槽式太阳能直接蒸汽发生系统的热力特性研究
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摘要
[目的]研究典型的槽式直接蒸汽循环系统的热力性能,给出该系统的结构组成和主要性能参数。针对DSG系统的两相区复杂的换热问题,结合两相区的实际流型,考虑分层现象对实际换热过程的影响,更加准确地对两相区的换热过程进行模拟研究。[方法]基于槽式集热器内的流动型态,建立槽式集热两相区内的传热模型,利用Matlab编程,针对槽式集热器内的DSG过程进行模拟。[结果]揭示了DSG技术沿着管长方向的换热特性变化规律,分层现象大约出现在两相流区域干度为0.7～0.8之间的位置,分层现象的出现降低了管内工质与金属管管壁之间的对流换热系数,减弱了换热效果。[结论]该研究为DSG电站的设计和运行提供了参考依据,验证了DSG集热场的最佳布置方式为再循环式。
[Introduction]In this paper, the thermal performance of a parabolic trough direct steam generation system(DSGS) is investigated. With the considerations of the stratified flow phenomenon and real flow patterns in the complex two-phase flow, the heat transfer progress in the DSG system is numerically studied, and the thermodynamic performances are revealed. [Method]Based on the flow pattern inside the trough collector, the two-phase heat transfer model in the trough-type heat collecting region was established, and the DSG process in the trough collector was simulated by MatLab programming. [Result] The variation of heat transfer characteristics of DSG technology along the length of the tube is revealed. The stratification phenomenon occurs in the two-phase flow region where the dryness is between 0.7 and 0.8. The occurrence of delamination reduces the heat transfer between the working medium and metal tube, which weakens the heat transfer effect. [Conclusion]This study provides a reference for the design and operation of DSG power stations, and verifies that the optimal arrangement of DSG collectors is recirculating.
[Introduction]In this paper, the thermal performance of a parabolic trough direct steam generation system(DSGS) is investigated. With the considerations of the stratified flow phenomenon and real flow patterns in the complex two-phase flow, the heat transfer progress in the DSG system is numerically studied, and the thermodynamic performances are revealed. [Method]Based on the flow pattern inside the trough collector, the two-phase heat transfer model in the trough-type heat collecting region was established, and the DSG process in the trough collector was simulated by MatLab programming. [Result] The variation of heat transfer characteristics of DSG technology along the length of the tube is revealed. The stratification phenomenon occurs in the two-phase flow region where the dryness is between 0.7 and 0.8. The occurrence of delamination reduces the heat transfer between the working medium and metal tube, which weakens the heat transfer effect. [Conclusion]This study provides a reference for the design and operation of DSG power stations, and verifies that the optimal arrangement of DSG collectors is recirculating.
引文
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[7] 高志超,隋军,刘启斌,等. 30 m2槽式太阳能集热器性能模拟研究 [J]. 工程热物理学报,2010,31(4):541-544. GAO Z C,SUI J,LIU Q B,et al. Simulation on the performance of a 30 m2 parabolic trough collector [J]. Journal of Engineering Thermophysics,2010,31(4):541-544.
[8] ODEH S D,MORRISON G L,BEHNIA M. Modelling of parabolic trough direct steam generation solar collectors [J]. Solar Energy,1998,62(6):395-406.
[9] STEPHEN K. Heat transfer in condensation and boiling [M]. Germany:Springer-Verlag,1992.
[10] FORRISTALL R. Heat transfer analysis and modeling of a parabolic trough solar receiver implemented in engineering equation solver [R]. Colorado:National Renewable Energy Laboratory,2003,NREL/TP—550—34169.
[2] ODEH S D,BEHNIA M,MORRISON G L. Hydrodynamic analysis of direct steam generation solar collectors [J]. Journal of Solar Energy Engineering-Transactions of the ASME,2000,122(1):14-22.
[3] ECK M,STEINMANN W D. Modelling and design of direct solar steam generating collector fields [J]. Journal of Solar Energy Engineering-Transactions of the ASME, 2005,127(3):371-380.
[4] FELDHOFF J F,BENITEZ D,ECK M,et al. Economic potential of solar thermal power plants with direct steam generation compared with HTF plants [J]. Journal of Solar Energy Engineering-Transactions of the ASME,2010,132(4):041001-1-041001-9.
[5] BIRNBAUM J,FELDHOFF J F,FICHTNER M,et al. Steam temperature stability in a direct steam generation solar power plant [J]. Solar Energy,2011,85(4):660-668.
[6] MONTES M J,ABáNADES A,MARTíNEZ-Val J M. Thermofluidynamic model and comparative analysis of parabolic trough collectors using oil,water/steam,or molten salt as heat transfer fluids [J]. Journal of Solar Energy Engineering-Transactions of the ASME,2010,132(2):021001-1-021001-7.
[7] 高志超,隋军,刘启斌,等. 30 m2槽式太阳能集热器性能模拟研究 [J]. 工程热物理学报,2010,31(4):541-544. GAO Z C,SUI J,LIU Q B,et al. Simulation on the performance of a 30 m2 parabolic trough collector [J]. Journal of Engineering Thermophysics,2010,31(4):541-544.
[8] ODEH S D,MORRISON G L,BEHNIA M. Modelling of parabolic trough direct steam generation solar collectors [J]. Solar Energy,1998,62(6):395-406.
[9] STEPHEN K. Heat transfer in condensation and boiling [M]. Germany:Springer-Verlag,1992.
[10] FORRISTALL R. Heat transfer analysis and modeling of a parabolic trough solar receiver implemented in engineering equation solver [R]. Colorado:National Renewable Energy Laboratory,2003,NREL/TP—550—34169.