Abstract:
In Ethiopia injera is the most dominant meal but, injera baking is an energy intensive process.
Currently, electrical energy source is used in and around cities to bake injera, due to environmental
impact, health issue, production and consumption time and GHG emission of biomass energy. The
convectional injera baking pan (Mitad) is inefficient because of thermal energy loss to the ambient,
poor thermo-physical properties of baking pan and geometry of the pan. This research paper
intended to optimize the material of the baking pan by forming a composite matrix of Clay soil
and Gray Cast Iron powder to reduce the power consumption and time required for injera baking.
To attain the main aim of the proposed system, composaite matrix of Clay Soil and Gray Cast Iron
with 0%,5%,10%,15%,20%, 25%,30%,35% and 40% ratio were taken to formed injera baking
pan. The thermo-physical properties of the composite material were determined to analyze heat
transfer interaction of injera baking system. Initial heat up time and temperature distribution over
the top surface of the baking pan were investigated through ANSYS Fluent simulation. The
optimum ratio of composite matrix was selected through comparative method based on heat up
time and temperature parameters. The simulation result was valideted by comparing it with related
previous experimental work.
The simulation result revales that as the composite matrix ratio increases the heat up time required
to achieve 180โ decreases. At 9.667 𝑚𝑖𝑛 time period the baking pan reachs the desired
temperature when the amount of gray cast iron is above 15%. The heat up time highly decline
when the amount of gray cast iron increase from 15% up to 25%, but further increasing the
amount, only 1.3 second decreases. When the pan thickness increases the heat up time increases
and also when the electrical power input increases the heat up time decreases.
The result revels that, the optimum combination of thermo-physical proprties which gives lower
time and uniform temperature distribution over the baking pan is obtained when the composition
ratio is 25%, when the baking pan thickness is 15 𝑐𝑚 and electrical power input is 3 𝐾𝑊. The
heat up efficiency of the selected composite matrix ratio (25%) reaches 80.5%. The result clearly
indicates the time required for heat up, idle and baking as well as the temperature distribution
mainly affected by the thermo-physical properties, thickness and power input
