Effect of HTF Flow Direction on Thermal Performance in an Upward Facing Cavity Receiver
Abstract
An analysis is carried out to examine the influence of heat transfer fluid (HTF) flow direction on thermal performance in an upward-facing cone-cylindrical receiver. The receiver is modeled as a helical coil receiver which is subjected to concentrated solar flux from a 60 sq.m. Scheffler parabolic dish. The receiver is inclined at an angle equal to 25˚. Therminol-55 is taken as the HTF flowing through the coil receiver. A numerical approach is adopted to evaluate the convective and radiative heat loss parameters from the coil receiver. These parameters are used to evaluate the thermal efficiency of the coil receiver for two fluid flow configurations: a) upwards (bottom-to-mouth), and b) downward (mouth-to-bottom). It is observed that for downwards HTF flow configuration, the mean coil temperature is lower than upward flow configuration, resulting in reduced thermal losses and higher thermal efficiency up to 5-10% under different operating conditions. The results will help in designing optimal helical coil solar cavity receiver for medium and high-temperature decentralized power generation applications