Reid, R. S. (2002). Ann. Space Nuclear Reactor Engineering. Eng. The greater the power, the more evaporation and the greater vapor flow in vapor space. Figure 7A shows the surface temperature distribution with different heating powers, and Figure 7B shows the temperature variation of heat pipe with time. (A) Temperature difference with different heating power. To simplify the modeling, the lift table and support structure are all ignored; only the reactor is established (Figure 11). When the reactor shuts down, decay heat can be taken out of the reactor core through the decay heat exchanger. Appl. J. FIGURE 13. Therefore, it is important for the numerical calculation of heat pipe cooled reactor to obtain the accurate temperature distribution as much as possible. Thermionic Conversion Specialist Conference, This article is part of the Research Topic, https://doi.org/10.3389/fenrg.2022.819033. (1993). The typical heat pipe cooled reactor named KRUSTY is chosen as the research object. is the emissivity of material, and is the Stefan-Boltzmann coefficient. rubber flexible resistant temperature heat hose drain pressure steam larger pipe The sodium heat pipe with 1.0m length is selected as the experiment object. Using recommended equations to calculate the heat transfer limitation, this model can realize the safety judgment of heat pipe. Nucl. When the heating power is low enough, more power leads to the larger temperature difference. During the load-following analysis (section 4.3), it is set as the fixed temperature gradient. J. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher. By continuing you agree to the use of cookies. Combined with the thermal resistance, the evaporation and condensation at vapor-liquid interface can be obtained: where qv is the vapor mass flow rate at vapor-liquid interface, Tw is the temperature in wall subregion, Tv is the temperature in vapor space, R is the thermal resistance, and hv is the vapor enthalpy. Los Alamos, NM (United States): Los Alamos National Lab, McClure, P. R., Poston, D. I., Clement, S. D., Restrepo, L., Miller, R., and Negrete, M. (2020). Copyright 2020 Elsevier B.V. or its licensors or contributors. temperature directly provide heat factory resistant pvc pipe conduit electricity korean plastic larger Eng. Calculated temperature distribution of reactor core. The key to the realization of this model is to determine the thermophysical parameters and heating source of each subregion. Nucl. Based on the network method, Ferrandi et al. Based on Fouriers law, higher heat flux will lead to a larger temperature gradient, resulting in non-uniformity of temperature distribution on the contact surface. 33) is not completely equal to the real value. Combined with the network method, the evaporation rate, the condensation rate, and the flow rate in the wick region can be preliminarily obtained. CFD Simulation on the Heat Transfer and Flow Characteristics of a Microchannel Separate Heat Pipe under Different Filling Ratios. Busse, C. A. This study was funded by the National Key Research and Development Project of China, No. Los Alamos, NM (United States): Los Alamos National Lab, Poston, D. I. Kilowatt Reactor Using Stirling TechnologY (KRUSTY) Component-Critical Experiments. FIGURE 7. 135, 106948. doi:10.1016/j.anucene.2019.106948, Yuan, Y., Shan, J., Zhang, B., Gou, J., Zhang, B., Lu, T., et al. To meet the requirements of heat pipe cooled reactor simulation, the super thermal conductivity model (STCM) is proposed. airduct semirigid ducts ducting Thermal Performance Analysis of Nanofluids in a Thermosyphon Heat Pipe Using CFD Modeling. The electric heater is simplified as the thin layer with a thickness of 2mm, and the heating source is set in this layer as equivalent to an electrical heating. Received: 20 November 2021; Accepted: 06 January 2022;Published: 27 January 2022. Generally, there is no heat source in wall, and the heat transfer between heat pipe and environment can be described using suitable boundary conditions. Dynamics of Heat Pipe Start-Up from a Frozen State. In this section, the load-following transient is selected. Front. Theoretical Investigation of Heat Pipes Operating at Low Vapor Pressures. FIGURE 15. 35). The raw data supporting the conclusion of this article will be made available by the authors, without undue reservation. Considering the high temperature of the condenser section, not only the natural convection, but the radiation heat transfer also exist. Am. Int. Using the network method, the flow of working medium is approximately accounted for. For load-following transient calculation, calculated results are in good agreement with the experimental results, showing the applicability of the proposed model to this type of reactor system. Heat pipes using alkali metal can realize efficient heat transport in special environments with high temperature (Faghri, 2014). everychina heat temperature edge pipes leading wing pipe transfer act sodium Benefiting from the reactivity feedback of fuel, fission power gradually decreases to slow the rate of temperature rise. During this period, several typical models for heat pipe were put forward successively, including the self-diffusion model (Cao and Faghri, 1993a), the plat-front model (Cao and Faghri, 1993b), the network model (Zuo and Faghri, 1998), and the improved network model (Ferrandi et al., 2013). It should be noted that the two-phase flow simulation using CFD method requires large amounts of computing resources. heat resistant sleeve temperature tubing silicone rubber hose wire fire fiberglass protection braided treated flame cable oxide thermal insulating very Tech. This type of reactor system has the advantages of having a compact structure and high safety. Transfer 49 (5), 667678. HPTAMheatpipe Transient Analysis Model: an Analysis of Water Heat Pipes. Nucl. (1967). The three-dimensional CFD model of the experimental system is shown in Figure 6, which includes the sodium heat pipe, the electric heater, and the insulating layer. doi:10.1080/00295450.2020.1722544, McClure, P. R., Poston, D. I., Gibson, M. A., Mason, L. S., and Robinson, R. C. (2020). 65, 102114. Energ. At T = 0.0s, the cooling power of the condenser of heat pipe is set as 2.54kW to represent the decrease of engine power, and the initial fission power is set as 2.67kW. 206 (Suppl. 5mm2 everychina pipe Inst. Proc. Wall is usually a cylindrical closed shell made of metal. (1993). After the load-following accident, reactor temperature rises slightly due to the reduction of the output power of the Stirling generators. Then, the temperature is recorded with the increase of heating power. At about T = 300.0s, fuel reaches the peak temperature of about 1,080.3K. At about T = 2,200.0s, the reactor reaches the new steady state. Phys. If the calculated value is less than the heating power, the heat transfer limitation will be deemed to occur, and it is assumed that the heat pipe will be damaged. Nucl. However, the proposed model can consider the nonuniformity of temperature on contact surface. Figure 8A shows the variation of total temperature difference of heat pipe under the different heating power conditions. Heat Pipes: Review, Opportunities and Challenges. 1), S13S30. doi:10.1007/s00231-013-1110-6, Brown, O. L. I. (A) T = 0.0s. The thermophysical properties are determined by two materials. The thermal power of the reactor is 5.0kW. About ScienceDirectShopping cartContact and supportTerms and conditionsPrivacy policy. temperature heat processing material pipes disk act pipe sodium Ohse, R. W. (1985). When heating power is 1600W, it takes about 13min to enter the quasi-steady state; when heating power is 3000W, it takes only about 7min. 17 (6), 643646. heat temperature pipes waste recovery panel pipe act sodium AIP Conf. pipes alkali The comparison of calculated results between experimental results (Poston, 2017). A Transient Multiphysics Coupling Method Based on OpenFOAM for Heat Pipe Cooled Reactors[J]. Nucl. The main parameters of this heat pipe are listed in Table. (2022). Zuo divided the heat pipe into several subregions, and the lumped temperature was used to represent the real temperature of specific subregions. ASME J. Eng. tubing conduction The reason for this phenomenon is the uneven power distribution in space. 14, Eqs 2123, the total pressure drop can be determined. Thermionic Conversion Specialist Conference, United States, November 1-2, 1967, 391398. Heat Pipes 5 (1). 49 (1), 7. doi:10.7538/yzk.2015.49.01.0089, Lin, Z., Wang, S., Shirakashi, R., and Winston Zhang, L. (2013). The difference between the two values is the heat leakage through shield. Therm. The characteristics of this reactor are also discussed. The friction coefficient f can be divided into: The velocity profile correction factor , is the function of the radial Reynolds number: where Qin is the heating power, hfg is the latent heat of vaporization, dv is the diameter of vapor space, v is the dynamic viscosity, and Levap is the length of evaporator. ronteix wuhan Chi, S. W. (1976). Compared with the results using network model, the peak temperature of fuel increases from 1,087.6k to 1,090.8k, and the total temperature difference increases from 14.4k to 21.2k. For KRUSTY reactor, the operation is sensitive to fuel temperature, so the slight variation of temperature may cause an obvious change in fission power. doi:10.1063/1.1449720, Sanchez, R., Grove, T., Hayes, D., Goda, J., McKenzie, G., Hutchinson, J., et al. (B) T = 2,200.0s. Transient Two-Dimensional Compressible Analysis for High-Temperature Heat Pipes with Pulsed Heat Input. resistant temperature heat stainless antique steel larger flexible hose The Stirling generators are also ignored, the operation of generators is approximated by setting reasonable boundary conditions of the condenser section of heat pipes. (A) Grooving processing on heat pipe surface. From Figures 1214, it can be concluded that only the three-dimensional modeling of heat pipes and the coupling calculation between heat pipe and the reactor core can obtain the accurate results of heat transfer. The proposed model can calculate the variation of absorbed power of heat pipes. Combined with the network method, the proposed model can preliminarily calculate the evaporation, condensation, and flow rate of working medium. Therm. Ann. FIGURE 5. 2020YFB1901700, Science Challenge Project (TZ2018001), Project 11775126/11775127 by National Natural Science Foundation of China, and Tsinghua University Initiative Scientific Research Program. Then, they are fixed with the high-temperature adhesive tape. pipe sb165 exchanger sb111 The thermophysical parameters required to solve Eq. Temperature distribution of heat pipe (3000W). (1998). Costello (FA), Inc NM (USA): Los Alamos National Lab. Heat generated in the reactor core is absorbed by high-temperature heat pipes. temperature tp446 everychina who will be happy to help. doi:10.1115/1.2910657, Cao, Y., and Faghri, A. Using the feedback coefficient, this important phenomenon can be preliminarily simulated (Guo et al., 2022). The comparison between simulated results using the proposed model and experimental results shows in Figure 15. Proc. Appl. FIGURE 9. Handbook of Thermodynamic and Transport Properties of Alkali Metals. Figure 12 shows the fuel temperature distribution using the proposed model and network model. Using a high-temperature adhesive, all K-type armored thermocouples are fixed in the groove (Figure 5A). Am. Sci. China Technol. The heat transport of vapor flow is simplified as high efficiency heat conductance. Thermodynamic and Transport Properties of Sodium Liquid and Vapor. Temperature on the contact surface between fuel and heat pipe is always consistent. Tech. calcium Combining Eq. 18 (4), 483502. Model verification with experimental results. J. Comparing with the experimental results, the applicability of the proposed model on heat pipe cooled reactor is verified. In the future, further numerical analysis and experimental studies will be carried out to investigate the real characteristics of heat pipe when the heat transfer limitation occurs. Department of Engineering Physics, Tsinghua University, Beijing, China. 246 (1), 10231037. Oxford: Blackwell. (1986). Meanwhile, the nonstandard operation during the experiment will also lead to uncertainty of the results. Int. larger Front. FIGURE 1. Poston, D. I.