An experimental device and method for simulating a heat pipe failure transient accident in a micro-rod bundle

Abstract

The present application relates to heat pipe reactor technical field, especially a kind of test device for simulating heat pipe failure transient accident in heat pipe microreactor, including heat pipe microreactor simulation device, including reactor assembly, heat exchange component and a plurality of high-temperature heat pipes for heat transfer between the two;Heat pipe failure simulation device, including heat pipe simulation piece and the cooling circulation component communicated with it, the heat pipe simulation piece is arranged in the reactor assembly;Wherein, the heat pipe simulation piece is composed of inner tube and outer tube, and annular gap is left between the two tubes, inert mixed gas is introduced into the annular gap, the inert mixed gas is used to adjust the thermal resistance of the annular gap, the inner tube is communicated with the cooling circulation component;The present application can realize the heat transfer of different temperature and different power by adjusting gas component and the flow of cooling water, so as to realize heat pipe heat transfer and heat pipe failure transient simulation under different conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pipe reactor, in particular to a test device and method for simulating heat pipe failure transient accident in heat pipe micro reactor. BACKGROUND

[0002] As a typical type of micro reactor, heat pipe micro reactor has the advantages of safety, flexibility and reliability. Heat pipe reactor is a passive energy transfer device that inserts heat pipes into the reactor core to transfer heat from the reactor core to the heat sink. Therefore, heat pipe micro reactor has the characteristics of passive energy transfer, eliminating the need for pumps and valves in traditional reactors, thereby greatly improving its reliability.

[0003] Among the main equipment of heat pipe micro reactor, heat pipe is the core component connecting the reactor core and the heat and electricity conversion module, and is the most important link in the heat transfer path. The possibility of heat pipe failure during the service life of the reactor core should be considered when designing the reactor core and operating the reactor. When a small number of heat pipes in the reactor core fail, the heat transfer capacity of the failed heat pipes still needs to be transferred through the surrounding heat pipes, without the need to shut down the reactor and without causing damage to the reactor core. In addition, heat pipe failure accident is a typical accident of heat pipe micro reactor, so the analysis of heat pipe failure characteristics in heat pipe reactor is an important part of heat pipe reactor design and performance test verification.

[0004] High-temperature heat pipes are a kind of efficient heat transfer equipment with large heat transfer power and small temperature difference. The normal working state of the heat pipe is taken as the initial state of the heat pipe failure accident in the heat pipe micro reactor. When the heat pipe is working normally, it can achieve large heat transfer power transmission under small temperature difference. When the heat pipe fails, the heat pipe loses its heat transfer function, and the heat in the reactor core cannot be transferred out, causing the temperature of the reactor core to gradually rise. For the simulation of the transient characteristics of heat pipe failure accident, the key is to simulate the normal working state of the heat pipe and the working state of the heat pipe losing heat transfer capacity, and to observe the transient changes of the reactor core after the heat pipe fails. However, the existing simulation test device cannot achieve this well, and therefore cannot truly reflect the influence of heat pipe failure on the thermal and mechanical characteristics of the reactor core. SUMMARY

[0005] The purpose of the present application is to provide a test device and method for simulating heat pipe failure transient accident in heat pipe micro reactor, to solve the problem that the existing simulation test device cannot truly reflect the influence of heat pipe failure on the thermal and mechanical characteristics of the reactor core. In order to achieve the above purpose, the present application solves the problem by the following technical scheme:

[0006] In a first aspect, the present application provides a test device for simulating heat pipe failure transient accident in heat pipe micro reactor, comprising:

[0007] The heat pipe micro reactor simulation device comprises a reactor assembly, a heat exchange assembly, and a plurality of high-temperature heat pipes arranged between the two for heat transfer.

[0008] The simulation device for heat pipe failure comprises a heat pipe simulation part and a cooling circulation assembly in communication with the heat pipe simulation part, and the heat pipe simulation part is arranged in the reactor assembly.

[0009] The heat pipe simulation part is composed of an inner pipe and an outer pipe sleeve, and an annular gap is left between the two pipes for the inert mixed gas to adjust the thermal resistance of the annular gap.

[0010] As a further technical solution, the inert mixed gas is helium-argon mixed gas, and the thermal resistance of the annular gap is adjusted by changing the proportion of helium and argon.

[0011] As a further technical solution, the cooling circulation assembly uses cooling water as the medium.

[0012] As a further technical solution, the cooling circulation assembly comprises a pump, a valve, a flow meter for monitoring the water flow, and a thermocouple for detecting the inlet and outlet temperatures of the cooling water.

[0013] As a further technical solution, the reactor assembly comprises a reactor grid base and a heating device arranged therein, and the high-temperature heat pipe and the heat pipe simulation part are inserted into the reactor grid base.

[0014] As a further technical solution, the outer diameter of the outer pipe is consistent with the high-temperature heat pipe.

[0015] As a further technical solution, the heat pipe simulation part is arranged according to the position of the heat pipe failure simulation.

[0016] In the second aspect, the application provides a simulation method for heat pipe failure of the test device according to the first aspect, comprising the following steps:

[0017] The working state of the high-temperature heat pipe at the position of the heat pipe simulation part is calculated and analyzed through calculation analysis or numerical simulation;

[0018] According to the heat transfer power of the high-temperature heat pipe at the position of the heat pipe simulation part, the flow of the cooling water in the cooling circulation assembly is calculated, the heat transfer resistance of each heat transfer process is calculated by assuming the thermal conductivity of the annular gap, and a check heat transfer power is calculated according to the average temperature difference between the pipe wall of the evaporation section of the heat pipe and the cooling water. The check heat transfer power is compared with the heat pipe heat transfer power, and iterative calculation is performed so that the final check heat transfer power is equal to the heat pipe heat transfer power, thereby determining the thermal conductivity of the annular gap and the proportion of the inert mixed gas components.

[0019] The test device is adjusted to the design value, the cooling circulation assembly is turned off after the test device reaches the set power and stabilizes, the cooling medium in the inner pipe is emptied, the change of the core temperature is measured, and the transient simulation of the heat pipe failure is realized.

[0020] As a further technical solution, according to the heat transfer power of the high-temperature heat pipe and the average temperature of the pipe wall of the evaporation section of the heat pipe, the proportion of the inert mixed gas components is preliminarily set;

[0021] According to the structural parameters, material properties of the inner pipe and the outer pipe, and the material properties of the inert mixed gas, the thermal resistance of the inner pipe, the outer pipe and the annular gap is obtained, and then the design value of the proportion of the inert mixed gas is obtained by checking the heat transfer power.

[0022] As a further technical solution, when designing the annular gap thermal resistance and the cooling medium flow, it is ensured that the outlet temperature of the cooling medium does not exceed 60 DEG C.

[0023] The beneficial effects of the above-mentioned application are as follows:

[0024] (1) The heat pipe simulation piece of the application is a double-layer sleeve structure, and the annular gap composed of the inner pipe and the outer pipe is filled with helium-argon mixed gas. During the test, the adjustment of the proportion of the two gases can realize the adjustment of the thermal conductivity of the annular gap. By adjusting the gas components and the flow of the cooling water, the heat transfer of the outer pipe wall of the heat pipe simulation piece at different temperatures and the heat transfer of the heat pipe simulation piece at different powers can be realized, so that the simulation under different working conditions of the heat pipe can be realized.

[0025] (2) The heat pipe simulation piece of the application adopts the form of sleeve, and the inert mixed gas with low thermal conductivity is added between the water cooling medium and the core of the high-temperature reactor, so that the simulation of the high-temperature working condition of the heat pipe wall can be realized.

[0026] (3) The cooling circulation assembly of the application uses water as the medium, and utilizes the characteristics of large specific heat of water, so that the heat transfer power can be large under the condition of small temperature rise, the characteristics of high heat transfer power and small temperature difference of the heat pipe can be simulated; at the same time, the working temperature of the cooling water is low, the heat exchange capacity is strong, the annular gap filled with inert mixed gas can ensure that the outer wall temperature of the heat pipe simulation piece is close to the outer wall temperature of the real heat pipe, and the simulation accuracy is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings accompanying the specification of the application form a part of the application and serve to provide further understanding of the application. The schematic embodiments of the application and the description thereof serve to explain the application, and do not constitute a limitation of the application. It should also be understood that these drawings are shown for simplicity and clarity, and are not necessarily drawn to scale. The application will now be described and explained in additional features and details by using the drawings, in which:

[0028] Figure 1 The overall structure of the test device in the embodiment of the application is shown in the schematic diagram;

[0029] Figure 2 The structure of the heat pipe simulation piece in the embodiment of the application is shown in the schematic diagram;

[0030] Figure 3 The figure shows the cross-sectional view of the heat pipe simulation piece in the embodiment of the present application.

[0031] In the figure: 1, pump; 2, electromagnetic valve; 3, flow meter; 4, connecting pipeline; 5, heat pipe simulation piece; 51, inner tube; 52, outer tube; 53, annular gap; 54, inlet nozzle; 55, outlet nozzle; 56, gas inlet nozzle; 57, gas outlet nozzle; 6, cooling water tank; 7, reactor grid base; 8, electric heating rod; 9, high-temperature heat pipe; 10, heat pipe heat exchanger; 11, inlet thermocouple; 12, outlet thermocouple. DETAILED DESCRIPTION

[0032] The technical solutions in the typical embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application.

[0033] Embodiment 1

[0034] As shown in the figure, the present embodiment provides a test device for simulating the heat pipe failure transient accident in the heat pipe microreactor, which comprises a heat pipe microreactor simulation device and a heat pipe failure simulation device, and the two devices work in cooperation. Figures 1-3 As shown in the figure, the heat pipe microreactor simulation device comprises a reactor assembly, a heat exchange assembly and a plurality of high-temperature heat pipes 9 arranged between the two assemblies for heat transfer. The heat exchange assembly adopts a heat pipe heat exchanger 10, and the reactor assembly comprises a reactor grid base 7 and a heating device arranged in the reactor grid base 7. The number, size and distribution of the holes in the reactor grid base 7 are determined by the design scheme of the heat pipe microreactor. In the present embodiment, the heating device is an electric heating rod 8, and the power, number, size and position of the electric heating rod 8 are determined by the design scheme of the heat pipe microreactor. The reactor grid base 7 is inserted into the plurality of high-temperature heat pipes 9, and the high-temperature heat pipes 9 are normal ordinary heat pipes used for cooperation test. The size, structure and position of the high-temperature heat pipes 9 are determined by the design scheme of the heat pipe microreactor.

[0035] Figure 1 The heat pipe failure simulation device comprises a heat pipe simulation piece 5 and a cooling circulation assembly in communication with the heat pipe simulation piece 5. The heat pipe simulation piece 5 is arranged in the reactor assembly, and the heat pipe simulation piece 5 is inserted into the reactor grid base 7 according to the position of the simulated heat pipe failure. Before the test, the high-temperature heat pipes 9, the electric heating rod 8 and the heat pipe simulation piece 5 are inserted into the reactor grid base 7 according to the positions determined by the design scheme of the heat pipe microreactor and the test scheme. After the insertion, the heat pipe simulation piece 5 is connected to the pump 1, the electromagnetic valve 2, the flow meter 3, the cooling water tank 6 and the thermocouples for detecting the inlet and outlet temperatures of the cooling water, and the thermocouples comprise the inlet thermocouple 11 and the outlet thermocouple 12, thereby forming a complete heat pipe failure simulation device.

[0036] As shown in the figure, the heat pipe failure simulation device comprises a heat pipe simulation piece 5 and a cooling circulation assembly in communication with the heat pipe simulation piece 5. The heat pipe simulation piece 5 is arranged in the reactor assembly, and the heat pipe simulation piece 5 is inserted into the reactor grid base 7 according to the position of the simulated heat pipe failure. Before the test, the high-temperature heat pipes 9, the electric heating rod 8 and the heat pipe simulation piece 5 are inserted into the reactor grid base 7 according to the positions determined by the design scheme of the heat pipe microreactor and the test scheme. After the insertion, the heat pipe simulation piece 5 is connected to the pump 1, the electromagnetic valve 2, the flow meter 3, the cooling water tank 6 and the thermocouples for detecting the inlet and outlet temperatures of the cooling water, and the thermocouples comprise the inlet thermocouple 11 and the outlet thermocouple 12, thereby forming a complete heat pipe failure simulation device.

[0037] As​Figure 2 and Figure 3 As shown in the figure, the heat pipe simulation 5 is composed of inner tube 51, outer tube 52, annular gap 52, inlet nozzle 54, outlet nozzle 55, gas inlet nozzle 56, and gas outlet nozzle 57. The inlet nozzle 54 and outlet nozzle 55 are used for the inlet and outlet of cooling water, and the gas inlet nozzle 56 and gas outlet nozzle 57 are used for the inlet and outlet of inert gas mixture.

[0038] To ensure the accuracy of the simulation test, the outer diameter of the outer tube 52 is consistent with the real high-temperature heat pipe 9.

[0039] The heat pipe simulation 5 is composed of the inner tube 51 and the outer tube 52, which is a double-layered sleeve structure. The annular gap 53 between the two tubes is filled with inert gas mixture, which is used to adjust the thermal resistance of the annular gap 53. The inner tube 51 is in communication with the cooling circulation assembly and serves as a cooling medium flow channel for heat exchange.

[0040] The annular gap 53 composed of the inner tube 51 and the outer tube 52 is filled with helium-argon gas mixture. During the test, the thermal conductivity of the annular gap 53 is adjusted by adjusting the proportion of the two gases, and then the thermal resistance of the annular gap 53 is adjusted. By adjusting the gas composition and the flow rate of the cooling water, different temperatures and different heat transfer powers can be achieved, thereby realizing the heat transfer of the heat pipe under different conditions and the transient simulation of the failure of the heat pipe.

[0041] The cooling circulation assembly uses water as the medium. Due to the large specific heat capacity of water, a large heat transfer power can be achieved under the condition of a small temperature rise, which simulates the characteristics of high heat transfer power and small temperature difference of the heat pipe. At the same time, the working temperature of the cooling water is low, and the heat exchange capacity is strong. The annular gap 53 filled with inert gas mixture can ensure that the outer wall temperature of the heat pipe simulation is close to the outer wall temperature of the real heat pipe, ensuring the accuracy of the simulation test.

[0042] In this embodiment, the annular gap 53 is 2mm, and the helium-argon gas mixture is filled in the annular gap 53. By adjusting the proportion of helium and argon, the thermal resistance is adjusted, and then the heat transfer power is adjusted by adjusting the flow rate of the cooling water circuit. The inlet temperature of the cooling water is about 20℃. To ensure safety, the cooling water cannot reach the saturation state under normal pressure. When designing the annular gap thermal resistance and the cooling water flow rate, it is necessary to ensure that the outlet temperature of the cooling water does not exceed 60℃.

[0043] The test device for simulating the failure of the heat pipe in the heat pipe micro reactor proposed in this embodiment can simulate the heat transfer power under the conditions of heat pipe startup, normal operation, heat transfer limit phenomenon in operation and accident, complete failure of the heat pipe, and partial failure of the heat pipe, and can be used to study the transient response characteristics of the reactor core when the heat pipe at a certain position in the heat pipe micro reactor encounters heat transfer limit and heat pipe failure.

[0044] Example 2

[0045] The embodiment provides a simulation heat pipe failure method according to the test device in embodiment 1, comprising the following steps:

[0046] According to the heat transfer power of the high-temperature heat pipe at the position of the heat pipe simulation piece, the flow of the cooling water in the cooling circulating assembly is calculated. Assuming the heat conduction coefficient of the annular gap, the heat exchange thermal resistance of each heat transfer process is calculated, and then according to the average temperature difference between the pipe wall of the evaporation section of the heat pipe and the cooling water, a check heat transfer power is calculated. The check heat transfer power is compared with the heat transfer power of the heat pipe, and iterative calculation is performed, so that the final check heat transfer power is equal to the heat transfer power of the heat pipe, so as to determine the heat conduction coefficient of the annular gap, and finally determine the proportion of the inert mixed gas components.

[0047] Adjust the test device to the design value, and after the test device reaches the set power and stabilizes, close the cooling circulating assembly, empty the cooling medium in the inner pipe, measure the change of the core temperature, and realize the transient simulation of the heat pipe failure.

[0048] Specifically: before the test, the working state of the high-temperature heat pipe at the position of the heat pipe simulation piece is calculated and analyzed through calculation analysis or numerical simulation, including heat transfer power Φ, average temperature T E of the pipe wall of the evaporation section of the heat pipe, etc. The heat transfer power of the heat pipe and the pipe wall temperature are taken as the design input of the heat pipe simulation piece. The proportion of helium and argon in the annular gap 53 is initially set, and the heat conduction coefficient λgas W / m℃ of the gas is calculated. According to the structural parameters and material properties of the inner pipe 51 and the outer pipe 52 and the material properties of the inert mixed gas, the heat conduction thermal resistances R1, R2 and R3 ℃ / W of the inner pipe 51, the outer pipe 52 and the annular gap 53 are calculated respectively.

[0049] The inlet temperature of the water in the inner pipe 51 is T li , the outlet temperature of the water in the inner pipe 51 is set as T lo , and the mass flow of the water is:

[0050]

[0051] In the formula, im is the mass flow of the water in the inner pipe 51, unit: kg / s; c p is the specific heat of water.

[0052] According to the mass flow of the water in the inner pipe 51, the convective heat transfer coefficient h of the water flow in the inner pipe 51 is calculated. Then the convective heat transfer thermal resistance of the water is obtained:

[0053]

[0054] In the formula, A1 is the inner surface area of the inner pipe 51.

[0055] According to the calculated R1, R2, R3 and R4, and the average temperature T EThe inlet and outlet temperature T of water in the inner tube 51 li T lo The heat transfer power is checked:

[0056]

[0057] If Φ check < Φ, it means that the thermal resistance is too large, the gas composition is adjusted to reduce R3, so that Φ check = Φ.

[0058] If Φ check > Φ, it means that the thermal resistance is too small, the gas composition is adjusted to increase R3, so that Φ check = Φ.

[0059] The inert mixed gas component ratio and the flow of water in the inner tube 51 are adjusted to the design value, the electric heating system of the test device is opened, and the electric heating rod 8 is used to start heating the core. After the test system reaches the set power and stabilizes, the electromagnetic valve is closed, and the water in the inner tube 51 is quickly emptied. The change of the core temperature is measured, and the transient simulation of the heat pipe failure can be realized.

[0060] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. A test apparatus for simulating transient accidents of heat pipe failure in a heat pipe microreactor, characterized in that, include: A heat pipe microreactor simulation device includes a reactor assembly, a heat exchange assembly, and several high-temperature heat pipes disposed between the two for heat transfer. A heat pipe failure simulation device includes a heat pipe simulation component and a cooling circulation assembly connected thereto, the heat pipe simulation component being disposed in the reactor assembly; The heat pipe simulation component consists of an inner tube and an outer tube, with an annular gap between the two tubes for introducing an inert gas mixture. The inert gas mixture is used to adjust the thermal resistance of the annular gap. The inner tube is connected to the cooling circulation assembly and serves as a heat exchange channel for the flow of the cooling medium. The inert gas mixture is a helium-argon mixture, and the thermal resistance of the annular gap is adjusted by changing the ratio of helium and argon. The proportion of inert gas mixture components is adjusted as follows: assuming the thermal conductivity of the annulus, the heat transfer resistance of each heat transfer process is calculated. Then, based on the average temperature difference between the pipe wall and the cooling water in the heat pipe evaporation section, a check heat transfer power is calculated. The check heat transfer power is compared with the heat pipe heat transfer power, and iterative calculations are performed to ensure that the final check heat transfer power is equal to the heat pipe heat transfer power, thereby determining the thermal conductivity of the annulus and ultimately determining the proportion of inert gas mixture components.

2. The experimental apparatus for simulating transient accidents of heat pipe failure in a heat pipe microreactor as described in claim 1, characterized in that, The cooling circulation assembly uses cooling water as the medium.

3. The experimental apparatus for simulating transient accidents of heat pipe failure in a heat pipe micro-pile as described in claim 2, characterized in that, The cooling circulation assembly includes a pump, valves, a flow meter for monitoring water flow, and thermocouples for detecting the inlet and outlet temperatures of the water.

4. The experimental apparatus for simulating transient accidents of heat pipe failure in a heat pipe microreactor as described in claim 1, characterized in that, The reactor assembly includes a reactor grid substrate and a heating device disposed therein, wherein the high-temperature heat pipe and the heat pipe simulator are inserted into the reactor grid substrate.

5. The experimental apparatus for simulating transient accidents of heat pipe failure in a heat pipe microreactor as described in claim 1, characterized in that, The outer diameter of the outer tube is the same as that of the high-temperature heat pipe.

6. The experimental apparatus for simulating transient accidents of heat pipe failure in a heat pipe microreactor as described in claim 1, characterized in that, The heat pipe simulators are arranged according to the locations where heat pipe failure needs to be simulated.

7. The method for simulating heat pipe failure according to the test apparatus as described in any one of claims 1-6, characterized in that, Includes the following steps: The working state of the high-temperature heat pipe at the location of the heat pipe simulation component is obtained through calculation analysis or numerical simulation. The flow rate of cooling water in the cooling circulation assembly is calculated based on the heat transfer power of the high-temperature heat pipe at the location of the heat pipe simulator. Assuming the thermal conductivity of the annulus, the heat transfer resistance of each heat transfer process is calculated. Then, based on the average temperature difference between the pipe wall and the cooling water in the heat pipe evaporation section, a check heat transfer power is calculated. The check heat transfer power is compared with the heat pipe heat transfer power and iteratively calculated until the final check heat transfer power is equal to the heat pipe heat transfer power, thereby determining the thermal conductivity of the annulus and finally determining the composition ratio of the inert gas mixture. Adjust the test device to the design value. After the test device reaches the set power and stabilizes, shut down the cooling circulation components, drain the cooling medium from the inner tube, and measure the change in core temperature to achieve transient simulation of heat pipe failure.

8. The method for simulating heat pipe failure as described in claim 7, characterized in that: Based on the heat transfer power of the high-temperature heat pipe and the average wall temperature of the evaporation section of the heat pipe, the proportion of inert mixed gas components is initially determined. Based on the structural parameters and material properties of the inner and outer tubes, as well as the material properties of the inert gas mixture, the thermal resistance of the inner tube, outer tube, and annular gap is obtained. Then, the design value of the component ratio of the inert gas mixture is obtained by checking the heat transfer power.

9. The method for simulating heat pipe failure as described in claim 7, characterized in that, When designing the annular gap thermal resistance and cooling medium flow rate, ensure that the cooling medium outlet temperature does not exceed 60℃.

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