Application of Combined Heat and Power for Drying Agricultural Products (apple slices) to Save Energy

Abstract

In this research work, the waste heat of exhaust gas of an engine-generator for the process of apple slice drying was used and tested. Drying
experiments were conducted at different engine loads (25%, 50%, 75% and full load) and thickness of the samples (3, 5 and 7 mm). Experiments
were conducted to evaluate the drying kinetics, comparison of energy consumption and efficiency of the combined heat and power (CHP) and
electricity generation. The results showed that drying time decreased significantly with increasing the engine load and decreasing thickness of test
samples. Also, the specific energy consumption (SEC) was decreased with a decrease in the thickness of the samples. The SEC varied between
518-1071kWh/kgwater. The lowest value of SEC of 518 kWh/kgwater was observed at 75% engine load and thickness of 3 mm. Energy efficiency of
CHP was from 68% to 210% higher than that of electricity generation. The maximum efficiency was obtained at 75% engine load. The brake
specific fuel consumption (BSFC) was from 40.7% to 67.7% lower than that of electricity generation under different engine loads. This study
showed that the use of exhaust waste heat of an engine-generator for drying process in the final energy consumption is very reasonable.