Design, Numerical Optimization and Experimental Investigation of Waste - Heat Recovery System Coupled To Electric Injera Baking Pans (MITADS)

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Addis Ababa University


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.



waste heat recovery, waste heat recovery, baking pan, heat loss, saturated porous media