Experimental investigation of a hybrid compound parabolic collector integrated with flow through-type evacuated tube collector under hot and humid conditions in India

This study offers an experimental analysis of a hybrid solar thermal collector that is best suited for the summer climate in Vadodara, Gujarat, India. It combines a Compound Parabolic Collector (CPC) with a flow-through type Evacuated Tube Collector (ETC). Three types of reflector materials were examined: polished aluminum, glass mirror, and acrylic mirror. The control was an independent ETC unit. Every configuration ran at a flow rate of 1.0 L/min. The temperature outside reached 43°C during the tests, and the maximum solar intensity was 1050 W/m². The aluminum CPC-ETC system demonstrated superior performance, achieving 82°C outlet temperature compared to 63°C for the ETC-only baseline - representing a 30% improvement. Daily heat gain increased by 99% from 42.3 MJ/day (ETC-only) to 84.2 MJ/day (aluminum CPC-ETC). The aluminum reflector configuration achieved an average thermal efficiency of 66% compared to 50% for the standalone ETC system, demonstrating a 32% relative improvement. The findings show that under tropical summer conditions, CPC-ETC systems have an increased thermal potential.