A film boiling test device and test method

Abstract

The present invention provides a film boiling test device and a test method. The film boiling test device includes: a heating plate, a medium flow channel surrounded by the heating plate, and a heat-conducting block for heating the heating plate at a constant temperature; wherein, along the height direction of the film boiling test device, the area corresponding to the heat-conducting block in the medium flow channel is an anti-annular flow generation section, and the area staggered from the heat-conducting block in the medium flow channel is an anti-annular flow flow section; the anti-annular flow generation section and the anti-annular flow flow section are arranged in sequence along the flow direction of the medium in the medium flow channel. Thus, in the first aspect, the heat-conducting block can be considered to be heated at a constant temperature, so that the temperature during the entire test process is controllable, and the highest temperature of the test is the preset temperature reached by the heat-conducting block before the test, thus effectively avoiding the problem of melting of the heating plate; in the second aspect, by continuously heating the heating plate, the stability of the anti-annular flow film boiling state of the medium can be maintained, ensuring the effective conduction of the test.

Description

Technical Field

[0001] The present invention relates to the field of thermal medium tests, and particularly relates to a film boiling test device and a test method. Background Art

[0002] Plate fuel is one of the commonly used nuclear fuel forms and is widely used in various nuclear reactors. Under the extreme accident conditions of the reactor, the heat transfer on the surface of the fuel element will deteriorate, and the local heat transfer in the core will enter the post-critical heat flux (Post-CHF) heat transfer area. Therefore, it is necessary to carry out film boiling tests after the critical heat flux to ensure the safe use of plate fuel through relevant research.

[0003] The film boiling after the critical heat flux can be divided into reverse circulation film boiling after departure from nucleate boiling (DNB) and dispersed flow film boiling after dryout. Among them, the reverse circulation film boiling test is less applied, mainly due to the following problems with the reverse circulation film boiling test:

[0004] On the one hand, the temperature is very high after DNB. Adopting a heating scheme with a direct heating plate, in the film boiling stage after entering DNB, a steam film will be generated between the heating plate wall and the fluid. The insulation of the steam film makes the heat exchange very poor, so that the wall of the heating plate will reach a very high temperature, resulting in the risk of the heating plate being burned out, burned off, or burned through.

[0005] On the other hand, the reverse circulation film boiling after DNB is relatively unstable, and constructing a more stable reverse circulation flow pattern is a prerequisite for its measurement.

[0006] In summary, there are problems such as unstable boiling and easy burnout of the heating plate in the reverse circulation film boiling test in the related technology. Summary of the Invention

[0007] The present invention provides a film boiling test device and a test method, which can solve the problems of unstable boiling and easy burnout of the heating plate in the film boiling test.

[0008] In a first aspect, the present invention provides a film boiling test device, comprising: a heating plate, a medium flow channel surrounded by the heating plate, and a heat conducting block for performing constant temperature heating on the heating plate, the heat conducting block being configured to maintain its own temperature within a range greater than or equal to the minimum temperature required for film boiling of the medium in the test device and less than the melting point temperature of the heating plate when heating the heating plate; wherein, along the height direction of the film boiling test device, the area of the medium flow channel corresponding to the heat conducting block is an inverse annular flow generation section, and the area of the medium flow channel offset from the heat conducting block is an inverse annular flow passage section; the inverse annular flow generation section and the inverse annular flow passage section are arranged in sequence along the flow direction of the medium in the medium flow channel.

[0009] Optionally, within 5 minutes of the test process of the film boiling test device, the temperature drop of the heat conducting block is less than or equal to 50 °C.

[0010] Optionally, the heat transfer coefficient of the heat conducting block is greater than 150 W / (m·K), and the specific heat capacity is greater than 300 J / (kg·K).

[0011] Optionally, both the length range and the height range of the heat conducting block are 100 mm to 200 mm.

[0012] Optionally, it further includes electrodes provided on the heating plate, the electrodes are arranged in pairs along the medium flow direction, and the heat conducting block is located between the paired electrodes.

[0013] Optionally, it further includes a first temperature measuring element provided on the heat conducting block.

[0014] Optionally, a heating rod is inserted into the heat conducting block.

[0015] Optionally, the heating rod is arranged on the side of the heat conducting block away from the heating plate, and the first temperature measuring element is arranged on the side of the heat conducting block close to the heating plate.

[0016] Optionally, it further includes a second temperature measuring element provided on the heating plate, and the second temperature measuring element corresponds to the inverse annular flow passage section along the height direction.

[0017] Optionally, it further includes a second protective shell, and the medium flow channel, the heating plate, and the second protective shell are arranged in sequence from the inside to the outside; the second temperature measuring element passes through the second protective shell to be provided on the heating plate.

[0018] Optionally, the second protective shell includes a pair of pressing shells arranged in pairs, and the pair of pressing shells enclose a channel for the heating plate and the medium flow channel to pass through, and the heating plate is pressed between the pair of pressing shells arranged in pairs.

[0019] Optionally, it further includes a second insulating shell, and the second insulating shell is provided between the second protective shell and the heating plate.

[0020] Optionally, it also includes an insulating tube and a protective tube, the insulating tube is arranged on the heating plate and wraps the second temperature measuring element, and the protective tube wraps the insulating tube; a gap is reserved between the protective tube and the insulating tube, and / or between the insulating tube and the second temperature measuring element.

[0021] Optionally, it also includes a fixing base arranged on the heating plate, and the second temperature measuring element is detachably inserted into the fixing base.

[0022] Optionally, it also includes a main joint, which is connected to the heating plate, the outlet of the medium flow channel, and / or the inlet of the medium flow channel is connected to the main joint; along the direction away from the heating plate, the main joint includes a cross-section gradually decreasing section, a cross-section gradually expanding section and a cross-section constant section that are connected in sequence; the cross-sectional shape of the constant cross-sectional section is different from the cross-sectional shape of the medium flow channel; the cross-sectional area of ​​the cross-sectional gradually expanding section increases in the direction approaching the medium flow channel; the cross-sectional area of ​​the cross-sectional gradually decreasing section decreases in the direction approaching the medium flow channel, and the outlet cross-sectional area of ​​the cross-sectional gradually decreasing section is the same as the cross-sectional area of ​​the medium flow channel.

[0023] In a second aspect, the present application also provides a film boiling test method, which is applied to a test device, and the method comprises:

[0024] The medium is introduced into the medium flow channel;

[0025] Preheating the heat conducting block to a preset temperature so that the medium flowing through the anti-annular flow generating section is in the anti-annular flow film boiling stage;

[0026] The heating plate is heated so that the medium flowing through the anti-annular flow flow section maintains the anti-annular flow film boiling stage;

[0027] Get the temperature of the heat conducting block;

[0028] Get the temperature of the heating plate.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention provides a film boiling test device, comprising: a heating plate, a medium flow channel surrounded by the heating plate, and a heat-conducting block for heating the heating plate at a constant temperature, wherein the heat-conducting block is constructed so as to maintain its own temperature within a range greater than or equal to a minimum temperature required for film boiling of a medium in the test device and less than a melting point temperature of the heating plate when heating the heating plate; wherein, along the height direction of the film boiling test device, an area in the medium flow channel corresponding to the heat-conducting block is an anti-annular flow generating section, and an area in the medium flow channel staggered from the heat-conducting block is an anti-annular flow circulation section; the anti-annular flow generating section and the anti-annular flow circulation section are sequentially arranged along the flow direction of the medium in the medium flow channel.

[0031] In this application, in the first aspect, the heat-conducting block has a relatively high heat capacity, and its temperature drops slowly over a period of time. Therefore, when the fluid flows through the heat-conducting block, it can be approximately considered as isothermal heating, that is, a relatively constant boundary condition is provided within a certain time, which facilitates the measurement. An important advantage of this is that the temperature during the entire test process is controllable, and the highest temperature of the test is the preset temperature reached by the heat-conducting block before the test, thus effectively avoiding the problem of the heating plate melting. In the second aspect, by continuously heating the heating plate, the stability of the medium's inverse annular flow film boiling state can be maintained, ensuring the effective progress of the test. Description of the Drawings

[0032] After reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings, the above features and advantages of the present invention can be better understood. In the drawings, the components are not necessarily drawn to scale, and components with similar related characteristics or features may have the same or similar reference numerals.

[0033] Figure 1 is the structural diagram of the test device of the present invention;

[0034] Figure 2 is the internal view of the test device of the present invention;

[0035] Figure 3 is the present invention Figure 2 A-A cross-sectional view;

[0036] Figure 4 is the installation schematic diagram of the second temperature measuring element in an embodiment of the present invention;

[0037] Figure 5 is the installation schematic diagram of the second temperature measuring element in another embodiment of the present invention;

[0038] Figure 6 is the structural diagram of the main joint of the present invention;

[0039] Figure 7 is the internal view of the main joint of the present invention.

[0040] Description of the Reference Numerals:

[0041] X - Flow direction, Z - Height direction, Y - Width direction,

[0042] 10 - Heating plate,

[0043] 11 - Medium flow channel, 111 - Inverse annular flow generation section, 112 - Inverse annular flow passage section,

[0044] 20 - Heat-conducting block,

[0045] 21 - Heating rod,

[0046] 30 - First temperature measuring element,

[0047] 40 - Second temperature measuring element,

[0048] 41 - Insulating tube, 42 - Protection tube, 43 - Fixed seat,

[0049] 50 - Electrode,

[0050] 60 - First protective shell,

[0051] 61 - Insulating plate,

[0052] 70 - Second protective shell,

[0053] 701 - Compression shell,

[0054] 71 - Second insulating shell, 711 - End insulating plate, 712 - Side insulating plate,

[0055] 72 - Fastening assembly,

[0056] 80 - Main joint,

[0057] 801 - Section gradually reducing section, 802 - Section gradually expanding section, 803 - Section constant section,

[0058] 81 - Temperature measuring joint,

[0059] 82 - Pressure measuring joint. Specific embodiments

[0060] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0061] It should be noted that these and subsequent other drawings are only examples, and they are not drawn under the condition of equal proportion, and should not be used to limit the actual claimed protection scope of the present invention.

[0062] In the related art, problems such as boiling instability and easy burning of the heating plate exist in the counter - circulation film boiling test. Therefore, the technical solution of this application is developed. The following will be described in conjunction with Figures 1 to 7 for elaboration.

[0063] As Figure 1 , Figure 2 and Figure 4 shown, this application discloses a film boiling test device, including a heating plate 10, a heat conducting block 20, a first temperature measuring element 30 and a second temperature measuring element 40.

[0064] Among them, the heating plate 10 is a metal plate made of Inconel nickel-based alloy, with dimensions of 500 mm to 800 mm in length, 60 to 70 mm in width, and 2 to 3 mm in thickness. The heating plates 10 are arranged in pairs along the height direction Z of the test device, and the edges of the two heating plates 10 are connected by nickel-based brazing, with an interval in the middle to form a medium flow channel 11 for introducing media such as water. The medium flow channel 11 is a narrow slit structure with a rectangular cross-section.

[0065] The heat conducting block 20 is arranged on the heating plate 10, and the heat conducting block 20 is used to perform constant-temperature heating on the heating plate 10. Here, the constant-temperature heating means that as the heat source of the heating plate 10, the heat conducting block 20 will be within the required temperature range after preheating to ensure the smooth progress of the film boiling test. Specifically, the heat conducting block 20 is configured to maintain its own temperature within a range greater than or equal to the minimum temperature required for the film boiling of the medium in the test device and less than the melting point temperature of the heating plate 10 when heating the heating plate 10. For example, when the minimum film boiling temperature is 350 degrees Celsius, the heat conducting block 20 will be heated to above 600 degrees Celsius and less than the melting point temperature of the heating plate 10.

[0066] Furthermore, during the test process, the temperature of the heat conducting block 20 drops by less than or equal to 50 °C within 5 minutes, so that the heating temperature of the heating plate 10 is stable, avoiding large temperature fluctuations during the test process and improving the effect of constant-temperature heating.

[0067] Furthermore, to meet the heating temperature required for the test and avoid the heating plate 10 from being melted during the test process to achieve the purpose of stable heating temperature, the specific selection criteria for the size, thermal coefficient, and specific heat capacity of the heat conducting block 20 are as follows: The heat conducting block 20 can be made of materials such as pure copper, brass with material grade H96, and lead brass with material grade HPb89-2. The thermal coefficient of the heat conducting block 20 is greater than 150 W / (m·K), the specific heat capacity is greater than 300 J / (kg·K), and the length range and height range of the heat conducting block 20 are both 100 mm to 200 mm.

[0068] The heat conducting block 20 and the heating plate 10 can be welded to each other using nickel-based brazing sheets with equal contact areas. On the one hand, nickel-based brazing can withstand high temperatures of 500 °C to 800 °C, ensuring a firm connection between the heating plate 10 and the heat conducting block 20 throughout the test process; on the other hand, the brazing sheet will melt and fully fill the gap between the heating plate 10 and the heat conducting block 20 during the welding process, greatly reducing the contact thermal resistance between the two.

[0069] Along the height direction of the film boiling test device, the area corresponding to the heat conductive block 20 in the medium flow channel 11 is the anti-annular flow generation section 111, and the area staggered from the heat conductive block 20 in the medium flow channel 11 is the anti-annular flow flow section 112; the anti-annular flow generation section 111 and the anti-annular flow flow section 112 are sequentially arranged along the flow direction X of the medium in the medium flow channel 11, and the flow direction X can be understood as the length direction of the test device, that is, Figure 2 the length of the anti-annular flow generating section 111 is smaller than the length of the anti-annular flow flow section 112, and the heat conductive block 20 is disposed at a position 20mm to 50mm from the inlet of the medium flow channel 11.

[0070] The first temperature measuring element 30 is arranged on the heat conductive block 20, and the second temperature measuring element 40 is arranged on the heating plate 10, and the second temperature measuring element 40 corresponds to the anti-annular flow circulation section 112 along the height direction; the first temperature measuring element 30 and the second temperature measuring element 40 can both adopt thermocouples, etc., and a plurality of first temperature measuring elements 30 are arranged on the heat conductive block 20, and a plurality of second temperature measuring elements 40 are arranged on the heating plate 10. Through multi-point measurement, the first temperature measuring element 30 can accurately measure the temperature of the heat conductive block 20, that is, the temperature of the anti-annular flow generating section 111, and the second temperature measuring element 40 can accurately measure the temperature of the heating plate 10, that is, the temperature of the anti-annular flow circulation section 112.

[0071] During the test process of the present application, the heat conductive block 20 is first preheated to a preset temperature, which is greater than or equal to the minimum film boiling temperature of the medium. Then, the heat conductive block 20 transfers heat to the heating plate 10, so as to heat the water or other medium flowing through the anti-annular flow generating section 111 in the medium flow channel 11 through the heating plate 10. The medium is quickly heated and vaporized to form a gas film, and enters the anti-annular flow film boiling stage; then, the medium flows from the anti-annular flow generating section 111 to the anti-annular flow circulation section 112 in the anti-annular flow film boiling state; at the same time, the heating plate 10 is also heated, so that the medium entering the anti-annular flow circulation section 112 continues to be heated, thereby maintaining the stability of the anti-annular flow film boiling state of the medium. At the same time, during the test process of the present application, the first temperature measuring element 30 measures the temperature of the heat conductive block 20, and the second temperature measuring element 40 measures the temperature of the heating plate 10. This can monitor the temperature changes during the entire test process to ensure that the test is carried out effectively. At the same time, the obtained temperature parameters can be further calculated to obtain the film boiling heat transfer coefficient, thereby completing the entire test.

[0072] In the present application, in the first aspect, the heat conductive block 20 has a high specific heat capacity, and the specific heat capacity is greater than 300 J / (kg·K), so that the temperature of the heat conductive block 20 drops slowly over a period of time, and it can be ensured that the temperature drops by less than or equal to 50°C within 5 minutes during the test. Therefore, when the fluid flows through the heat conductive block 20, it can be considered as constant temperature heating, that is, relatively constant boundary conditions are provided within a certain period of time, which facilitates the measurement. An important advantage of this is that the temperature during the entire test process is controllable, and the highest temperature of the test is the preset temperature reached by the heat conductive block 20 before the test, which effectively avoids the problem of melting of the heating plate 10; in the second aspect, by continuously heating the heating plate 10, the stability of the anti-annular film boiling state of the medium can be maintained, ensuring the effective conduct of the test.

[0073] Alternatively, if Figure 1 , Figure 2 As shown, each heating plate 10 is provided with a heat conductive block 20 and a second temperature measuring element 40, so that the heat conductive block 20 is arranged in a pair along the height direction Z, thereby improving the heating effect of the heating plate 10 and more effectively putting the medium in the reverse annular film boiling stage. Similarly, the second temperature measuring element 40 is also arranged in a pair along the height direction Z so as to independently measure the temperature of each heating plate 10.

[0074] Alternatively, if Figure 1 , Figure 2 As shown, the test device also includes an electrode 50, which is arranged on the heating plate 10. The electrodes 50 are arranged in pairs along the medium flow direction X. The area between the paired electrodes 50 corresponds to the anti-annular flow generation section 111 and the anti-annular flow flow section 112. The heat conductive block 20 and the second temperature measuring element 40 are both located between the paired electrodes 50. The electrode 50 is made of a conductive copper plate and is connected to the heating plate 10 by nickel-based brazing. An electrical circuit can be formed by the arranged electrode 50 so that a low-voltage direct current of 120 is passed to the heating plate 10, so that the medium entering the anti-annular flow flow section 112 can continue to be electrically heated to maintain stability.

[0075] Alternatively, if Figure 1 , Figure 2 As shown, a heating rod 21 is inserted into the heat conductive block 20, and the heating rod 21 can be powered to preheat the heat conductive block 20. A plurality of heating rods 21 can be provided on the heat conductive block 20 to form a plurality of preheating points on the heat conductive block 20 to achieve uniform heating; the heating rod 21 is connected to the heat conductive block 20 by an interference fit, so that the heating rod 21 expands after being heated and will fit more closely with the heat conductive block 20, so as to reduce the gap thermal resistance between the heat conductive block 20 and the heating rod 21 as much as possible.

[0076] Alternatively, if Figure 1 , Figure 2As shown, the heating rod 21 is arranged on the side of the heat conduction block 20 away from the heating plate 10, and the first temperature measuring element 30 is arranged on the side of the heat conduction block 20 close to the heating plate 10. For example, the bottom of the heat conduction block 20 is connected to the heating plate 10, the first temperature measuring element 30 is arranged at the bottom of the heat conduction block 20, and the heating rod 21 is arranged at the top of the heat conduction block 20. In this way, the heat generated by the heating rod 21 is first transferred to the top of the heat conduction block 20. After the heat is fully dissipated in the heat conduction block 20 to heat the entire heat conduction block 20, the heat is then transferred from the bottom of the heat conduction block 20 to the heating plate 10, which further improves the heating effect of the heat conduction block 20 on the heating plate 10, and at the same time enables the temperature measured by the first temperature measuring element 30 to more accurately reflect the overall temperature of the heat conduction block 20.

[0077] Optionally, as Figure 1 , Figure 2 shown, the test device further includes a first protective shell 60, and the first protective shell 60 covers the exposed part of the heat conduction block 20, and the exposed part is the part of the heat conduction block 20 that is not in contact with the heating plate 10; both the first temperature measuring element 30 and the heating rod 21 pass through the first protective shell 60 and are arranged on the heat conduction block 20. The setting of the first protective shell 60 can achieve the shielding protection of the heating plate 10.

[0078] Optionally, as Figure 1 , Figure 2 shown, an insulating board 61 is arranged between the first protective shell 60 and the heat conduction block 20 to achieve insulation protection for the heat conduction block 20 and prevent the heat conduction block 20 from leaking electricity to the first protective shell 60.

[0079] Optionally, as Figures 1 to 4 shown, the test device further includes a second protective shell 70, and the medium flow channel 11, the heating plate 10, and the second protective shell 70 are arranged in sequence from the inside to the outside; the second temperature measuring element 40 passes through the second protective shell 70 and is arranged on the heating plate 10; both ends of the heating plate 10 extend out of the second protective shell 70 to arrange the electrodes 50. The protected area covered by the second protective shell 70 includes the reverse annular flow generation section 111 and the reverse annular flow passage section 112. The heat conduction block 20 passes through the second protective shell 70 to contact the heating plate 10, and the first protective shell 60 is connected to the second protective shell 70 through fasteners such as bolts, so that the first protective shell 60 covers the part of the heat conduction block 20 extending out of the second protective shell 70. In this way, the shielding protection of the medium flow channel 11 and the heating plate 10 can be achieved through the setting of the second protective shell 70.

[0080] Optionally, as Figures 2 to 4As shown, the second protective shell 70 includes pressing shells 701 arranged in pairs along the height direction Z. The pressing shells 701 can be made of stainless steel with a material grade of 316L or the like. The pressing shells 701 arranged in pairs enclose a channel for the heating plate 10 and the medium flow channel 11 to pass through, and the heating plate 10 is pressed between the pressing shells 701 arranged in pairs. The pressing shells 701 arranged in pairs can be connected to each other through a fastening assembly 72. The fastening assembly 72 can be a combination of bolts and nuts. By loosening or tightening the fastening assembly 72, the pressing shells 701 arranged in pairs can approach or move away from each other, thereby adjusting the pressing degree on the heating plate 10. In this way, through the pressing of the heating plate 10 by the pressing shells 701, it can be ensured that the heating plate 10 will not have obvious bending deformation during the test, thereby ensuring the accuracy of the temperature measurement of the second temperature measuring element 40 and the safety of the test.

[0081] Optionally, as Figure 3 and Figure 4 shown, the test device further includes a second insulating shell 71. The second insulating shell 71 is arranged between the second protective shell 70 and the heating plate 10. The second temperature measuring element 40 sequentially passes through the second protective shell 70 and the second insulating shell 71 to be arranged on the heating plate 10. The second insulating shell 71 can include end insulating plates 711 arranged in pairs along the height direction Z and side insulating plates 712 arranged in pairs along the width direction Y. The end insulating plates 711 and the side insulating plates 712 are alternately arranged to form a shield for the heating plate 10. In this way, on the one hand, it can be ensured that the heating plate 10 will not leak electricity to structures such as the second protective shell 70 when being electrified and heated, realizing insulation protection and improving safety; on the other hand, all the current passing through the electrode 50 is used to heat the heating plate 10, so as to reduce energy consumption and facilitate the calculation of the heating power.

[0082] Optionally, both the end insulating plates 711 and the side insulating plates 712 can be made of ceramics. The ceramics can withstand temperatures above 800 °C to ensure normal use during the heating process.

[0083] Optionally, as Figure 3 and Figure 4 shown, the test device further includes an insulating tube 41. The insulating tube 41 can be made of materials such as ceramics and mica that can withstand temperatures above 800 °C. The insulating tube 41 sequentially passes through the second protective shell 70 and the second insulating shell 71 to be arranged on the heating plate 10, and the insulating tube 41 wraps the second temperature measuring element 40 to provide insulation protection for the second temperature measuring element 40 and prevent the second temperature measuring element 40 from leaking electricity.

[0084] Optionally, as Figure 3 and Figure 4As shown, the test device further includes a protective tube 42. A threaded hole is provided on the second protective shell 70, and the protective tube 42 is threadedly connected to the second protective shell 70 for easy disassembly and assembly. The protective tube 42 wraps the insulating tube 41 and the part of the second temperature measuring element 40 extending outside the second protective shell 70 to provide shielding protection for the insulating tube 41 made of brittle material.

[0085] Optionally, when the heating plate 10 expands due to heat, the second temperature measuring element 40 will also move accordingly. Therefore, a gap is reserved between the protective tube 42 and the insulating tube 41, and / or between the insulating tube 41 and the second temperature measuring element 40. For example, the inner diameter of the protective tube 42 is 15 mm and the outer diameter of the insulating tube 41 is 8 mm, so as to provide sufficient space for the displacement of the second temperature measuring element 40.

[0086] As Figure 5 shown, in some other alternative embodiments, the test device further includes a fixing seat 43 provided on the heating plate 10, and the second temperature measuring element 40 is detachably inserted into the fixing seat 43. In this way, when replacing the heating plate 10, it is not necessary to replace the second temperature measuring element 40 thereon, reducing the manufacturing difficulty and cost.

[0087] Optionally, as Figure 1 、 Figure 6 and Figure 7 shown, the test device further includes a main joint 80. The main joint 80 is connected to the heating plate 10 by means of nickel-based brazing or the like, and the outlet of the medium flow channel 11, and / or the inlet of the medium flow channel 11 communicates with the main joint 80; along the direction away from the heating plate 10, the main joint 80 includes a gradually tapered section 801, a gradually expanding section 802 and a constant cross-section section 803 that are sequentially connected.

[0088] Among them, the cross-sectional shape of the constant cross-section section 803 is different from the cross-sectional shape of the medium flow channel 11. Specifically, the flow cross-section of the constant cross-section section 803 is circular to facilitate the connection of the main joint 80 to the external pipeline, while the cross-section of the medium flow channel 11 is a rectangular narrow slit to meet the test requirements as described above. In other words, the dimension of the constant cross-section section 803 along the width direction Y is smaller than the dimension of the medium flow channel 11 along the width direction Y, and the dimension of the constant cross-section section 803 along the height direction Z is larger than the dimension of the medium flow channel 11 along the height direction Z.

[0089] The cross-sectional area of the gradually expanding section 802 increases in the direction close to the medium flow channel 11. Specifically, the gradually expanding section 802 has a trapezoidal structure in the direction close to the medium flow channel 11, and the dimension of the gradually expanding section 802 in the width direction Y gradually increases while the dimension in the height direction Z remains unchanged, so as to first adjust the width dimension of the flow-through cross-section in the main joint 80 to be the same as that of the flow-through cross-section in the medium flow channel 11; the cross-sectional area of the gradually contracting section 801 decreases in the direction close to the medium flow channel 11. Specifically, the gradually contracting section 801 has a gradually shrinking structure in the direction close to the medium flow channel 11, and the dimension of the gradually contracting section 801 in the width direction Y remains unchanged while the dimension in the height direction Z decreases, so as to adjust the height dimension of the flow-through cross-section in the main joint 80 to be the same as that of the flow-through cross-section in the medium flow channel 11; the outlet cross-section of the gradually contracting section 801 is the same as the cross-section of the medium flow channel 11.

[0090] It can be seen that the flow-through cross-section in the medium flow channel 11 is a rectangular narrow slit, while the flow-through cross-section of the medium in the external pipeline is circular. Therefore, the main joint 80 is provided for transition. Through the structural design of the gradually contracting section 801, the gradually expanding section 802 and the constant cross-section section 803 of the main joint 80, when the medium flows into the medium flow channel 11, it will first be fully expanded in the gradually expanding section 802 of the main joint 80 to make the width dimension of the flow-through cross-section of the main joint 80 the same as that of the medium flow channel 11, and then gradually converge in the gradually contracting section 801 to make the height dimension of the flow-through cross-section of the main joint 80 the same as that of the medium flow channel 11. Furthermore, the velocity and flow rate of the medium entering the medium flow channel 11 are balanced at each position. On the contrary, when the medium flows out of the medium flow channel 11, it first expands fully in the height direction Z in the gradually contracting section 801 to adjust the cross-section height dimension to be close to the constant cross-section section 803, and then converges in the width direction Y in the gradually expanding section 802 to adjust the cross-section width dimension to be close to the constant cross-section section 803, so that the velocity and flow rate of the medium entering the constant cross-section section 803 are balanced at each position. Such a setting enables the flow-through cross-section of the medium to switch between circular and rectangular, but the flow of the medium between the medium flow channel 11 and the external pipeline can ensure the balance of the flow velocity and flow rate.

[0091] Optionally, as Figure 6 and Figure 7 shown, the test device further includes a temperature measurement joint 81 communicating with the main joint 80. The temperature measurement joint 81 is connected to a temperature measurement element to measure the temperature of the medium. Further, the test device further includes a pressure measurement joint 82 communicating with the main joint 80. The pressure measurement joint 82 is connected to a pressure measurement element to measure the pressure of the medium.

[0092] This application also discloses a film boiling test method, including:

[0093] Introducing a medium into the medium flow channel 11;

[0094] Energize the heating rod 21 to preheat the heat conducting block 20 to a preset temperature, so that the medium passing through the inverse annular flow generation section 111 is in the inverse annular flow film boiling stage; the preset temperature is greater than or equal to the minimum temperature required for the film boiling of the medium in the test device and less than the melting point temperature of the heating plate 10. For example, when the minimum film boiling temperature is 350 °C, the heat conducting block 20 will be heated to above 600 °C; the inverse annular flow generation section 111 corresponds to the setting area where the heat conducting block 20 is located.

[0095] Energize the electrode 50 to heat the heating plate 10, so that the medium in the inverse annular flow passage section 112 maintains the inverse annular flow film boiling stage; the inverse annular flow passage section 112 corresponds to the setting area where the second temperature measuring element 40 is located.

[0096] When the medium is in the inverse annular flow generation section 111 and maintains the inverse annular flow film boiling stage, obtain the temperature of the heat conducting block 20 through the first temperature measuring element 30.

[0097] When the medium is in the inverse annular flow passage section 112 and maintains the inverse annular flow film boiling stage, obtain the temperature of the heating plate 10 through the second temperature measuring element 40.

[0098] In this way, by obtaining the temperature of the heat conducting block 20 and the temperature of the heating plate 10, the film boiling heat transfer coefficient can be further obtained, thereby achieving the test purpose. The film boiling heat transfer coefficient can be calculated by the formula in the related technology and will not be elaborated here.

[0099] Although the present invention is disclosed above with preferred embodiments, it is not used to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, all modifications, equivalent changes and decorations made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention fall within the protection scope defined by the claims of the present invention.

Claims

1. A film boiling test device, characterized in that: include: A heating plate (10), wherein the heating plate (10) encloses a medium flow channel (11); a heat conducting block (20) for heating the heating plate (10) at a constant temperature, the heat conducting block (20) being configured to maintain its own temperature within a range greater than or equal to a minimum temperature required for film boiling of a medium in a test device and less than a melting point temperature of the heating plate (10) when heating the heating plate (10); in, Along the height direction of the film boiling test device, the area of ​​the medium flow channel (11) corresponding to the heat conductive block (20) is a counter-annular flow generation section (111), and the area of ​​the medium flow channel (11) offset from the heat conductive block (20) is a counter-annular flow flow section (112); The anti-annular flow generating section (111) and the anti-annular flow circulating section (112) are arranged in sequence along the flow direction (X) of the medium in the medium flow channel (11).

2. The test device according to claim 1, characterized in that: During the test process of the film boiling test device for 5 minutes, the temperature of the heat conductive block (20) drops by less than or equal to 50°C.

3. The test device according to claim 1, characterized in that: The thermal coefficient of the heat-conducting block (20) is greater than 150 W / (m·K), and the specific heat capacity is greater than 300 J / (kg·K).

4. The test device according to claim 1, characterized in that: The length range and height range of the heat conducting block (20) are both 100 mm to 200 mm.

5. The test device according to any one of claims 1 to 4, characterized in that: It also includes electrodes (50) arranged on the heating plate (10), the electrodes (50) being arranged in pairs along the medium flow direction (X), The heat conducting block (20) is located between the electrodes (50) that are arranged in pairs.

6. The test device according to claim 1, characterized in that: It also includes a first temperature measuring element (30) arranged on the heat conducting block (20).

7. The test device according to claim 6, characterized in that A heating rod (21) is inserted into the heat conducting block (20).

8. The test device according to claim 7, characterized in that: The heating rod (21) is arranged on a side of the heat conducting block (20) away from the heating plate (10), and the first temperature measuring element (30) is arranged on a side of the heat conducting block (20) close to the heating plate (10).

9. The test device according to any one of claims 1 to 4, characterized in that: It also includes a second temperature measuring element (40) disposed on the heating plate (10), the second temperature measuring element (40) corresponding to the anti-annular flow flow section (112) along the height direction.

10. The test device according to claim 9, characterized in that It also includes a second protective shell (70), wherein the medium flow channel (11), the heating plate (10), and the second protective shell (70) are arranged in sequence from the inside to the outside; The second temperature measuring element (40) passes through the second protective shell (70) to be disposed on the heating plate (10).

11. The test device according to claim 10, characterized in that The second protective shell (70) comprises a pair of compression shells (701), the pair of compression shells (701) enclosing a channel for the heating plate (10) and the medium flow channel (11) to pass through, and the heating plate (10) is compressed between the pair of compression shells (701).

12. The test device according to claim 10, characterized in that: It also comprises a second insulating shell (71), wherein the second insulating shell (71) is arranged between the second protective shell (70) and the heating plate (10).

13. The test device according to claim 9, characterized in that: It also includes an insulating tube (41) and a protective tube (42), wherein the insulating tube (41) is disposed on the heating plate (10) and wraps the second temperature measuring element (40), and the protective tube (42) wraps the insulating tube (41); A gap is reserved between the protection tube (42) and the insulating tube (41), and / or between the insulating tube (41) and the second temperature measuring element (40).

14. The test device according to claim 13, characterized in that It also includes a fixing seat (43) provided on the heating plate (10), and the second temperature measuring element (40) is detachably inserted into the fixing seat (43).

15. The test device according to any one of claims 1 to 4, characterized in that: It also comprises a main joint (80), the main joint (80) being connected to the heating plate (10), the outlet of the medium flow channel (11), and / or the inlet of the medium flow channel (11) being connected to the main joint (80); Along a direction away from the heating plate (10), the main joint (80) comprises a cross-section gradually contracting section (801), a cross-section gradually expanding section (802), and a cross-section constant section (803) which are connected in sequence; The cross-sectional shape of the constant cross-sectional section (803) is different from the cross-sectional shape of the medium flow channel (11); The cross-sectional area of ​​the gradually expanding cross-sectional section (802) increases in a direction approaching the medium flow channel (11); The cross-sectional area of ​​the cross-sectional tapering section (801) decreases in a direction approaching the medium flow channel (11), and the outlet cross-sectional area of ​​the cross-sectional tapering section (801) is the same as the cross-sectional area of ​​the medium flow channel (11).

16. A film boiling test method, applied to the test device according to claim 1, characterized in that: Methods include: Passing a medium into the medium flow channel (11); preheating the heat conducting block (20) to a preset temperature so that the medium flowing through the anti-annular flow generating section (111) is in an anti-annular flow film boiling stage; The heating plate (10) is heated so that the medium flowing through the anti-annular flow flow section (112) maintains the anti-annular flow film boiling stage; Obtaining the temperature of the heat conducting block (20); The temperature of the heating plate (10) is obtained.

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