Numerical investigation on the startup performance of high-temperature heat pipes for heat pipe cooled reactor application

A suitable model for high-temperature heat pipe startup is a prerequisite to realizing the numerical simula-tion for the heat pipe cooled reactor startup from the cold state.It is required that this model not only describes the transient behavior during the startup period,but also reduces the computing resources of the heat pipe cooled reactor simulation in the simplest way.In this study,a simplified model that integrates the two-zone and network models is proposed.In this model,vapor flow in the vapor space,evaporation,and condensation in the vapor–liquid interface are decoupled with heat conduction to achieve a fast calculation of the transient characteristics of the heat pipe.An experimental system for a high-temperature heat pipe was developed to validate the proposed model.A potassium heat pipe was utilized as the experimental material.Startup experiments were performed with differ-ent heating powers.Compared with the experimental results,the accuracy of the proposed model was verified.Moreover,the proposed model can predict the vapor flow,pressure drop,and temperature drop in the vapor space.As indicated by the analysis results,the essential requirements for successful startup are also determined.The heat pipe cannot achieve a successful startup until the heating power satisfies these requirements.All the discussions indicate the capability of the proposed model for the simulation of a high-temperature heat pipe startup from the frozen state;hence,can act as a basic tool for the heat pipe cooled reactor simulation.

A Comprehensive Review of Thermal Performance Improvement of High-Temperature Heat Pipes

Energy efficiency issues are being focused on the growing concern of global warming and environmental pollution.The high-temperature heat pipe(HTHP) is an effective and environmental-friendly heat transfer device employed in many industries,including solar power generation,high-temperature flue gas waste heat recovery,industrial furnaces,nuclear industries,and aviation.As a critical factor in HTHPs,thermal performance is mainly introduced in the entire paper.To date,most reviews have been published concerning one or several application scenarios.However,to the best of authors' knowledge,it is hard to find a review discussing how to improve the thermal performance of HTHPs comprehensively.First,the impact on the performance of three main components of HTHPs over the past 30 years is introduced:the working fluid,the HTHP structure,and the wick structure.Herein,it is a considerable review of the optimal operating conditions for each direction,and we expect this paper contribute to improving the thermal performance of HTHPs.Then,current numerical simulations and theoretical research on the heat transfer limit of HTHPs are recommended.The significant hypotheses used in numerical simulations and the present theoretical studies are compiled here.Finally,some potential future directions and tentative suggestions for HTHP research are put forward.

Effect of La_2O_3, Y_2O_3 Additives on Structure and Mechanical Property of Ceramic-Lined Composite Pipe Under Centrifugation

The effect of additives containing rare earth elements La and Y on the structure and mechanical property of ceramic-lined composite pipe was studied in presence of centrifugation. The fracture and shearing strength of ceramic-lined composite pipe containing different additives were measured and analyzed through the fracture and shearing strength experiments. The distribution of shear stress on the interface of ceramic layer and the pipe is computed by finite element method.

太阳能高温热化学反应器研究进展

将高温光热转换和热化学过程集成,可使太阳能和化石资源(包括水或生物质)提级为氢或合成气资源,是热点课题之一。太阳能高温反应器是实现该过程的关键,但存在均温性差、转化效率低及反应物烧结失效的缺点。本文简述了太阳能高温热化学转化过程的原理,回顾了其由直接热解水制氢演变至化石资源改质和提级的历程,分析了塔式和碟式高温热发电集热器(也称为吸热器或接收器)移植用作太阳能高温反应器的可行性及其局限。综述了直接照射式和间接照射式太阳能高温反应器的研究进展,评述了热管(板)在改善太阳能高温反应器均温性和提高传热效率上的优势,阐述了间接照射式太阳能高温反应器在热化学转化过程的典型示范。指出基于热管(板)的间接照射式太阳能高温反应器为主导发展方向之一。