In the steady state calculation, the results show that the temperature distribution on contact surface between fuel and heat pipe is nonuniform, which will lead to higher peak temperature and temperature difference for the reactor core. Wang, C., Sun, H., Tang, S., Tian, W., Qiu, S., and Su, G. (2020). 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. To simplify the experiment, the heat pipe is kept horizontal and is cooled by the natural convection of air. din exchanger resistant seamless temperature tubes pipe heat steel Power density distribution along axial distribution. When the heating power is high enough, the increase of total temperature difference will become inconspicuous, which means heat pipe has entered the optimal working range. According to the comparison with the experimental results, the accuracy of the model is verified. Energ. About ScienceDirectShopping cartContact and supportTerms and conditionsPrivacy policy. Meanwhile, to ensure the safety of heat transport, there are a large number of high-temperature heat pipes in the reactor core. 1), S56S67. pipe sb165 exchanger sb111 It is the prototype reactor to evaluate the performance of Kilopower reactor system (Poston et al., 2020; Sanchez et al., 2020; McClure et al., 2020b) The composition of KRUSTY reactor is shown in Figure 10.

Adding the heat transfer limitation, it can realize the judgment of heat pipe safety. Tech. Heat Pipe Failure Accident Analysis in Megawatt Heat Pipe Cooled Reactor. The thermophysical properties are determined by two materials. (A) Temperature difference with different heating power. To verify the proposed model, a heating system for high-temperature heat pipe is built (Figure 4). (B) Mass flow rate with different heating power. CFD modeling and calculation have gradually become the main method for heat pipe analysis. doi:10.1080/00295450.2020.1722554. Lumped Parameter Model of Sintered Heat Pipe: Transient Numerical Analysis and Validation. (2017). Energ. In this section, the proposed model will be used for numerical simulation of KRUSTY reactor. Heat Pipes 5 (1). Then, the temperature is recorded with the increase of heating power. The editor and reviewer's affiliations are the latest provided on their Loop research profiles and may not reflect their situation at the time of review. Therefore, for heat conduction calculation of vapor space, the key is to solve the equivalent thermal conductivity of this subregion. Backflow calculation using network model. Study on Startup Characteristics of Heat Pipe Cooled and AMTEC Conversion Space Reactor System. It can be predicted that if heat pipe is not well insulated, a considerable part of the heat will be transferred to the environment through the adiabatic section, leading to the decrease in heat transfer efficiency of the heat pipe. Wall is usually a cylindrical closed shell made of metal. Nucl. TABLE 1. 15 (3), 759772. Three-dimensional CFD model of the experimental system. At. Core thermal-hydraulic Evaluation of a Heat Pipe Cooled Nuclear Reactor. The boundary temperature of the condenser of heat pipes is set as 1,052.0K, and the fission power is set as 5.0kW. Inst. The heating experiments with different heating powers is tested. Front. Generally, the convective heat transfer coefficient obtained from equation (Eq. The characteristics of this reactor are also discussed. Proc. Sci. Tech. Heat pipe processing for heating experiments. China Technol. doi:10.1063/1.41777. For heat pipe, it includes the wall, the wick, and the vapor space. Combined with the recommended heat transfer limitation model (Busse, 1973; Levy, 1968; Deverall et al., 1970; Tien and Chung, 1979), the fast calculation of heat pipe performance and the evaluation of heat pipe safety are realized. ASME J. Eng. AIP Conf. Inst. Oxford, United Kingdom: Butterworth-Heinemann. Three boundary conditions (Eqs 24) can be selected for heat transfer: where Q is the heating source, A is the surface area, h is the convective coefficient, T(i) is the surface temperature of wall, and T is the environment temperature. 14, Eqs 2123, the total pressure drop can be determined. Washington, DC: Hemispere Publishing Corporation. Los Alamos, NM (United States): Los Alamos National Lab. *Correspondence: Zeguang Li, lizeguang@mail.tsinghua.edu.cn, Experimental and Analytical Investigations on Nuclear Reactor Safety, Severe Accident Phenomena and Severe Accident Mitigation of Nuclear Power Plants, View all The uncertainty of boundary conditions will directly lead to the deviation of calculated temperature. Chi, S. W. (1976). Numer. Nucl. Nucl. During the steady state calculation, it can be found that the proposed model can obtain a more realistic fuel temperature distribution. FIGURE 12. (1998). Nucl. The physical processes such as heat conduction, evaporation, condensation, and vapor flow in the heat pipe can be modeled and calculated. J. (1992). The greater the power, the more evaporation and the greater vapor flow in vapor space. 142, 107412. doi:10.1016/j.anucene.2020.107412, Ma, Y., Chen, E., Yu, H., Zhong, R., Deng, J., Chai, X., et al. The raw data supporting the conclusion of this article will be made available by the authors, without undue reservation. doi:10.1080/00295450.2020.1722544, McClure, P. R., Poston, D. I., Gibson, M. A., Mason, L. S., and Robinson, R. C. (2020).

Transient Two-Dimensional Compressible Analysis for High-Temperature Heat Pipes with Pulsed Heat Input. Phys. The Technology of Micro Heat Pipe Cooled Reactor: A Review. Proc. Differing from the traditional Pressurized Water Reactor (PWR), heat pipe cooled reactor adopts the high-temperature heat pipes to transport fission heat generated in the reactor core. Busse, C. A. In this section, the load-following transient is selected. This study was funded by the National Key Research and Development Project of China, No. Heat Mass Transfer 41 (11), 14731484. In this paper, the proposed model simplified the heat transport into multi-region heat conduction. Temperature distribution of reactor. Simulation of the Early Startup Period of High-Temperature Heat Pipes from the Frozen State by a Rarefied Vapor Self-Diffusion Model[J]. Eng. 49 (1), 7. doi:10.7538/yzk.2015.49.01.0089, Lin, Z., Wang, S., Shirakashi, R., and Winston Zhang, L. (2013). 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. (1991). Int. All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Kilowatt Reactor Using Stirling TechnologY (KRUSTY) Component-Critical Experiments. doi:10.1016/j.ijheatmasstransfer.2012.09.007, Liu, X., Zhang, R., Liang, Y., Tang, S., Wang, C., Tian, W., et al. AIP Conf. Nucl. It can be a powerful tool for the design and simulation of heat pipe cooled reactor systems. Because of the large aspect ratio of this reactor, the power density presents the distribution of a large value in the middle and a small value on both sides. KRUSTY Reactor Design. who will be happy to help. Experimental Investigation and CFD Analysis of a Air Cooled Condenser Heat Pipe. For network model, lumped temperature is used to represent the temperature distribution of a specific subregion. Ohse, R. W. (1985). here Sci. doi:10.5098/fhp.5.1, Ferrandi, C., Iorizzo, F., Mameli, M., Zinna, S., and Marengo, M. (2013). Deverall, J. E., Kemme, J. E., and Florschuetz, L. W. (1970). Heat Transfer Capacity Analysis of Heat Pipe for Space Reactor[J]. It can well predict the temperature variation of high-temperature heat pipes under different conditions. Then it is released in the primary heat exchanger through the heat convection between heat pipes and coolant in the secondary system. Wick is composed of a porous structure and liquified working medium. Energ. 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. 149, 107755. doi:10.1016/j.anucene.2020.107755, Mcclure, P. R. (2015). Meanwhile, the nonstandard operation during the experiment will also lead to uncertainty of the results. Using this model, the numerical simulation on KRUSTY reactor is executed. On the one hand, to realize the coupling calculation of the heat pipe cooled reactor, the proposed heat pipe model does not directly calculate the working fluid circulation, but adopts a simplified method, which may cause uncertainty to a certain extent. Zuo ignored the temperature drop caused by the vapor flow and considered that the temperature drop of the heat pipe was mainly caused by the heat conduction in wall and wick. Forms of it include channels, screen, and concentric annulus (Reay et al., 2013). FIGURE 1. (A) Proposed model. Due to these characteristics, high-temperature heat pipe is widely used for the design of heat pipe cooled reactor systems. Appl. Theory of the Ultimate Heat Transfer Limit of Cylindrical Heat Pipes. [J] J. During this accident, with the decrease of engine power, heat transport power of heat pipes also reduces, leading to the increase of fuel temperature. J. Sci. Poston, D. I. J. Chem. The difference between two results can be approximately considered to be caused by the uncertainty of parameters used in the model and the uncertainty of the experimental system. From Figure 8B, it can also be found that although there is an insulating layer wrapped outside the adiabatic section, the high-temperature vapor will still be partially condensed in this section, resulting in the reduction of vapor flow rate in vapor space. Combining Eq. After the load-following accident, reactor temperature rises slightly due to the reduction of the output power of the Stirling generators. Phys. doi:10.1016/j.net.2019.06.021, Yan, B. H., Wang, C., and Li, L. G. (2020). Sonic Limitations and Startup Problems of Heat Pipes. In this paper, the super thermal conductivity model (STCM) for high-temperature heat pipe is proposed for this purpose. FIGURE 7. doi:10.1115/1.2910657, Cao, Y., and Faghri, A. Meanwhile, the detailed information about this experiment is inadequate, and the three-dimensional modeling and the setting of boundary conditions may not be accurate enough. 65, 102114. Dynamics of Heat Pipe Start-Up from a Frozen State. The reason for this phenomenon is the uneven power distribution in space. (B) T = 2,200.0s. 86, 1830. This subregion is usually regarded as the compound material. FIGURE 14. FIGURE 16. During the load-following analysis (section 4.3), it is set as the fixed temperature gradient. Sci. Thermodynamic and Transport Properties of Sodium Liquid and Vapor. 33) is not completely equal to the real value. FIGURE 3. The equation that needs to be solved is the differential equation of heat conduction (Eq. Using recommended equations to calculate the heat transfer limitation, this model can realize the safety judgment of heat pipe. (2020). In this paper, the super thermal conductivity model (STCM) for high-temperature heat pipe is proposed, which simplifies the vapor flow and heat transport in vapor space into heat conductance. support team who will be happy to help. In this model, the recommended equations for heat transfer limitations are adopted (Busse, 1973; Levy, 1968; Deverall et al., 1970; Tien and Chung, 1979): Pv is the vapor pressure, Av is the cross-sectional area of vapor space, is the specific ratio, Rv is the gap constant, is the surface tension coefficient, rc is the capillary radius, is the angle of inclination, fl is the friction coefficient of liquified working medium, and fv is the friction coefficient of vapor. Phys. To meet the requirements of heat pipe cooled reactor simulation, the super thermal conductivity model (STCM) is proposed. Considering the high temperature of the condenser section, not only the natural convection, but the radiation heat transfer also exist. During this accident, the control rod always remains stationary, and the reactor only relies on the reactivity feedback to achieve the power regulation, showing the automatic-stability-regulation ability of this reactor. Using the feedback coefficient, this important phenomenon can be preliminarily simulated (Guo et al., 2022). Conceptual Design of HPSTMCs Space Reactor Power System for 110 kWe.

(2016). In general, due to the nonuniformity of reactor power distribution and the directionality of coolant flow in the heat exchanger, the actual heat transport and temperature distribution of each heat pipe are different. Geometric model for KRUSTY reactor. (2001). 135, 106948. doi:10.1016/j.anucene.2019.106948, Yuan, Y., Shan, J., Zhang, B., Gou, J., Zhang, B., Lu, T., et al. 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. 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). Then, this model is applied on the numerical calculation of Kilowatt Reactor Using Stirling TechnologY (KRUSTY) reactor. Minsk, Belarus: CIS. Proc. Tech. Heat Mass. Proc. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. 2020YFB1901700, Science Challenge Project (TZ2018001), Project 11775126/11775127 by National Natural Science Foundation of China, and Tsinghua University Initiative Scientific Research Program. For heat pipe models using the analysis on heat pipe cooled reactors, it is hoped that it can describe the transient behavior of heat pipes well, and it should be simple enough to reduce the computational resources as much as possible. doi:10.2514/3.61190, Tournier, J. M., and ElGenk, M. S. (1992). Before the 1990s, computing power was limited, so the complex physical phenomena that existed in heat pipe could not be simulated in detail. 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. 1), S13S30. doi:10.1063/1.1358010, Poston, D. I., Gibson, M. A., Godfroy, T., and McClure, P. R. (2020). Tech. Am. Copyright 2020 Elsevier B.V. or its licensors or contributors. Figure 8A shows the variation of total temperature difference of heat pipe under the different heating power conditions. Parameter description of sodium heat pipe. Not only is it required that this model can well describe the transient characteristics of heat pipe, but it should be simple enough to reduce the computational resource.

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