Energy and exergy analysis of the thermal distillation system using diesel engine waste thermal energy and radial finned tube evaporator

Abstract

The performance of the waste heat-driven distillation system was investigated. The waste heat energy in the exhaust gas of the 7-hp diesel engine generator was utilized for distillation purposes. The thermal distillation system is comprised of a submerged copper tube evaporator and water-cooled U-tube condenser. Four copper tube evaporators were used, including one plain evaporator and three radial finned evaporators with pitch 30, 60, and 90 mm. The efficiency of the thermal distillation system was determined by varying engine load and evaporator type. The net recovered energy and exergy, overall first and second law efficiency, and distillate yield rate was determined relative to the applied load and evaporator type. The results revealed that the net recovered energy and exergy improved by 6.04%-23.22% and factor 1.07-1.23, respectively, at 75% engine load for radial finned evaporator with a pitch of 30 mm relative to plane tube evaporator. The distillate yield was also improved by 23.75% at the highest applied load 75% and the lowest radial fin pitch compared with the plane tube.