Design and experimental investigation of adryer with two types of combined solar concentratorsusing two natural heattransfer fluids

Abstract

In this experimental study, a new solar dryer has been designed and manufactured by combining a concave solar concentrator with a series of convergent lenses whose concentrated radiation are reflected on the same absorber. Our main goal for this combination is to reduce the thermal losses by increasing the receiver bottom temperature. In our dryer, the receiver design uses air and water as the heat transfer fluid; these two fluids are heated and sent a heat exchanger to raise the drying air temperature. Furthermore, in order to improve the thermal performance, our approach is based on some techniques such as; the combination of two types of solar concentrators, simultaneous use of two natural heat transfer fluids, tilting concentrators, the insertion of obstacles at the absorber, and a specific solar tracker for explosive atmosphere. Our dryer has been tested for the first time in gas filling plant in Morocco for drying painted gas cylinders. The experimental results show that compared with flat-plate solar collector, the proposed dryer can significantly improve the performance in terms of air drying temperature. In fact, our solar dryer has reduced the drying time from 420 seconds to just 40 seconds and has improved drying air the temperature from 40 °C to 65 °C. Also, the health risks of workers have been reduced and the number of painted bottles has been increased by more than 43%.