This paper focuses on a review of the recent patents of the solar air heaters which are used
for drying, space heating and timber seasoning, etc. A solar air heater deals with a simple blackened
absorber tray, an insulation material to prevent heat losses, one or more transparent glass covers for
thermal trap, two individual ducts for air inlet and exhaust and an electric blower (for forced convection).
Some novel designs of the solar air heaters from 1952 up to now have been discussed (depending
on the fundamental design principles) and categorized by using a classification system. After reviewing
some good patents, it has been originated that there are many comprehensive patents covering the detail design, importance
of part elements functioning and performance of the air heaters. Conversely, there are a limited data available, research
articles, and viable products to compare the advantages over each other. Therefore, the modification or the improvement
must be focused on the design and configuration of the elements of the system. It will direct to understand the performance
limitations, tradeoffs, and advantages of typical designs and components in comparison against each other. This
study will improve the understanding of students, scholars, researchers and developers as well as strengthen the overall
logical asset archive and the knowledge pool for the solar air heating systems.