A comparative energy analysis of natural convection and forced convection in a solar greenhouse coffee dehydrator

This study presents a technological alternative analysis including modeling, measurement, and comparison of a forced convection dryer aided by photovoltaic energy and a natural convection greenhouse-type solar dryer. The semi-cylindrical solar greenhouse dryer with dimensions of 4 m x 4.7 m and the capacity to dry 200 kg of wet parchment coffee was able to achieve drying times of three and a half days for natural convection and two and a half days for forced convection, reducing the moisture content from 52% to 12% on a wet basis. In the same manner, desiccant air temperatures in the range of 60 – 70 °C and 50 – 60 °C were attained for natural convection and forced convection, respectively, significantly enhancing the coffee’s quality and properties.