Supercritical carbon dioxide flow heat transfer experiment system

Abstract

The invention discloses a supercritical carbon dioxide flow heat transfer experiment system which comprises a carbon dioxide steel cylinder and a subcritical carbon dioxide tank connected with the gas outlet end of the carbon dioxide steel cylinder, a heating belt is installed on the outer surface of the carbon dioxide steel cylinder, and a cooling pipe is installed on the outer surface of the subcritical carbon dioxide tank. And a vacuum pumping interface and a high-pressure stop valve are arranged between the carbon dioxide steel cylinder and the subcritical carbon dioxide tank. The device has the beneficial effects that subcritical carbon dioxide liquid can be effectively pressurized to a supercritical state by utilizing the diaphragm metering pump, and the device has excellent performance in application scenes needing high-pressure carbon dioxide, such as the fields of supercritical fluid extraction, material treatment and the like due to the efficient pressurizing capability; the device can perform supercritical carbon dioxide flow heat transfer experiment research on test single tubes with different pressures and temperatures and different specifications, is suitable for various industrial and research scenes due to the wide pressure adjusting range, and enhances the market adaptability and application value.

Description

Technical Field

[0001] The present invention relates to the technical field, in particular to a supercritical carbon dioxide flow and heat transfer experimental system. Background Art

[0002] With the change of environmental temperature and pressure, some substances exist in three phases - gas phase, liquid phase, and solid phase. The point where the three phases coexist in an equilibrium state is called the triple point, and the state point where the liquid-gas two-phase interface disappears is called the critical point. The temperature and pressure at the critical point are called the critical temperature and critical pressure respectively. Different substances have different critical point pressures and temperatures. Supercritical fluids refer to fluids with temperatures and pressures both higher than their critical points. Commonly used supercritical fluids include carbon dioxide, ammonia, ethylene, propane, propylene, water, etc. When an object is in a supercritical state, since the properties of the gas and liquid phases are very similar and it is impossible to clearly distinguish them, it is called a "supercritical fluid". Supercritical fluid extraction technology has attracted great interest in people in the past 30-odd years. This new chemical technology has carried out extensive and in-depth research in the fields of chemical reactions and separation and purification, and has made great progress, with fruitful results in the fields of medicine, chemical industry, food, and environmental protection. Among them, supercritical carbon dioxide has a wide range of applications in many fields such as heat pumps, drug extraction, nanoparticle preparation, electronic component cleaning, and the energy field. However, the existing supercritical carbon dioxide flow and heat transfer experimental devices cannot collect the pressure, flow rate, heat load, and internal / wall temperature during the flow and heat transfer process of supercritical / subcritical carbon dioxide at different temperatures in real time, and cannot meet the experimental requirements for studying the flow and heat transfer conditions of supercritical carbon dioxide fluids. Summary of the Invention

[0003] The purpose of the present invention is to overcome the disadvantages that the existing supercritical carbon dioxide flow and heat transfer experimental devices cannot collect the pressure, flow rate, heat load, and internal / wall temperature during the flow and heat transfer process of supercritical / subcritical carbon dioxide at different temperatures in real time, and cannot meet the experimental requirements for studying the flow and heat transfer conditions of different heat transfer single-tube supercritical carbon dioxide fluids, and to provide a supercritical carbon dioxide flow and heat transfer experimental system.

[0004] The purpose of the present invention is achieved through the following technical solutions: A supercritical carbon dioxide flow and heat transfer experimental system includes a carbon dioxide cylinder, a subcritical carbon dioxide tank connected to the gas outlet end of the carbon dioxide cylinder, a heating belt installed on the outer surface of the carbon dioxide cylinder, a cooling pipe installed on the outer surface of the subcritical carbon dioxide tank, a vacuum pumping interface and a high-pressure stop valve are arranged between the carbon dioxide cylinder and the subcritical carbon dioxide tank, and the vacuum pumping interface is connected to an external vacuum generator;

[0005] The outlet end of the subcritical carbon dioxide tank is connected to a diaphragm metering pump. The outlet end of the diaphragm metering pump is respectively connected to a cooler and a test pipe section. The outlet end of the test pipe section is connected to the cooler. The outlet end of the cooler is connected to the inlet end of the subcritical carbon dioxide tank through a back pressure valve and a bypass ball valve. Pressure sensors and temperature sensors are installed at both ends of the test pipe section.

[0006] A pressure stabilizing tank and a cooling heater are connected between the outlet end of the diaphragm metering pump and the test pipe section;

[0007] This device can effectively boost subcritical carbon dioxide liquid to the supercritical state (pressure exceeding 7.38 MPa) by using a diaphragm metering pump, and the maximum pressure can reach above 30 MPa. This efficient boosting ability makes this device perform excellently in application scenarios that require high-pressure carbon dioxide, such as supercritical fluid extraction, material processing and other fields. This device can conduct experimental research on the flow and heat transfer of supercritical carbon dioxide with different pressure and temperature requirements. Its wide pressure regulation range makes it suitable for a variety of industrial and research scenarios, enhancing its market adaptability and application value;

[0008] A further technical solution is that electromagnetic valves are installed at both the inlet end and the outlet end of the diaphragm metering pump.

[0009] A further technical solution is that both the inlet end and the outlet end of the cooling pipe are connected to a cooling water tank, and the cooling water tank is connected to a cooling unit.

[0010] A further technical solution is that a regulating working fluid pump and a precision regulating valve for adjusting the flow rate of the test pipe section are installed between the diaphragm metering pump and the cooler.

[0011] A further technical solution is that the diaphragm metering pump is connected to an expansion tank. The expansion tank has an automatic pressure relief function. By setting a dynamic expansion air release design, it effectively avoids the excessive stress of the diaphragm caused by the internal residual high pressure after the diaphragm metering pump stops, significantly reduces the loss of the diaphragm, extends the service life of the equipment, and also reduces the maintenance cost. The automatic pressure relief function not only reduces the risk of equipment failure, but also enhances the operation safety of the safety valve. It avoids accidental leakage or equipment damage that may be caused by pressure accumulation, ensuring the continuity and stability of the production process.

[0012] A further technical solution is that the outside of the cooling heater is connected to the cooling water tank, and a heating pipe is installed on the cooling heater.

[0013] A further technical solution is that flanges are installed on both sides of the test pipe section. The two groups of flanges are connected through insulating sheaths and insulating gaskets to ensure that the test single pipe is completely insulated from other parts of the system. The test single pipe can be heated only by a DC power supply. At the same time, different specifications of test single pipes can be replaced through the flanges.

[0014] A further technical solution is that insulating sealing gaskets are installed inside both groups of flanges;

[0015] The present invention has the following advantages: The present invention utilizes a diaphragm metering pump to effectively boost subcritical carbon dioxide liquid to the supercritical state (pressure exceeding 7.38 MPa), and the maximum pressure can reach above 30 MPa. This efficient boosting ability enables the device to perform excellently in application scenarios requiring high-pressure carbon dioxide, such as supercritical fluid extraction, material processing, etc. The device can conduct experimental studies on the flow and heat transfer of supercritical carbon dioxide with different pressure and temperature requirements. Its wide pressure adjustment range makes it applicable to a variety of industrial and research scenarios, enhancing its market adaptability and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0017] Figure 2 is an enlarged schematic diagram of the test pipe section in the present invention;

[0018] In the figure, 1. carbon dioxide cylinder; 2. subcritical carbon dioxide tank; 3. heating tape; 4. cooling pipe; 5. vacuum pumping interface; 6. high-pressure stop valve; 7. back pressure valve; 8. bypass ball valve; 9. cooler; 10. expansion tank; 11. diaphragm metering pump; 12. pressure stabilizing tank; 13. cooling and heating device; 14. cooling water tank; 15. cooling unit; 16. test pipe section; 17. insulating sealing gasket; 18. insulating sheath; 19. insulating gasket. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0022] It should be noted that like reference numerals and letters refer to like items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] As Figures 1 to 2 shown, a supercritical carbon dioxide flow and heat transfer experimental system includes a carbon dioxide cylinder 1, a subcritical carbon dioxide tank 2 connected to the gas outlet end of the carbon dioxide cylinder 1, a heating tape 3 installed on the outer surface of the carbon dioxide cylinder 1, a cooling pipe 4 installed on the outer surface of the subcritical carbon dioxide tank 2, a vacuum pumping interface 5 and a high-pressure stop valve 6 provided between the carbon dioxide cylinder 1 and the subcritical carbon dioxide tank 2, and the vacuum pumping interface 5 is connected to an external vacuum generator;

[0026] The gas outlet end of the subcritical carbon dioxide tank 2 is connected to a diaphragm metering pump 11. The gas outlet end of the diaphragm metering pump 11 is respectively connected to a cooler 9 and a test pipe section 16. The gas outlet end of the test pipe section 16 is connected to the cooler 9. The gas outlet end of the cooler 9 is connected to the gas inlet end of the subcritical carbon dioxide tank 2 through a back pressure valve 7 and a bypass ball valve 8. Pressure sensors and temperature sensors are installed at both ends of the test pipe section 16.

[0027] A pressure stabilizing tank 12 and a cooling and heating device 13 are connected between the gas outlet end of the diaphragm metering pump 11 and the test pipe section 16;

[0028] This device utilizes a diaphragm metering pump 11 to effectively boost subcritical carbon dioxide liquid to a supercritical state with a pressure exceeding 7.38 MPa, and the maximum pressure can reach above 30 MPa. This efficient boosting ability enables the device to perform outstandingly in application scenarios that require high-pressure carbon dioxide, such as supercritical fluid extraction, material processing, etc. The device can conduct experimental studies on the flow and heat transfer of supercritical carbon dioxide with different pressure and temperature requirements. Its wide pressure adjustment range makes it suitable for a variety of industrial and research scenarios, enhancing its market adaptability and application value;

[0029] A further technical solution is that electromagnetic valves are installed at both the intake end and the outlet end of the diaphragm metering pump 11.

[0030] A further technical solution is that both the water inlet end and the water outlet end of the cooling pipe 4 are connected to the cooling water tank 14, and the cooling water tank 14 is connected to a cooling unit 15.

[0031] A further technical solution is that an adjusting working fluid pump and a precision regulating valve for adjusting the flow rate of the test pipe section 16 are installed between the diaphragm metering pump 11 and the cooler 9.

[0032] A further technical solution is that the diaphragm metering pump 11 is connected to an expansion tank 10. The expansion tank 10 has an automatic pressure relief function. By setting a dynamic expansion and gas release design, it effectively avoids the excessive stress of the diaphragm caused by the internal residual high pressure after the diaphragm metering pump 11 stops, significantly reduces the loss of the diaphragm, extends the service life of the equipment, and also reduces the maintenance cost. The automatic pressure relief function not only reduces the risk of equipment failure, but also enhances the safety of operation. It avoids accidental leakage or equipment damage that may be caused by pressure accumulation, ensuring the continuity and stability of the production process.

[0033] A further technical solution is that the outside of the cooling heater 13 is connected to the cooling water tank 14, and a heating pipe is installed on the cooling heater 13.

[0034] A further technical solution is that flanges are installed on both sides of the test pipe section 16. The two groups of flanges are connected through an insulating sheath 18 and an insulating gasket 19. Different specifications of the test pipe section 16 can be replaced, and the test pipe section 16 can be heated by a direct current (DC) power supply. The insulating sheath 18 and the insulating gasket 19 ensure that the test pipe section 16 is completely insulated from other parts of the system. The test pipe section 16 can be heated only by the direct current power supply, and at the same time, different specifications of the test pipe section 16 can be replaced through the flanges.

[0035] A further technical solution is that insulating sealing gaskets 17 are installed inside the two groups of flanges.

[0036] A further technical solution is that the test pipe section 16 can be filled with glass beads or other regular or irregular particles or substances of different specifications to conduct tests on this working condition, and the heat transfer coefficient of supercritical carbon dioxide in the test pipe section 16 can be measured.

[0037] Among them, given the wall temperature (To) of the single wall for heat transfer of supercritical carbon dioxide and the internal temperature Ti of the fluid, the steps for calculating the total heat transfer coefficient h are as follows:

[0038] 1. Calculate the heat flux density q

[0039] The heat flux density q is obtained through experiments or simulations, and the formula is:

[0040] q = Q / A

[0041] Where:

[0042] - Q is the heat transfer amount (W), which is the heating power of the DC power supply in this experimental system.

[0043] - A is the heat transfer area (m 2 ), which is the heat exchange area of the single heat transfer pipe in this experimental system.

[0044] 2. Calculate the heat transfer coefficient h

[0045] The heat transfer coefficient is calculated using Newton's law of cooling:

[0046] h = q / (To - Ti)

[0047] Where:

[0048] - To is the wall temperature (K or °C)

[0049] - Ti is the internal temperature of the fluid (K or °C).

[0050] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A supercritical carbon dioxide flow heat transfer experimental system, comprising a carbon dioxide cylinder (1), characterized in that: A subcritical carbon dioxide tank (2) is connected to the gas outlet end of the carbon dioxide cylinder (1), a heating belt (3) is installed on the outer surface of the carbon dioxide cylinder (1), a cooling pipe (4) is installed on the outer surface of the subcritical carbon dioxide tank (2), a vacuum exhaust interface (5) and a high-pressure stop valve (6) are arranged between the carbon dioxide cylinder (1) and the subcritical carbon dioxide tank (2), and the vacuum exhaust interface (5) is connected to an external vacuum generator; The gas outlet end of the subcritical carbon dioxide tank (2) is connected to a diaphragm metering pump (11), and the gas outlet end of the diaphragm metering pump (11) is respectively connected to a cooler (9) and a test pipe section (16), the gas outlet end of the test pipe section (16) is connected to the cooler (9), and the gas outlet end of the cooler (9) is connected to the gas inlet end of the subcritical carbon dioxide tank (2) through a back pressure valve (7) and a bypass ball valve (8), and pressure sensors and temperature sensors are installed at both ends of the test pipe section (16). A pressure stabilizing tank (12) and a cooling heater (13) are connected between the gas outlet end of the diaphragm metering pump (11) and the test pipe section (16).

2. A supercritical carbon dioxide flow heat transfer experimental system according to claim 1, characterized in that: Solenoid valves are installed at both the air inlet and outlet ends of the diaphragm metering pump (11).

3. A supercritical carbon dioxide flow heat transfer experimental system according to claim 1, characterized in that: The water inlet and outlet ends of the cooling pipe (4) are both connected to a cooling water tank (14), and the cooling water tank (14) is connected to a cooling unit (15).

4. A supercritical carbon dioxide flow heat transfer experimental system according to claim 1, characterized in that: A regulating fluid pump and a precision regulating valve for regulating the flow of the test pipe section (16) are installed between the diaphragm metering pump (11) and the cooler (9).

5. The supercritical carbon dioxide flow heat transfer experimental system according to claim 1, characterized in that: The diaphragm metering pump (11) is connected to an expansion tank (10), and the expansion tank (10) has an automatic pressure relief function.

6. A supercritical carbon dioxide flow heat transfer experimental system according to claim 1, characterized in that: The outside of the cooling heater (13) is connected to a cooling water tank (14), and a heating pipe is installed on the cooling heater (13).

7. A supercritical carbon dioxide flow heat transfer experimental system according to claim 1, characterized in that: Flanges are installed on both sides of the test pipe section (16), and the two sets of flanges are connected through insulating sheaths (18) and insulating gaskets (19).

8. A supercritical carbon dioxide flow heat transfer experimental system according to claim 7, characterized in that: Insulating sealing gaskets (17) are installed in both sets of flanges.

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