Thermal analysis of recuperator developed for waste heat recycling in liquid-fuel fired furnaces

Abstract

Three major parameters for efficient liquid-fuel-fired melting-furnaces include fuel-economy, thermal efficiency and environmental friendliness of operation. These key parameters form the basis for the adoption of recuperator in the waste gas recycling released during many melting operations in furnaces. This work analysed the thermal performance of both cold and hot fluids across the length of a double-pipe recuperator coupled to a ferrous-melting furnace. The thermal analysis carried out was anchored on some basic assumptions including taking the radiant and temperature characteristics of the exiting waste gases from the exhaust of the furnace as being constant over the volume of the furnace while the temperature at various positions on metal surface is equally taken as being constant. In addition, the heat flow transferred from the waste gases to the lining of the furnace is taken to be by convection and it is equal to the heat flow that the lining gives up to the adjourning surrounding. The derived equations were thereafter analysed and subsequently solved. The obtained results were thereafter used to graphically illustrate the variation of temperature of the agents of heat transfer over the entire length of the recuperator at different instances for parallel flow of the constituent working fluids. The analysis was observed to have conformed to a very great extent to the theoretical pattern expected for similar flows.