Nonlinear Thermal Analysis of Solar Air Heater for the Purpose of Energy Saving

In this article, nonlinear thermal Analysis of air-heating flat-plate solar collectors was conducted to obtain temperature distribution inside the heat transfer unit. Due to temperature-dependency of specific heat coefficient of air, the governing differential equation had a noticeable nonlinear nature. Therefore, for the solution of nonlinear equation a highly accurate and simple analytical method which is called Differential Transformation Method (DTM) and basic numerical method, Runge-Kutta (RG) was employed. As a significant result, it is depicted that the DTM results have an interesting conformity with numerical ones. After this verification, the effects of physical applicable parameters on temperature distribution, useful gained heat and thermal efficiency of collectors were investigated. It was concluded that increase in dimension of collector may not increase the efficiency (about 10% decreased). However an increase in the effectiveness coefficient (τα) and air mass flow rate ( ) enhanced the performance of solar collectors and the process efficiency increased up to 12%.