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RISS 인기검색어
- 검색키워드
- 저자 : Zhiwen Dai (검색결과 3 건)
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Design and analysis of a free-piston stirling engine for space nuclear power reactor
Dai, Zhiwen,Wang, Chenglong,Zhang, Dalin,Tian, Wenxi,Qiu, Suizheng,Su, G.H. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.2
The free-piston Stirling engine (FPSE) has been widely used in aerospace owing to its advantages of high efficiency, high reliability, and self-starting ability. In this paper, a 20-kW FPSE is proposed by analyzing the requirements of space nuclear power reactor. A code was developed based on an improved simple analysis method to evaluate the performance of the proposed FPSE. The code is benchmarked with experimental data, and the maximum relative error of the output power is 17.1%. Numerical results show that the output power is 21 kW, which satisfies the design requirements. The results show that: a) reducing the pressure shell's thickness can improve the output power significantly; b) the system efficiency increases with the wire porosity, while the growth of system efficiency decreases when the porosity is higher than 80%, and system efficiency exhibits a linear relationship with the temperatures of the cold and hot sides; c) the system efficiency increases with the compression ratio; the compression ratio increases by 16.7% while the system efficiency increases by 42%. This study can provide valuable theoretical support for the design and analysis of FPSEs for space nuclear power reactors.
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Impact of axial power distribution on thermal-hydraulic characteristics for thermionic reactor
Zhiwen Dai,Chenglong Wang,Dalin Zhang,Wenxi Tian,Suizheng Qiu,G.H. Su 한국원자력학회 2021 Nuclear Engineering and Technology Vol.53 No.12
Reactor fuel's power distribution plays a vital role in designing the new generation thermionic SpaceReactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numericallyanalyzed with two kinds of different axial power distribution, to identify their impacts on thermalhydraulic and thermoelectric characteristics. In the benchmark study, the maximum error betweennumerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions wereobtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the corepower was cosine distributed, the maximum temperature of the emitter was 194 K higher than that ofthe uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axialpower distribution would make the maximum temperature in each component of the reactor core muchlower, reducing the requirements for core fuel material. d) Voltage and current distribution were similarto the axial electrode temperature distribution, and the axial power distribution has little effect on theoutput power
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Dai, Zhiwen,Wang, Chenglong,Zhang, Dalin,Tian, Wenxi,Qiu, Suizheng,Su, G.H. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7
The Free-Piston Stirling engine (FPSE) is of interest for many research in aerospace due to its advantages of long operating life, higher efficiency, and zero maintenance. In this study, a 1-kW FPSE was proposed by analyzing the requirements of Space Reactor Power Systems (SRPS), of which performance was evaluated by developing a code through the Simple Analysis Method. The results of SAM showed that the critical parameters of FPSE could satisfy the designed requirements. The heater of the FPSE was designed with the copper rectangular fins to enhance heat transfer, and the parametric study of the heater was performed with Computational Fluid Dynamics (CFD) software STAR-CCM<sup>+</sup>. The Performance Evaluation Criteria (PEC) was used to evaluate the heat transfer enhancement of the fins in the heater. The numerical results of the CFD program showed that pressure drop and Nusselt number ratio had a linear growth with the height of fins, and PEC number decreased as the height of fins increased, and the optimum height of the fin was set as 4 mm according to the minimum heat exchange surface area. This paper can provide theoretical supports for the design and numerical analysis of an FPSE for SRPSs.
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