Performance of a natural circulation solar air heating system with phase change material energy storage

The design, construction and performance evaluation of a passive solar powered air heating system is presented. The system, which has potential applications in crop drying and poultry egg incubation, consists of a single-glazed flat plate solar collector integrated with a phase change material (PCM) heat storage system, The PCM is prepared in modules, with the modules equispaced across the absorber plate. The spaces between the module pairs serve as the air heating channels, the channels being connected to common air inlet and discharge headers. The system was tested experimentally under daytime no-load conditions at Nsukka, Nigeria, over the ambient temperature range of 19-41 degreesC, and a daily global irradiation range of 4.9-19.9 MJ m(-2). Peak temperature rise of the heated air was about 15 K, while the maximum airflow rate and peak cumulative useful efficiency were about 0.058 kg s(-1) and 22%, respectively. These results show that the system can be operated successfully for crop drying applications. With Suitable valves to control the working chamber temperature, it can also operate as a poultry egg incubator. (C) 2002 Elsevier Science Ltd. All rights reserved.