Heat Transfer Analysis During the Process of Injera Baking by Finite Element Method
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Date
2011-11
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Addis Ababa University
Abstract
The main objective of this study was the modeling and simulation of the heat transfer during the
process of injera baking. In doing these, mathematical models and finite element formulations for
baking pan and injera during baking was developed. In this study, thermo physical properties of
injera were studied analytically and were used for the temperature profile prediction using the
numerical model. The main properties of interest were specific heat capacity, thermal
conductivity, and density.
The mathematical model of injera during baking employs the coupled partial differential
equations proposed by Luikov. Resulting system of non linear partial differential equations in
time and two space dimensions were reduced to algebraic system by applying the finite element
numerical method. The fundamental two-dimensional axisymmetric transient finite element
model with triangular elements to predict the heat transfer for the baking pan and heat and mass
transfer that occur during baking of injera was solved using the Finite Element Method by
MATLAB. The backward difference time stepping technique was used for the transient analysis.
The simulation was done in terms of temperature profile during heat up, and cyclic injera baking.
Simulation was carried out for four different input heated oil temperatures (250, 275, 300, and
325° ) and for four different electric power sources (1.867, 2.2, 2.5, and 3 ). Two types of
baking pans (clay and ceramic) with different thicknesses were investigated. Experiments on
conventional clay baking pan were conducted to measure heat up time, and mass balance of batter
and injera. The heat up time obtained from simulation was compared with experimental test; from
the comparison a relatively good agreement was obtained.
The energy utilization and efficiency of electric baking pans were determined based on the
amount of energy baking pans use in a baking session for a given power input. A relatively better
efficiency was obtained for 10 thick clay and 8 thick ceramic baking pans with a power
source of 2.5 . While the 10 pan was not practically realized, the 8 ceramic pan
manufactured by Tabor ceramic factory is currently under study.
Key Words: Finite element method, Injera, Heat and Mass Transfer, Simulation, Efficiency.
Description
Keywords
Finite element method; Injera; Heat and Mass Transfer, Simulation; Efficiency