ENERGETIC ANALYSIS OF CLAY OVEN USED FOR BREAD BAKING

Abstract

Food processing including baking consumes a lot of energy thereby increasing cost of production.
Therefore, energy and exergy distribution patterns in clay oven were determined, and computer software
to evaluate the energy was developed. Ten clay oven bakeries were used for the study. Sizes, shapes,
thicknesses and sources of energy were recorded and temperature taken at an interval of 30min for 7hrs.
Energy, exergy and energy losses of the ovens were computed using standard equations. Software was
developed using Visual Basic programming language and the performance was evaluated. The ovens
were of dome shape, the sizes ranged between 27.40m² and 36m² and the thickness ranged from 0.19m to
1.11m. Mass of fossil fuel (dry wood) used ranged between 244kg and 270kg as the source of energy.
Peak mean temperature of 451 ± 5.6oC was achieved after 180min of heating un-loaded oven. At this
temperature, the mean energy, exergy and energy loss recorded were 184.85 ± 8.78MJ, 169.33 ± 7.65MJ
and 3.31 ± 1.25MJ respectively. Loading with bread dough reduced the temperature to 153^oC after 1hr.
The mean energy, exergy ranged between 24.85 ± 0.14MJ and 184.85 ± 8.78MJ and from 15.9 ± 1.86MJ
to 169.33 ± 7.65MJ respectively. The mean energy loss ranged between 0.44 ± 0.14MJ and 3.32 ±
1.25MJ. The mean total energy loss was 26.3MJ out of which the door contributed about 26.2MJ
(99.5%) of the heat loss. Validation of the software indicated that less than 0.5% marginal error was
recorded. The computer software developed served as a useful tool for estimating energy distribution
pattern in clay oven.