Studies on Scheffler solar concentrator to optimise thermal efficiency

Abstract

Parametric analysis of Scheffler solar concentrator system is performed for improvement in thermal efficiency. A Scheffler concentrator of size 2.7 m2 has been used for experimentation. Cylindrical and conical shape receivers each with 8-liter capacity was used for experimentation which serve a dual purpose of absorber as well as steam storage device. The thermal efficiencies with different receivers were calculated on the basis of parameters like shape of receiver, initial heating of inlet water, tilting angle of receiver and receiver with the glass cover for steam pressures up to 3 bars. Cylindrical receiver has the maximum efficiency of 56.64% in case of initial heating of water (50°C) and conical receiver has the maximum efficiency of 76.04% in case of tilting position of receiver (45°) at 1 bar. Response surface method was used to optimise the thermal efficiency of receiver. A general mathematical model for obtaining thermal efficiency has been developed for both types of receivers in terms of incident average solar radiation and mass flow rate of steam. The optimum predicted value of thermal efficiency is calculated from the general mathematical model and there is a good agreement found between the experimental and predicted results.