Development and experimental investigation of a novel combined solar cooker and dryer unit

Abstract

Solar cookers and dryers are normally used as separate units due to different operating temperature requirements for cooking and drying of food products. A unique design of a compounded solar cooker and dryer unit is presented in this paper and its performance is evaluated on the basis of outdoor experimentation. Two separate compartments serving as cooker and dryer units are joined together by providing small air flow passages in such a manner that the lower high-temperature cooker portion also acts as an air heater for the upper low-temperature dryer unit and the movement of air is by buoyancy-driven natural convection flow across the entire unit. Experiments are performed to assess the performance of the developed combined unit in terms of various performance factors such as figures of merits (F1, F2 ), energy efficiency, heat utilization factor (HUF), coefficient of performance (COP), and dryer efficiency. A promising feature of the proposed unit is the attainment of two different temperature ranges in the cooker (80 °C – 135 °C) and the dryer compartment (35 °C – 65 °C) under the same ambient conditions. The figure of merits of the cooking unit are determined to be 0.11 (F1 ) and 0.303 (F2 ). The heat utilization factor, coefficient of performance, and drying efficiency of the dryer unit are evaluated to be 34 %, 66 %, and 14 %, respectively.