Analysis of a non-porous double-flow solar air heater

In this paper, we present the theory of a non-porous air heater in which the air is blown both below and above the absorbing surface. Explicit expressions for the outlet air temperature and useful heat flux have been obtained in terms of mass flow rate of the air, distance along the direction of air flow and other relevant parameters. The double-flow air heater is found to perform more efficiently than a single-flow air heater.