Experimental investigations of thermal and flow characteristics of a novel microjet air solar heater

• A novel construction of a microjet air solar heater is proposed.
• The supply and return channels of heater are made in the shape of a triangular prism.
• The thermal efficiency of novel microjet air solar heater ranged from 66% up to 90%.
• The microjet air solar heater is characterized by low pressure loss.

Air solar heaters have more and more applications in many areas, including the building sector, food industry, and agricultural sector. This paper presents a novel construction of a forced air solar heater based on a confined single slot jet of air impinging on the flat surface of an absorber plate. The heat exchanger structure comprises two parallel air ducts (a supply channel and a return channel) in the shape of a triangular prism that are physically separated from one another. Results of experimental research showed that the efficiency of energy conversion ranged from 66% up to 90%. A comparison of results of thermal-flow performance of different types of air solar heaters, including the newly-developed heat exchanger indicated that the tested device can compete with the best commercially available solutions. It was found that the single glass covering significantly improves the efficiency of solar energy conversion from 16% up to 24%. As it turned out, the pressure losses associated with air passing through the device under test were the lowest of five selected solar air heaters.