Indian Journal of Science and Technology

Abstract

Objectives: Equipment sizing and method of utilizing exhaust gas waste heat for food crops drying are presented.

Methods/findings: The sizing of the components of the equipment was achieved using known design principles. The system uses an axial flow turbine and a heat exchanger to harness the energy of the exhaust gas of a diesel engine generator. A 250 kVA generator with measured exhaust gas flow rate and temperature of 44.5 m³/min and 382.7 °C was selected for this work. The purpose of the recovered energy is for the drying of food crops. An arduino platform was used to control the operation of the components of the dryer. The drying chamber consists of three trays whose calculated total volume per batch is 0.0463 m³. Weight losses across the trays, drying air temperature and humidity in the chamber are monitored by sensors. The test rig of the sized and fabricated equipment is currently undergoing extensive experimentation. Preliminary investigation of the dryer showed that the drying air in the chamber initially at the temperature and humidity of 31ºC and 71.2% was heated to 88ºC and 22.3% when the dryer operated without load for 45 min at an air speed of 2.0 m/s

Application: After cooling and maintaining the drying chamber averagely at 59ºC, each tray was loaded with 400 g of the grains of freshly harvested maize. The dryer was allowed to run for 30 min and the results obtained showed weight losses of 127.81 g, 118.36 g, and 116.91 g for the grains in trays 1, 2, and 3, respectively. The application of this energy recovery system to the drying of food products, would help to save a considerable amount of primary fuel which is considered a viable means of cost saving and amelioration of environmental degradation.

Keywords: Waste Heat Recovery, Drying, Global Warming, Environment, Cost Saving, Food Quality.