Enhancement of natural ventilation of a circular greenhouse with double wall solar chimney

Abstract

The study has been devoted to develop an energy efficient agricultural greenhouse system. To serve this purpose a circular greenhouse with double walled vertical hollow cylindrical type solar chimney has been selected. The circular shape is beneficial to allow the outside wind from any direction. The solar chimney is constructed with double wall- the outer wall is made of fibre reinforced plastic (FRP) sheet to transmit solar radiation and the inner wall is made of blackened aluminium sheet to absorb solar radiation. Thus ventilation is occurred by solar as well as wind effect. It is found that 0.6-0.8 air change per minute (ACM) ventilation rate could be obtained, when total radiation intensity level remains 100-600 W/m2 as well as the ambient temperature remains 30°C. It is found that solar chimney a circular greenhouse can improve ventilation rate 1.6-1.7 times.