Visual measurement device and method for refrigerant liquid drops

Abstract

The invention belongs to the technical field of refrigerants, and particularly relates to a visual measuring device and method for refrigerant liquid drops, and the device comprises a liquid drop sampling system, and a sampling cabin is connected with a capillary needle tube through a sampling valve, and the capillary needle tube is arranged along the gravity direction; a capillary needle tube of the high-pressure visualization system extends into an observation bin communicated with the sample injection bin; the visible windows are arranged on the opposite side walls of the observation bin, the observation platform is fixed in the observation bin and located between the visible windows and below the capillary needle tube, and the thermoelectric effect semiconductor is arranged on the observation platform; the pressure control system, the electric heating module and the semiconductor chilling plate are arranged on the sample injection bin, and the pressure micro-control unit is electrically connected with the two; the optical imaging system, the high-speed camera and the light source are arranged outside the visible window, and the computer is electrically connected with the two. Compared with the prior art, the problems that in the prior art, high-pressure sampling equipment which is high in cost and complex in operation is needed, and only the liquid drop contact angle can be measured are solved. According to the scheme, through the gravity action of the liquid working medium, sample injection in a high-pressure environment is achieved, and high-pressure sample injection equipment is not needed.

Description

Technical Field

[0001] The present invention belongs to the technical field of refrigerants, and particularly relates to a visualization measurement device and method for refrigerant droplets. Background Art

[0002] With the development of refrigeration technology, refrigerants are widely used in many fields, such as refrigeration and cryogenic fields, chemical engineering fields, electronic device heat dissipation fields, etc. The research on the wettability of refrigerants is crucial for optimizing the design of refrigeration devices and improving system efficiency. Among them, the contact angle is an important parameter for measuring wettability. However, the commonly used open contact angle measuring instruments at present can only measure the contact angle of normal temperature working fluids such as water under normal pressure conditions, and to measure refrigerant working fluids, a high-pressure closed environment needs to be provided.

[0003] Currently, there are already visualization measurement devices for measuring refrigerant droplets. In order to achieve the function of droplet injection under high-pressure environment, corresponding high-pressure injection equipment is configured. For example: the invention patent with the publication number CN109470603A uses a high-pressure micro-flow plunger pump to achieve droplet injection under high-pressure environment; the invention patent with the publication number CN109632580A uses a high-pressure micro-flow injection pump to achieve droplet injection under high-pressure environment; the invention patent with the publication number CN110411904A is equipped with a high-pressure gas tank to push the injection to achieve droplet injection under high-pressure environment. It can be seen that the high-pressure injection equipment supporting droplet injection under high-pressure environment in these existing technologies has the defects of high cost, complex operation, and single function, and can only achieve the measurement of the droplet contact angle.

[0004] In view of this, the present invention proposes a visualization measurement device for refrigerant droplets without supporting high-pressure injection and a usage method for supporting this device, which can achieve droplet contact angle measurement and observation of droplet evaporation and condensation, and meet the needs of research on the wettability of refrigerant droplets. Summary of the Invention

[0005] The purpose of the present invention is to provide a visualization measurement device and method for refrigerant droplets to solve at least one of the above problems, so as to solve the defects that the high-pressure injection equipment supporting droplet injection under high-pressure environment in the prior art has high cost, complex operation, single function, and can only achieve the measurement of the droplet contact angle. This solution realizes injection under high-pressure environment through the gravity of the liquid working fluid, without the need to support high-pressure injection equipment. At the same time, to meet the current needs of research on the wettability of refrigerant droplets, in addition to being able to achieve droplet contact angle measurement, this device can also implement the observation of droplet evaporation and condensation.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The first aspect of the present invention discloses a visualization measurement device for refrigerant droplets, comprising a droplet injection system, a high-pressure visualization system, a pressure control system, and an optical imaging system;

[0008] The droplet injection system includes an injection chamber, an injection valve, a capillary needle, and a connecting pipe; the injection chamber is connected to the capillary needle through an injection pipe, the injection valve is arranged on the injection pipe, and the capillary needle is arranged along the direction of gravity;

[0009] The high-pressure visualization system includes an observation chamber, a visual window, an observation platform, and a thermoelectric effect semiconductor; the capillary needle extends into the observation chamber, and the observation chamber is connected to the injection chamber through a connecting pipe; the visual window is arranged on a pair of opposite side walls of the observation chamber, the observation platform is fixed inside the observation chamber, and the observation platform is located between the visual windows and below the capillary needle, and the thermoelectric effect semiconductor is arranged on the observation platform;

[0010] The pressure control system includes an electric heating module, a semiconductor refrigeration sheet, and a pressure micro-control unit; the electric heating module is arranged on the side of the injection chamber, the semiconductor refrigeration sheet is arranged on the top of the injection chamber, and the pressure micro-control unit is electrically connected to the electric heating module and the semiconductor refrigeration sheet;

[0011] The optical imaging system includes a high-speed camera, a light source, and a computer; the high-speed camera is arranged outside the visual window on one side of the observation chamber, and the field of view of the high-speed camera covers the capillary needle and the observation platform, the light source is arranged outside the visual window on the other side of the observation chamber, and the light source is arranged towards the observation platform, and the computer is electrically connected to the high-speed camera.

[0012] Preferably, the injection chamber is of an inverted cone structure, the electric heating module is arranged on the inclined surface of the injection chamber, and the semiconductor refrigeration sheet is arranged on the top surface of the injection chamber. This inverted cone structure of the injection chamber is beneficial to controlling the droplet injection volume; at the same time, it can also increase the liquid level height in the injection chamber with a smaller refrigerant filling amount, so as to ensure that there is a sufficient amount of liquid refrigerant in the injection chamber and a relatively obvious liquid level change during the injection process.

[0013] Preferably, the high-pressure visualization system further includes a safety valve; the safety valve is arranged on the observation chamber and is used to connect the observation chamber with the atmosphere when the pressure inside the observation chamber exceeds the limit.

[0014] Preferably, the pressure control system further includes a temperature sensor and a pressure sensor; the temperature sensor is disposed inside the observation chamber for obtaining the temperature inside the observation chamber; the pressure sensor is disposed inside the observation chamber for obtaining the pressure inside the observation chamber; the temperature sensor and the pressure sensor are respectively electrically connected to the pressure micro control unit. The temperature sensor and the pressure sensor obtain the state data inside the observation chamber in real time and feedback them to the pressure micro control unit. The pressure micro control unit adjusts the heating and cooling powers of the electric heating module and the semiconductor refrigerating sheet according to the obtained data, and then controls the pressures of the sample injection chamber and the observation chamber to be maintained at the set value according to the saturated vapor pressure of the refrigerant, so as to realize the feedback regulation of the pressure inside the observation chamber.

[0015] Preferably, the visualization measurement device further includes a vacuum pumping system;

[0016] The droplet injection system further includes a refrigerant liquid storage tank and a filling valve; the refrigerant liquid storage tank is connected to the sample injection chamber through a feeding pipe, and the filling valve is disposed on the feeding pipe;

[0017] The vacuum pumping system includes a vacuum pump, a vacuum buffer container, a pressure gauge and a vacuum valve; the vacuum pump is connected to the sample injection chamber through a vacuum pipe, and the vacuum buffer container is connected between the vacuum pump and the sample injection chamber through a vacuum pipe; the pressure gauge is connected to the vacuum buffer container for obtaining the pressure inside the vacuum buffer container; the vacuum valve is disposed on the vacuum pipe between the vacuum pump and the vacuum buffer container and on the vacuum pipe between the vacuum buffer container and the sample injection chamber.

[0018] Preferably, the droplet injection system further includes a liquid level gauge, and both ends of the liquid level gauge are respectively connected to the top and the bottom of the sample injection chamber for indicating the liquid level height inside the sample injection chamber.

[0019] Preferably, the sample injection chamber and the observation chamber are made of stainless steel material, and a heat insulation layer is provided on the outer surfaces of the sample injection chamber and the observation chamber; the capillary needle tube is made of stainless steel.

[0020] Preferably, the visual window is a sapphire window, the visual window is fastened to the side wall of the observation chamber through a window flange, and the visual window and the observation chamber are sealed through a polytetrafluoroethylene sealing ring.

[0021] Preferably, the light source is a cold light source.

[0022] The second aspect of the present invention discloses a method for visualizing and measuring refrigerant droplets, which uses the device described in any one of the above for visualization measurement;

[0023] The method includes the following steps:

[0024] S1: Close all valves and check the airtightness of the experimental device;

[0025] S2: Fill the injection chamber with liquid refrigerant, and the filled refrigerant gathers at the bottom end of the injection chamber (the lower tip of the inverted cone);

[0026] S3: Adjust the power of the electric heating module and the thermoelectric cooler through the pressure micro-control unit to maintain the pressure in the observation chamber at the set value and keep it stable;

[0027] S4: When the pressure and temperature in the observation chamber reach the set values and are stable, open the injection valve, and use the gravity of the liquid to drip the liquid onto the observation platform through the capillary needle. After the dripping is completed, close the injection valve;

[0028] S5: Observe the morphology of the liquid droplet through the visual window. After waiting for the liquid droplet to stabilize on the observation platform, use a high-speed camera to capture the morphology of the liquid droplet;

[0029] S6: The images captured by the high-speed camera are transmitted to a computer for analysis and processing. Select multiple groups of images with the same morphology to measure the contact angle of the liquid droplet and take the average value;

[0030] S7: Adjust the temperature of the observation platform through the thermoelectric effect semiconductor to observe the evaporation and condensation phenomena of the liquid droplet;

[0031] S8: After the measurement is completed, turn off the device and all valves. After the injection chamber and the observation chamber are cooled, collect the residual liquid refrigerant in the injection chamber. After the device is depressurized, clean the inner cavities of the injection chamber and the observation chamber.

[0032] Preferably, when the high-speed camera captures the morphology of the liquid droplet, the shooting time is greater than 5 seconds.

[0033] The working principle of the present invention is as follows:

[0034] The injection chamber and the observation chamber are in a high-pressure environment. Inject an appropriate amount of liquid refrigerant into the injection chamber, and connect the injection chamber and the observation chamber to make the two chambers reach the gas-liquid phase equilibrium pressure; under the action of gravity, the liquid refrigerant in the injection chamber can be directly dripped and injected onto the observation platform in the observation chamber to observe the contact angle.

[0035] In addition, a thermoelectric effect semiconductor chip is arranged in the observation platform of this device, and a current can be applied to it to control the temperature of the observation platform, thereby realizing the observation of the evaporation and condensation of the liquid droplet.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The object of the present invention is to provide a measurement device for visualizing refrigerant droplets. Compared with other existing measurement devices for visualizing refrigerant droplets, the advantage of this device is that it does not require a supporting high-pressure sampling device, and only relies on gravity sampling to achieve the measurement of the droplet contact angle, and further realizes the observation of droplet evaporation and condensation.

[0038] This measurement device does not require a supporting high-pressure sampling device, which reduces the device cost and makes the operation more convenient. At the same time, it adds the function of measuring the evaporation and condensation of refrigerant droplets, and further meets different research needs for refrigerant droplets through a single device. Brief Description of the Drawings

[0039] Figure 1 It is a schematic structural diagram of a measurement device for visualizing refrigerant droplets;

[0040] Reference numerals in the figure: sampling chamber 1-1, liquid level gauge 1-2, sampling valve 1-3, capillary needle 1-4, refrigerant storage tank 1-5, filling valve 1-6, connecting pipe 1-7, observation chamber 2-1, visual window 2-2, observation platform 2-3, thermoelectric effect semiconductor 2-4, safety valve 2-5, electric heating module 3-1, semiconductor refrigeration sheet 3-2, pressure micro control unit 3-3, temperature sensor 3-4, pressure sensor 3-5, high-speed camera 4-1, light source 4-2, computer 4-3, vacuum pump 5-1, vacuum buffer container 5-2, pressure gauge 5-3 and vacuum valve 5-4. Detailed Description of the Invention

[0041] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Embodiment 1

[0043] A measurement device for visualizing refrigerant droplets, as Figure 1 shown, includes a droplet sampling system, a high-pressure visualization system, a pressure control system and an optical imaging system;

[0044] The droplet sampling system includes a sampling chamber 1-1, a sampling valve 1-3, a capillary needle 1-4 and a connecting pipe 1-7; the sampling chamber 1-1 is connected to the capillary needle 1-4 through a sampling pipe, the sampling valve 1-3 is arranged on the sampling pipe, and the capillary needle 1-4 is arranged along the direction of gravity;

[0045] The described high-pressure visualization system includes an observation chamber 2-1, a visual window 2-2, an observation platform 2-3, and a thermoelectric effect semiconductor 2-4; the capillary needle 1-4 extends into the interior of the observation chamber 2-1, and the observation chamber 2-1 is connected to the sample injection chamber 1-1 through a connecting pipe 1-7; the visual window 2-2 is arranged on a pair of opposite side walls of the observation chamber 2-1, the observation platform 2-3 is fixed inside the observation chamber 2-1, and the observation platform 2-3 is located between the visual windows 2-2 and below the capillary needle 1-4, and the thermoelectric effect semiconductor 2-4 is arranged on the observation platform 2-3;

[0046] The described pressure control system includes an electric heating module 3-1, a semiconductor refrigeration sheet 3-2, and a pressure micro control unit 3-3; the electric heating module 3-1 is arranged on the side of the sample injection chamber 1-1, the semiconductor refrigeration sheet 3-2 is arranged on the top of the sample injection chamber 1-1, and the pressure micro control unit 3-3 is electrically connected to the electric heating module 3-1 and the semiconductor refrigeration sheet 3-2;

[0047] The described optical imaging system includes a high-speed camera 4-1, a light source 4-2, and a computer 4-3; the high-speed camera 4-1 is arranged outside the visual window 2-2 on one side of the observation chamber 2-1, and the field of view of the high-speed camera 4-1 covers the capillary needle 1-4 and the observation platform 2-3, the light source 4-2 is arranged outside the visual window 2-2 on the other side of the observation chamber 2-1, and the light source 4-2 is arranged facing the observation platform 2-3, and the computer 4-3 is electrically connected to the high-speed camera 4-1.

[0048] More specifically, in this embodiment:

[0049] A visualization measurement device for refrigerant droplets includes a droplet injection system, a high-pressure visualization system, a pressure control system, an optical imaging system, and a vacuum pumping system; among them:

[0050] The droplet injection system specifically includes: a sample injection chamber 1-1, a liquid level gauge 1-2, a sample injection valve 1-3, a capillary needle 1-4, a refrigerant liquid storage tank 1-5, a filling valve 1-6, a connecting pipe 1-7;

[0051] The high-pressure visualization system specifically includes: an observation chamber 2-1, a visual window 2-2, an observation platform 2-3, a thermoelectric effect semiconductor 2-4, a safety valve 2-5;

[0052] The pressure control system specifically includes: an electric heating module 3-1, a semiconductor refrigeration sheet 3-2, a pressure micro control unit 3-3, a temperature sensor 3-4, a pressure sensor 3-5;

[0053] The optical imaging system specifically includes: a high-speed camera 4-1, a light source 4-2, a computer 4-3;

[0054] The vacuum pumping system specifically includes: a vacuum pump 5-1, a vacuum buffer container 5-2, a pressure gauge 5-3, and a vacuum valve 5-4.

[0055] The sample injection chamber 1-1 is an inverted cone structure, whose top and bottom are respectively connected to the top and bottom of the liquid level gauge 1-2. Furthermore, the liquid level gauge 1-2 can be used to observe the refrigerant liquid level inside the sample injection chamber 1-1. The bottom end of the sample injection chamber 1-1 is connected to the capillary needle 1-4 through a sample injection tube, and the capillary needle 1-4 further extends into the observation chamber 2-1; a sample injection valve 1-3 is provided on the sample injection tube, and the sample injection valve 1-3 is located outside the observation chamber 2-1 to regulate the rate of refrigerant liquid injection through the capillary needle 1-4. The refrigerant liquid storage tank 1-5 is connected to the upper part of the sample injection chamber 1-1 through a feeding tube, and a filling valve 1-6 is provided on the feeding tube to control the filling amount of the liquid refrigerant.

[0056] The connecting pipe 1-7 is connected between the upper part of the sample injection tube and the observation chamber 2-1, and is used to balance the pressures in the cavities of the sample injection chamber 1-1 and the observation chamber 2-1, so that the liquid refrigerant can drip into the observation chamber 2-1 from the capillary needle 1-4 by gravity.

[0057] The observation chamber 2-1 is located directly below the sample injection chamber 1-1. On a pair of opposite side walls of the observation chamber 2-1 (as Figure 1 shown, the left and right sides of the observation chamber 2-1), two visual windows 2-2 are provided. An observation platform 2-3 is arranged inside the observation chamber 2-1, which is located between the two visual windows 2-2 and directly below the capillary needle 1-4, and can be used to carry the observed liquid droplets dripping from the capillary needle 1-4. A thermoelectric effect semiconductor 2-4 is installed inside or on the lower surface of the observation platform 2-3, which can heat or cool the liquid droplets by heat transfer through the observation platform 2-3 to achieve the evaporation and condensation of the liquid droplets, and can further be used to observe the evaporation and condensation phenomena of the refrigerant liquid droplets. A safety valve 2-5 is also provided at the top of the observation chamber 2-1. When the pressure in the observation chamber 2-1 is too high, it can connect the inner cavity of the observation chamber 2-1 to the atmosphere for pressure relief to prevent safety accidents.

[0058] The temperature sensor 3-4 and the pressure sensor 3-5 are respectively arranged in the observation chamber 2-1 to obtain the temperature data and pressure data inside the observation chamber 2-1 in real time; the pressure microcontroller unit 3-3 is electrically connected to the temperature sensor 3-4 and the pressure sensor 3-5 respectively. Furthermore, the data obtained by the temperature sensor 3-4 and the pressure sensor 3-5 will be transmitted to the pressure microcontroller unit 3-3 in real time for processing and analysis (such as: comparing with the set value). The electric heating module 3-1 and the semiconductor refrigeration chip 3-2 are respectively arranged on the sample injection chamber 1-1 to change the temperature of the sample injection chamber 1-1. Specifically, the electric heating module 3-1 is arranged on the side wall of the sample injection chamber 1-1 to heat the liquid refrigerant inside the sample injection chamber 1-1, and the semiconductor refrigeration chip 3-2 is arranged on the top of the sample injection chamber 1-1 to condense the gaseous refrigerant located at the top of the sample injection chamber 1-1; the pressure microcontroller unit 3-3 is also electrically connected to the electric heating module 3-1 and the semiconductor refrigeration chip 3-2 respectively. Thus, the pressure microcontroller unit 3-3 sends instructions to the electric heating module 3-1 and the semiconductor refrigeration chip 3-2 according to the processing results to adjust the heating / cooling power, so that the pressure inside the observation chamber 2-1 is maintained at the set value to achieve feedback temperature regulation.

[0059] The high-speed camera 4-1 and the light source 4-2 are respectively arranged outside two visual windows 2-2 and are both oriented towards the observation platform 2-3, as Figure 1 shown in the figure, the high-speed camera 4-1 is arranged outside the left visual window 2-2 (left side) and is oriented towards the observation platform 2-3, and the light source 4-2 is arranged outside the right visual window 2-2 (right side) and is oriented towards the observation platform 2-3. Among them, the field of view of the high-speed camera 4-1 should cover the capillary needle 1-4 to the observation platform 2-3 to well capture the process of the liquid droplet dripping onto the surface of the observation platform 2-3 and the state of the liquid droplet after stabilization on the observation platform 2-3; particularly, the high-speed camera 4-1 and the light source 4-2 can be set coaxially, and the height of the observation platform 2-3 can be controlled so that the liquid droplet stabilized on the observation platform 2-3 is also located on the optical axis to obtain the optimal image effect. The computer 4-3 is electrically connected to the high-speed camera 4-1. Furthermore, the computer 4-3 can obtain the images taken by the high-speed camera 4-1 and perform image analysis and processing to achieve the measurement and analysis of the liquid droplet.

[0060] The vacuum pump 5-1 is connected to the sample injection chamber 1-1 through a vacuum tube. Among them, a vacuum buffer container 5-2 is also connected between the vacuum pump 5-1 and the sample injection chamber 1-1 through a vacuum tube. A pressure gauge 5-3 is arranged on the vacuum buffer container 5-2 to measure the pressure (vacuum degree) reached by the instrument, and a vacuum valve 5-4 is arranged on each of the vacuum tubes between the vacuum pump 5-1 and the vacuum buffer container 5-2 and between the vacuum buffer container 5-2 and the sample injection chamber 1-1 to control the on / off of the vacuum tube.

[0061] Among the above, the sample injection chamber 1-1 and the observation chamber 2-1 are made of stainless steel materials, and the designed pressure and temperature can reach 40 MPa and 500 °C. Moreover, heat insulation layers are respectively arranged around the outer walls of the sample injection chamber 1-1 and the observation chamber 2-1 to reduce heat loss and facilitate maintaining the constant temperature control of the device. In addition, the interfaces related to circuit connections on the sample injection chamber 1-1 and the observation chamber 2-1 all adopt aviation connectors to ensure the airtightness of the high-pressure environment chambers (the sample injection chamber 1-1 and the observation chamber 2-1) while realizing the input and output of electrical signals. The capillary needle 1-4 is made of stainless steel material to provide reliable structural strength and will not affect the determination of the refrigerant.

[0062] Among the above, the visual window 2-2 is a sapphire window, which is fixedly assembled to the side wall of the observation chamber 2-1 through a window flange. After being sealed between the window flange and the observation chamber 2-1 with a polytetrafluoroethylene sealing ring, it is fastened with a compression bolt.

[0063] Among the above, the observation platform 2-3 is a cylindrical boss structure, which is connected to the observation chamber 2-1 through a flange. The surface of the observation platform 2-3 can be designed as a replaceable surface (replaced according to the plane to be measured), and its surface is fixed by a bayonet connection. The distance between the surface of the observation platform 2-3 and the lower end of the capillary needle 1-4 is controlled between 3 - 10 mm.

[0064] Among the above, after the sample injection chamber 1-1 and the observation chamber 2-1 of the device jointly form a sealed space and a liquid refrigerant is filled into the sample injection chamber 1-1, the temperature and pressure inside the sealed space are related to the saturated vapor pressure of the liquid refrigerant. Furthermore, the power of the electric heating module 3-1 and the semiconductor refrigeration sheet 3-2 can be adjusted through the instruction of the pressure micro-control unit 3-3 to achieve the regulation of temperature, and then the regulation of pressure, so that the pressure in the observation chamber 2-1 reaches and maintains at the set value.

[0065] Among the above, each structure can adopt existing products. For example, the electric heating module 3-1 can adopt an electric heating jacket, etc., the pressure micro-control unit 3-3 can adopt a single-chip microcomputer, etc., the temperature sensor 3-4 can adopt a thermocouple, etc., the pressure sensor 3-5 can adopt a piezoelectric pressure sensor, etc., and both the thermoelectric effect semiconductor 2-4 and the semiconductor refrigeration sheet 3-2 can adopt semiconductor refrigeration sheets with the Peltier effect, etc. The power consumption of the thermoelectric effect semiconductor 2-4 does not exceed 1 / 10 of the refrigeration power of the semiconductor refrigeration sheet 3-2 to avoid the out-of-control of the system pressure.

[0066] Among the above, the light source 4-2 adopts a cold light source 4-2 to avoid the volatilization of liquid droplets from affecting the measurement of the contact angle.

[0067] The working process of this device is as follows:

[0068] Before the experiment starts, close all valves and check the airtightness of the experimental device.

[0069] Open the vacuum valve 5-4, start the vacuum pump 5-1 to extract the air in the sample injection chamber 1-1 and the observation chamber 2-1, and then close the vacuum valve 5-4 and the vacuum pump 5-1. Open the filling valve 1-6, and use the pressure difference to fill an appropriate amount of liquid refrigerant into the sample injection chamber 1-1. The filled refrigerant gathers at the bottom end of the sample injection chamber 1-1. After the sample filling is completed, close the filling valve 1-6. The pressure micro-control unit 3-3 controls the heating power and refrigeration power of the electric heating module 3-1 and the semiconductor refrigeration chip 3-2 according to the data collected by the temperature sensor 3-4 and the pressure sensor 3-5, so as to regulate the pressure in the observation chamber 2-1 to the target set value and keep it stable.

[0070] When the pressure and temperature in the observation chamber 2-1 reach the set values and remain stable within a certain period of time, open the sample injection valve 1-3, and use the gravity of the liquid to drip the liquid through the stainless steel capillary needle 1-4 onto the observation platform 2-3. After the dripping is completed, close the sample injection valve 1-3. Observe the droplet shape through the visual window 2-2. After the droplet shape on the observation platform 2-3 is stable, use the high-speed camera 4-1 and the cold light source 4-2 to photograph the droplet to record its shape for at least 5 seconds. The images obtained by the high-speed camera 4-1 are transmitted to the computer 4-3 for analysis and processing (such as operations such as cropping, denoising, grayscale, and edge extraction, all of which are carried out by existing methods), select multiple groups of images with the same shape to measure the contact angle of the droplet, and take the average value to obtain the measured value of the droplet contact angle.

[0071] After the measurement is completed, close all valves and equipment in sequence. After the sample injection chamber 1-1 and the observation chamber 2-1 are cooled, let the residual liquid refrigerant in the container flow into the vacuum buffer container 5-2 for recycling, and clean the inner cavities of the sample injection chamber 1-1 and the observation chamber 2-1 after pressure relief.

[0072] This solution can: control the thermoelectric effect semiconductor 2-4 (control the direction of the current flowing through it) to adjust the temperature of the observation platform 2-3. Furthermore, this device can also be used to observe the evaporation and condensation phenomena of droplets; by replacing the surface of the experimental solid (observation platform 2-3), changing surface characteristics such as surface type and surface structure, the contact angle of different solid surfaces can be measured; by adjusting the sample injection of the sample injection valve 1-3, the droplet size can be changed; by changing the refrigerant storage tank 1-5, the type of test droplet can be changed.

[0073] Repeat the above experimental steps to accurately measure and observe the contact angles and evaporation and condensation phenomena of different refrigerant types, different droplet sizes, and different solid surfaces. This device is convenient to operate when in use and can quickly change the test conditions, providing extensive support for the research on the wettability of refrigerant droplets.

[0074] Taking the measurement of the contact angle of R134a refrigerant as an example, the operation steps are as follows:

[0075] (1) Before the experiment starts, close all valves and check the airtightness of the experimental device.

[0076] (2) Open the vacuum valve 5-4, start the vacuum pump 5-1, evacuate the air in the high-pressure environmental chamber, and then close the vacuum valve 5-4.

[0077] (3) Open the filling valve 1-6 and use the pressure difference to fill 200 mL of R134a refrigerant into the sampling chamber 1-1, which will gather at the bottom of the sampling chamber 1-1. After completion, close the filling valve 1-6.

[0078] (4) Turn on the electric heating module 3-1, use the pressure micro-control unit 3-3 to collect the data of the temperature sensor 3-4 and the pressure sensor 3-5, and command to control the heating power and refrigeration power of the electric heating module 3-1 and the semiconductor refrigeration chip 3-2, so that the observation chamber 2-1 reaches 303.15 K and 5.2 bar and stabilizes for 10 min.

[0079] (5) Control the sampling valve 1-3, and then use the gravity of the liquid droplet to drip the liquid through the stainless steel capillary needle 1-4 onto the observation platform 2-3. After dripping, close the sampling valve 1-3.

[0080] (6) After the liquid droplet stabilizes on the observation platform 2-3, turn on the cold light source 4-2, and use the high-speed camera 4-1 to continuously capture the shape of the liquid droplet through the visual window 2-2 for 8 seconds. The image is transmitted to the computer 4-3 for analysis and processing.

[0081] (7) Select images with the same shape to measure the contact angle of the liquid droplet and take the average value.

[0082] (8) After the measurement, close all valves and equipment in sequence. After the high-pressure environmental chamber cools down, let the residual liquid in the container flow into the vacuum bottle for recovery. After pressure relief, clean the inner cavity of the high-pressure environmental chamber.

[0083] The advantages of the measuring device for visualizing refrigerant droplets of the present invention are that it can realize the measurement of the contact angle of the liquid droplet and the observation of the evaporation and condensation of the liquid droplet without supporting high-pressure sampling equipment. The working principle of the device is as follows: The sampling chamber 1-1 and the observation chamber 2-1 are in a high-pressure environment. An appropriate amount of liquid refrigerant is filled in the sampling chamber 1-1, and the sampling chamber 1-1 and the observation chamber 2-1 are connected to make the two chambers reach the gas-liquid equilibrium pressure. Under the action of gravity, the liquid in the sampling chamber 1-1 is sampled into the observation platform 2-3 in the observation chamber 2-1 for observation. In addition, a thermoelectric effect semiconductor 2-4 chip is arranged in the observation platform 2-3 of the present invention, which can realize the observation of the evaporation and condensation of the liquid droplet. This measuring device does not require supporting high-pressure sampling equipment, reduces the cost of the device, is easier to operate, and at the same time increases the function of measuring the evaporation and condensation of refrigerant droplets, and can meet the various test needs of testers.

[0084] The above description of the embodiments is provided to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention should fall within the protection scope of the present invention according to the disclosure of the present invention.

Claims

1. A visualization measurement device for refrigerant droplets, characterized in that, It includes a droplet injection system, a high-pressure visualization system, a pressure control system, and an optical imaging system; The droplet injection system includes an injection chamber (1-1), an injection valve (1-3), a capillary needle (1-4), and a connecting pipe (1-7); the injection chamber (1-1) is connected to the capillary needle (1-4) through an injection pipe, the injection valve (1-3) is arranged on the injection pipe, and the capillary needle (1-4) is arranged along the gravity direction; The high-pressure visualization system includes an observation chamber (2-1), a visual window (2-2), an observation platform (2-3), and a thermoelectric effect semiconductor (2-4); the capillary needle (1-4) extends into the observation chamber (2-1), and the observation chamber (2-1) is connected to the injection chamber (1-1) through the connecting pipe (1-7); the visual window (2-2) is arranged on a pair of opposite side walls of the observation chamber (2-1), the observation platform (2-3) is fixed inside the observation chamber (2-1), and the observation platform (2-3) is located between the visual windows (2-2) and below the capillary needle (1-4), and the thermoelectric effect semiconductor (2-4) is arranged on the observation platform (2-3); The pressure control system includes an electric heating module (3-1), a semiconductor refrigeration sheet (3-2), and a pressure micro-control unit (3-3); the electric heating module (3-1) is arranged on the side of the injection chamber (1-1), the semiconductor refrigeration sheet (3-2) is arranged on the top of the injection chamber (1-1), and the pressure micro-control unit (3-3) is electrically connected to the electric heating module (3-1) and the semiconductor refrigeration sheet (3-2); The optical imaging system includes a high-speed camera (4-1), a light source (4-2), and a computer (4-3); the high-speed camera (4-1) is arranged outside the visual window (2-2) on one side of the observation chamber (2-1), and the field of view of the high-speed camera (4-1) covers the capillary needle (1-4) and the observation platform (2-3), the light source (4-2) is arranged outside the visual window (2-2) on the other side of the observation chamber (2-1), and the light source (4-2) is arranged facing the observation platform (2-3), and the computer (4-3) is electrically connected to the high-speed camera (4-1).

2. The visualization measurement device for refrigerant droplets according to claim 1, wherein The injection chamber (1-1) is of an inverted cone structure, the electric heating module (3-1) is arranged on the inclined surface of the injection chamber (1-1), and the semiconductor refrigeration sheet (3-2) is arranged on the top surface of the injection chamber (1-1).

3. The visualization measurement device for refrigerant droplets according to claim 1, wherein, The high-pressure visualization system further includes a safety valve (2-5); the safety valve (2-5) is arranged on the observation chamber (2-1) and is used to connect the observation chamber (2-1) with the atmosphere when the pressure inside the observation chamber (2-1) exceeds the limit.

4. The visualization measurement device for refrigerant droplets according to claim 1, characterized in that, The described pressure control system further includes a temperature sensor (3-4) and a pressure sensor (3-5); the temperature sensor (3-4) is disposed inside the observation chamber (2-1) for obtaining the temperature inside the observation chamber (2-1); the pressure sensor (3-5) is disposed inside the observation chamber (2-1) for obtaining the pressure inside the observation chamber (2-1); the temperature sensor (3-4) and the pressure sensor (3-5) are respectively electrically connected to the pressure micro control unit (3-3).

5. The visualization measurement device for refrigerant droplets according to claim 1, characterized in that, The described visualization measurement device further includes a vacuum pumping system; The described droplet injection system further includes a refrigerant liquid storage tank (1-5) and a filling valve (1-6); the refrigerant liquid storage tank (1-5) is connected to the injection chamber (1-1) through a feed pipe, and the filling valve (1-6) is disposed on the feed pipe; The described vacuum pumping system includes a vacuum pump (5-1), a vacuum buffer container (5-2), a pressure gauge (5-3) and a vacuum valve (5-4); the vacuum pump (5-1) is connected to the injection chamber (1-1) through a vacuum pipe, and the vacuum buffer container (5-2) is connected between the vacuum pump (5-1) and the injection chamber (1-1) through a vacuum pipe; the pressure gauge (5-3) is connected to the vacuum buffer container (5-2) for obtaining the pressure inside the vacuum buffer container (5-2); the vacuum valve (5-4) is disposed on the vacuum pipe between the vacuum pump (5-1) and the vacuum buffer container (5-2) and on the vacuum pipe between the vacuum buffer container (5-2) and the injection chamber (1-1).

6. The visualization measurement device for refrigerant droplets according to claim 1, characterized in that, The described droplet injection system further includes a liquid level gauge (1-2), and both ends of the liquid level gauge (1-2) are respectively connected to the top and the bottom of the injection chamber (1-1) for indicating the liquid level height inside the injection chamber (1-1).

7. A visualization measurement device for refrigerant droplets according to claim 1, characterized in that, The injection chamber (1-1) and the observation chamber (2-1) are made of stainless steel material, and a heat insulation layer is provided on the outer surfaces of the injection chamber (1-1) and the observation chamber (2-1); the capillary needle tube (1-4) is made of stainless steel material.

8. The visualization measurement device for refrigerant droplets according to claim 1, characterized in that The described visual window (2-2) is a sapphire window, the visual window (2-2) is fastened to the side wall of the observation chamber (2-1) through a window flange, and the visual window (2-2) and the observation chamber (2-1) are sealed through a polytetrafluoroethylene sealing ring.

9. A visualization measurement method for refrigerant droplets, characterized in that, Visualization measurement is performed using the device according to any one of claims 1-8; The described method includes the following steps: S1: Close all valves and check the airtightness of the experimental device; S2: Fill the injection chamber (1-1) with liquid refrigerant, and the filled refrigerant gathers at the bottom end of the injection chamber (1-1); S3: Adjust the power of the electric heating module (3-1) and the semiconductor refrigerating sheet (3-2) through the pressure micro control unit (3-3) to maintain the pressure in the observation chamber (2-1) at a set value and keep it stable; S4: When the pressure and temperature in the observation chamber (2-1) reach the set values and become stable, open the sampling valve (1-3), and use the gravitational force of the liquid to drip the liquid onto the observation platform (2-3) through the capillary needle (1-4). After the dripping is completed, close the sampling valve (1-3); S5: Observe the morphology of the liquid droplet through the visual window (2-2). After waiting for the liquid droplet to become stable on the observation platform (2-3), use the high-speed camera (4-1) to capture the morphology of the liquid droplet; S6: The images captured by the high-speed camera (4-1) are transmitted to the computer (4-3) for analysis and processing. Select multiple groups of images with the same morphology to measure the contact angle of the liquid droplet and take the average value; S7: Adjust the temperature of the observation platform (2-3) through the thermoelectric effect semiconductor (2-4) to observe the evaporation and condensation phenomena of the liquid droplet; S8: After the measurement is completed, turn off the device and all valves. After the sampling chamber (1-1) and the observation chamber (2-1) are cooled, collect the remaining liquid refrigerant in the sampling chamber (1-1), and clean the inner cavities of the sampling chamber (1-1) and the observation chamber (2-1) after the device is depressurized.

10. A method for visual measurement of refrigerant droplets according to claim 9, characterized in that, When the high-speed camera (4-1) captures the morphology of the liquid droplet, the shooting time is greater than 5 seconds.

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