TY - JOUR
T1 - Analysis of tubular receivers for concentrating solar tower systems with a range of working fluids, in exergy-optimised flow-path configurations
AU - Zheng, Meige
AU - Zapata, José
AU - Asselineau, Charles Alexis
AU - Coventry, Joe
AU - Pye, John
N1 - Publisher Copyright:
© 2020
PY - 2020/11/15
Y1 - 2020/11/15
N2 - Central tower concentrating solar power (CSP) systems typically focus solar radiation upon a tubular solar receiver where radiation is absorbed and then transferred, by conduction and convection, into a heat transfer fluid. In this paper, a range of heat transfer fluids are compared, using energy and exergy analysis, and varying the tube diameter, tube wall thickness, and tube-bank flow configuration. The model optimises exergy efficiency including pumping work, assuming uniform flux, and neglecting the effects of thermal stresses, circumferential tube temperature variations and cost. Suitable temperature and pressure conditions are chosen for each fluid, based on a realistic configuration of an applicable thermal energy storage (TES) and power block (PB). The examined heat transfer fluids are molten salt (60% NaNO3, 40% KNO3), liquid sodium, supercritical carbon dioxide (sCO2), air, and water/steam. Results showed that liquid sodium at an elevated (540–740 °C) temperature range performed best, with a solar-to-fluid exergy efficiency of 61%. At a low temperature range (290–565 °C), sodium was still marginally superior to molten salt, even after allowing for some exergy destruction in a sodium-to-salt heat exchanger. Water/steam also performs relatively well in the receiver, although the difficulties of integrating it with large-scale storage make it a challenging heat transfer fluid for an integrated system. Using sCO2 as the heat transfer fluid appears infeasible due to excessively-high pressure stresses on the tubes. Air also appears unsuitable for simple tubular receivers, since poor heat internal transfer results in high losses due to much hotter external surfaces.
AB - Central tower concentrating solar power (CSP) systems typically focus solar radiation upon a tubular solar receiver where radiation is absorbed and then transferred, by conduction and convection, into a heat transfer fluid. In this paper, a range of heat transfer fluids are compared, using energy and exergy analysis, and varying the tube diameter, tube wall thickness, and tube-bank flow configuration. The model optimises exergy efficiency including pumping work, assuming uniform flux, and neglecting the effects of thermal stresses, circumferential tube temperature variations and cost. Suitable temperature and pressure conditions are chosen for each fluid, based on a realistic configuration of an applicable thermal energy storage (TES) and power block (PB). The examined heat transfer fluids are molten salt (60% NaNO3, 40% KNO3), liquid sodium, supercritical carbon dioxide (sCO2), air, and water/steam. Results showed that liquid sodium at an elevated (540–740 °C) temperature range performed best, with a solar-to-fluid exergy efficiency of 61%. At a low temperature range (290–565 °C), sodium was still marginally superior to molten salt, even after allowing for some exergy destruction in a sodium-to-salt heat exchanger. Water/steam also performs relatively well in the receiver, although the difficulties of integrating it with large-scale storage make it a challenging heat transfer fluid for an integrated system. Using sCO2 as the heat transfer fluid appears infeasible due to excessively-high pressure stresses on the tubes. Air also appears unsuitable for simple tubular receivers, since poor heat internal transfer results in high losses due to much hotter external surfaces.
KW - Concentrating solar power (CSP)
KW - Exergy analysis
KW - Heat transfer fluid
KW - Receiver design
UR - http://www.scopus.com/inward/record.url?scp=85093654834&partnerID=8YFLogxK
U2 - 10.1016/j.solener.2020.09.037
DO - 10.1016/j.solener.2020.09.037
M3 - Article
SN - 0038-092X
VL - 211
SP - 999
EP - 1016
JO - Solar Energy
JF - Solar Energy
ER -