Experimental Study of Radiative Properties of Charcoal Combustion in Grills

Abstract

This research focuses on the heat transfer characteristics of charcoal combustion in grills. Experiments were performed to observe the effects of fuel type, fuel amount, and fuel arrangement on the various thermal characteristics of charcoal. The experiments were conducted in a natural draft uncontrolled ventilation atmosphere. Two commercially available charcoals, and a hardwood lump charcoal were observed during combustion while thermal measurements were recorded and are presented here. A single wavelength pyrometer was used to measure the temperature of charcoal as a black body source, whereas the true temperature measurements were done by several thermocouples. A model for calculating the emissivity was developed, and the variation of emissivity as a function of temperature was studied for the black and gray-ash surface conditions of the charcoals. The end goal of this study was to obtain correlations for emissivities of these fuels at different surface conditions. Additionally, these results are beneficial in the design of grills and also for benchmarking CFD and other combustion models with observed experimental data. The results showed that one of the commercially available charcoals had higher emissivities and also higher rates of combustion than the other two fuels tested. Emissivity was observed to increase with an increase in the amount of fuel. It was found that the emissivities varied greatly and were highest at the center of the fuel arrangement, but also depended on how tightly the fuel was arranged. The average emissivity values of black and gray surface conditions of one of the commercially available charcoals were 0.77 and 0.80 respectively.