Effect of Once-through and Recirculated Fluid Flow on Thermal Performance of Parabolic Dish Solar Receiver

Objectives: The effect of mass flow rate of heat transfer fluid (HTF) during once-through (OTF) and recirculation (RF) operations, through its solar receiver was analyzed in a parabolic dish (PD) collector. Methods/Statistical Analysis: Inlet temperature of HTF and mass flow rate are the most important operating parameters in solar concentrating collectors along with local solar irradiance. The solar receiver was tested on sunny days (solar beam radiation intensity in the range of 500 - 700 W/m²) in February and March 2016 at Chennai, India (Latitude: 13°N, Longitude: 80°E) with HTF mass flow rates of 25, 50, 75, 100 and 125 kg/h. Findings: The instantaneous temperature gain by the HTF was observed to be around 100°C for the OTF with 25 kg/h due to effective heat absorption than that of 40.5°C for the RF due to more heat loss. The instantaneous energy efficiency during the RF mode is around three times more than the efficiency of OTF mode. Exergy efficiency of OTF is 3.28% more than the RF due to lower exergy destruction. Application/Improvements: The once-through flow has an advantage over recirculation by the way of less thermal stress effect on the receiver and piping.