Membrane boiling test device and test method

Abstract

The invention provides a film state boiling test device and a test method. The film state boiling test device comprises a heating plate, a medium flow channel enclosed by the heating plate, and a heat conduction block for carrying out constant-temperature heating on the heating plate, wherein in the height direction of the film boiling test device, the area, corresponding to the heat conduction block, in the medium flow channel is a reverse annular flow generation section, and the area, staggered with the heat conduction block, in the medium flow channel is a reverse annular flow circulation section; the reverse annular flow generation section and the reverse annular flow circulation section are sequentially arranged in the flowing direction of a medium in the medium flow channel. In this way, in the first aspect, the heat conduction block can be considered to be heated at a constant temperature, the temperature in the whole test process is controllable, the highest temperature of the test is the preset temperature reached by the heat conduction block before the test, and therefore the problem that the heating plate is melted down is effectively avoided; on the second aspect, by continuously heating the heating plate, the stability of the reverse annular flow film boiling state of the medium can be maintained, and it is guaranteed that the test is effectively carried out.

Description

Technical Field

[0001] The invention relates to the field of thermal medium testing, and in particular to a film boiling testing device and a testing method. Background Art

[0002] Plate fuel is one of the commonly used forms of nuclear fuel and is widely used in a variety of nuclear reactors. Under 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 zone (Post-CHF, Post-Critical Heat Flux). Therefore, it is necessary to carry out film boiling tests after the critical heat flux density to ensure the safe use of plate fuel through relevant research.

[0003] Film boiling after critical heat flux can be divided into reverse circulation film boiling after departure from nucleate boiling (DNB) and diffuse flow film boiling after drying up. The reverse circulation film boiling test is less used, mainly because the reverse circulation film boiling test has the following problems: On the one hand, the temperature after DNB is very high. If the heating scheme of direct heating plate is adopted, a steam film will be generated between the wall of the heating plate and the fluid in the film boiling stage after entering DNB. 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 danger of burning, burning off, and burning through of the heating plate. On the other hand, the counter-circulation film boiling after DNB is relatively unstable, and constructing a relatively stable counter-circulation flow pattern is a prerequisite for its measurement.

[0004] In summary, the counter-circulation film boiling test in the related art has problems such as unstable boiling and easy burning of the heating plate. Summary of the invention

[0005] The invention provides a film boiling test device and a test method, which can solve the problems of unstable boiling and easy burning of a heating plate in the film boiling test.

[0006] 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 conductive block for heating the heating plate at a constant temperature, wherein the heat conductive block is constructed to maintain its own temperature within a range greater than or equal to a minimum temperature required for film boiling of the 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 conductive block is an anti-annular flow generating section, and an area in the medium flow channel that is staggered from the heat conductive block is an anti-annular flow circulation section; the anti-annular flow generating section and the anti-annular flow circulation section are arranged in sequence along the flow direction of the medium in the medium flow channel.

[0007] Optionally, within 5 minutes of the test process of the film boiling test device, the temperature of the heat conductive block drops by less than or equal to 50°C.

[0008] Optionally, the thermal coefficient of the heat conductive block is greater than 150 W / (m·K), and the specific heat capacity is greater than 300 J / (kg·K).

[0009] Optionally, the length range and height range of the heat conducting block are both 100 mm to 200 mm.

[0010] Optionally, it further includes electrodes arranged on the heating plate, the electrodes are arranged in pairs along the flow direction of the medium, and the heat conducting block is located between the paired electrodes.

[0011] Optionally, it also includes a first temperature measuring element arranged on the heat conductive block.

[0012] Optionally, a heating rod is inserted into the heat conductive block.

[0013] Optionally, the heating rod is arranged on a side of the heat conductive block away from the heating plate, and the first temperature measuring element is arranged on a side of the heat conductive block close to the heating plate.

[0014] Optionally, it further includes a second temperature measuring element arranged on the heating plate, and the second temperature measuring element corresponds to the anti-annular flow flow section along the height direction.

[0015] 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 and is arranged on the heating plate.

[0016] Optionally, the second protective shell includes compression shells arranged in pairs, the compression shells arranged in pairs form a channel for the heating plate and the medium flow channel to pass through, and the heating plate is compressed between the compression shells arranged in pairs.

[0017] Optionally, a second insulating shell is further included, and the second insulating shell is arranged between the second protective shell and the heating plate.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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: The medium is introduced into the medium flow channel; 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; 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; Get the temperature of the heat conducting block; Get the temperature of the heating plate.

[0022] The beneficial effects of the present invention are as follows: 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.

[0023] In the present application, on the first hand, the heat capacity of the heat conductive block is relatively high, and its temperature drops slowly over a period of time. Therefore, when the fluid flows through the heat conductive block, it can be approximately considered as constant temperature heating, that is, relatively constant boundary conditions are provided within a certain period of time, which facilitates 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 before the test, which effectively avoids the problem of melting of the heating plate; on the second hand, by continuously heating the heating plate, the stability of the anti-annular film boiling state of the medium can be maintained, ensuring the effective conduct of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0025] Figure 1 It is a structural diagram of the test device of the present invention; Figure 2 is an internal diagram of the test device of the present invention; Figure 3 The present invention Figure 2 AA section view; Figure 4 It is a schematic diagram of the installation of the second temperature measuring element in one embodiment of the present invention; Figure 5 is a schematic diagram of the installation of a second temperature measuring element according to another embodiment of the present invention; Figure 6 It is the main joint structure diagram of the present invention; Figure 7 It is an internal view of the main joint of the present invention.

[0026] Description of reference numerals: X-flow direction, Z-height direction, Y-width direction, 10- Heating plate, 11- medium flow channel, 111- anti-annular flow generating section, 112- anti-annular flow flow section, 20-heat conducting block, 21-Heating rod, 30- first temperature measuring element, 40- second temperature measuring element, 41-insulating tube, 42-protective tube, 43-fixed seat, 50-electrode, 60-first protective shell, 61-Insulation board, 70-Second protective shell, 701-Compression shell, 71-second insulating shell, 711-end insulating plate, 712-side insulating plate, 72- Fastening components, 80-main connector, 801- cross-section gradually shrinking section, 802- cross-section gradually expanding section, 803- cross-section constant section, 81- Temperature measuring joint, 82-Pressure measuring connector. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific embodiments and 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 a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating 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.

[0028] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual protection scope of the present invention.

[0029] In the related art, the reverse circulation film boiling test has problems such as unstable boiling and easy burning of the heating plate. Therefore, the technical solution of this application is produced. Figure 1 to Figure 7 To elaborate.

[0030] like Figure 1 , Figure 2 and Figure 4 As shown, the present application discloses a film boiling test device, which includes a heating plate 10 , a heat conductive block 20 , a first temperature measuring element 30 and a second temperature measuring element 40 .

[0031] Among them, the heating plate 10 is a metal plate made of Inconel nickel-based alloy, and its dimensions are 500mm to 800mm in length, 60 to 70mm in width, and 2 to 3mm 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, and are spaced in the middle to form a medium flow channel 11 for passing water and other media. The medium flow channel 11 is a narrow slit structure with a rectangular cross-section.

[0032] The heat-conducting block 20 is arranged on the heating plate 10, and the heat-conducting block 20 is used to heat the heating plate 10 at a constant temperature. The constant temperature heating here means that as the heat source of the heating plate 10, the heat-conducting block 20 will be in the required temperature range after preheating to ensure the smooth progress of the film boiling test. Specifically, the heat-conducting block 20 is constructed to keep its own temperature greater than or equal to the minimum temperature required for film boiling of the medium in the test device when heating the heating plate 10, and less than the melting point temperature of 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.

[0033] Furthermore, the temperature of the heat conductive block 20 drops by less than or equal to 50° C. within 5 minutes during the test, thereby stabilizing the heating temperature of the heating plate 10, avoiding large temperature fluctuations during the test, and improving the effect of constant temperature heating.

[0034] Furthermore, in order to meet the heating temperature required for the test while avoiding the heating plate 10 from being melted during the test, so as to achieve the purpose of stabilizing the heating temperature, the specific selection criteria such as the size, thermal coefficient and specific heat capacity of the heat conductive block 20 are as follows: the heat conductive block 20 can be made of materials such as red copper, brass with a material grade of H96, and lead brass with a material grade of HPb89-2. The thermal coefficient of the heat conductive block 20 is greater than 150W / (m·K), the specific heat capacity is greater than 300J / (kg·K), and the length range and height range of the heat conductive block 20 are both 100mm~200mm.

[0035] The thermal 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 thermal block 20 during the entire test process; on the other hand, the brazing sheet will melt during the welding process and fully fill the gap between the heating plate 10 and the thermal block 20, greatly reducing the contact thermal resistance between the two.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Alternatively, if Figure 1 , Figure 2As 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.

[0042] 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.

[0043] Alternatively, if Figure 1 , Figure 2 As shown, the heating rod 21 is arranged on the side of the heat-conducting block 20 away from the heating plate 10, and the first temperature measuring element 30 is arranged on the side of the heat-conducting block 20 close to the heating plate 10. For example, the bottom of the heat-conducting block 20 is connected to the heating plate 10, the first temperature measuring element 30 is arranged at the bottom of the heat-conducting block 20, and the heating rod 21 is arranged at the top of the heat-conducting block 20. In this way, the heat generated by the heating rod 21 is first transferred to the top of the heat-conducting block 20. After the heat is fully dissipated in the heat-conducting block 20 so that the heat-conducting block 20 is heated as a whole, the heat is then transferred from the bottom of the heat-conducting block 20 to the heating plate 10, and the heating effect of the heat-conducting block 20 on the heating plate 10 is further improved. At the same time, the temperature measured by the first temperature measuring element 30 can more accurately reflect the overall temperature of the heat-conducting block 20.

[0044] Alternatively, if Figure 1 , Figure 2 As shown, the test device also includes a first protective shell 60, which covers the exposed portion of the heat-conducting block 20, i.e., the portion of the heat-conducting block 20 that is not in contact with the heating plate 10; the first temperature measuring element 30 and the heating rod 21 both pass through the first protective shell 60 to be arranged on the heat-conducting block 20, and the setting of the first protective shell 60 can achieve shielding protection for the heating plate 10.

[0045] Alternatively, if Figure 1 , Figure 2As shown, an insulating plate 61 is disposed between the first protective shell 60 and the heat-conducting block 20 to provide insulation protection for the heat-conducting block 20 and prevent the heat-conducting block 20 from leaking electricity to the first protective shell 60 .

[0046] Alternatively, if Figure 1 to Figure 4 As shown, the test device also 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 to be arranged on the heating plate 10; the two ends of the heating plate 10 extend out of the second protective shell 70 to set the electrodes 50. The protection area covered by the second protective shell 70 includes the anti-annular flow generation section 111 and the anti-annular flow flow section 112, the heat conductive 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 by fasteners such as bolts, so that the first protective shell 60 covers the part of the heat conductive block 20 extending outside 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 by the setting of the second protective shell 70.

[0047] Alternatively, if Figure 2 to Figure 4 As shown, the second protective shell 70 includes a compression shell 701 arranged in pairs along the height direction Z. The compression shell 701 can be made of stainless steel with a material grade of 316L. The compression shell 701 arranged in pairs surrounds 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 compression shells 701 arranged in pairs. The compression 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 compression shells 701 arranged in pairs can be made to move closer to or away from each other, thereby adjusting the degree of compression on the heating plate 10. In this way, the compression of the heating plate 10 by the compression shell 701 can ensure 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.

[0048] Alternatively, if Figure 3 and Figure 4As shown, the test device also includes a second insulating shell 71, which is arranged between the second protective shell 70 and the heating plate 10, and the second temperature measuring element 40 passes through the second protective shell 70 and the second insulating shell 71 in sequence to be arranged on the heating plate 10; the second insulating shell 71 may 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, and the end insulating plates 711 and the side insulating plates 712 are arranged alternately 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 the second protective shell 70 and other structures when it is powered on for heating, so as to achieve insulation protection and improve 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 heating power.

[0049] Optionally, both the end insulating plate 711 and the side insulating plate 712 can be made of ceramics, which have a temperature resistance of over 800° C., ensuring normal use during the heating process.

[0050] Alternatively, if Figure 3 and Figure 4 As shown, the test device further includes an insulating tube 41, which can be made of ceramic, mica or other materials with a high temperature resistance of more than 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 to prevent the second temperature measuring element 40 from leaking electricity.

[0051] Alternatively, if Figure 3 and Figure 4 As shown, the test device also includes a protection tube 42. A threaded hole is provided on the second protection shell 70. The protection tube 42 is threadedly connected to the second protection shell 70 to facilitate disassembly. The protection tube 42 wraps the insulating tube 41 and the part of the second temperature measuring element 40 extending outside the second protection shell 70 to provide shielding protection for the insulating tube 41 made of brittle material.

[0052] Optionally, since the second temperature measuring element 40 will also be displaced when the heating plate 10 expands due to heat, 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. This provides sufficient space for the displacement of the second temperature measuring element 40.

[0053] like Figure 5 As shown, in some other optional embodiments, the test device 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. In this way, when the heating plate 10 is replaced, there is no need to replace the second temperature measuring element 40 thereon, thereby reducing manufacturing difficulty and cost.

[0054] Alternatively, if Figure 1 , Figure 6 and Figure 7 As shown, the test device also includes a main joint 80, which is connected to the heating plate 10 by 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 are connected to the main joint 80; along the direction away from the heating plate 10, the main joint 80 includes a cross-section tapering section 801, a cross-section expanding section 802 and a cross-section constant section 803 which are connected in sequence.

[0055] Among them, the cross-sectional shape of the constant-section section 803 is different from the cross-sectional shape of the medium flow channel 11. Specifically, the flow cross-section of the constant-section section 803 is circular, so that the main joint 80 can be connected to the external pipeline, and the cross-section of the medium flow channel 11 is a rectangular narrow slit that meets the test requirements as mentioned above. In other words, the dimension of the constant-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-section section 803 along the height direction Z is larger than the dimension of the medium flow channel 11 along the height direction Z.

[0056] The cross-sectional area of ​​the gradually expanding section 802 increases in the direction approaching the medium flow channel 11. Specifically, the gradually expanding section 802 is a trapezoidal structure in the direction approaching the medium flow channel 11, and the size of the gradually expanding section 802 in the width direction Y gradually increases, and the size in the height direction Z remains unchanged, so that the width dimension of the flow cross section in the main joint 80 is first adjusted to be consistent with the width dimension of the flow cross section in the medium flow channel 11; the cross-sectional area of ​​the gradually narrowing section 801 decreases in the direction approaching the medium flow channel 11. Specifically, the gradually narrowing section 801 is a gradually narrowing structure in the direction approaching the medium flow channel 11, and the size of the gradually narrowing section 801 in the width direction Y remains unchanged, and the size in the height direction Z decreases, so that the height dimension of the flow cross section in the main joint 80 is adjusted to be consistent with the height dimension of the flow cross section in the medium flow channel 11; the outlet cross section of the gradually narrowing section 801 is the same as the cross section of the medium flow channel 11.

[0057] It can be seen that the flow cross section in the medium flow channel 11 is a rectangular narrow slit, while the flow cross section of the medium in the external pipeline is circular, so the main joint 80 is set for transition. Through the structural design of the cross-section gradually contracting section 801, the cross-section gradually expanding section 802 and the cross-section constant section 803 of the main joint 80, when the medium flows into the medium flow channel 11, it will first be fully expanded by the cross-section gradually expanding section 802 in the main joint 80, so that the width dimension of the flow cross section of the main joint 80 is consistent with that of the medium flow channel 11, and then gradually contracted by the cross-section gradually contracting section 801, so that the height dimension of the flow cross section of the main joint 80 is consistent with that of the medium flow channel 11, thereby making the medium entering the medium flow channel 11 1 has a balanced speed and flow rate at each position, while the opposite is true when the medium flows out of the medium flow channel 11. The medium first fully expands along the height direction Z through the cross-section tapering section 801 to adjust the cross-section height dimension to be close to the cross-section constant section 803, and then contracts along the width direction Y through the cross-section expanding section 802 to adjust the cross-section width dimension to be close to the cross-section constant section 803, so that the medium entering the cross-section constant section 803 has a balanced speed and flow rate at each position. This setting ensures that although the flow cross section of the medium is switched between circular and rectangular, the flow of the medium between the medium flow channel 11 and the external pipeline can ensure the balance of flow rate and flow rate.

[0058] Alternatively, if Figure 6 and Figure 7 As shown, the test device also includes a temperature measuring joint 81 connected to the main joint 80, and the temperature measuring joint 81 is connected to a temperature measuring element to measure the temperature of the medium. Further, the test device also includes a pressure measuring joint 82 connected to the main joint 80, and the pressure measuring joint 82 is connected to a pressure measuring element to measure the pressure of the medium.

[0059] The present application also discloses a film boiling test method, comprising: A medium is introduced into the medium flow channel 11; The heating rod 21 is powered on to preheat the heat-conducting block 20 to a preset temperature, so that the medium passing through the anti-annular flow generating section 111 is in the anti-annular flow film boiling stage; the preset temperature is greater than or equal to the minimum temperature required for film boiling of the medium in the test device and is less than the melting point temperature of 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 more than 600 degrees Celsius; the anti-annular flow generating section 111 corresponds to the setting area where the heat-conducting block 20 is located; The electrode 50 is energized to heat the heating plate 10, so that the medium in the anti-annular flow flow section 112 maintains the anti-annular flow film boiling stage; the anti-annular flow flow section 112 corresponds to the setting area where the second temperature measuring element 40 is located; When the medium is in the anti-annular flow generating section 111 and maintains the anti-annular flow film boiling stage, the temperature of the heat conducting block 20 is obtained by the first temperature measuring element 30; When the medium is in the anti-annular flow section 112 and maintains the anti-annular flow film boiling stage, the temperature of the heating plate 10 is obtained by the second temperature measuring element 40 .

[0060] Thus, 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 a formula in the relevant technology, which will not be described in detail here.

[0061] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall 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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