Performance analysis of a forced convection mixed mode horizontal solar cabinet dryer for drying of black ginger (Kaempferia parviflora) using two successive air mass flow rates

Abstract

The main aim of this paper is to accelerate the drying process of black ginger in a forced convection mixed mode horizontal solar dryer (FCMHSD) by using two successive air mass flow rates. When the drying rate attains the falling rate period, air mass flow rate has minimal effect on drying rate. To diffuse bound moisture present in the product, air mass flow rate has to be reduced for raising the air temperature in the solar dryer. In this manuscript, two cases were considered for drying; Case – 1 with constant air mass flow rate of 0.062 kg/s and Case – 2 with two successive air mass flow rates of 0.062 kg/s during the initial period of drying and 0.018 kg/s during the falling rate period. The performance of FCMHSD was evaluated in terms of drying time, drying efficiency, specific energy consumption (SEC) and moisture diffusivity. The estimated SECs for Case – 1 and Case – 2 were 1.07 kWh/kg and 0.56 kWh/kg, respectively. A significant improvement in thermal performance and moisture diffusivity were observed when the FCMHSD operated under Case – 2 than under Case – 1. The use of two successive air mass flow rate is a new approach for accelerating the drying process.