Experimental analysis and comparison of flat plate solar air heater with and without integrated sensible heat storage

In the present work, a novel flat plate solar air heater (SAH) has been designed to yield a good outlet air temperature irrespective of fluctuations in solar radiation. It was achieved with the help of a specially designed, integrated absorber plate cum storage unit, together acted as a single component. The integrated unit consists of a set of copper tubes with black painted copper foil, welded longitudinally on two main header tubes. High quality synthetic oil (Therminol-55) had been contained in those copper tubes, which acted as a sensible heat storage medium. To understand the characteristics of the novel SAH, a comparison study was made with a conventional SAH of similar dimensions experimented without any thermal storage. Both the SAHs were tested for three different mass flow rates (0.017 kg/s, 0.02 kg/s and 0.028 kg/s) at one of the hottest cities in India, Madurai. The results show that the novel SAH had operated at a maximum efficiency of 67.7% when the mass flow rate was 0.028 kg/s, before the solar radiation started to decrease around 14:00 h Indian standard time. It also concluded that sensible heat storage at the absorber plate improves the thermal output, therefore leads to a consistent performance. Thus, the SAH with integrated storage unit performed with better efficiency compared to the conventional SAH with no storage. (C) 2020 Elsevier Ltd. All rights reserved.