A review of solar air heaters: techniques for thermal performance enhancement

Omar Hamdoon

doi:10.33899/rengj.2020.128374.1065

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.

Highlights

The Solar Air Heater (SAH) is a simple device in which solar energy is converted into thermal energy to heat the air
The thermal efficiency of the solar air heater is defined as the ratio of the useful heat that the solar collector has acquired to the solar radiation falling on the surface of the solar collector [7,8,9], so the thermal efficiency of the solar air heater can be defined by the following law: ηth
The results showed that the best performance was for the finned plus baffled double-pass solar air heater, as the efficiency of this heater reached 72.06% at a mass flow rate 77.04 kg /h

Summary

INTRODUCTION

The Solar Air Heater (SAH) is a simple device in which solar energy is converted into thermal energy to heat the air. The main components of the solar air heater are one or more glass cover, absorber plate, one or more airflow channels, insulation to reduce heat loss from both the bottom and sidewalls of the solar collector. These systems produce heat at minimal initial and running costs. Many previous studies have studied the possibility of improving the performance of solar collectors and raising their thermal efficiency through additions and improvements that have been added to the solar heater Among these improvements are: adding extended surfaces to the upper or lower channels, or both, attaching baffles to the absorber plate surface, using corrugated absorber plate, and storing additional thermal energy and releasing it during sunset.

Energy Analysis

Exergy Analysis

Findings

Conclusion