Numerical study on flow and heat transfer characteristics of S-CO_(2) in a novel parabolic trough collector tube utilizing impinging jets under non-uniform heat flux boundary  

作　　者：HE Zheng LI Qing ZHANG YaRu ZHOU Ping WEN ZheXi 

机构地区：[1]School of Energy Science and Technology,Central South University,Changsha 410083,China

出　　处：《Science China(Technological Sciences)》2024年第12期3724-3740,共17页中国科学(技术科学英文版)

基　　金：supported by the National Natural Science Foundation of China(Grant No.52376087);Hunan Provincial Natural Science Foundation of China(Grant No.2023JJ30688)。

摘　　要：Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel jet structure is proposed in this paper to explore the feasibility of adopting impinging jets to improve the heat transfer performance of the collector tube with supercritical carbon dioxide(S-CO_(2))as the working fluid.The physical model is built based on several assumptions,and numerical simulations are performed under the mass flow rate of 0.25-0.75 kg/s and the average surface heat flux of 14.7-33 kW/m^(2).Firstly,performance comparisons are made between the jet and tube-in-tube structures.The results show that the average heat transfer coefficient h of the jet structure is 46.5%higher than that of the tube-in-tube structure and the corresponding average temperature differenceΔT between the wall and S-CO_(2)is 31.7%lower.Secondly,the effects of the jet hole circumferential position and diameter on heat transfer are investigated.It's found that by adjusting the circumferential position of the jet hole from 60°to 120°and matching the impingement area of the jets and the high heat flux region,h can be increased by 14.2%andΔT can be reduced by 12.4%.h is also found to be increased by 77.4%when the jet hole diameter is reduced from D=9.7 mm to D=5 mm.Furthermore,the jet structure is further modified by incorporating it with the eccentric configuration.The effect of eccentricity e is studied in detail,and results show that appropriate eccentricity results in higher h and smallerΔT due to the decreased impingement distance and the increased heat transfer.This study can guide the design and optimization of parabolic trough collectors.

关 键 词：supercritical CO_(2) non-uniform heat flux jet impingement eccentric structure parabolic trough collector 

分 类 号：TM615[电气工程—电力系统及自动化] TK513.1[动力工程及工程热物理—热能工程]