This article studies the influence of environmental conditions on overall thermal efficiency and heat loss of molten salt receiver for Concentrating Solar Power, including concentrated incident energy, ambient temperature, wind velocity and wind direction. Operation strategy of the receiver and its influence on system energy efficiency are discussed. The operation performance of the receiver is mainly affected by wind velocity and concentrated incident energy. Wind direction and ambient temperature, however, do not have significant influence on it. If wind velocity is over 7 m/s, the overall convective heat loss under rated outlet temperature mode surpasses the radiative heat loss. The local convective heat loss of the receiver is greatly influenced by wind velocity, while the local radiative heat loss is almost independent of it. When operated under rated outlet temperature mode, thermal efficiency of the receiver is lower. However, its exergy efficiency and the overall energy efficiency of the whole system are higher than that of rated mass flow rate mode. Compared to rated mass flow rate mode, it is recommended to adopt rated outlet temperature mode when direct normal irradiance（DNI） remains stable. In such case, the enhancement of overall system energy efficiency will be up to 2% if concentrated incident energy reaches 80% and above of the designed value. And the enhancement increases from 2% to 9% when concentrated incident energy decreases from 80% to 30% of the designed value. It is noted that an equivalent rated outlet temperature mode can be adopted when （DNI） fluctuates violently.
Key words
solar power tower /
numerical simulation /
heat loss /
efficiency analysis /
molten salt receiver /
operation strategy
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References
[1] DENHOLM P, JORGENSON J, MILLER M, et al.Methods for analyzing the economic value of concentrating solar power with thermal energy storage[R]. NREL/TP-6A20-64256, 2015.
[2] TYNER C E, SUTHERLAND J P, GOULD W R.Solar Two: a molten salt power tower demonstration. SAND-95-1828C, 1995.
[3] LOGIE W R, PYE J D, COVENTRY J.Thermoelastic stress in concentrating solar receiver tubes: A retrospect on stress analysis methodology, and comparison of salt and sodium[J]. Solar energy, 2018, 160: 368-379.
[4] EL HEFNI B, BOURDIL C.Dynamic detailed model of a molten salt tower receiver, with ThermoSysPro library: Impacts of several failures or operational transients on the receiver dynamic behavior[C]//AIP Conference Proceedings, Yogyakarta, Indonesia, 2017, 1850(1):030014.
[5] PACHECO J E.Final test and evaluation results from the solar two project[R]. SAND2002-0120, 2002.
[6] CHRISTIAN J M, HO C K.CFD simulation and heat loss analysis of the solar two power tower receiver[C]//ASME 2012 6th International Conference on Energy Sustainability, San Diego, California, USA, 2012.
[7] UHLIG R, FRANTZ C, FRITSCH A.Effects of vertically ribbed surface roughness on the forced convective heat losses in central receiver systems[C]//SOLARPACES 2015: International Conference on Concentrating Solar Power and Chemical Energy Systems, Cape Town, South Africa, 2016.
[8] LATA J M, RODRÍGUEZ M, DE LARA M Á. High flux central receivers of molten salts for the new generation of commercial stand-alone solar power plants[J]. Journal of Solar Energy Engineering, 2008, 130(2): 021002-021006.
[9] Special Metals Corporation.The story of the “INCOLOY® alloys series,” from 800, through 800H,800HT®[EB/OL]. https://www.specialmetals.com/tech-center/alloys.html.
[10] ALBERTO S G, RODRÍGUEZ-SÁNCHEZ M R, SANTANA D. Aiming strategy model based on allowable flux densities for molten salt central receivers[J]. Solar energy, 2017, 157: 1130-1144.
[11] ZAVOICO A B.Solar power tower design basis document, revision 0[R]. U.S. Department of Energy Office of Scientific and Technical Information, SAND2001-2100, 2001.
[12] 杨世铭, 陶文铨. 传热学[M]. 第4版. 北京: 高等教育出版社, 2006.
YANG S M, TAO W Q.Heat Transfer[M]. 4th ed. Beijing: Higher Education Press, 2006.
[13] QUESADA-RUIZ S, CHU Y, TOVAR-PESCADOR J, et al.Cloud-tracking methodology for intra-hour DNI forecasting[J]. Solar energy, 2014, 102: 267-275.
[14] ZHU J, WANG K, WU H, et al.Experimental investigation on the energy and exergy performance of a coiled tube solar receiver[J]. Applied energy, 2015, 156: 519-527.
[15] MARQUEZ R, COIMBRA C FM.Intra-hour DNI forecasting based on cloud tracking image analysis[J]. Solar energy, 2013, 91: 327-336.
[16] KRAAS B, SCHROEDTER-HOMSCHEIDT M, MADLENER R.Economic merits of a state-of-the-art concentrating solar power forecasting system for participation in the Spanish electricity market[J]. Solar energy, 2013, 93: 244-255.
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