Validation of the simulation of solar air collector prototypes

The solar air systems can be appropriated into constructions due to the easy integration of air collectors in building facades, either into walls and roofs or by replacing one of them. There are several types of solar air collectors, which differ from each other on how the cover, absorber and airflow pattern are laid out in the collector. It is important to know the collector performance in order to design other system elements. Designs of solar air collectors and their respective models can be found in some solar engineering books. The model equations allow measuring the collector performance at a particular time. However, it is necessary to know some state variables of the collector such as the collector element temperatures, and heat transfer coefficients. It is important to emphasize that the collector state variables are changing with time due to the environmental effects. This study deals with the mathematical models, the implementations and the validations of numerical simulation for three experimental prototypes of solar air collector. The Solar-Institute Julich of Germany developed the prototypes. In a general form the mathematical one-dimensional transient model of heat flux of each solar air collector is presented. Besides, the implementation of the collector models in the MATLAB-Simulink software is described. As a result of the validation of experimental data, the mathematical models and numerical implementations are able to estimate the air temperature inside of the collector. Average absolute error between integrals of simulated and measured temperatures reached hardly 1.2 degrees C. In general, the three solar air collector models had a very good performance. (C) 2014 The Authors. Published by Elsevier Ltd.