Solar Energy, Vol.108, 421-431, 2014
Novel non-concentrating solar collector for intermediate-temperature energy capture
Tremendous research efforts have been conducted studying the capturing and conversion of solar energy. Solar thermal power systems offer a compelling opportunity for renewable energy utilization with high efficiencies and excellent cost-effectiveness. The goal of this work was to design a non-concentrating collector, capable of reaching stagnation temperatures above 250 degrees C and fluid outlet temperatures under flow above 200 degrees C at 1000 W/m(2) solar irradiance. The study provides a detailed description of the methods and materials for construction of non-concentrating, high-temperature, evacuated solar collectors, the output fluid temperature depending on the input flow rate of working fluid in a low-flow rate, high-temperature regime, and an analytical description of the heat transfer between the collector and the working fluid. Temperature gains compared to ambient far above 200 degrees C were possible under solar irradiance of 1000 W/m(2) with collector efficiencies of 30% and more. For a temperature gain of 227 degrees C (fluid outlet temperature 253 degrees C), the collector efficiency was 30%, and for a temperature gain of 214 degrees C (fluid outlet temperature 240 degrees C), the collector efficiency was 49%. This result opens up many new uses for non-concentrating solar collectors in fields such as power generation, fuel reforming, and catalysis. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords:Solar energy;Renewable energy;Heat transfer;Solar collector;Evacuated tube collector;Non-concentrating