A NEW DESIGN OF EFFICIENT PLANE SOLAR COLLECTORS FOR AIR AND WATER HEATING

In this paper, a new design of solar air-water heater for the purpose of performance improvement is introduced for the first time. This thermal system will be a good alternative for both space heating and providing domestic hot water for use in buildings. In the proposed solar collector, the absorbed incoming solar irradiation is transferred into both air and water flows. In numerical simulations, the governing equations for turbulent forced convection airflow with the conduction equation for glass cover, absorber plate, water tubes, and insulation are solved by means of the finite element method using the COMSOL Multiphysics software. In the studied test cases, from the total absorbed thermal energy by the absorber, about 18% is transferred to the airflow and 50% into the water flow. The effects of solar heat flux and the diameter of water tubes are also studied in this paper and thermal efficiency shows an increasing trend as the values of these parameters increase. A comparison of the thermal efficiencies between the designed solar air-water heater and a conventional solar air heater under the same operating conditions shows an increase of over 50%.