Liquid metal electromagnetic pump and multi-physical field parameter collaborative design method thereof

Abstract

The application discloses a liquid metal electromagnetic pump and a multi-physical field parameter collaborative design method thereof, and comprises the following steps: a first annular flow channel is designed, the inlet of the first annular flow channel is connected with a high-temperature area of liquid metal, and the outlet of the first annular flow channel is connected with an inlet area of a heat exchanger or a liquid metal heat exchange device; a second annular flow channel is designed, the inlet of the second annular flow channel is connected with an outlet area of the heat exchanger or the liquid metal heat exchange device, and the outlet of the second annular flow channel is connected with a low-temperature area of liquid metal; the gap size and flow of the first annular flow channel are set based on fixed parameters of a system in which the liquid metal electromagnetic pump is located and temperature rise of an excitation coil; the gap size and flow of the second annular flow channel are set based on temperature rise of the excitation coil; and the convective heat exchange rate of the low-temperature liquid metal and the pump shell when the low-temperature liquid metal passes through the second annular flow channel is set; through the multi-physical field parameter collaborative design of cold flow and hot flow isolation transportation and pump structure parameters, the best matching of the pump structure size, the coil temperature resistance and the cooling system parameters is realized, and the safety of the electromagnetic pump structure, the reliability of the coil heat dissipation and the stability of the operation temperature of the system are ensured.

Description

Technical Field

[0001] This invention relates to the field of nuclear industry technology, specifically to a liquid metal electromagnetic pump and its multi-physics parameter collaborative design method. Background Technology

[0002] Liquid metal electromagnetic pumps are used in scattering target systems of accelerator-driven transmutation devices, cooling systems of fourth-generation nuclear reactors, advanced thermal equipment, or high-temperature metallurgical circulation systems. Their function is to transport liquid metal from high-temperature zones to low-temperature zones, ensuring that the system's operating temperature remains within a controllable range.

[0003] When liquid metal electromagnetic pumps transport liquid metal, the heat generated by the electromagnetic coil needs to be dissipated promptly; otherwise, the pump will overheat and be damaged. Existing liquid metal electromagnetic pumps employ a dual-loop design: the inner loop transports liquid metal from the high-temperature zone to the low-temperature zone, while the outer loop transports the low-temperature liquid metal from the outer loop to dissipate heat from the electromagnetic coil. The cooled liquid metal from the outer loop, along with the liquid metal from the high-temperature zone, is then transported to the low-temperature zone through the inner loop. The drawback of this design is that, because the operating temperature of nuclear reaction systems needs to be within a controllable range and is relatively high, if the liquid metal used to dissipate heat from the electromagnetic coil is transported through the inner loop, the heat from the high-temperature zone transported by the outer loop will be lost. The quantity and flow rate of liquid metal can be affected, leading to uncontrollable inlet and outlet temperatures of the system, which in turn affects the stability of the operating temperature of the nuclear reaction system. Furthermore, based on different parameters of the nuclear reaction system, the inlet and outlet temperatures of the system are different. The design parameters of the liquid metal electromagnetic pump will inversely affect the stability of the operating temperature of the nuclear reaction system. Different inlet and outlet temperatures require the efficiency of the liquid metal electromagnetic pump in delivering liquid metal in the high-temperature zone to be within a certain range. Therefore, the power generated by the electromagnetic coil needs to meet the delivery requirements. There is a dynamic relationship between the heat dissipation of the electromagnetic coil and the size and heat dissipation efficiency of the outer tube. Therefore, the parameter design of the electromagnetic pump is also crucial.

[0004] Therefore, how to solve the problem of the disconnect between the cooling design of the high-temperature liquid metal conveying system and the electromagnetic pump coil in the existing technology, and the inability to effectively control the coil temperature while ensuring the stability of the system's operating temperature, is a technical problem in this field. Summary of the Invention

[0005] This invention provides a liquid metal electromagnetic pump and its multi-physics parameter collaborative design method. Through multi-physics collaborative optimization, the optimal matching of electromagnetic pump structure size, coil temperature resistance and cooling system parameters is achieved, ensuring electromagnetic pump structure safety, reliable coil heat dissipation and stable liquid metal flow, and stable system operating temperature.

[0006] This invention provides the following technical solution: a multi-physics parameter collaborative design method for a liquid metal electromagnetic pump, comprising: an inner core assembly, a pump groove, a heat shield, an excitation coil, an outer core assembly, a pump casing, an outer pipe, a pump groove support, and a pump casing support. A first annular flow channel is formed between the inner core assembly and the pump groove. The pump groove support is supported within the first annular flow channel. The inlet of the first annular flow channel is connected to the high-temperature zone of the liquid metal, and the outlet is connected to the inlet area of ​​a heat exchanger or liquid metal heat exchange equipment for outputting liquid metal from the high-temperature zone. The heat shield is fitted outside the pump groove, the excitation coil is located outside the heat shield, the outer core assembly is located outside the excitation coil, and the pump casing is fitted outside the outer core assembly. The outer pipe is fitted outside the pump casing, forming a second... The pump casing is supported within a second annular flow channel. The inlet of the second annular flow channel connects to the outlet area of ​​a heat exchanger or liquid metal heat exchange equipment, and the outlet connects to the low-temperature zone of the liquid metal, for conveying liquid metal from the low-temperature zone. The gap size and flow rate of the first annular flow channel are based on the fixed parameters of the system containing the liquid metal electromagnetic pump and the temperature rise setting of the excitation coil. The temperature rise of the excitation coil is calculated based on the Joule heat of electromagnetic induction of the excitation coil and the conductive heat of the high-temperature liquid metal. The gap size and flow rate of the second annular flow channel are based on the temperature rise of the excitation coil and the convective heat transfer rate between the low-temperature liquid metal and the pump casing when passing through the second annular flow channel. The operating temperature of the excitation coil is controlled below a preset safety threshold as a limiting condition.

[0007] This liquid metal electromagnetic pump separates the first annular flow channel for outputting liquid metal in the high-temperature zone from the second annular flow channel for transporting liquid metal in the low-temperature zone. The cold and hot flows are transported completely separately without merging, avoiding poor system temperature stability caused by the fusion of cold and hot flows. At the same time, combined with the specific parameters of the system in which the liquid metal electromagnetic pump is located, the structural parameters of the liquid metal electromagnetic pump are optimized by multi-physics field collaborative design to achieve the best match between the electromagnetic pump structural dimensions, coil temperature resistance and cooling system parameters, ensuring the safety of the electromagnetic pump structure, reliable coil heat dissipation and stable liquid metal flow, and stable system operating temperature.

[0008] This application also provides a multi-physics parameter collaborative design method for liquid metal electromagnetic pumps, including:

[0009] S1. Determine the volumetric flow rate Qh of the high-temperature liquid metal based on the fixed parameters of the conveying system where the liquid metal electromagnetic pump is located and the preset temperature difference between the inlet and outlet of the hot and cold zones.

[0010] S2. Initially select the high-temperature flow velocity Vh, calculate and round it to obtain the outer diameter dp of the inner core assembly and the gap δ1 of the first annular flow channel, and then calculate the actual high-temperature flow velocity Vhs.

[0011] S3. Determine the initial volumetric flow rate Qc of the cryogenic liquid metal based on the excitation coil heating power and the preset allowable temperature rise of the cryogenic liquid metal.

[0012] S4. Preset the second annular flow channel gap δ2, and determine the inner diameter D of the outer pipe. o Calculate the cross-sectional area of ​​the second annular flow channel and determine the actual cryogenic flow velocity vc;

[0013] S5. Calculate the Reynolds number Rec on the low temperature side. If Rec is in the transition zone between 2300 and 10000, adjust the gap δ2 of the second annular flow channel or the preset allowable temperature rise ΔTe to make Rec less than 2300 or greater than 10000, so as to avoid the flow transition zone and ensure smooth flow.

[0014] S6. Establish a thermal coupling model to calculate the heat transfer between the high-temperature liquid metal and the pump casing and thermal shield; the heating of the excitation coil; the heat transfer between the outer wall of the pump casing and the low-temperature liquid metal; and solve for the temperature of the outer wall of the pump casing and the temperature of the excitation coil.

[0015] S7. If the temperature of the excitation coil is higher than the preset safety threshold, adjust the gap δ2 of the second annular flow channel or the preset allowable temperature rise ΔTe, and repeat steps S4 to S7.

[0016] S8. Perform pressure drop verification, calculate the pressure drop along the high temperature circuit and the local pressure drop in the low temperature circuit. If the total pressure drop exceeds the pump head range, adjust the actual high temperature flow rate Vhs or the first annular flow channel clearance δ1, and repeat steps S3 to S8.

[0017] S9. Perform thermal expansion verification and calculate the gap δ of the second annular flow channel under hot conditions. 2hot If the hot gap exceeds the preset range, adjust the second annular flow channel gap δ2 or select a different material and repeat steps S4 to S9.

[0018] S10. Output the final design parameters, including the outer diameter dp of the inner core assembly and the first annular flow channel clearance δ1; the inner diameter D of the outer pipe. o The second annular flow channel gap δ2, high temperature flow velocity Vhs, low temperature flow velocity vc, low temperature volumetric flow rate Qc, and excitation coil temperature.

[0019] As an optional scheme of the multi-physics parameter collaborative design method for liquid metal electromagnetic pumps described in this invention, the fixed parameters include the core thermal power P. core ΔTcore, liquid metal inlet and outlet temperature difference, and average temperature of the hot zone T h Average temperature T in the cold zone c The system allows a maximum pressure drop ΔPma, and the physical properties of high-temperature and low-temperature liquid metals.

[0020] As an optional scheme of the multi-physics parameter collaborative design method for liquid metal electromagnetic pumps described in this invention, the calculation of the volumetric flow rate Qh of the high-temperature liquid metal includes: P coreρh is the core thermal power, Cph is the density of the high-temperature liquid metal, ΔTcore is the isobaric specific heat capacity of the high-temperature liquid metal, and ΔTcore is the temperature difference between the inlet and outlet of the liquid metal.

[0021] As an optional scheme of the multi-physics field parameter collaborative design method for the liquid metal electromagnetic pump described in this invention, the following steps are taken: initially selecting the high-temperature flow velocity Vh, and calculating and rounding to obtain the outer diameter dp of the inner iron core assembly and the gap δ1 of the first annular flow channel, including: initially selecting the high-temperature flow velocity Vh = 2 m / s, and calculating the outer diameter dp of the inner iron core assembly, including: The actual outer diameter dps of the inner core assembly is obtained by rounding the calculated result of the inner core assembly outer diameter dp, the inner diameter d of the pump groove, and the clearance δ1 of the first annular flow channel. The calculation of the actual high-temperature flow velocity Vhs includes: calculating the cross-sectional area of ​​the first annular flow channel, and calculating the actual high-temperature flow velocity Vhs based on the cross-sectional area of ​​the first annular flow channel. The calculation of the cross-sectional area Ah of the first annular flow channel includes: The calculation of the actual high-temperature flow velocity Vhs includes: .

[0022] As an optional scheme of the multi-physics field parameter collaborative design method for the liquid metal electromagnetic pump described in this invention, the following is provided: the second annular flow channel gap δ2 is preset to 7.5mm, the allowable temperature rise at low temperature ΔTe is 20℃, and the initial coil heating power is set to P. coil =6.5kW, the initial volumetric flow rate Qc of cryogenic liquid metal includes: Where Cpc is the isobaric specific heat capacity of the cryogenic liquid metal, and ρc is the density of the cryogenic liquid metal, the inner diameter D of the outer pipe is determined. o =565, and pump casing outer diameter D i Calculate the annular cross-sectional area of ​​the second annular channel and the actual low-temperature flow velocity vc.

[0023] As an optional scheme of the multi-physics parameter collaborative design method for the liquid metal electromagnetic pump described in this invention, the temperature rise of the excitation coil is determined by the superposition of two heat sources: one is the Joule heat generated by the coil itself being energized, and the other is the heat conducted from the high-temperature side liquid metal. Both of these heat sources ultimately need to be transferred to the low-temperature side liquid metal. The following is a method for constructing a combined series and parallel thermal coupling model:

[0024] S6.1 Calculate the heat transfer resistance on the high-temperature side. The heat transfer resistance on the high-temperature side is the sum of the convective heat transfer resistance between the high-temperature liquid metal and the pump channel, the thermal conductivity resistance of the pump channel, and the thermal conductivity resistance of the heat shield.

[0025] S6.2 Calculate the thermal resistance of the low-temperature side. The thermal resistance of the low-temperature side is the sum of the thermal resistance of the coil and the pump housing and the convective thermal resistance between the pump housing and the low-temperature liquid metal.

[0026] S6.3 Calculate the average temperature of the coil, where the average temperature of the coil shall not exceed 450℃.

[0027] High-temperature side heat transfer thermal resistance R hot The calculations include: , where h hot A is the heat transfer coefficient between the high-temperature liquid metal and the pump channel. hot The convective heat transfer area of ​​the pump trench, R wall R is the thermal resistance of the pump channel. screen The thermal resistance of the heat shield is the ratio of the wall thickness to the thermal conductivity of the wall material.

[0028] h hot The calculations include:

[0029] Calculate the Reynolds number Reh on the high-temperature side. ρh is the density of the high-temperature liquid metal, Vhs is the actual high-temperature flow velocity, Dh is the difference between the inner diameter d of the pump channel and the actual outer diameter dps of the inner iron core assembly, and is the hydraulic diameter.

[0030] Calculate the Prandtl number Prh. Cph is the isobaric specific heat capacity of the high-temperature liquid metal, μh is the viscosity of the high-temperature liquid metal, and kh is the thermal conductivity of the high-temperature liquid metal.

[0031] Calculate the Nusel number N u , n is set based on either cold or hot flow; for hot flow, n = 0.4. N u It is an infinite number, which is related to the flow state (determined by the Reynolds number) and geometry, and is calculated using the heat transfer correlation formula (Dittus-Boelter modified formula);

[0032] Calculate the heat transfer area A of the first annular flow channel. hot , Lp is the length of the first annular flow channel.

[0033] Low-temperature side heat transfer resistance R cold The calculations include: , where h cold A is the heat transfer coefficient between the cryogenic liquid metal and the pump casing. cold The convective heat transfer area of ​​the pump casing, R shell h is the thermal resistance of the pump casing. cold Calculation process and h hot The calculation process is the same; when calculating the Nusselt number, n=0.3.

[0034] Calculate the average temperature T of the coil coil , T cP represents the average temperature of the cold zone. coil To initially determine the coil heating power, Q hot The heat is transferred from the high-temperature liquid metal to the coil; T h This represents the average temperature of the hot zone.

[0035] As an optional scheme of the multi-physics parameter collaborative design method for liquid metal electromagnetic pumps described in this invention, wherein: δ 2hot δ is determined based on the coefficients of thermal expansion of the pump casing material and the external pipe material, as well as the operating temperature. 2hot The calculations include: , where a shell Let a be the coefficient of linear expansion of the pump casing material. outer T is the coefficient of linear expansion of the external pipe material. w T represents the average temperature of the outer wall of the pump casing. c D represents the average temperature of the cold zone. i D is the outer diameter of the pump casing. o δ is the inner diameter of the outer pipe. 2hot Not less than 3mm and not more than 20mm.

[0036] As an optional scheme of the multi-physics field parameter collaborative design method for liquid metal electromagnetic pumps described in this invention, it also includes a non-design condition verification step: performing transient thermal analysis on start-up conditions, shutdown conditions, and transient power change conditions to ensure that the excitation coil temperature does not exceed the preset safety threshold under all conditions and that the structural thermal stress is within the allowable range of the material; for liquid metals with melting points higher than the ambient temperature, a heat tracing system is set up to prevent solidification.

[0037] The present invention has the following beneficial effects:

[0038] 1. This liquid metal electromagnetic pump separates the first annular flow channel for outputting liquid metal in the high-temperature zone from the second annular flow channel for transporting liquid metal in the low-temperature zone. The cold and hot flows are completely separated and transported separately, avoiding the poor system temperature stability caused by the fusion of cold and hot flows. At the same time, combined with the specific parameters of the system in which the liquid metal electromagnetic pump is located, the structural parameters of the liquid metal electromagnetic pump are optimized by multi-physics field collaborative design to achieve the best match between the electromagnetic pump structural dimensions, coil temperature resistance and cooling system parameters, ensuring the safety of the electromagnetic pump structure, reliable coil heat dissipation and stable liquid metal flow, and stable system operating temperature.

[0039] 2. The multi-physics parameter collaborative design method of this liquid metal electromagnetic pump accurately reflects the heat transfer relationship between the two by establishing a thermal coupling model between the high-temperature main circuit and the coil cooling system, thus avoiding the coil temperature prediction deviation caused by the traditional step-by-step design.

[0040] 3. The multi-physics parameter collaborative design method of this liquid metal electromagnetic pump adopts a heat transfer correlation suitable for liquid metal, which improves the calculation accuracy of the convective heat transfer coefficient and makes the coil temperature verification more reliable.

[0041] 4. The multi-physics parameter collaborative design method of this liquid metal electromagnetic pump avoids the transition zone by controlling the Reynolds number on the low temperature side, thus ensuring the stability of the flow and avoiding heat transfer fluctuations and structural vibrations caused by flow oscillations.

[0042] 5. The multi-physics parameter collaborative design method of this liquid metal electromagnetic pump takes into account the influence of thermal expansion on the annular gap and sets a reasonable gap range to ensure the structural safety and cooling effect under all operating conditions.

[0043] 6. The multi-physics parameter collaborative design method of this liquid metal electromagnetic pump incorporates electromagnetic parameters (current density, coil resistance, heat loss, etc.) into the collaborative design, realizing the joint optimization of electromagnetic performance and thermal performance.

[0044] 7. The multi-physics parameter collaborative design method of this liquid metal electromagnetic pump establishes an iterative design process that includes multiple constraints such as steady state, transient state, pressure drop, and thermal expansion, which can quickly obtain the global optimal solution that meets all design requirements. Attached Figure Description

[0045] Figure 1 This is a physical image of the liquid metal electromagnetic pump of Embodiment 1 of the present invention.

[0046] Figure 2 This is a physical diagram of the internal structure of the liquid metal electromagnetic pump of Embodiment 1 of the present invention.

[0047] Figure 3 This is a cross-sectional view of the liquid metal electromagnetic pump according to Embodiment 1 of the present invention.

[0048] Figure 4 This is a cross-sectional view of the liquid metal electromagnetic pump according to Embodiment 1 of the present invention from another angle. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Example 1

[0051] Please see Figures 1-4A liquid metal electromagnetic pump includes: an inner core assembly 1, a pump groove 2, a heat shield 3, an excitation coil 4, an outer core assembly 5, a pump casing 6, an outer pipe 7, a pump groove support 8, and a pump casing support 9. A first annular flow channel is formed between the inner core assembly 1 and the pump groove 2. The pump groove support 8 is supported within the first annular flow channel. The inlet of the first annular flow channel connects to the high-temperature zone of the liquid metal, and the outlet connects to the inlet zone of a heat exchanger or liquid metal heat exchange equipment, for outputting liquid metal from the high-temperature zone. The heat shield 3 is fitted outside the pump groove 2, the excitation coil 4 is located outside the heat shield 3, the outer core assembly 5 is located outside the excitation coil 4, and the pump casing 6 is fitted outside the outer core assembly 5. The outer pipe 7 is fitted outside the pump casing 6, forming a second annular flow channel between the two. The pump casing support 9 is supported within the second annular flow channel. The inlet of the second annular flow channel connects to the outlet area of ​​a heat exchanger or liquid metal heat exchange equipment, and the outlet connects to the low-temperature liquid metal zone for conveying liquid metal from the low-temperature zone. The gap size and flow rate of the first annular flow channel are set based on the fixed parameters of the system containing the liquid metal electromagnetic pump and the temperature rise of the excitation coil 4. The temperature rise of the excitation coil 4 is calculated based on the Joule heat induced by the electromagnetic induction of the excitation coil 4 and the conductive heat of the high-temperature liquid metal. The gap size and flow rate of the second annular flow channel are set based on the temperature rise of the excitation coil 4 and the convective heat transfer rate between the low-temperature liquid metal and the pump casing 6 when passing through the second annular flow channel. The operating temperature of the excitation coil 4 is controlled below a preset safety threshold as a limiting condition. The pump channel 2, pump casing 6, and outer pipe 7 are made of corrosion-resistant materials compatible with the conveyed liquid metal. When the conveyed liquid metal is sodium or a sodium-potassium alloy, the material is austenitic stainless steel. When the conveyed liquid metal is a lead-bismuth alloy, the material surface is coated with a lead-bismuth corrosion-resistant coating or a protective film is formed through oxygen control.

[0052] Example 2

[0053] Please see Figures 1-4 The multi-physics parameter collaborative design method for the liquid metal electromagnetic pump in Example 1 includes:

[0054] S1. Determine the volumetric flow rate Qh of the high-temperature liquid metal based on the fixed parameters of the conveying system where the liquid metal electromagnetic pump is located and the preset temperature difference between the inlet and outlet of the hot and cold zones.

[0055] S2. Initially select the high-temperature flow velocity Vh, calculate and round it to obtain the outer diameter dp of the inner core assembly and the gap δ1 of the first annular flow channel, and then calculate the actual high-temperature flow velocity Vhs.

[0056] S3. Determine the initial volumetric flow rate Qc of the cryogenic liquid metal based on the excitation coil heating power and the preset allowable temperature rise of the cryogenic liquid metal.

[0057] S4. Preset the second annular flow channel gap δ2, and determine the inner diameter D of the outer pipe. oCalculate the cross-sectional area of ​​the second annular flow channel and determine the actual cryogenic flow velocity vc;

[0058] S5. Calculate the Reynolds number Rec on the low temperature side. If Rec is in the transition zone between 2300 and 10000, adjust the gap δ2 of the second annular flow channel or the preset allowable temperature rise ΔTe to make Rec less than 2300 or greater than 10000, so as to avoid the flow transition zone and ensure smooth flow.

[0059] S6. Establish a thermal coupling model to calculate the heat transfer between the high-temperature liquid metal and the pump casing and thermal shield; the heating of the excitation coil; the heat transfer between the outer wall of the pump casing and the low-temperature liquid metal; and solve for the temperature of the outer wall of the pump casing and the temperature of the excitation coil.

[0060] S7. If the temperature of the excitation coil is higher than the preset safety threshold, adjust the gap δ2 of the second annular flow channel or the preset allowable temperature rise ΔTe, and repeat steps S4 to S7.

[0061] S8. Perform pressure drop verification, calculate the pressure drop along the high temperature circuit and the local pressure drop in the low temperature circuit. If the total pressure drop exceeds the pump head range, adjust the actual high temperature flow rate Vhs or the first annular flow channel clearance δ1, and repeat steps S3 to S8.

[0062] S9. Perform thermal expansion verification and calculate the gap δ of the second annular flow channel under hot conditions. 2hot If the hot gap exceeds the preset range, adjust the second annular flow channel gap δ2 or select a different material and repeat steps S4 to S9.

[0063] S10. Output the final design parameters, including the outer diameter dp of the inner core assembly and the first annular flow channel clearance δ1; the inner diameter D of the outer pipe. o The second annular flow channel gap δ2, high temperature flow velocity Vhs, low temperature flow velocity vc, low temperature volumetric flow rate Qc, and excitation coil temperature.

[0064] Specifically, the fixed parameters include the core thermal power P. core =5MW, liquid metal inlet and outlet temperature difference ΔTcore=130℃, average temperature of hot zone T h =450℃, average temperature of cold zone T c=320℃, maximum allowable pressure drop ΔPma = 200kPa, length of pump channel 2 Lp = 1000mm, physical properties of high-temperature and low-temperature liquid metal include: ρh = 10139kg / m³, density of high-temperature liquid metal; Cph = 143.1J / (kg·K), specific heat capacity at isobaric pressure of high-temperature liquid metal, temperature of high-temperature liquid metal set at 450℃; kh = 14.371W / (m·K), thermal conductivity of high-temperature liquid metal; μh = 0.0014016 Pa·s is the viscosity of the high-temperature liquid metal, the temperature of the low-temperature liquid metal is set to 320℃, ρc=10311kg / m³ is the density of the low-temperature liquid metal, Cpc=145.37J / (kg·K) is the specific heat capacity at constant pressure of the low-temperature liquid metal, kc=12.459W / (m·K) is the thermal conductivity of the low-temperature liquid metal, and μc=0.00176143Pa·s is the viscosity of the low-temperature liquid metal.

[0065] The calculation of the volumetric flow rate Qh of high-temperature liquid metal includes: Substituting the values ​​into the calculation, we get Qh = 0.0265 m³ / s.

[0066] It should be noted that the combined effects of corrosion and abrasion from high-temperature liquid heavy metals affect the lifespan of the pipeline. Controlling the flow velocity below 2 m / s can significantly reduce the erosion impact. Therefore, the initial high-temperature flow velocity is selected as Vh = 2 m / s. The calculation of the outer diameter dp of the iron core assembly includes: The calculation yielded dp=0.130m. Based on the pipeline standard, the actual outer diameter of the inner core assembly was dps=150mm, the inner diameter of the pump groove was d=200mm, and the gap of the first annular flow channel was δ1=25mm.

[0067] Calculating the actual high-temperature flow velocity Vhs includes: calculating the cross-sectional area of ​​the first annular flow channel, and calculating the actual high-temperature flow velocity Vhs based on the cross-sectional area of ​​the first annular flow channel, wherein the calculation of the cross-sectional area Ah of the first annular flow channel includes: The calculated value is Ah = 0.013744m. 2 .

[0068] The calculation of the actual high-temperature flow rate Vhs includes: The calculated value is Vhs = 1.929 m / s.

[0069] The preset gap of the second annular flow channel is δ2=7.5mm, the allowable temperature rise at low temperature is ΔTe=20, and the initial setting of the coil heating power is P. coil =6.5kW, the allowable temperature rise at low temperatures and the coil heating power are designed according to specific product specifications. The gap of the second annular flow channel is preset according to the system's operating requirements. The initial volumetric flow rate Qc of the cryogenic liquid metal includes: The calculated value is Qc = 0.00002164 m³ / s.

[0070] The second annular flow channel clearance δ2 is preset to 7.5mm, and the inner diameter D of the outer pipe is determined. o =565mm, and pump casing outer diameter D i =550mm, calculate the annular cross-sectional area of ​​the second annular channel and the actual low-temperature flow velocity vc.

[0071] The annular cross-sectional area of ​​the second annular channel and the actual cryogenic flow velocity vc were calculated using the same method as the first annular channel, resulting in an annular cross-sectional area Ac = 0.013136 m². 2 The actual cryogenic flow rate vc = 0.165 m / s.

[0072] Perform flow stability checks, hydraulic diameter D c =0.015mm: The Reynolds number Rec = 1449, which is less than 2300.

[0073] Heat transfer calculation using a combined series and parallel thermal coupling model:

[0074] High-temperature side heat transfer thermal resistance R hot The calculations include: , where h hot A is the heat transfer coefficient between the high-temperature liquid metal and the pump channel. hot The convective heat transfer area of ​​the pump trench, R wall R is the thermal resistance of the pump channel. screen The thermal resistance of the heat shield is the ratio of the wall thickness to the thermal conductivity of the wall material.

[0075] h hot The calculations include:

[0076] Calculate the Reynolds number Reh on the high-temperature side. Reynolds number Reh = 697598;

[0077] Dh is the difference between the inner diameter d of the pump channel and the actual outer diameter dps of the inner iron core assembly, which is the hydraulic diameter;

[0078] Calculate the Prandtl number Prh. Prandtl number Prh = 0.1396;

[0079] Calculate the Nusel number N u , n is set based on either cold or hot flow; for hot flow, n = 0.4. N u It is an infinite number, related to the flow state (determined by the Reynolds number) and geometry, and is used to calculate the Nusselt number N. u=19.7; h was calculated. hot =5662.9;

[0080] Calculate the heat transfer area A of the first annular flow channel. hot , A was calculated. hot =0.628m 2 ;

[0081] Calculate R wall and R screen Thermal resistance is the ratio of wall thickness to the thermal conductivity of the wall material. In this embodiment, R... wall =0.000271084, R screen =0.16667;

[0082] Calculate R hot =0.1672.

[0083] Low-temperature side heat transfer resistance R cold The calculations include: , where h cold A is the heat transfer coefficient between the cryogenic liquid metal and the pump casing. cold The convective heat transfer area of ​​the pump casing, R shell h is the thermal resistance of the pump casing. cold Calculation process and h hot The calculation process is the same; when calculating the Nusselt number, n=0.3.

[0084] Calculate R cold =0.003176.

[0085] Calculate the average temperature of the coil, where the average coil temperature does not exceed 450℃. Average coil temperature T. coil , Q hot The heat is transferred from the high-temperature liquid metal to the coil; Q is calculated hot =2691.1, T coil =352℃. Safety determination: T coil Temperature not exceeding 450℃ meets the requirements.

[0086] It should also be noted that: δ 2hot δ is determined based on the coefficients of thermal expansion of the pump casing material and the external pipe material, as well as the operating temperature. 2hot The calculations include: , where a shell Let a be the coefficient of linear expansion of the pump casing material. outer T is the coefficient of linear expansion of the external pipe material. w T represents the average temperature of the outer wall of the pump casing. c D represents the average temperature of the cold zone.i D is the outer diameter of the pump casing. o δ is the inner diameter of the outer pipe. 2hot Not less than 3mm and not more than 20mm.

[0087] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A liquid metal electromagnetic pump, characterized in that, include: Inner core assembly (1), pump groove (2), heat shield (3), excitation coil (4), outer core assembly (5), pump casing (6), outer pipeline (7), pump groove support (8), and pump casing support (9). A first annular flow channel is formed between the inner core assembly (1) and the pump groove (2). The pump groove support (8) is supported in the first annular flow channel. The inlet of the first annular flow channel is connected to the high temperature zone of liquid metal, and the outlet is connected to the inlet zone of the heat exchanger or liquid metal heat exchange equipment for outputting liquid metal from the high temperature zone. The heat shield (3) is fitted outside the pump groove (2), the excitation coil (4) is located outside the heat shield (3), the outer iron core assembly (5) is located outside the excitation coil (4), and the pump casing (6) is fitted outside the outer iron core assembly (5). The outer pipe (7) is fitted outside the pump casing (6), forming a second annular flow channel between the two. The pump casing support (9) is supported inside the second annular flow channel. The inlet of the second annular flow channel is connected to the outlet area of ​​the heat exchanger or liquid metal heat exchange equipment, and the outlet is connected to the low temperature zone of the liquid metal, for conveying liquid metal in the low temperature zone. The design method for liquid metal electromagnetic pumps includes: S1. Determine the volumetric flow rate Qh of the high-temperature liquid metal based on the fixed parameters of the conveying system where the liquid metal electromagnetic pump is located and the preset temperature difference between the inlet and outlet of the hot and cold zones. S2. Initially select the high-temperature flow velocity Vh, calculate and round it to obtain the outer diameter dp of the inner core assembly and the gap δ1 of the first annular flow channel, and then calculate the actual high-temperature flow velocity Vhs. S3. Determine the initial volumetric flow rate Qc of the cryogenic liquid metal based on the excitation coil heating power and the preset allowable temperature rise of the cryogenic liquid metal. S4. Preset the second annular flow channel gap δ2, and determine the inner diameter D of the outer pipe. o Calculate the cross-sectional area of ​​the second annular flow channel and determine the actual cryogenic flow velocity vc; S5. Calculate the Reynolds number Rec on the low temperature side. If Rec is in the transition zone between 2300 and 10000, adjust the gap δ2 of the second annular flow channel or the preset allowable temperature rise ΔTe to make Rec less than 2300 or greater than 10000. S6. Establish a thermal coupling model to calculate the heat transfer between the high-temperature liquid metal and the pump casing and thermal shield; the heating of the excitation coil; the heat transfer between the outer wall of the pump casing and the low-temperature liquid metal; and solve for the temperature of the outer wall of the pump casing and the temperature of the excitation coil. S7. If the temperature of the excitation coil is higher than the preset safety threshold, adjust the gap δ2 of the second annular flow channel or the preset allowable temperature rise ΔTe, and repeat steps S3 to S7. S8. Perform pressure drop verification, calculate the pressure drop along the high temperature circuit and the local pressure drop in the low temperature circuit. If the total pressure drop exceeds the pump head range, adjust the actual high temperature flow rate Vhs or the first annular flow channel clearance δ1, and repeat steps S2 to S8. S9. Perform thermal expansion verification and calculate the gap δ of the second annular flow channel under hot conditions. 2hot If the hot gap exceeds the preset range, adjust the second annular flow channel gap δ2 or select a different material and repeat steps S4 to S9. S10. Output the final design parameters, including the outer diameter dp of the inner core assembly and the first annular flow channel clearance δ1; the inner diameter D of the outer pipe. o The second annular flow channel gap δ2, high temperature flow velocity Vhs, low temperature flow velocity vc, low temperature volumetric flow rate Qc, and excitation coil temperature.

2. The liquid metal electromagnetic pump according to claim 1, characterized in that: Fixed parameters include core thermal power P core ΔTcore, liquid metal inlet and outlet temperature difference, and average temperature of the hot zone T h Average temperature T in the cold zone c The system allows a maximum pressure drop ΔPma, and the physical properties of high-temperature and low-temperature liquid metals.

3. The liquid metal electromagnetic pump according to claim 1, characterized in that: The calculation of the volumetric flow rate Qh of high-temperature liquid metal includes: P core ρh is the core thermal power, Cph is the density of the high-temperature liquid metal, ΔTcore is the isobaric specific heat capacity of the high-temperature liquid metal, and ΔTcore is the temperature difference between the inlet and outlet of the liquid metal.

4. The liquid metal electromagnetic pump according to claim 1, characterized in that: The initial high-temperature flow velocity Vh is selected, and the outer diameter dp of the inner core assembly and the first annular flow channel clearance δ1 are calculated and rounded. The calculation of the outer diameter dp of the inner core assembly includes: The actual outer diameter dps of the inner core assembly, the inner diameter d of the pump groove, and the gap δ1 of the first annular flow channel are obtained by rounding the calculated result of the outer diameter dp of the inner core assembly.

5. The liquid metal electromagnetic pump according to claim 4, characterized in that: Calculating the actual high-temperature flow velocity Vhs includes: calculating the cross-sectional area of ​​the first annular flow channel, and calculating the actual high-temperature flow velocity Vhs based on the cross-sectional area of ​​the first annular flow channel, wherein the calculation of the cross-sectional area Ah of the first annular flow channel includes: The calculation of the actual high-temperature flow velocity Vhs includes: .

6. The liquid metal electromagnetic pump according to claim 1, characterized in that: The preset second annular flow channel gap δ2, the allowable temperature rise at low temperatures ΔTe, and the initial setting of coil heating power P coil The calculation of the initial volumetric flow rate Qc of cryogenic liquid metal includes: Where Cpc is the isobaric specific heat capacity of the cryogenic liquid metal, and ρc is the density of the cryogenic liquid metal, the inner diameter D of the outer pipe is determined. o and pump casing outer diameter D i Calculate the annular cross-sectional area of ​​the second annular channel and the actual low-temperature flow velocity vc.

7. The liquid metal electromagnetic pump according to claim 1, characterized in that: Establishing a thermally coupled model includes: S6.1 Calculate the heat transfer resistance on the high-temperature side. The heat transfer resistance on the high-temperature side is the sum of the convective heat transfer resistance between the high-temperature liquid metal and the pump channel, the thermal conductivity resistance of the pump channel, and the thermal conductivity resistance of the heat shield. S6.2 Calculate the thermal resistance of the low-temperature side. The thermal resistance of the low-temperature side is the sum of the thermal resistance of the coil and the pump housing and the convective thermal resistance between the pump housing and the low-temperature liquid metal. S6.3 Calculate the average temperature of the coil, where the average temperature of the coil shall not exceed 450℃.

8. The liquid metal electromagnetic pump according to claim 7, characterized in that: High-temperature side heat transfer thermal resistance R hot The calculations include: , where h hot A is the heat transfer coefficient between the high-temperature liquid metal and the pump channel. hot The convective heat transfer area of ​​the pump trench, R wall R is the thermal resistance of the pump channel. screen The thermal resistance of the heat shield is the ratio of the wall thickness to the thermal conductivity of the wall material. h hot The calculations include: Calculate the Reynolds number Reh on the high-temperature side. ρh is the density of the high-temperature liquid metal, Vhs is the actual high-temperature flow velocity, and Dh is the difference between the inner diameter d of the pump channel and the actual outer diameter dps of the inner iron core assembly. Calculate the Prandtl number Prh. Cph is the isobaric specific heat capacity of the high-temperature liquid metal, μh is the viscosity of the high-temperature liquid metal, and kh is the thermal conductivity of the high-temperature liquid metal. Calculate the Nusel number N u , n is set based on either cold or hot flow; for hot flow, n = 0.

4. ; Calculate the heat transfer area A of the first annular flow channel. hot , Lp is the length of the first annular flow channel.

9. The liquid metal electromagnetic pump according to claim 8, characterized in that: Low-temperature side heat transfer resistance R cold The calculations include: , where h cold A is the heat transfer coefficient between the cryogenic liquid metal and the pump casing. cold The convective heat transfer area of ​​the pump casing, R shell h is the thermal resistance of the pump casing. cold Calculation process and h hot The calculation process is the same; when calculating the Nusselt number, n=0.

3.

10. The liquid metal electromagnetic pump according to claim 1, characterized in that: δ 2hot δ is determined based on the coefficients of thermal expansion of the pump casing material and the external pipe material, as well as the operating temperature. 2hot The calculations include: , where a shell Let a be the coefficient of linear expansion of the pump casing material. outer T is the coefficient of linear expansion of the external pipe material. w T represents the average temperature of the outer wall of the pump casing. c D represents the average temperature of the cold zone. i D is the outer diameter of the pump casing. o δ is the inner diameter of the outer pipe. 2hot Not less than 3mm and not more than 20mm.

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