Performance enhancement of a chimney operated passive solar dryer

摘要

This paper presents a performance evaluation of a passive solar dryer by a chimney effect experimentally. In this study, three different configurations of solar dryers have been proposed: two passive dryers (Case-1 and Case-2) and an active dryer (Case-3), one of the passive dryer with a chimney (Case-2) and the other without a chimney (Case-1). The energy and exergy efficiencies have been determined for the proposed solar dryers, and comparisons were made with one another. It also presents the effect of temperature rise and airflow rate. Thermocouples were placed to different locations along the solar dryer to collect temperature data for experimental analysis. The energy efficiency varied from 3% to 7% for Case-1, from 20% to 26% for Case-2, and from 21% to 42% for Case-3, while the exergy efficiency changed between 2% and 12% for all cases. The highest exergy efficiency was achieved by Case-1. The results revealed that a chimney dryer improved the airflow rate to a maximum of 0.71 m.s～(-1) while a dryer without a chimney was 0.3 m.s～(-1). Moreover, this paper found that energy efficiency increased with the airflow rate, whereas exergy efficiency decreased.