CN219871115U

CN219871115U - Vacuum sleeve and supercritical circulating heat insulation test loop

Info

Publication number: CN219871115U
Application number: CN202320582003.5U
Authority: CN
Inventors: 陈林; 杨董
Original assignee: Institute of Engineering Thermophysics of CAS
Current assignee: Institute of Engineering Thermophysics of CAS
Priority date: 2023-03-22
Filing date: 2023-03-22
Publication date: 2023-10-20
Anticipated expiration: 2033-03-22

Abstract

The utility model provides a vacuum sleeve and a supercritical circulating heat insulation test loop, which belong to the technical field of energy, wherein the vacuum sleeve comprises a vacuum coating shell layer sleeved on the outer side of a test section, the vacuum coating shell layer is fixedly connected with an inlet and an outlet of the test section through a first flange, an observation window, a vacuumizing hole and an insulating wiring terminal are arranged on the vacuum coating shell layer, and the test section is connected with a heating power supply through the insulating wiring terminal. The supercritical circulation heat insulation test loop comprises a main circulation loop which is composed of a gas cylinder, a cooler, a heat preservation liquid storage tank, a circulating pump, a flowmeter, a preheater, a test section and a condenser, and further comprises a buffer tank and a water chilling unit, wherein the buffer tank is located between the flowmeter and the circulating pump and connected with the main circulation loop, the water chilling unit is connected with the condenser and the cooler, and the vacuum sleeve is connected with the outer side of the test section. By the processing scheme, heat loss of the test section is effectively reduced, and visual monitoring of the wall surface state of the test section is realized.

Description

Vacuum sleeve and supercritical circulating heat insulation test loop

Technical Field

The utility model relates to the technical field of energy, in particular to a vacuum sleeve and a supercritical circulating heat insulation test loop.

Background

With the rapid development of science and technology in recent years, research on the problems of flow and convection heat exchange in supercritical pressure fluid pipes has gained a great deal of attention in more and more industrial technical fields, such as heat pumps and low-temperature refrigeration systems, aerospace, nuclear energy utilization, thermal energy power, chemical industry, material manufacturing, environmental engineering and the like. The supercritical pressure fluid has special properties and physical properties, so that the flow and convection heat exchange of the supercritical pressure fluid are greatly different from those of the conventional fluid, the problem is more complex, and higher requirements are put on the design of an experimental system.

In the existing flow heat exchange experimental system, the design of a small-sized test section is less, heat loss is difficult to avoid when heating is performed on a large-sized long pipeline, and small temperature errors can cause large supercritical flow and heat transfer calculation, especially on experimental working conditions including processes such as transcritical or near critical points. Most of experiments adopt a test section to be covered with an insulating layer, the method easily causes the device to be redundant, is difficult to overhaul, and has limited heat insulation effect. Therefore, there is a need to provide a set of experimental system designs suitable for large circulation loops that reduce heat loss to address the above-mentioned problems.

Disclosure of Invention

In view of the above, the embodiment of the utility model provides a vacuum sleeve and a supercritical circulating heat insulation test loop, the core part is a test section comprising the vacuum sleeve and an observation window, the test loop has the capability of carrying out heat exchange performance test experiments of various working media such as supercritical water, supercritical carbon dioxide and the like, and the heat loss of the test section is effectively reduced by utilizing the structure of the vacuum sleeve; and visual monitoring of the wall surface state of the test section is realized through the observation window.

In a first aspect, an embodiment of the present utility model provides a vacuum casing, for a test section of a supercritical circulating heat insulation test loop, where the vacuum casing includes a vacuum coating shell sleeved on an outer side of the test section, the vacuum coating shell is fixedly connected with an inlet and an outlet of the test section through a first flange, an observation window, a vacuumizing hole and an insulating connection terminal are disposed on the vacuum coating shell, and the test section is connected with a heating power supply through the insulating connection terminal.

According to a specific implementation manner of the embodiment of the utility model, two insulating wiring terminals are arranged, the two insulating wiring terminals are respectively close to the inlet and the outlet of the test section, a metal block for heating is connected to the test section, the metal block is connected with one end of the insulating wiring terminal, which is positioned on the inner side of the vacuum coating shell, and one end of the insulating wiring terminal, which is positioned on the outer side of the vacuum coating shell, is connected with the heating power supply.

According to a specific implementation manner of the embodiment of the utility model, the first flange is fixed through a bolt and a nut, an insulating washer is sleeved on the bolt, and the insulating washer is located between the nut and the first flange.

According to a specific implementation manner of the embodiment of the utility model, a plane light source is arranged at the position of the observation window.

According to a specific implementation manner of the embodiment of the utility model, the observation window is fixed on the vacuum coating shell through a second flange.

According to a specific implementation manner of the embodiment of the utility model, the vacuum coating shell is set as a pressure-resistant sleeve of a metal sleeve or a glass sleeve.

In a second aspect, an embodiment of the present utility model further provides a supercritical circulation heat insulation testing circuit, which adopts the vacuum sleeve according to any one of the embodiments of the first aspect, the supercritical circulation heat insulation testing circuit includes a main circulation circuit formed by a gas cylinder, a cooler, a heat preservation liquid storage tank, a circulation pump, a flowmeter, a preheater, a test section and a condenser, which are sequentially connected, the supercritical circulation heat insulation testing circuit further includes a buffer tank and a water chilling unit, the buffer tank is located between the flowmeter and the circulation pump and is connected with the main circulation circuit, the water chilling unit is connected with the condenser and the cooler, and the vacuum sleeve is connected with the outer side of the test section.

According to a specific implementation of the embodiment of the utility model, the circulating pump is set as a magnetic gear pump, a high-pressure plunger pump or a supercritical pump.

According to a specific implementation manner of the embodiment of the utility model, the heating mode of the preheater is water bath heating, oil bath heating or electric heating.

According to a specific implementation manner of the embodiment of the utility model, the test section is a metal channel, and the metal channel is arranged as a circular channel, a rectangular channel or a triangular channel.

Advantageous effects

According to the supercritical circulating heat insulation test loop provided by the embodiment of the utility model, the heating loss of the test section is effectively reduced by utilizing the vacuum sleeve structure, and compared with the traditional heat insulation cotton, the heat leakage rate can be reduced by 8 times by adopting the vacuum sleeve structure. The supercritical circulation heat insulation test loop is suitable for various large heating experiment systems, realizes accurate measurement of supercritical heat exchange data, and meets test requirements of various application scenes such as supercritical Brayton cycle, rankine cycle and the like. Meanwhile, an observation window is arranged at a key position of the vacuum sleeve, so that the visual monitoring of the wall surface state of the test section is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of a vacuum sleeve according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram of a supercritical circulating thermal insulation test circuit according to an embodiment of the utility model.

In the figure: 1. a first flange; 2. an insulating gasket; 3. a vacuum hole; 4. an insulated terminal block; 5. an observation window; 6. a metallic copper block; 7. a gas cylinder; 8. a cooler; 9. a heat-preserving liquid storage tank; 10. a circulation pump; 11. a buffer tank; 12. a flow meter; 13. a preheater; 14. a test section; 15. a vacuum sleeve; 16. a condenser; 17. a water chiller; 18. a back pressure valve.

Detailed Description

Embodiments of the present utility model will be described in detail below with reference to the accompanying drawings.

Other advantages and effects of the present utility model will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present utility model with reference to specific examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the utility model. The utility model may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present utility model. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.

It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present utility model by way of illustration, and only the components related to the present utility model are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.

In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.

In a first aspect, embodiments of the present utility model provide a vacuum sleeve, described in detail below with reference to FIGS. 1-2.

Referring to fig. 1, a vacuum sleeve 15 of the present embodiment is used for a test section 14 of a supercritical circulation heat insulation test loop, the vacuum sleeve 15 includes a vacuum coating shell layer sleeved outside the test section 14, the vacuum coating shell layer is fixedly connected with an inlet and an outlet of the test section 14 through a first flange 1, the first flange 1 is sealed by a rubber gasket, an observation window 5, a vacuumizing hole 3 and an insulation connection terminal 4 are arranged on the vacuum coating shell layer, and the test section 14 is connected with a heating power supply through the insulation connection terminal 4.

In most tube bundle heat exchange experiments, the test section 14 inevitably exchanges heat with air to cause heat leakage, and the traditional method adopts the test section 14 to be externally covered with the heat insulation layer, so that the device is easy to be mixed and difficult to overhaul, and meanwhile, the heat insulation effect is limited. In addition, in the prior art, it is difficult to visually observe the wall surface state of the tube bundle in a large-scale system, and in this example, on the basis of the vacuum sleeve heat insulation design, an observation window 5 is provided at a key position of the vacuum sleeve 15, and the wall surface state change of the test section 14 can be directly observed through the observation window 5.

In one embodiment, two insulating connecting terminals 4 are arranged, the two insulating connecting terminals 4 are respectively close to the inlet and outlet positions of the test section 14, a metal block for heating the test section 14 is connected to the test section 14, the metal block is connected with one end of the insulating connecting terminal 4, which is located inside the vacuum coating shell, and one end of the insulating connecting terminal 4, which is located outside the vacuum coating shell, is connected with a heating power supply.

In a specific embodiment, the heating power source is a direct current power source, and the metal block is provided as a metal copper block 6.

In another specific embodiment, the first flange 1 is fixed by a bolt and a nut, the bolt is sleeved with an insulating washer 2, the insulating washer 2 is located between the nut and the first flange 1, and the insulating washer 2 is used for preventing leakage of heating current.

In order to make the observation at the observation window 5 clearer, the observation window 5 is provided with a plane light source, and the wall surface condition inside the vacuum sleeve 15 can be observed clearer by arranging the plane light source, so that the experiment is more accurate. The shape of the viewing window 5 includes, but is not limited to, a circular shape, a rectangular shape, etc., and the position of the viewing window 5 can be adjusted as needed.

In one embodiment, the viewing window 5 is secured to the vacuum envelope by a second flange, the second flange being sealed therebetween using a rubber gasket.

In one embodiment, the vacuum-clad sheath is provided as a pressure-resistant sleeve of a metal sleeve or glass sleeve.

In a second aspect, an embodiment of the present utility model further provides a supercritical circulation heat insulation testing circuit, which adopts the vacuum sleeve 15 according to any embodiment of the first aspect, referring to fig. 2, the supercritical circulation heat insulation testing circuit includes a main circulation circuit formed by a gas cylinder 7, a cooler 8, a heat preservation liquid storage tank 9, a circulation pump 10, a flowmeter 12, a preheater 13, a testing section 14 and a condenser 16, which are sequentially connected, the supercritical circulation heat insulation testing circuit further includes a buffer tank 11 and a water chilling unit 17, the buffer tank 11 is located between the flowmeter 12 and the circulation pump 10 and is connected with the main circulation circuit, the water chilling unit 17 is connected with the condenser 16 and the cooler 8, and the vacuum sleeve 15 is connected to the outer side of the testing section 14.

The cooler 8 is used for liquefying the working medium flowing out of the gas cylinder 7 before the experiment, and cooling the high-temperature working medium at the outlet of the test section 14 in the circulation loop during the experiment so as to be recycled. The heat-preservation liquid storage tank 9 is used for uniformly mixing the liquid at the outlet of the cooler 8, so as to ensure that the working medium entering the circulating pump 10 is in a liquid state. In this embodiment, the circulating pump 10 adopts a design of a magnetic gear pump, and realizes contactless torque transmission through a magnetic driver so as to replace dynamic seal with static seal, so that the pump reaches a volumetric gear pump completely without leakage, and liquid is conveyed and pressurized by virtue of working volume change and movement formed between the pump body and the meshing gear. Buffer tank 11 is located at the bypass between circulation pump 10 and flowmeter 12 for stabilizing the flow rate at the outlet of circulation pump 10 so that the flow rate measurement by flowmeter 12 is more accurate. The preheater 13 is connected with the outlet of the flowmeter 12, and heats the working medium in the pipe so that the working medium entering the test section 14 reaches the required temperature condition. The condenser 16 is used for primary cooling of the working medium at the outlet of the test section 14.

In one embodiment, the circulation pump 10 may also be configured as a high pressure plunger pump or a supercritical pump.

In one embodiment, the heating mode of the preheater 13 is water bath heating, oil bath heating or electric heating, and the preheater 13 is arranged on the main circulation loop and is connected with the outlet of the flowmeter 12 and the inlet of the test section 14 through pressure-resistant pipelines.

In one particular implementation, the test section 14 is a metal channel configured as a circular channel, a rectangular channel, or a triangular channel.

In one embodiment, the insulated liquid storage tank 9 is connected with the outlet of the cooler 8 and the inlet of the circulating pump 10 through pressure-resistant pipelines.

Specifically, the circulating pump 10 is connected with the outlet of the heat preservation liquid storage tank 9 and the inlet of the flowmeter 12 through a pressure-resistant stainless steel pipe, the bottom of the circulating pump 10 is fixed with the bottom surface through an expansion screw, and the working vibration of the motor is slowed down.

Specifically, the buffer tank 11 is installed on a bypass between the circulation pump 10 and the flowmeter 12, and is connected with the main circulation loop through a three-way joint, and the buffer tank 11 can resist high pressure and has a larger volume, so as to balance flow fluctuation generated when the circulation pump 10 works, and the measured flow is more accurate.

The cooling capacity required by the condenser 16 and the cooler 8 is provided by a water chiller 17, and the cooling water exchanges heat with the fluid in the main circulation loop in the condenser 16 and the cooler 8. Specifically, the condenser 16 has two inlets and two outlets, the inlet and outlet in the axial direction is connected with the circulating cooling water of the chiller 17, and the outlet and outlet in the radial direction is connected with the outlet of the test section 14 and the inlet of the cooler 8 on the main circulation loop.

In one embodiment, the test loop further includes, but is not limited to, the following connection scheme: (1) The device comprises a gas cylinder 7, a compressor, a heat preservation liquid storage tank 9, a gas booster pump, a first oil bath heater, a second oil bath heater and a cooler 8 which are sequentially connected to form a main circulation loop. (2) The device comprises a gas cylinder 7, a heat preservation liquid storage tank 9, a supercritical pump, a pressure stabilizing tube, a flowmeter 12, a preheater 13, a test section 14, a mixing section and a cooler 16 which are sequentially connected to form a main circulation loop.

In most tube bundle heat exchange experiments, the test section 14 inevitably exchanges heat with air to cause heat leakage, and the traditional method adopts the test section 14 to be coated with an insulating layer, so that the device is easy to be mixed, difficult to overhaul and limited in heat insulation effect. Thus, the above embodiment provides a supercritical circulating thermal insulation test circuit design based on a vacuum sleeve 15, with a vacuum coating envelope over the test section 14. The test section 14 is a section of metal channel, and a first flange 1 is welded at the inlet and the outlet of the test section 14, and is connected with a vacuum sleeve 15 through the first flange 1. Simultaneously, two metal copper blocks 6 are welded below the first flange 1 at the inlet and the outlet of the test section 14, and the metal copper blocks 6 are welded on the test section 14 and are used for connecting a heating power supply. The vacuum sleeve 15 coated outside the test section 14 is fixed with the test section 14 through the first flange 1, and the insulating washer 2 is sleeved on the bolt to prevent the leakage of heating current. The vacuum coating shell is provided with a vacuum pumping port 3 for connecting a vacuum pump to perform vacuum pumping treatment on the vacuum sleeve 15. Two insulated wiring terminals 4 are arranged on the vacuum sleeve 15, the outside of the terminals is connected with a direct current power supply, and the inside of the terminals is connected with a metal copper block 6 on the test section 14.

In the prior experiment, the visual observation of the wall surface state of the tube bundle in a large-scale system is difficult, and the observation window 5 is arranged at the key position of the vacuum sleeve 15 on the basis of the heat insulation design of the vacuum sleeve. The viewing window 5 is secured to the tube by means of flanges, the flanges being sealed with rubber gaskets. A plane light source is arranged at a proper position on the side of the observation window 5, and the wall surface state of the heated test section 14 is monitored in real time.

The specific workflow comprises the following steps:

s1, firstly, opening a gas cylinder 7, and introducing CO into an experimental system ₂ The system pressure was raised to 4MPa. The gas is discharged outwards through the gas outlet, the pressure of the system is reduced to half of the original pressure, and then CO is refilled ₂ . This procedure was repeated 3-4 times to complete the system rinse.

S2, fixing the vacuum sleeve 15 on the test section 14 through the first flange 1, connecting the vacuum sleeve 15 with a vacuum pump, and continuously pumping air in the vacuum sleeve 15 until the pressure gauge number is-0.003 to-0.001 MPa, and finishing the vacuumizing operation. The vacuum pump and the connecting valve on the vacuum sleeve 15 are closed. Two insulated terminals 4 mounted on the vacuum bushing 15 are connected to a direct current source. A light source is arranged at a proper position on the side of the observation window 5, light irradiates the test section 14 through the observation window 5, and whether the wall surface heated by the subsequent test section 14 has a red burning state or not is monitored in real time.

And S3, inflating the experimental system and opening the circulating system of the water chilling unit 17.

And S4, operating the circulating pump 10 according to the estimated flow, adjusting the back pressure valve 18 to control the inlet pressure of the test section 14 to rise to the required pressure, and adjusting the preheating voltage of the preheater 13 to control the inlet temperature to the set working condition.

And S5, turning on a heating power supply of the test section 14, and adjusting the heating current to a preset value to obtain the set heating heat flow density of the test section.

S6, opening the cooler 8 after the experimental section, and after the whole system is stable, keeping the pressure, flow, inlet temperature, outlet temperature and outer wall temperature of the experimental section unchanged for about 60-120 minutes.

And S7, collecting experimental data, including parameters such as system pressure, flow, temperature and the like.

According to the supercritical circulating heat insulation test loop design based on the vacuum sleeve, the vacuum sleeve structure is utilized, heating loss of a test section is effectively reduced, for example, the temperature of flowing working media in a pipe is 200 ℃, the external environment temperature is 20 ℃, the heat conductivity coefficient of common heat insulation cotton is 0.04W (m.K), the heat conductivity coefficient of a vacuum layer is generally 0.005W (m.K), and the heat leakage rate of the test section is obtained according to the derivation of a one-dimensional heat conduction problem to a plane:

wherein phi is the heat leakage rate, lambda is the heat conductivity coefficient of the heat preservation medium, T _in T is the temperature of working medium in the pipe _env The external environment temperature, A is the surface area, delta is the thickness of the heat preservation medium. The formula of the heat leakage rate can be used for obtaining that the heat leakage rate can be reduced by 8 times compared with the traditional heat insulation cotton by adopting the vacuum sleeve structure. The design is suitable for various large heating experiment systems, realizes the accurate measurement of supercritical heat exchange data, and meets the test requirements of various application scenes such as supercritical Brayton cycle, rankine cycle and the like. Meanwhile, an observation window is arranged at a key position of the vacuum sleeve, so that the visual monitoring of the wall surface state of the test section is realized.

The foregoing is merely illustrative of the present utility model, and the present utility model is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present utility model should be included in the present utility model. Therefore, the protection scope of the utility model is subject to the protection scope of the claims.

Claims

1. The utility model provides a vacuum sleeve for test section (14) of thermal-insulated test circuit of supercritical cycle, its characterized in that, vacuum sleeve is including the cover to be established the vacuum cladding shell in test section (14) outside, vacuum cladding shell with the entry and the export of test section (14) are through first flange (1) fixed connection, be equipped with observation window (5), evacuation hole (3) and insulating binding post (4) on the vacuum cladding shell, test section (14) are passed through insulating binding post (4) are connected with heating power supply.

2. Vacuum sleeve according to claim 1, characterized in that two insulating terminals (4) are provided, two insulating terminals (4) are respectively close to the inlet and outlet positions of the test section (14), a metal block for heating is connected to the test section (14), the metal block is connected with one end of the insulating terminal (4) located inside the vacuum coating shell, and one end of the insulating terminal (4) located outside the vacuum coating shell is connected with the heating power supply.

3. Vacuum sleeve according to claim 1, characterized in that the first flange (1) is fixed by means of a bolt and a nut, the bolt being provided with an insulating washer (2), the insulating washer (2) being located between the nut and the first flange (1).

4. Vacuum sleeve according to claim 1, characterized in that a planar light source is provided at the position of the viewing window (5).

5. Vacuum sleeve according to claim 1, characterized in that the viewing window (5) is fixed to the vacuum envelope by means of a second flange.

6. A vacuum sleeve according to any one of claims 1-5, characterized in that the vacuum coating envelope is provided as a pressure-resistant sleeve of a metal sleeve or a glass sleeve.

7. A supercritical circulation heat insulation test loop adopting the vacuum sleeve according to any one of claims 1-6, characterized in that the supercritical circulation heat insulation test loop comprises a main circulation loop formed by a gas cylinder (7), a cooler (8), a heat preservation liquid storage tank (9), a circulation pump (10), a flowmeter (12), a preheater (13), a test section (14) and a condenser (16) which are sequentially connected, the supercritical circulation heat insulation test loop further comprises a buffer tank (11) and a water chilling unit (17), the buffer tank (11) is positioned between the flowmeter (12) and the circulation pump (10) and is connected with the main circulation loop, the water chilling unit (17) is connected with the condenser (16) and the cooler (8), and the vacuum sleeve is connected to the outer side of the test section (14).

8. The supercritical cycle thermal insulation test circuit according to claim 7, characterized in that the circulation pump (10) is provided as a magnetic gear pump, a high pressure plunger pump or a supercritical pump.

9. The supercritical circulation heat insulation test circuit according to claim 7, wherein the heating mode of the preheater (13) is water bath heating, oil bath heating or electric heating.

10. The supercritical circulation thermal insulation test circuit according to claim 7, characterized in that the test section (14) is a metal channel, which is arranged as a circular channel, a rectangular channel or a triangular channel.