A Review of Solar Air Heaters: Techniques for Thermal Performance Enhancement

Abstract

The solar air heater is a simple device which captures solar energy. Producing hot air by using a solar air heater is a renewable energy heating technology used to process heat generation for space heating. Such systems produce heat at a minimum initial and running cost. Minimum maintenance like cleaning of collectors only is required. Many studies have studied the possibility of improving the performance of solar collectors and raising their thermal efficiency through additions and improvements that were added to the solar heater. Among these improvements are: Adding the extended surfaces to the upper or lower channels, or both, attaching baffles to the absorber plate surface, using corrugated absorber plate, and storing the extra thermal energy and releasing it during sunset. The objective of the present paper is to review the various studies dealing with previous improvements, to present the design modifications, in addition to summarizing their most important results. Based on the review, it is found that: Adding the fins and baffles together to the absorber plate surface of the single or double pass solar air heater has a great effect on improving the thermal efficiency. The use of a corrugated absorber plate leads to a significant increase in the efficiency of the solar air heater. The heat stored in the solar air heater can be used to produce useful heat for several hours after the absence of solar radiation and raise daily efficiency.

The Experimental Investigation of Double -Pass Solar Air Heater with V-Corrugated Plate, Phase -Change Material and Baffles Under Recycling Operation

“…Charging and discharging experiments had been conducted and the performance results obtained in the solar air heater with PCM, corrugated absorber plate, baffles and conventional solar air heater are compared under the same climatic conditions in Duhok Governorate/ Kurdistan region/ Iraq. The thermal efficiency of a SAH may be defined as the ratio of useable heat obtained by the solar collector to solar radiation falling on the collector's surface [18]. Hence, the thermal efficiency of a SAH can be written as follows:…”