| abstract |
A solar air heater including a housing having a transparent front wall and an inlet and outlet for establishing a flow path for a gas such as air to be heated and a porous radiation absorbent collector plate positioned across the flow path and arranged to accept incident solar radiation passing through the front wall wherein a radiation trap is placed inside the housing either adjacent to the front wall, directly on top of the collector plate or between the collector plate and the front wall. The radiation trap has a cellular structure such as honeycomb and is made from a material which is light-transmitting but opaque to infrared radiation emitted from the collector plate in a direction toward the front wall. When the radiation trap is placed adjacent to the front wall the trap can additionally serve as an air buffer layer. In this instance, however, the radiation trap must be maintained in at least firm mechanical contact with the front wall and preferably the trap is actually bonded to the front wall. |