Visualized test system for saturation point of CO2 mixed working fluid

Abstract

The present application relates to a kind of visualization CO2 mixed working medium saturation state point test system, including working medium precooler, working medium storage tank, evaporator, heat exchanger, front end precooler, front end condenser, supercooler and visual observation, working medium precooler outlet end is connected to working medium storage tank inlet end, working medium storage tank outlet end is connected to evaporator inlet end, pipeline sight glass is set in the outlet end of working medium precooler and working medium storage tank, visual precooled observation is set between front end precooler and front end condenser, visual condensing observation is set between front end condenser and supercooler.The present application is by the setting of visual window, so that experimental personnel can visually observe the state that working medium phase change process droplet generates and bubble disappears, and record using high-speed camera, can effectively guarantee the accuracy of measured data, CO2 mixed working medium saturation state point test experiment has important use value, applicable to conversion application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of thermal equipment, and relates to a mixed working medium measurement technology, in particular to a visual CO2 mixed working medium saturation state point test system. BACKGROUND

[0002] With the increasingly prominent energy shortage problem and the strengthening of environmental protection awareness, the society's attention, research and utilization of renewable energy are continuously strengthened. Geothermal power generation and ground source heat pump heating are the main ways to utilize geothermal resources at present, and selecting appropriate working medium for different grade heat source conditions and utilization modes becomes the research focus, so as to maximize the utilization of geothermal resources, improve efficiency and reduce loss.

[0003] In order to improve the efficiency of geothermal power generation and ground source heat pump system and reduce the loss of heat transfer process in the evaporator and condenser, the temperature difference between the working medium and the cold and hot source fluid should be as small as possible in the heat transfer process. The existing system mainly uses a single working medium, and the working medium in the evaporator and condenser undergoes a constant temperature and pressure phase change process. The temperature difference between the working medium and the cold and hot source fluid is large, the heat transfer loss is large, and the net output of the system is reduced. The CO2 mixed working medium is mixed by CO2 and organic working medium, and the temperature of the constant pressure heat transfer process in the evaporator and condenser is variable, and there is a temperature glide phenomenon. The temperature difference between the working medium and the cold and hot source fluid is small, the loss is small, and the system output is more.

[0004] The existing mixed working medium heat transfer experiment mainly focuses on the influence of fluid flow, heat exchanger structure and size on the heat transfer coefficient, and does not involve the measurement of the constant pressure and variable temperature phase change process in the two-phase region and the saturation liquid point and saturation vapor point. The critical pressure of CO2 and its mixture is relatively high, and the pressure resistance of the system pipeline components is required to be relatively large, especially the design, processing and manufacturing of the visualization components are difficult. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a visual CO2 mixed working medium saturation state point test system. The system can realize the condensation process of CO2 mixed working medium with temperature glide and the measurement of the saturation liquid point and saturation vapor point of the mixed working medium, and can record the phase change process through a high-speed camera. The components in the system are arranged compactly and reasonably, the measurement point position is selected to accurately measure the thermophysical property parameters of the working medium, and the visualization window facilitates the most intuitive observation of the experimental phenomena by the experimenter.

[0006] The technical problem of the present application is solved by adopting the following technical scheme:

[0007] The application discloses a visual CO2 mixed working medium saturation state point test system, which comprises a carbon dioxide gas cylinder, an organic working medium tank, a working medium pre-cooler, a working medium storage tank, an evaporator, a heat exchanger, a front end pre-cooler, a front end condenser, a super-cooler and a visual observer, the outlet ends of the carbon dioxide gas cylinder and the organic working medium tank are communicated to the inlet end of the working medium pre-cooler, the outlet end of the working medium pre-cooler is connected to the inlet end of the working medium storage tank, the outlet end of the working medium storage tank is connected to the inlet end of the evaporator, a pipeline sight glass is arranged at the outlet end of the working medium pre-cooler and the working medium storage tank, the evaporator is sequentially connected to the heat exchanger, the front end pre-cooler, the front end condenser and the super-cooler, the outlet end of the super-cooler is communicated to the working medium storage tank in a reflux mode, a first visual observer, namely a visual pre-cooling observer, is arranged between the front end pre-cooler and the front end condenser, and a second visual observer, namely a visual condensing observer, is arranged between the front end condenser and the super-cooler.

[0008] The visual pre-cooling observer and the visual condensing observer have the same structure, which comprises a shell, a working medium inlet is arranged at the upper end of the shell, a cooling water inlet is arranged at the lower end of the shell, aluminum-silicon glass windows are arranged at the front and back sides of the shell, a high-speed camera is arranged at the front end of the aluminum-silicon glass window, and a temperature measuring kit is arranged on the visual pre-cooling observer and the visual condensing observer.

[0009] The application has the advantages and positive effects that:

[0010] The application has the advantages and positive effects that: BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a system connection schematic diagram of the application;

[0012] Figure 2 It is a side view of the application; Figure 1 It is a visual assembly structure schematic diagram (front view) of the application;

[0013] Figure 3 It is a side view of the application; Figure 2 DETAILED DESCRIPTION

[0014] ​The present invention will be further described in detail below with reference to the accompanying drawings and through specific embodiments. The following embodiments are merely illustrative and non-restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0015] A visual CO2 mixed working medium saturation state point test system, such as Figure 1 As shown, it includes a carbon dioxide gas cylinder 3, an organic working fluid tank 2, a working fluid precooler 5, a working fluid storage tank 20, an evaporator 9, a heat exchanger 12, a front-end precooler 13, a front-end condenser 16, a supercooler 18 and a visual observer. The outlet ends of the carbon dioxide gas cylinder and the organic working fluid tank are merged and connected to the inlet end of the working fluid precooler, the outlet end of the working fluid precooler is connected to the inlet end of the working fluid storage tank, and the outlet end of the working fluid storage tank is connected to the inlet end of the evaporator. Pipe sight glasses 6 are provided at the outlet ends of the working fluid precooler and the working fluid storage tank.

[0016] The evaporator is connected to the heat exchanger, the front-end precooler, the front-end condenser, and the subcooler in sequence. The outlet end of the subcooler is refluxed and connected to the working fluid storage tank. A first visual observer, namely the visual precooling observer 14, is provided between the front-end precooler and the front-end condenser. A second visual observer, namely the visual condensation observer 17, is provided between the front-end condenser and the subcooler.

[0017] The visual pre-cooling observer and the visual condensation observer have the same structure. Figure 2 、 Figure 3 As shown, it includes a shell 23, a working medium inlet 25 is provided at the upper end of the shell, a cooling water inlet 26 is provided at the lower end, and aluminum silicon glass windows 24 are respectively provided on the front and rear sides of the shell. The aluminum silicon glass windows are installed on both sides of the shell through mounting flanges 25. A high-speed camera 15 is provided at the front end of the aluminum silicon glass window, and a temperature measuring kit 22 is provided on both the visual pre-cooling observer and the visual condensation observer.

[0018] A weight sensor 1 is provided at the lower part of the carbon dioxide gas cylinder and the organic working fluid tank, and a pressure reducing valve 4 is provided at the outlet end of the carbon dioxide gas cylinder and the organic working fluid tank.

[0019] A safety valve 10 and a throttle valve 11 are provided between the evaporator and the heat exchanger.

[0020] The refrigerant for the working medium pre-cooler and the sub-cooler is provided by a liquid nitrogen tank 21 .

[0021] A vacuum pump 19 and a carbon dioxide booster pump 7 are provided at the working fluid storage tank end, and a gear flowmeter 8 is also provided at the outlet end of the working fluid storage tank.

[0022] At the same time, sensor elements with monitoring functions such as flow sensors, temperature sensors and pressure sensors are set at the ends of the above-mentioned chemical components according to monitoring needs.

[0023] The working process of the system is as follows:

[0024] Vacuumizing process: open the valve in the working medium pre-cooling pipeline and the circulating loop, open the vacuum pump to vacuumize the experimental system, and when the value displayed by the vacuum pump pressure gauge no longer decreases, close the valve and the vacuum pump.

[0025] Working medium charging process: first, record the initial measurement value of the weight sensor, open the liquid nitrogen tank valve and the liquid nitrogen pre-cooling pipeline valve, make the liquid nitrogen flow into the working medium pre-cooler to reduce the temperature in the heat exchanger. Close the stop valve, adjust the working medium pressure at the outlet of the pressure reducing valve, then the working medium flows into the working medium pre-cooler through the stop valve and is cooled by the liquid nitrogen, and the working medium state is observed through the pipeline sight glass, and the temperature and pressure data measured by the pressure sensor and the temperature sensor are used to determine whether the working medium is completely condensed into liquid state.

[0026] When the working medium is in liquid state, open the stop valve to make the working medium flow into the working medium storage tank, at this time the valve is closed, and the weight sensor value after charging is recorded. According to the same method, the second working medium is injected, and after charging is completed, the stop valve is closed to disconnect the charging system from the working medium circulating loop.

[0027] Working medium circulating loop: open the stop valve to make the liquid mixed working medium in the working medium storage tank enter the booster pump through the pipeline sight window, the liquid working medium is pressurized to the required condition of the experiment, and then enters the evaporator through the flowmeter, pressure sensor and temperature sensor. The opening degree of the valve is adjusted to adjust the return flow, and then the working medium flow into the evaporator is controlled.

[0028] The working medium absorbs heat in the evaporator to vaporize to superheated state, and the superheating degree of the steam is determined by the values measured by the pressure sensor and the temperature sensor. The safety valve is installed behind the evaporator to ensure that the pressure value of the working medium after absorbing heat and vaporizing is within a safe range to avoid safety accidents. The working medium flows through the throttle valve, and the pressure and temperature are reduced. The working medium state after throttling is determined by measuring the data through the pressure sensor and the temperature sensor, and the working medium temperature is changed by adjusting the cooling water flow through the heat exchanger.

[0029] The working medium flowing out of the heat exchanger is sent into the front end pre-cooler after passing through the temperature sensor, and is cooled to the vicinity of the saturation gas point. The superheating degree of the gaseous working medium is determined by the pressure sensor and the temperature sensor. Then, the working medium is sent into the visual pre-cooling observer and is further cooled by the cooling water to generate liquid droplets. The liquid droplet generation phenomenon can be captured by the high-speed camera, and the temperature at which the liquid droplets are generated can be measured by the temperature sensor built in the visual observer.

[0030] There are two sets of open windows on the visual observer to facilitate the observation of droplet generation. The front end condenser is connected to the visual pre-cooling observer through a pipeline. The working medium releases heat to the cooling water in the front end condenser, and the dryness continuously decreases, the gas composition continuously reduces, and only a few bubbles are left, which is close to the saturated liquid point.

[0031] The working medium flowing out of the front end condenser flows into the visual condensing observer, and the cooling water continues to provide cold to the working medium. In the window, the bubbles in the working medium can be seen to reduce until they disappear, and the working medium is completely condensed into a liquid state. The change at this time is recorded by a high-speed camera, and the temperature data is recorded by a temperature sensor built in the visual component. The cooled working medium is sent to the supercooler, and is supercooled to a certain degree by liquid nitrogen to ensure that the working medium returned to the working medium storage tank is completely liquid, completing a cycle.

[0032] The hot water pump in the above pipeline provides the power required for the flow of hot water. The cooling and heat release load in other heat exchangers is provided by the cooling water. The water pump provides power for each cooling water circuit. The cooling water flow is measured by a turbine flowmeter, and the inlet and outlet temperatures of each cooling water circuit are measured by a temperature sensor.

[0033] Although the embodiments of the present application and the drawings are disclosed for the purpose of illustration, those skilled in the art can understand that various alternatives, changes and modifications are possible without departing from the spirit and scope of the present application and the appended claims, therefore, the scope of the present application is not limited to the disclosed content of the embodiments and the drawings.

Claims

1. A visual CO2 mixed working medium saturation state point test system, characterized by: The invention comprises a carbon dioxide gas cylinder, an organic working fluid tank, a working fluid precooler, a working fluid storage tank, an evaporator, a heat exchanger, a front end precooler, a front end condenser, a subcooler and a visual observer. The outlet ends of the carbon dioxide gas cylinder and the organic working fluid tank are connected to the inlet end of the working fluid precooler, the outlet end of the working fluid precooler is connected to the inlet end of the working fluid storage tank, and the outlet end of the working fluid storage tank is connected to the inlet end of the evaporator. Pipe sight glasses are provided at the outlet ends of the working fluid precooler and the working fluid storage tank. The evaporator is connected to the heat exchanger, the front end precooler, the front end condenser, the subcooler, the subcooler in sequence. The outlet end of the device is refluxed and connected to the working medium storage tank. A first visual observer, namely, a visual precooling observer, is provided between the front end precooler and the front end condenser. A second visual observer, namely, a visual condensing observer, is provided between the front end condenser and the subcooler. The visual precooling observer and the visual condensing observer have the same structure, including a shell, a working medium inlet is provided at the upper end of the shell, a cooling water inlet is provided at the lower end, and aluminum silicon glass windows are provided on the front and rear sides of the shell, respectively. A high-speed camera is provided at the front end of the aluminum silicon glass window; A temperature measurement kit is provided on both the visual pre-cooling observer and the visual condensation observer; A weight sensor is provided at the bottom of the carbon dioxide gas cylinder and the organic working fluid tank, and a pressure reducing valve is provided at the outlet of the carbon dioxide gas cylinder and the organic working fluid tank; A safety valve and a throttle valve are provided between the evaporator and the heat exchanger; A vacuum pump and a carbon dioxide booster pump are provided at the working fluid storage tank end, and a gear flow meter is also provided at the outlet end of the working fluid storage tank.

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