Design, Numerical Optimization and Experimental Investigation of Waste - Heat Recovery System Coupled To Electric Injera Baking Pans (MITADS)
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Date
2018-06
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Addis Ababa University
Abstract
Electric Injera baking pans (Mitads) are the most prevalent and energy-intensive appliances used
in Ethiopia and encounters bulk amounts of heat loss in the systems. However, only few and
rarely published research and development were made to improve the thermal efficiency and
reduce the heat loss encountered in the system. Therefore, this study aims to make design;
numerical optimization and experimental investigation of waste heat recovery system coupled to
electric injera baking pans to improve the efficiency of baking pan and reduce the wastage of
energy in the baking process. Thus, to verify (quantify) the amount of heat loss accounted in the
baking process intensive experimental investigation was made, and data obtained was
analytically analyzed and electric Injera baking process was encountered 46.15% heat loss in
which bottom insulation encountered 70% of total loss accounted in the process. Therefore, to
reduce the major loss accounted in the bottom insulation analytical design and numerical
optimization of waste heat recovery system was carried out by using comsol multiphysics
software and 6.5mm thick ash insulation at the top and bottom of oil pan and 1.5mm oil pan
thickness was obtained as the optimum dimension of heat recovery system. Then, the waste heat
recovery system was manufactured as per optimization result and some of the insulation was
replaced by simple heat recovery oil pan, with the diameter of 540mm and thickness of 19mm`
and coupled to heat recovery tank, to discharge the energy recovered to make coffee and water
heating. The performance evaluation of the system was carried out by experimental investigation
and the system was recovered 60.66kJ (which account 9.63%) of heat energy at each baking and
tested experimentally by boiling water. This study also quantifies the loss accounted in the new
system and the system encountered 34.57% heat loss and bottom insulation accounted 22.57%.
Compared to the ordinary baking pan the electric injera baking pan coupled with waste heat
recovery system will improves the efficiency of baking process by 11.53%. The heat energy
recovered by the system is utilized for water heating purpose and for making coffee.
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Keywords
waste heat recovery, waste heat recovery, baking pan, heat loss, saturated porous media