Rectangular narrow channel lead bismuth alloy flow heat exchange experimental device and experimental method

Abstract

The application relates to a rectangular narrow-channel lead-bismuth alloy flow heat exchange experimental device and an experimental method. The application is used to solve the problem that the existing experimental device cannot meet the demand of the research on the flow heat exchange characteristics of lead-bismuth alloy in a rectangular narrow channel. The flow direction of the lead-bismuth alloy in the experimental section is from top to bottom. The inlet and outlet cylindrical chambers and the rectangular variable-diameter passage of the experimental section are fixed by welding and an external mechanical fixing device. The rectangular narrow channel is composed of stainless steel sheets. The inner side of the narrow side of the channel is supported and sealed by a first-stage stainless steel pad. The outer side is supported and fixed by a second-stage stainless steel fixing pad through bolt connection. The third-stage sealing is realized by smearing high-temperature-resistant sealing glue between the stainless steel pad, the bolt and the bolt gap. The rectangular narrow-channel sheet is heated by an indirect electric heating mode. The application is used for the flow heat exchange experiment of lead-bismuth alloy.

Description

TECHNICAL FIELD

[0001] The application relates to a lead-bismuth alloy flow heat exchange experimental device and an experimental method, in particular to an experimental device for measuring pressure drop and temperature parameters in the flow heat exchange process of a lead-bismuth alloy in a rectangular narrow channel and an experimental method of the experimental device, which is applied to the measurement of frictional resistance of the lead-bismuth alloy in the rectangular narrow channel, calculation of local frictional resistance coefficients, judgment of flow state transition, calculation of convective heat exchange coefficients and the like, and mainly relates to the technical fields of fluid mechanics, reactor thermal hydraulic, heat transfer and the like. BACKGROUND

[0002] The lead-bismuth alloy has low melting point and high boiling point, and a reactor taking liquid lead-bismuth as a coolant can be operated at low temperature under normal pressure, which reduces the pressure bearing requirement of equipment, is beneficial to improving the safety and reliability of the reactor, has weak slow-down capacity and small neutron absorption cross section, can effectively reduce the core power density, is chemically stable and cannot react with water, air and the like, cannot react with the core structure, greatly reduces the possibility of accidents in the reactor, improves the inherent safety of the reactor, simplifies the structure of equipment and improves the economy.

[0003] The rectangular narrow channel is composed of plate-shaped fuel elements and a rectangular coolant channel, the fuel plate is narrow, long and extremely thin, has a thickness of only about 2 mm, the plate spacing is only 2-3 mm, has the characteristics of compact structure, has the advantages of certain heat exchange enhancement, and the plate-shaped fuel assembly has the advantages of high heat release rate and heat exchange efficiency due to the low temperature of the fuel core and the high burnup of the fuel, can meet the needs of miniaturization of nuclear power devices, and therefore the research on the pressure drop and temperature change in the rectangular narrow channel taking the lead-bismuth alloy as a coolant is of great significance.

[0004] As to the research on the flow heat exchange characteristics in the rectangular narrow channel, a large number of related experiments have been carried out at home and abroad, and the calculation correlation formula suitable for the related parameters in the narrow gap channel is summarized, but the coolant used in the research on the plate-shaped fuel element is still water, and the research progress of the liquid metal coolant is relatively slow, the research means for the lead-bismuth fast reactor at home and abroad is mainly numerical simulation and program analysis, and is mainly concentrated in the heat exchange characteristic research of the rod bundle channel or the annular channel, and part of the research is on the heat exchange characteristic mechanism of the lead-bismuth alloy in the steam generator.

[0005] Due to the low Prandtl number characteristics of lead-bismuth alloy, the flow and heat exchange process in the rectangular narrow channel is quite different from that of water medium. Compared with the convection heat exchange mechanism caused by momentum transfer, the heat conduction diffusion mechanism is more dominant. At this time, the temperature boundary layer is thicker, and the main stream turbulence core area also mainly shows the characteristics of heat conduction. Based on this characteristic, the similarity between the velocity distribution and the temperature distribution in the boundary layer is lost, and the flow boundary layer and the temperature boundary layer are separated. The existing mechanism model and flow and heat exchange correlation are not suitable for predicting and researching the flow and heat exchange characteristics of lead-bismuth alloy in the rectangular narrow channel. Therefore, it is of great theoretical value and engineering significance to carry out experimental research on the flow and heat exchange characteristics of lead-bismuth alloy in the rectangular narrow channel.

[0006] Chinese patent CN113345611A discloses a plate-type fuel element multi-rectangular flow channel uniform heat release simulation experimental device. The experimental device can carry out experimental research on the flow and heat exchange characteristics of plate-type fuel element multi-rectangular flow channel under uniform heat release conditions, and can realize flow and heat transfer characteristics research under different power and flow conditions according to research needs. However, the water medium in the coolant channel of the device directly contacts with the stainless steel heating plate, and this heating method cannot be applied to lead-bismuth alloy coolant with electrical conductivity.

[0007] Chinese patent CN112683337A discloses a parallel plate bundle pressure field and flow field synchronous measurement experimental device. The device includes a measurement body, a water storage system, an adjusting system and a collection system. The measurement body includes a plate bundle cylinder, a plate bundle partition, an upper development chamber, an upper buffer chamber, a lower development chamber, a lower buffer chamber, a positioning groove, a positioning protrusion and a visualization window. However, the visualization window used in the device must ensure that the medium in the rectangular narrow channel has no corrosive property, and lead-bismuth alloy coolant as liquid metal has strong corrosive property. Therefore, this method cannot be used for velocity measurement of lead-bismuth alloy.

[0008] In summary, the existing experimental devices cannot meet the research needs of lead-bismuth alloy flow and heat exchange characteristics in the rectangular narrow channel. SUMMARY

[0009] The purpose of the present application is to solve the problem that the existing experimental devices cannot meet the research needs of lead-bismuth alloy flow and heat exchange characteristics in the rectangular narrow channel. A rectangular narrow channel lead-bismuth alloy flow and heat exchange experimental device and experimental method are provided.

[0010] The technical scheme of the present application is: a rectangular narrow channel lead bismuth alloy flow heat exchange experimental device, which comprises two cylindrical chambers and two rectangular chambers, a rectangular chamber is installed on one side of the horizontal end face of each cylindrical chamber, the two rectangular chambers are arranged adjacently and maintain the same spacing as the length of the body rectangular channel of the experimental section, and the two cylindrical chambers are coaxially arranged; it further comprises two channel plates, two stainless steel pads, two sets of fixing pads, a plurality of fixing bolts, magnesium oxide insulation material, a heating plate and aluminum silicate insulation cotton, the two channel plates are arranged in parallel, the two stainless steel pads are clamped between the left and right sides of the two channel plates, a coolant channel is formed between the two channel plates and the two stainless steel pads, the two sets of fixing pads are installed on the left and right sides of the two channel plates through a plurality of fixing bolts, the outer sides of the two channel plates between the two sets of fixing pads are coated with magnesium oxide insulation material and the heating plate is installed, and the aluminum silicate insulation cotton is wrapped on the outer sides of the two sets of fixing pads.

[0011] Further, the material of the channel plate is 316L stainless steel, and the material of the heating plate is stainless steel.

[0012] Further, high-temperature resistant sealant is applied between the fixing bolts and the outer side wall of the channel plate.

[0013] Further, a plurality of pressure introduction holes and a plurality of thermocouple probe holes are processed on the surface of the heating plate, the pressure introduction holes and the thermocouple probe holes are staggered, the thermocouple passes through the thermocouple probe hole to contact the channel plate, and the lead bismuth alloy is introduced into the differential pressure transmitter through the pressure introduction hole for measurement.

[0014] Further, it further comprises chamber aluminum silicate insulation cotton, and the outer side walls of the cylindrical chamber and the rectangular chamber are wrapped with aluminum silicate insulation cotton.

[0015] Further, the heating plate has the same size as the size of the coolant channel.

[0016] Further, it further comprises a heat tracing band and insulation cotton, the cylindrical chamber is wrapped with insulation cotton after being wound with a heat tracing band, and the temperature of the lead bismuth alloy in the upper and lower cylindrical chambers is monitored in real time through an external measurement system.

[0017] Further, it further comprises a mechanical fixing device and an experimental section body rack, and the cylindrical chamber is connected and fixed with the experimental section body rack by the mechanical fixing device.

[0018] The present application also provides a method for measuring the flow heat exchange of lead bismuth alloy in a rectangular narrow channel, which comprises the following steps:

[0019] Step one: continuously filter and purify the lead bismuth alloy before measurement;

[0020] Step two: pressure measurement of the lead bismuth alloy:

[0021] The pressure measurement of lead-bismuth alloy includes global pressure drop measurement and local pressure drop measurement, the global pressure drop measurement is obtained by measuring the pressure of lead-bismuth alloy in the upper and lower cylindrical chambers using pressure sensors, and the local pressure drop measurement is obtained by arranging a pressure tapping hole on the rectangular narrow channel steel plate and then measuring the lead-bismuth alloy introduced into the differential pressure transmitter;

[0022] Step three: temperature measurement of lead-bismuth alloy:

[0023] The temperature of lead-bismuth alloy in the coolant channel is calculated according to the heat conduction law and convective heat transfer calculation principle, the armored thermocouple mounting and fixing base is arranged on the outer wall surface of the channel plate, high thermal conductivity filler is used, the probe penetrates the experimental device, and heat insulation material is applied to ensure the accuracy of the temperature measurement of the outer wall surface of the steel plate;

[0024] Considering the energy loss in the electric heating process of the power supply system and the heat loss caused by imperfect heat preservation measures of the experimental system, the following treatment scheme is proposed for the conversion efficiency of electric power and heating power:

[0025] P elec =U·I

[0026] P heat =G LBE ·c p,LBE (T outlet -T inlet )

[0027]

[0028] In the above formula, the actual output electric power can be obtained by monitoring the voltage and current of the power supply system, the heat absorbed by the lead-bismuth alloy flowing through the experimental section is obtained by energy conservation relationship, the mass flow rate is obtained by the volume flow rate measured by the electromagnetic flowmeter and the physical property parameters, the inlet and outlet temperatures are the temperatures of lead-bismuth alloy in the upper and lower cylindrical chambers, and the specific heat at constant pressure is determined according to the qualitative temperature; the heating efficiency is obtained by electric power and heating power.

[0029] Further, the continuous filtering and purifying process of lead-bismuth alloy before measurement in step one is as follows:

[0030] The filtering device is located at the flange between the outlet of the experimental section and the inlet of the lead-bismuth storage tank, and the lead-bismuth alloy is purified by installing a perforated plate and a filter screen in the lead-bismuth pipeline, the experimental device is replaced with a circular tube before the filtering is completed, and the experimental device is installed after the lead-bismuth alloy is fully filtered, and the filter screen is replaced;

[0031] The lead bismuth alloy for the whole system internal circulation is filtered by the filtering device, lead bismuth oxide and pipeline equipment impurities corroded by the lead bismuth alloy are removed; and the continuous filtering and purification of the lead bismuth alloy during the experiment are ensured.

[0032] Compared with the prior art, the present application has the following effects:

[0033] 1. The lead bismuth alloy in the experimental section (referring to the experimental device) is indirectly heated, and the heating plate-heated plate (referring to the channel plate)-medium heat transfer mode is used, so that the experimental safety problem induced by the electrical conductivity of the liquid metal is effectively solved, and the heat supply module and the heated module are isolated by using insulating paint, so that the risk of electrical accidents caused by possible lead bismuth alloy leakage is effectively reduced.

[0034] 2. The circulating pressure head of the lead bismuth alloy in the experimental loop is completely provided by the electromagnetic pump, and the circulating pressure provided by the argon system is not needed, so that the stability of the lead bismuth alloy circulating flow in the loop is effectively ensured, the flow control is facilitated, and the real-time monitoring and control of the flow parameters of the lead bismuth alloy flowing from top to bottom in the experimental section are facilitated.

[0035] 3. The inlet and outlet of the present application are designed as rectangular variable-diameter and cylindrical chamber, both of which have a buffering effect on the lead bismuth alloy flow, the cylindrical chamber realizes the transition of the medium flow cross section from "circular cross section" to "rectangular cross section", and the size of the rectangular variable-diameter cross section is slightly larger than the size of the experimental section channel, so that the stable flow state of the medium flowing into and out of the experimental section from the cylindrical chamber is fully ensured, and the inlet and outlet effects are minimized. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1A is the axial side view of the experimental device of the present application applied to the experimental system, Figure 1B is the right view of Figure 1A , Figure 1C is the front view of Figure 1A ;

[0037] Figure 2A is the axial side view of the experimental section of the present application, Figure 2B is the sectional view of the experimental section;

[0038] Figure 3 is the structural schematic view of the experimental system;

[0039] Figure 4A is the transverse sectional view of the experimental section, Figure 4B is the longitudinal sectional view of the experimental section. DETAILED DESCRIPTION

[0040] Detailed implementation one: combined with Figure 2A , Figure 2B , Figure 4A andFigure 4B The embodiment is described, the embodiment includes two cylindrical chambers 27 and two rectangular chambers 29, one horizontal end face of each cylindrical chamber 27 is provided with a rectangular chamber 29, the two rectangular chambers 29 are arranged adjacent and keep the same spacing as the length of the rectangular channel of the experimental section body, the two cylindrical chambers 27 are coaxially arranged; it also includes two channel plates 20, two stainless steel pads 23, two groups of fixed pads 24, a plurality of fixed bolts 26, magnesium oxide insulation material 21, a heating plate 22 and aluminum silicate insulation cotton 51, the two channel plates 20 are arranged in parallel, the left and right sides between the two channel plates 20 clamp the two stainless steel pads 23, the cooling agent channel 19 is formed between the two channel plates 20 and the two stainless steel pads 23, the two groups of fixed pads 24 are respectively installed on the left and right sides of the two channel plates 20 through a plurality of fixed bolts 26, the outer side of the two channel plates 20 between the two groups of fixed pads 24 is sequentially provided with magnesium oxide insulation material 21 and a heating plate 22 from inside to outside, and the aluminum silicate insulation cotton 51 is wrapped on the outer side of the two groups of fixed pads 24.

[0041] The application can carry out research on the resistance characteristics and convective heat transfer characteristics of lead-bismuth alloy flow and heat transfer process in a rectangular narrow channel under different working conditions according to research needs, research the flow friction pressure drop of lead-bismuth alloy in a rectangular narrow channel under multiple working conditions, obtain the local friction resistance coefficient, and judge the flow laminar region, transition region and turbulent region of lead-bismuth alloy in the rectangular narrow channel. The non-isothermal experiment is carried out by indirect electric heating of the stainless steel plate, the non-isothermal experiment under the conditions of constant wall temperature and constant heat flux density is carried out, the temperature change law in the lead-bismuth alloy flow and heat transfer process is calculated based on the basic theory and model derivation of heat transfer, and the local Nusselt number and global Nusselt number of the convective heat transfer process are obtained.

[0042] The embodiment is designed with cylindrical chambers at the inlet and outlet of the experimental section, and the lead-bismuth alloy flowing into the coolant channel is buffered in advance, the high-temperature-resistant insulation material is filled between the stainless steel heating plate and the channel steel plate to avoid the safety problem of electric leakage caused by lead-bismuth alloy leakage during the experiment.

[0043] The experimental device of the embodiment uses two parallel stainless steel plates to position the narrow side size of the rectangular narrow channel, the steel plate is provided with a pressure lead-out hole for leading out lead-bismuth alloy, a slot hole for installing a thermocouple and a threaded hole for bolt fixation.

[0044] The rectangular narrow channel plate is indirectly heated by stainless steel heating plates, the heating surface size of the stainless steel heating plates is completely consistent with the size of the coolant channel, copper bars are vertically installed at the upper end and the lower end of the stainless steel heating plates respectively, in order to ensure that the experiment is convenient and safe and the existing experimental equipment is fully utilized, the stainless steel heating plates located on the two sides are connected to the power supply system in parallel to be electrified, the plate surface of the heating plate is also designed to have a pressure lead hole and a thermocouple probe hole. The indirect heating mode needs to add insulation materials between the heating plate and the channel plate to ensure that no electric conduction accident occurs in the possible lead-bismuth alloy leakage accident. In order to ensure that the heat of the heating plate is fully conducted in a single direction, heat preservation and heat insulation measures need to be taken in the non-research area, and the heat preservation mode of the application is to wrap aluminum silicate heat preservation cotton.

[0045] The application provides an experimental device for measuring pressure drop and temperature parameters in a lead-bismuth alloy flow heat exchange process in a rectangular narrow channel, lead-bismuth alloy circulation is realized through an electromagnetic pump, a high-temperature lead-bismuth alloy is cooled through an air cooler, heating of the lead-bismuth alloy in a lead-bismuth storage tank before the experiment is completed through a heat conduction oil circuit, and the experimental system further includes auxiliary systems such as a heat tracing system, an argon gas supply system, a vacuum system and a filtering system. The lead-bismuth alloy in the experimental section flows from top to bottom, the inlet and outlet cylindrical chambers and the rectangular variable-diameter section of the experimental section are fixed through welding and an external mechanical fixing device, the rectangular narrow channel is composed of a stainless steel sheet, the inner side of the narrow side of the channel is supported and sealed through a first-level support and sealing of a stainless steel pad, the outer side is supported and fixed through a second-level support and sealing of a stainless steel fixing pad bolt connection, and a high-temperature sealing glue is applied between the stainless steel pad, the bolt and the bolt gap to realize third-level sealing. The stainless steel sheet of the rectangular narrow channel is heated through an indirect electric heating mode, that is, a stainless steel heating plate with the same width size as the coolant channel is arranged outside the channel plate, copper bars are vertically installed at the upper end and the lower end of the heating plate and are connected with an external power supply, and the two side heating plates are connected in parallel in the power supply system. High-temperature insulation materials are uniformly applied between the heating plate and the stainless steel channel plate. The experimental section is heat preserved using aluminum silicate heat preservation cotton, and the fixing mode of the entire experimental section includes welding, bolt fixing and mechanical fixing. The experimental loop subsystem research scheme is mature, the experimental section heating mode is reasonable, data acquisition is convenient, and the research working condition range is wide.

[0046] Specific implementation method two: combining Figure 2A , Figure 2B and Figure 4B to illustrate the embodiment, the material of the channel plate 20 in the embodiment is stainless steel, and the material of the heating plate 22 is 316L stainless steel. In this way, the corrosion resistance is good. The other components and connection relationships are the same as those in the specific implementation method one.

[0047] Specific implementation method three: combining Figure 2A , Figure 2B , Figure 4A and Figure 4BIn this embodiment, the high-temperature-resistant sealant is applied between the fixed bolt 26 and the outer wall of the passage plate 20. In this way, the wide side of the rectangular narrow passage is supported by two stainless steel gaskets, and the high-temperature-resistant sealant is applied at the bolt fixing position of the rectangular narrow passage. This has the effect of preventing leakage of the lead-bismuth alloy and enhancing the impact resistance of the experimental section body. The other components and connection relationships are the same as those in Embodiment 1 or 2.

[0048] Embodiment 4: Combination Figure 2A and Figure 2B In this embodiment, the heating plate 22 has a plurality of pressure guide holes 50 and a plurality of thermocouple probe holes 55 formed on the plate surface. The pressure guide holes 50 and the thermocouple probe holes 55 are staggered. The thermocouple passes through the thermocouple probe hole 55 to contact the passage plate 20, and the lead-bismuth alloy is introduced into the differential pressure transmitter through the pressure guide hole 50 for measurement. In this way, the heating plate 22 can be heated and temperature measurement can be realized. The other components and connection relationships are the same as those in Embodiment 1, 2, or 3.

[0049] Embodiment 5: Combination Figure 2A and Figure 2B In this embodiment, the experimental device further includes a chamber silicate aluminum insulation cotton 51, and the outer wall of the cylindrical chamber 27 and the rectangular chamber 29 is wrapped with the chamber silicate aluminum insulation cotton 51. In this way, the experimental device can be easily insulated. The other components and connection relationships are the same as those in Embodiment 1, 2, 3, or 4.

[0050] Embodiment 6: Combination Figure 4A In this embodiment, the heating plate 22 has a heating surface size consistent with the size of the coolant passage 19. In this way, the heating plate 22 can be easily heated. The other components and connection relationships are the same as those in Embodiment 1, 2, 3, 4, or 5.

[0051] Embodiment 7: Combination Figure 2A and Figure 2B In this embodiment, the experimental device further includes a heat tracing band 53 and an insulation cotton 52. The cylindrical chamber 27 is wrapped with the heat tracing band 53 and then wrapped with the insulation cotton 52, and the temperature of the lead-bismuth alloy in the upper and lower cylindrical chambers 27 is monitored in real time by an external measurement system. In this way, the cylindrical chamber 27 can be easily insulated and heated. The other components and connection relationships are the same as those in Embodiment 1, 2, 3, 4, 5, or 6.

[0052] Embodiment 8: Combination Figure 2A and Figure 2BThe embodiment is described, and the embodiment further includes a mechanical fixing device 54 and an experimental section body stand, and the cylindrical chamber 27 is connected and fixed with the experimental section body stand by the mechanical fixing device 54. In this way, the experimental device is connected and fixed. The other components and connection relationship are the same as any one of the first to seventh embodiments.

[0053] The ninth embodiment is described in combination with FIGS. 1 to Figure 4B The embodiment is described, and the embodiment includes the following steps:

[0054] Step one: Before measurement, the lead-bismuth alloy is continuously filtered and purified;

[0055] Step two: The lead-bismuth alloy is measured for pressure:

[0056] The pressure measurement of the lead-bismuth alloy includes global pressure drop measurement and local pressure drop measurement. The global pressure drop measurement is obtained by measuring the pressure of the lead-bismuth alloy in the upper and lower cylindrical chambers 27 using pressure sensors. The local pressure drop measurement is obtained by arranging a pressure introduction hole on the rectangular narrow channel steel plate and then measuring the lead-bismuth alloy introduced into the differential pressure transmitter;

[0057] Step three: The lead-bismuth alloy is measured for temperature:

[0058] The temperature of the lead-bismuth alloy in the coolant channel 19 is calculated according to the heat conduction law and the heat transfer calculation principle by measuring the temperature of the outer wall of the channel plate 20 using a thermocouple. A armored thermocouple mounting and fixing base is arranged on the outer wall of the channel plate 20, and high-temperature resistant heat-conducting paint is used. The probe penetrates the experimental device and is coated with thermal insulation material to ensure the accuracy of the temperature measurement of the outer wall of the steel plate.

[0059] Considering the energy loss of the power supply system during the electric heating process of the heating plate 20 and the heat loss caused by the imperfect heat preservation measures of the experimental system, the following treatment scheme is proposed for the electric power and heating power conversion efficiency:

[0060] P elec = U·I

[0061] P heat = G LBE ·c p,LBE (T outlet -T inlet )

[0062]

[0063] In the above formula, the actual output electric power can be obtained by monitoring the voltage and current of the power supply system, the lead-bismuth alloy flowing through the experimental section absorbs heat through the energy conservation relationship, the mass flow rate is obtained by calculating the volume flow rate measured by the electromagnetic flowmeter and the physical property parameters, the inlet and outlet temperatures are the lead-bismuth alloy temperatures in the upper and lower cylindrical chambers 27, and the constant-pressure specific heat is determined according to the qualitative temperature; the heating efficiency is obtained by the electric power and the heating power.

[0064] The lead-bismuth alloy circulation of the present application relies on the electromagnetic pump to provide a circulating pressure head, the argon gas supply system only provides protective argon gas for the experimental circuit and cooperates with the vacuum system to maintain the system vacuum, and the electromagnetic pump is equipped with a frequency converter to automatically control the pump power; the front-end throttle valve of the electromagnetic flowmeter in the experimental system cooperates with the PLC system to adjust the circuit flow rate, thereby realizing accurate control of different measurement conditions; the data acquisition system can monitor and store the lead-bismuth alloy flow rate, the heating plate electric power, the outer wall temperature of the rectangular channel plate, the pressure difference of the experimental section measuring points, the liquid pressure in the cylindrical chamber, and the temperature, pressure, and vacuum degree of each measuring point during the experiment, thereby providing flow characteristic data indicators for the lead-bismuth alloy flow and heat exchange experiment in the rectangular narrow channel.

[0065] Specific implementation method ten: in combination with FIGS. 1 to Figure 4B In this embodiment, before measurement in step one, the lead-bismuth alloy is continuously filtered and purified as follows: the filtering device is located at the flange between the experimental section outlet and the lead-bismuth storage tank inlet, the lead-bismuth alloy is purified by installing a perforated plate and a filter screen in the lead-bismuth pipeline, the experimental device is replaced with a circular tube before the filtering is completed, the experimental device is installed after the lead-bismuth alloy is fully filtered, and the filter screen is replaced; the lead-bismuth alloy used for internal circulation of the entire system is filtered by the filtering device to remove lead-bismuth oxides and impurities of pipeline equipment corroded by the lead-bismuth alloy; and continuous filtering and purification of the lead-bismuth alloy during the experiment is ensured.

[0066] In this way, the pure lead-bismuth alloy can ensure the accuracy of the experimental measurement parameters, on the one hand, to avoid blockage of the heat exchange tubes in the heat exchanger causing insufficient heat exchange, and on the other hand, to ensure that the lead-bismuth alloy flowing through the experimental section is free of impurity particles and to minimize the uneven impact on the rectangular channel plate, therefore, the lead-bismuth alloy used for internal circulation of the entire system needs to be filtered by the filtering system before the experiment starts to remove lead-bismuth oxides and impurities of pipeline equipment corroded by the lead-bismuth alloy. The other components and connection relationships are the same as any one of the specific embodiments one to nine.

[0067] In combination with FIGS. 1 to Figure 4B The working principle of the present application is explained as follows:

[0068] The rectangular narrow channel lead bismuth alloy flow heat exchange experimental device of the present application is installed in an experimental system during actual use, and the experimental system is composed of a lead bismuth storage tank, a heat conducting oil furnace, an air cooling heat exchanger, an experimental section body, a filtering system, a heat tracing system, a valve system, an argon gas supply system, a vacuum system, a measuring system, a data acquisition system, a PLC control system, a power supply system, instruments and meters, pumps and pipelines and the like.

[0069] The heat conducting oil furnace is connected with the lead bismuth storage tank, and the lead bismuth alloy circulating in the whole experimental system is heated and melted before the experiment starts to ensure the liquid state of the lead bismuth alloy; the valve system is composed of stop valves, throttle valves and check valves to control the flow of fluid in each pipeline of the experimental system; the filtering system is located between the outlet of the experimental section and the inlet of the storage tank, and filters the impurities contained in the lead bismuth alloy through a hole plate and a filter screen; the heat tracing system is arranged in all pipelines, valves, instruments and meters in the lead bismuth circulating pipeline, as well as the cylindrical chamber and the rectangular variable-diameter periphery of the inlet and outlet of the experimental section to preheat the lead bismuth alloy flowing in the circulating pipeline; the argon gas supply system and the vacuum system share a pipeline to provide protective argon gas for the inside of the lead bismuth storage tank, maintain the vacuum degree of the system and reduce the oxidation degree of the lead bismuth alloy; the measuring system measures the parameters of each subsystem and instrument and meter of the experimental system, and measures the required parameters in the experimental section body, and the data obtained by the measuring system is monitored and stored through the data acquisition system and imported into a computer; the PLC control system automatically controls multiple systems and devices in the experimental system, including the heat tracing system, the power supply system, the data acquisition system, the heat exchange fan and the pump valve equipment; the experimental section body heats the lead bismuth alloy through indirect electric heating, and calculates and analyzes the related thermal hydraulic parameters by measuring the inlet and outlet pressure, local differential pressure, channel plate outer wall temperature and the like.

[0070] The lead bismuth alloy circulation relies on the circulating pressure head provided by the electromagnetic pump, the argon gas supply system only provides protective argon gas for the experimental circuit in cooperation with the vacuum system to maintain the vacuum of the system, and the electromagnetic pump is equipped with a frequency converter to realize automatic control of the pump power; the front end throttle valve of the electromagnetic flowmeter in the experimental system cooperates with the PLC system to adjust the flow of the circuit, and realizes accurate control of different measurement conditions.

[0071] The air cooler cools the high-temperature lead bismuth alloy flowing out of the lead bismuth storage tank in the non-isothermal experiment, and cools the lead bismuth alloy to the required temperature through the constant temperature air inhaled in the room, the high-temperature air flowing out of the air cooler is discharged into the environment through the heat exchange fan, and the frequency converter of the heat exchange fan is connected to the PLC control system to make the heat exchange fan have the function of real-time adjustment of the running power.

[0072] In combination Figure 3 with Fig. 4, the experimental device of the present application is composed of an experimental section body, subsystems, main equipment, pipelines and instruments and meters. As shown in Figure 3As shown, the entire experimental system includes: experimental section body 1, lead-bismuth storage tank 2, filtration system 3, argon gas supply system 7, vacuum system 8, PLC control system 13, data acquisition system 14, air cooling heat exchanger 15, heat exchanger fan 16, heat conducting oil furnace 18, lead-bismuth circulating pipeline 9, heat conducting oil circulating pipeline 10, argon gas supply pipeline 11, vacuum pipeline 12, and the heating system, power supply system, measurement system, valve system and instrument equipment fixing device not shown in the figure. The heat conducting oil furnace 18 provides high-temperature oil for the lead-bismuth storage tank 2 to heat and melt the solid lead-bismuth alloy stored in the tank body; the circulation of the lead-bismuth alloy in the experimental system relies on the driving head provided by the electromagnetic pump 4 to complete the counterclockwise flow circulation in the Figure 3 As shown, the entire experimental system includes: experimental section body 1, lead-bismuth storage tank 2, filtration system 3, argon gas supply system 7, vacuum system 8, PLC control system 13, data acquisition system 14, air cooling heat exchanger 15, heat exchanger fan 16, heat conducting oil furnace 18, lead-bismuth circulating pipeline 9, heat conducting oil circulating pipeline 10, argon gas supply pipeline 11, vacuum pipeline 12, and the heating system, power supply system, measurement system, valve system and instrument equipment fixing device not shown in the figure. The heat conducting oil furnace 18 provides high-temperature oil for the lead-bismuth storage tank 2 to heat and melt the solid lead-bismuth alloy stored in the tank body; the circulation of the lead-bismuth alloy in the experimental system relies on the driving head provided by the electromagnetic pump 4 to complete the counterclockwise flow circulation in the

[0073] The heat exchange equipment in the experimental system is the air cooling heat exchanger 15 and the heat exchanger fan 16. The high-temperature lead-bismuth alloy flowing through the lead-bismuth storage tank 2, the filtration system 3 and the electromagnetic pump 4 is cooled by indoor low-temperature air in the air cooler 15 for multiple passes and then enters the low-temperature lead-bismuth circulating pipeline to enter the experimental section body. The air used to cool the high-temperature lead-bismuth alloy is discharged into the external environment by the heat exchanger fan 16 connected to the air cooling heat exchanger 15. The power adjustment and air volume control of the heat exchanger fan 16 are controlled by the frequency converter connected to the PLC control system 13, which has the function of monitoring the working indicators of the air cooler in real time and adjusting the operating power.

[0074] In combination with Figure 4A The internal structure of the experimental section body is described in detail. Two 316L stainless steel channel plates 20 are placed in parallel to form a rectangular narrow channel cross section wide side. The stainless steel channel plates are arranged with stainless steel pads 23 with the same height and thickness as the narrow side of the coolant channel 19. Fixed pads 24 are provided on both sides of the stainless steel channel plates 20. The channel plates are fixed transversely by fixed bolts 26. High-temperature sealant is applied between the channel plates and the pads and in the gaps between the bolts and the threaded holes to enhance the strength and sealing performance of the coolant channel.

[0075] The heating mode adopts an indirect heating mode of "heating plate-heated plate-medium", the stainless steel channel plate 20 is in contact with the heating plate 22, the contact position of the heating plate 22 and the channel plate adopts 304 stainless steel material, the heating copper bar is vertically installed at the height of the inlet and outlet of the coolant channel and is connected with the power supply system through the wire, the magnesium oxide insulating material 21 is uniformly applied between the heating plate 22 and the stainless steel channel plate 20, so that the circuit can be isolated in time in the case of possible local leakage of the lead-bismuth alloy, and the insulation effect is achieved.

[0076] The experimental section body is heat-insulated by using aluminum silicate heat-insulating cotton 25, and reasonably increasing the use amount of the heat-insulating cotton can effectively improve the heat-insulating efficiency of the experimental section, is conducive to improving the accuracy and reliability of the flow heat exchange experimental research, and provides a larger installation space for the arrangement of the fixing plate for fixing the experimental section body, and is conducive to the connection and installation of the fixing mechanism.

[0077] Figure 4B A longitudinal sectional view of a near 1 / 4 scale structure of the experimental section body is shown. The cylindrical chamber 27 is connected with the lead-bismuth circulating pipeline 9 and has the functions of storing lead-bismuth alloy and buffering flow; there is a variable diameter 29 with a rectangular flow passage section between the cylindrical chamber and the coolant channel, the design size of the rectangular section of the rectangular variable diameter 29 is slightly larger than that of the coolant channel 19, and the rectangular variable diameter 29 has the functions of buffering flow and reducing the inlet and outlet effects; the cylindrical chamber 27 and the rectangular variable diameter 29 are both provided with heating bands and heat-insulating cotton, and the temperature of the lead-bismuth alloy in the upper and lower cylindrical chambers is monitored in real time through the measurement system, so that the inlet temperature of the coolant channel meets the experimental working condition requirements.

[0078] The rectangular variable diameter 29 is welded and connected with the stainless steel channel plate 20 and the stainless steel pad 23, the cylindrical chamber is welded and connected with the rectangular variable diameter, the cylindrical chamber is connected and fixed with the experimental section body rack by using a mechanical fixing device, the heat-insulating working forms of the cylindrical chamber and the rectangular variable diameter are different, the cylindrical chamber 27 is heat-insulated by covering thick heat-insulating cotton, the fixed pad plate 28 needs to be installed at the rectangular variable diameter 29, and the heat-insulating cotton is extruded to reduce its thickness, therefore, the power of the heating band at the rectangular variable diameter needs to be monitored and controlled separately to ensure that the temperature of the lead-bismuth alloy flowing into the coolant channel meets the experimental requirements. The coolant channel inlet and outlet fixed pad plates 28 can be connected with the experimental section body rack, have the effect of reinforcing the entire experimental section device, and the coolant channel outlet fixed pad plate has the effect of bearing the weight of all the equipment above the coolant channel outlet, which is conducive to the installation and fixation of the entire experimental section on the experimental platform.

[0079] Although the present application has been disclosed with reference to the preferred embodiments, it is not intended to limit the present application, and those skilled in the art can make other changes within the spirit of the present application and apply the present application to fields not mentioned in the present application, of course, the changes made according to the spirit of the present application should be included in the scope of protection claimed by the present application.

Claims

1. An experimental device for heat transfer of lead-bismuth alloy flow in a rectangular narrow channel, comprising two cylindrical chambers (27) and two rectangular chambers (29), wherein a rectangular chamber (29) is installed on one side of the horizontal end face of each cylindrical chamber (27), the two rectangular chambers (29) are arranged adjacent to each other and maintain a spacing equal to the length of the rectangular channel of the experimental section, and the two cylindrical chambers (27) are arranged coaxially. Its features are: It also includes two channel plates (20), two stainless steel pads (23), two sets of fixing pads (24), multiple fixing bolts (26), magnesium oxide insulation material (21), heating plate (22) and aluminum silicate insulation cotton (51). Two channel plates (20) are arranged in parallel relative to each other. Two stainless steel pads (23) are clamped between the two channel plates (20) on the left and right sides. The two channel plates (20) and the two stainless steel pads (23) form a coolant channel (19). Two sets of fixing pads (24) are installed on the left and right sides of the two channel plates (20) respectively by multiple fixing bolts (26). The outer side of the two channel plates (20) between the two sets of fixing pads (24) is coated with magnesium oxide insulating material (21) and a heating plate (22) is installed. Aluminum silicate insulation cotton (51) is wrapped around the outer side of the two sets of fixing pads (24). The inner side of the narrow side of the channel is supported and sealed with stainless steel pads, while the outer side is supported and fixed with stainless steel fixing pads and bolts. High-temperature resistant sealant is applied between the stainless steel pads and the fixing bolts and between the fixing bolts to achieve a third level of sealing. The lead-bismuth alloy flows from top to bottom inside the experimental section. The circulation head of the lead-bismuth alloy in the experimental circuit is entirely provided by an electromagnetic pump.

2. The experimental apparatus for heat transfer of lead-bismuth alloy in a rectangular narrow channel according to claim 1, characterized in that: The channel plate (20) is made of 316L stainless steel, and the heating plate (22) is made of stainless steel.

3. The experimental apparatus for heat transfer of lead-bismuth alloy flow in a rectangular narrow channel according to claim 2, characterized in that: High-temperature resistant sealant is applied between the fixing bolt (26) and the outer wall of the channel plate (20).

4. The experimental apparatus for heat transfer of lead-bismuth alloy in a rectangular narrow channel according to claim 3, characterized in that: The heating plate (22) has multiple pressure taps (50) and multiple thermocouple probe holes (55) machined on its surface. The pressure taps (50) and thermocouple probe holes (55) are staggered. The thermocouples pass through the thermocouple probe holes (55) and contact the channel plate (20). The lead-bismuth alloy is introduced into the differential pressure transmitter for measurement through the pressure taps (50).

5. The experimental apparatus for heat transfer of lead-bismuth alloy flow in a rectangular narrow channel according to claim 4, characterized in that: It also includes aluminum silicate insulation cotton (51) for the chambers, and aluminum silicate insulation cotton (51) is wrapped on the outer walls of the cylindrical chamber (27) and the rectangular chamber (29).

6. The experimental apparatus for heat transfer of lead-bismuth alloy in a rectangular narrow channel according to claim 5, characterized in that: The heating plate (22) has the same heating surface size as the coolant channel (19).

7. The experimental apparatus for heat transfer of lead-bismuth alloy in a rectangular narrow channel according to claim 6, characterized in that: It also includes a heat tracing cable (53) and insulation cotton (52). The cylindrical chamber (27) is wrapped with heat tracing cable (53) and then wrapped with insulation cotton (52). The temperature of the lead-bismuth alloy in the upper and lower cylindrical chambers (27) is monitored in real time by an external measurement system.

8. The experimental apparatus for heat transfer of lead-bismuth alloy in a rectangular narrow channel according to claim 7, characterized in that: It also includes a mechanical fixing device (54) and an experimental section body frame, with the cylindrical chamber (27) connected and fixed to the experimental section body frame by means of the mechanical fixing device (54).

9. A measurement method using the rectangular narrow channel lead-bismuth alloy flow heat transfer experimental apparatus as described in claim 1, characterized in that: It includes the following steps: Step 1: The lead-bismuth alloy is continuously filtered and purified before measurement; Step 2: Perform pressure measurement on the lead-bismuth alloy: Pressure measurement of lead-bismuth alloy includes global pressure drop measurement and local pressure drop measurement. Global pressure drop measurement is obtained by measuring the pressure of lead-bismuth alloy inside the upper and lower cylindrical chambers (27) using a pressure sensor. Local pressure drop measurement is obtained by arranging pressure taps on a rectangular narrow channel steel plate, introducing the lead-bismuth alloy into the differential pressure transmitter, and then measuring the pressure. Step 3: Temperature measurement of the lead-bismuth alloy: The temperature of the outer wall of the channel plate (20) is measured by thermocouples. The temperature of the lead-bismuth alloy in the coolant channel (19) is calculated according to the thermal conductivity law and the principle of convective heat transfer calculation. Armored thermocouple mounting bases are arranged on the outer wall of the channel plate (20). High thermal conductivity filler is used. The probe penetrates the experimental device and is coated with heat insulation material to ensure the accuracy of the temperature measurement of the outer wall of the steel plate. Considering the energy loss during the electric heating process of the power supply system to the heating plate (20) and the heat loss caused by the imperfect insulation measures of the experimental system, the following solutions are proposed for the conversion efficiency of electric power to heating power: In the above formula, the actual output power can be obtained by monitoring the voltage and current of the power supply system, and the heat absorbed by the lead-bismuth alloy flowing through the experimental section can be obtained by the energy conservation relationship. The mass flow rate is calculated by the volume flow rate and physical property parameters measured by the electromagnetic flow meter. The inlet and outlet temperatures are taken as the lead-bismuth alloy temperature in the upper and lower cylindrical chambers (27). The constant pressure specific heat is determined according to the qualitative temperature. The heating efficiency is obtained by the electric power and the heating power.

10. The measurement method according to claim 9, characterized in that: The continuous filtration and purification process of the lead-bismuth alloy before measurement in step one is as follows: The filtration device is located at the flange between the outlet of the experimental section and the inlet of the lead-bismuth storage tank. The lead-bismuth alloy is purified by installing a perforated plate and a filter screen in the lead-bismuth pipeline. Before the filtration is completed, the experimental device is replaced with a round pipe. After the lead-bismuth alloy is fully filtered, the experimental device is installed and the filter screen is replaced. A filtration device is used to filter the lead-bismuth alloy used for internal circulation throughout the system, removing lead-bismuth oxides and impurities from pipelines and equipment corroded by the lead-bismuth alloy; this ensures continuous filtration and purification of the lead-bismuth alloy during the experiment.

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