Heat Transfer Analysis of a Concentrated-Type Solar Dryer for Ginger

Abstract

In recent years, global concern about the preservation of agricultural products for usage and exports through drying has been outstanding. Solar Parabolic Trough Collectors (SPTC) are used to dry various agricultural products for effective moisture removal. A heat transfer fluid (HTF) flows through a receiver tube pipe that absorbs solar radiation reflected from the stainless-steel sheet surfaces of the SPTC. In order to reduce the heat losses, the pipe was linked through a flexible, thermally insulated cross-linked polyethene pipe to the copper tubes inside the drying chamber. The heat transfer analysis of the SPTC is essential to understand the thermal behavior and its performance during the drying process. This paper examined the heat exchanges developed in the designed concentrated-type solar dryer, and the heat transfer rates in the receiver tube and the drying chamber, as well as the heat transfer coefficients for the solar drying of ginger, were determined. The thermal analysis of the convective heat exchanges within the receiver tube and the drying chamber is presented. The heat transfer coefficients hRec and hDC for the convective heat transfer process in the receiver tube and the drying chamber were 1372.48W/m.K and 17.60W/m.K, respectively. The dryer’s thermal efficiency was 30%, showing considerable moisture removal from the ginger samples. The mean temperature difference between the drying chamber and the ambient showed a considerable increase of about +11oC. This resulted in considerable moisture removal, and the final moisture content achieved by the concentrated solar dryer for the ginger samples was 11.1%, compared to the 23.74% achieved by the open-air solar (OAS) drying method.