Thermal analysis of north wall insulated greenhouse dryer at different bed conditions operating under natural convection mode

An experimental investigation has been carried out on the modified greenhouse dryer with insulated north wall operating under natural convection mode of heat transfer for different floor conditions, namely ground floor, concrete floor, gravel floor, and black painted gravel floor. The terms like coefficient of diffusivity, coefficient of performance, overall heat transfer coefficient, heat loss factor, and heat utilization factor has been calculated for different floor conditions. The maximum difference between room temperature and ambient temperature was found to be 32.4°C at 13 O'clock for black painted gravel floor, followed by gravel floor, concrete floor, and ground floor which are 27, 14.1, and 11.5°C, respectively. It has been observed that the rise in the percentage of maximum room temperature in comparison to maximum ambient temperature for black painted gravel floor, gravel floor, concrete floor, and the ground floor was 50.31, 46.15, 30.1, and 26.6%, respectively at 13 O'clock. It has been found that the maximum temperature absorbed by black painted gravel bed. Hence, this type of floor condition is highly recommended for drying of low and medium moisture content type vegetables and fruits. The thermal parameters of the result obtain from the present setup was compared with the published literature, and it was found that all parameters show the similar trends; however, the present setup shows the superior performance compared to other research work.