high temperature heat pipes

Energ. For example, the vapor flow in vapor space was assumed to be one-dimensional, while heat conductance in solid region was treated as two-dimensional.



Based on the temperature field calculated at the latest time, the value of each temperature node can be obtained. The Technology of Micro Heat Pipe Cooled Reactor: A Review. doi:10.1007/s00231-013-1110-6, Brown, O. L. I. So far, proposed conceptual designs of heat pipe cooled reactor systems include the kilopower reactor system (McClure et al., 2020a), the Heatpipe-Operated Mars Exploration Reactor (HOMER) system (Poston, 2001), and the Heat Pipe-segmented Thermoelectric Module Converters Space Reactor (HP-STMCs) system (El-Genk and Tournier, 2004). (1993). Int. 65, 102114. J. Nucl. However, the proposed model can consider the nonuniformity of temperature on contact surface. Phys. AIP Conf. The key to the realization of this model is to determine the thermophysical parameters and heating source of each subregion. Experimental Investigation and CFD Analysis of a Air Cooled Condenser Heat Pipe. FIGURE 14. Thermodynamic and Transport Properties of Sodium Liquid and Vapor. The Clausius-Clapeyron Equation.

14, Eqs 2123, the total pressure drop can be determined. Eng. Proc. Sci. The Clausius-Clapeyron equation is chosen to describe the relationship between temperature and pressure (Brown, 1951): Changing Eq. Chi, S. W. (1976). Kilopower Project: The KRUSTY Fission Power Experiment and Potential Missions. Phys. The uncertainty of boundary conditions will directly lead to the deviation of calculated temperature. (A) Temperature difference with different heating power. larger 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. Adding the heat transfer limitation, it can realize the judgment of heat pipe safety. Simulation of the Early Startup Period of High-Temperature Heat Pipes from the Frozen State by a Rarefied Vapor Self-Diffusion Model[J]. China Technol. FIGURE 8. where Nu is the Nusselt number, Gr is Grashof number, Pr is the Prandtl number. doi:10.2298/tsci100331023a, Asmaie, L., Haghshenasfard, M., Mehrabani-Zeinabad, A., and Nasr Esfahany, M. (2013). FIGURE 2. Calculated temperature distribution of reactor core. FIGURE 16. Heat Transfer 114 (Nov), 10281035. The uncertainty of an experimental system is inevitable.

Minsk, Belarus: CIS.

Combined with the network method, the evaporation rate, the condensation rate, and the flow rate in the wick region can be preliminarily obtained. Design of Megawatt Power Level Heat Pipe Reactors. The typical heat pipe cooled reactor named KRUSTY is chosen as the research object. YG wrote the first draft of the manuscript. din exchanger resistant seamless temperature tubes pipe heat steel Oxford: Blackwell. 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.

Handbook of Thermodynamic and Transport Properties of Alkali Metals. Appl. FIGURE 5. braid

ElGenk, M. S., and Tournier, J. M. (2004). 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. Energ. Comparing with the experimental results, the applicability of the proposed model on heat pipe cooled reactor is verified. Am. Reay, D., McGlen, R., and Kew, P. (2013). *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

Energ. 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. 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. (2017). It is assumed that vapor in vapor space and liquified working medium in wick are homogeneous. Figure 16 shows the temperature distribution of reactor T = 0.0s and T = 2,200.0s respectively.

In this section, the proposed model will be used for numerical simulation of KRUSTY reactor. The sodium heat pipe with 1.0m length is selected as the experiment object. Heat Transfer 115 (1), 247254.

Proc. FIGURE 1. Tech. Meanwhile, the nonstandard operation during the experiment will also lead to uncertainty of the results. The comparison of calculated results between experimental results (Poston, 2017). No use, distribution or reproduction is permitted which does not comply with these terms. Wall is usually a cylindrical closed shell made of metal. doi:10.1080/00295450.2020.1722554. The natural convection between the insulating layer and environment causes heat leakage, and the convective heat transfer coefficient can be determined by Eqs 33, 34. Due to the high thermal conductivity of material and the compactness of this reactor, the total temperature difference of the reactor is small enough, and the peak temperature locates at the inner surface of the fuel. The equation that needs to be solved is the differential equation of heat conduction (Eq. It should be noted that the two-phase flow simulation using CFD method requires large amounts of computing resources. Using the feedback coefficient, this important phenomenon can be preliminarily simulated (Guo et al., 2022).

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. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Pressure Drop in the Vapor Phase of Long Heat Pipes, in Proc. Copyright 2022 Guo, Su, Li and Wang. Or contact our

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.

At. Moreover, it is assumed that the fluid circulation is always constant, so backflow in wick can be obtained based on the mass conservation: ql is the liquid mass flow rate in wick subregion, hl is the liquid enthalpy, and V is the subregion volume. (A) Grooving processing on heat pipe surface. The raw data supporting the conclusion of this article will be made available by the authors, without undue reservation. 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. 19 Articles, Proc. 33) is not completely equal to the real value. YG, ZL, and ZS contributed to conception and design of the study. Using the network method, the flow of working medium is approximately accounted for. [J] J. support team doi:10.1016/j.applthermaleng.2012.07.022, Fink, J. K., and Leibowitz, L. (1995). 206 (Suppl. Reid, R. S. (2002). FIGURE 15. 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). (A) Temperature distribution of heat pipe (B) Wall temperature variation with time. The Stirling cycle is adopted to generate 1kW electric power.

(2020). Nucl. 206 (Suppl. 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. Temperature distribution of heat pipe (3000W). Conceptual Design of HPSTMCs Space Reactor Power System for 110 kWe. (2001). It is then used for the simulation on KRUSTY reactor to discuss the applicability of this model and the characteristics of this type of reactor system. Then, they are fixed with the high-temperature adhesive tape. The iron-chrome wire heater can provide a maximum heating power of 4000W. To reduce heat leakage as much as possible, the evaporator and the adiabatic section are both wrapped by an insulating layer with aluminum silicate wool. Entrainment Limits in Heat Pipes. Heat Pipes: Review, Opportunities and Challenges. FIGURE 9. It can well predict the temperature variation of high-temperature heat pipes under different conditions. In this paper, the proposed model simplified the heat transport into multi-region heat conduction. 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. AIP Conf. 149, 107755. doi:10.1016/j.anucene.2020.107755, Mcclure, P. R. (2015). 1 are the physical parameters of the corresponding metal. Geometric model for KRUSTY reactor. Thermionic Conversion Specialist Conference, United States, November 1-2, 1967, 391398. The proposed model can calculate the variation of absorbed power of heat pipes. Sci.

(1993).

The thermophysical parameters required to solve Eq. uv is vapor velocity, Ladia is the length of adiabatic section, and Lcond is the length of condenser. CFD modeling and calculation have gradually become the main method for heat pipe analysis. (2022). The backflow of working medium is treated as a heating source in a differential equation of heat conduction. Figure 12 shows the fuel temperature distribution using the proposed model and network model. Annamalai, S., and Ramalingam, V. (2011). The Stirling generators are also ignored, the operation of generators is approximated by setting reasonable boundary conditions of the condenser section of heat pipes. Sci. For vapor space, the density and specific heat capacity of vapor are the physical parameters of alkali metal (Fink and Leibowitz, 1995; Ohse, 1985; Lee et al., 1969). These models were applied for the simulation of heat pipe cooled reactor (Yuan et al., 2016; Liu et al., 2020; Ma et al., 2020; Wang et al., 2020). 206 (Suppl. In this model, heat transport of vapor flow is simplified as high efficiency heat conductance. In these figures, the curve represents the calculated results using this model, and the scatter points represent the results measured by the experiment. During the steady state calculation, it can be found that the proposed model can obtain a more realistic fuel temperature distribution. Network model was proposed by Zuo and Faghri (1998); the schematic diagram of this model is shown in Figure 2.

Wick is composed of a porous structure and liquified working medium. Therm. KRUSTY Experiment: Reactivity Insertion Accident Analysis. During the load-following analysis (section 4.3), it is set as the fixed temperature gradient. (B) Network model. 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. (B) Temperature sensing point arrangement along the axial direction. Costello, F. A., Montague, A. F., and Merrigan, M. A. 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. To simplify the experiment, the heat pipe is kept horizontal and is cooled by the natural convection of air.

Schematic diagram of heating system. doi:10.1007/s11431-021-1874-0, Lee, C. S., Lee, D. I., and Bonilla, C. F. (1969).

AIP Conf. This is because that both the temperature drop caused by vapor flow and the temperature gradient caused by heat conduction will increase with the increase of power (Figures 8, 9). FIGURE 7. The heating system for high-temperature heat pipe is established to validate this model. 139, 2534. Wicks with a porous structure can generate an effective pressure head at the vapor-liquid interface, maintaining the stable circulation of working medium (Reay et al., 2013). The heating experiments with different heating powers is tested. unpublished data. FIGURE 4. Therefore, the basis of coupling calculation on this type of reactor system is to have a suitable model for high-temperature heat pipe simulation.

AV Luikov Heat and Mass Transfer Institute, Byelorussian Academy of Sciences. During this accident, with the decrease of engine power, heat transport power of heat pipes also reduces, leading to the increase of fuel temperature.

Closed-form Analytical Solutions of High-Temperature Heat Pipe Startup and Frozen Startup Limitation. FIGURE 12. 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. Due to these characteristics, high-temperature heat pipe is widely used for the design of heat pipe cooled reactor systems. here

A Network Thermodynamic Analysis of the Heat Pipe. support team who will be happy to help. FIGURE 10. 1), S1S12. Proc. Eng. The heat transport of vapor flow is simplified as high efficiency heat conductance. 1), S43S55. According to the comparison, it is found that the temperature calculated by this model differs little from the experimental results.

Calculation of the Thermodynamic and Transport Properties of Sodium, Potassium, Rubidium and Cesium Vapors to 3000K. The results obtained using the uniform temperature assumption will deviate from the reality. For heat pipe, it includes the wall, the wick, and the vapor space. Department of Engineering Physics, Tsinghua University, Beijing, China. 608 (1), 156162. Based on the network method, Ferrandi et al. (A) T = 0.0s. After the load-following accident, reactor temperature rises slightly due to the reduction of the output power of the Stirling generators. is the emissivity of material, and is the Stefan-Boltzmann coefficient.

When the heating power is low enough, more power leads to the larger temperature difference. doi:10.1080/00295450.2020.1722544, McClure, P. R., Poston, D. I., Gibson, M. A., Mason, L. S., and Robinson, R. C. (2020). We use cookies to help provide and enhance our service and tailor content and ads. HPTAMheatpipe Transient Analysis Model: an Analysis of Water Heat Pipes. 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.

Ann. (1991).

Tech.

18 (4), 483502. Tech. Nucl. It directly affects the actual temperature distribution of the core (Figure 13). Ann. 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. Forms of it include channels, screen, and concentric annulus (Reay et al., 2013). Energ.

For network model, lumped temperature is used to represent the temperature distribution of a specific subregion. Numer. Nucl. Even if the power is high enough, generated vapor can quickly transport heat to the condenser, meaning the heat pipe shows excellent isothermal property and efficient heat transfer capability. Am. doi:10.1063/1.41777. Educ. In total, eight sodium heat pipes are used to transport heat to the generators.

For example, the network model cannot consider the nonuniform heat transfer between the heat pipe and the environment.

Using recommended equations to calculate the heat transfer limitation, this model can realize the safety judgment of heat pipe. J. Chem. Am.

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high temperature heat pipes