of calculating the heat exchange area of the heat exchange pipe in the step S1 are as follows: Step S11: obtaining the temperature of the outer wall of the heat exchange tube through heat exchange between the cooling medium and the outer wall of the heat exchange tube T t,o ; For the heat exchange process between the cooling medium and the outer wall of the heat exchange tube, the heat exchange tube is immersed in the cooling medium, and it is considered that the outer wall temperature of the heat exchange tube is consistent with the temperature of the cooling medium T t,o When the cooling medium is selected, the outer wall temperature is a known value T t,o ; Step S12: establishing the heat transfer process of the outer wall of the heat exchange tube from outside to inside Q t of the heat transfer equation 1; Step S13: Establishing the convective heat transfer amount in the convective heat transfer process between the inner wall of the heat exchange pipe and the cooled gas Q c Heat transfer equation 2: Step S14: Establishing the heat absorption amount of the cooled gas per second Q g of the heat transfer equation 3; Step S15: Establishing Q t , Q c , Q g Constraint; Step S16: Calculate the heat absorption of the cooled gas according to heat transfer equation 3 Q g ; Step S17, calculating the heat conduction amount of the outer wall of the heat exchange tube from outside to inside according to the constraint condition Q t ; Step S18, initializing the heat exchange tube inner wall temperature interval [T low , T high ] , wherein T low is the cooling medium temperature and T high is the temperature after being cooled in the first iteration process; Step S19, midpoint of temperature interval T m As the current heat exchange tube inner wall temperature is calculated, the heat transfer equation 1 is obtained according to the heat exchange area of the current cycle A ; In this step, the inner diameter and the outer diameter of the heat exchange pipe are set values; Step S20, the heat exchange area of the current cycle A and the inner wall temperature T m The heat transfer equation 2 is introduced, and the convective heat transfer amount between the inner wall of the heat exchange pipe and the cooled gas is calculated Q c ; Step S21, comparison Q c , Q g If yes, the difference is less than the set value, go to step S23; if no, go to step S22. T m T is the inner wall temperature of the heat exchange tube, end the cycle, and obtain the heat exchange area at the required temperature A . Step S22, if Q c > Q g , it indicates that the inner wall temperature of the heat exchange tube is too high, and the lower limit T low of the temperature interval of step S18 approaches the inner wall temperature, and T T m is replaced by T high , and the temperature interval of [T low , T m ] is taken as the current inner wall temperature interval of the heat exchange tube, and the step S18 continues to loop; if Q c < Q g , it indicates that the inner wall temperature is too low, and the upper limit of the temperature interval of step S18 approaches the inner wall temperature, and T T m is replaced by T low , and the temperature interval of [T T m , T high ] is taken as the current inner wall temperature interval of the heat exchange tube, and the step S18 continues to loop; Step S23, obtaining the target length of the heat exchange tube according to the heat exchange area A The target length of the heat exchange tube is obtained under the conditions of the low-temperature gas target temperature and the set inner diameter and outer diameter of the heat exchange tube.

3. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas according to claim 2, characterized in that: The heat transfer equation 1 is specifically as follows: ； In the formula, Q t is the heat transfer amount of the outer wall of the heat exchange pipe from outside to inside, with a unit of W, which is a parameter to be solved; λ t is the heat conduction coefficient of the heat exchange pipe, which is related to the average temperature of the heat exchange pipe, the average temperature being the arithmetic average of the inner wall temperature and the outer wall temperature of the heat exchange pipe, with a unit of W / (m·K), which is an unknown value, when the inner wall temperature of the heat exchange pipe is known, then λ t is a known value; l t is the length of the heat exchange pipe, with a unit of m, which is a parameter to be solved; T t,i is the inner wall temperature of the heat exchange pipe, with a unit of ℃, which is a parameter to be solved; T t,o is the outer wall temperature of the heat exchange pipe, with a unit of ℃; r t,o is the outer diameter of the heat exchange pipe, with a unit of m; r t,i is the inner diameter of the heat exchange pipe, with a unit of m; The heat transfer equation 2 is specifically as follows: ； In the formula, Q c Q is the convective heat transfer amount of the inner wall of the heat exchange pipe and the cooled gas, in W, which is a parameter to be solved; A A is the heat exchange area in the heat exchange pipe, A = 2 × π × r t,i × l t , in m 2 Q is the convective heat transfer amount of the inner wall of the heat exchange pipe and the cooled gas, in W, which is a parameter to be solved; Δ T m T is the logarithmic mean temperature difference between the cooled gas and the inner wall of the heat exchange pipe, in ℃, calculated by the following formula: ； In the formula, T g,i T0 is the temperature of the gas before being cooled, in °C, which is a known value; T t,i T is the temperature of the inner wall of the heat exchange tube, in °C, which is a parameter to be solved; T g,o T1 is the temperature of the gas after being cooled, in °C, which is a set value; h is the convection heat transfer coefficient in the tube, unit is W / (m 2 K), calculated by the following formula: ； In the formula, λ g is the thermal conductivity of the cooled gas, which is related to the type of the cooled gas, the temperature before gas cooling, and the temperature after gas cooling, and has a unit of W / (m·K), which is a known value; r t,i is the inner diameter of the heat exchange tube, m; Nu is the Nusselt number, which is calculated using the following formula: ； wherein Re f Reynolds number, the formula is Re f = ur t,i / v , u Gas velocity, unit: m / s, is a set value; r t,i Heat exchange tube inner diameter, unit: m; v Gas viscosity, unit: m 2 / s, is a known value; Pr f Gas Prandtl number, obtained by consulting gas property parameter table, h is a known value; The heat transfer equation 3 is specifically as follows: ； In the formula, Q g Q is the heat absorption amount of the cooled gas per second, in W, which is the parameter to be solved. m is the mass of the cooled gas in kg, which is a known value; c is the specific heat of the gas in J / (kg K), which is a known value; Δ T g The temperature difference before and after the gas is cooled, ΔT T g = T g,i - T g,o in °C, which is a known value.

4. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas according to claim 2, characterized in that: The constraint is .

5. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas as claimed in claim 1, characterized in that: The gas supply device comprises a nitrogen tank, a pressure reducing valve and a flow controller which are connected in sequence, the nitrogen tank is connected with the pressure reducing valve, the pressure reducing valve is connected with the flow controller, the flow controller is connected with the heat exchange pipe, one end of the heat exchange pipe is connected with the cooler, the other end is connected with the cooling interlayer, the cooling interlayer is connected with the nozzle, and the nozzle is arranged in the water tank.

6. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas according to claim 5, characterized in that: The top of the cooler is provided with a heat preservation cover, the cooler is provided with a double-layer steel plate structure, the double-layer steel plates are vacuumized, and the cooler is externally coated with heat preservation material.

7. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas according to claim 1, characterized in that: The heat exchange pipe is installed at the bottom of the cooler; the material of the heat exchange pipe is high-thermal-conductivity material, the heat exchange pipe is externally provided with a cooling medium, and the heat exchange pipe is internally provided with a cooled gas, and the cooled gas exchanges heat with the cooling medium through the wall surface of the heat exchange pipe.

8. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas according to claim 1, characterized in that: The cooling interlayer is connected with the heat exchange pipe and the water tank, the cooler is arranged adjacent to the water tank, the cooling interlayer is provided with a double-layer pipe structure and comprises a first pipe, a second pipe and a circular ring piece, the first pipe and the second pipe are coaxially arranged inside and outside, a cooling gap is formed between the inner pipe wall of the first pipe and the outer pipe wall of the second pipe, the side wall of the cooler is provided with an outlet end, the heat exchange pipe is located inside the outlet end, and a gap is formed between the heat exchange pipe and the outlet end; one end of the first pipe is fixedly connected with the outlet end, the other end is fixedly connected with the water tank, the second pipe is fixedly connected with the outlet end of the heat exchange pipe, and the other end is fixedly connected with the nozzle; the gap and the cooling gap are communicated, the cooling gap of the first pipe and the second pipe close to the water tank is sealingly connected through the circular ring piece, the cooling medium flows into the cooling gap through the gap, and the cooled gas flows out of the heat exchange pipe and then enters the second pipe of the cooling interlayer.

9. A method of controlling the temperature of a cryogenic gas and the properties of the bubbles formed by the gas according to claim 1, characterized in that: The measuring device comprises a high-speed camera and a computer, an image acquisition end of the high-speed camera is arranged to face a water tank to acquire images of bubbles sprayed by a nozzle, the high-speed camera is in communication connection with the computer, the high-speed camera transmits the acquired bubble images to the computer, and the computer measures flow characteristics of the gas-liquid two-phase flow through the bubble images.

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