| Abstract | The work involved in this thesis are associated with a
review of the standard testing methods for determining and
comparing the stove efficiency, an experimental investigation of
a charcoal stove performance, and development of a mathematical
model of the stove.
Stove testing methods proposed so far include the water
boiling test, constant heat output method, constant temperature
rise method, constant time method, cooking simulation tests,
approximate method, and combustion test. These methods are
discussed and some remarks are given on their reproducibility and
validity. Influence of other parameters such as size of
charcoal, initial quantity of water, pot size etc. are also
investigated and discussed. The empirical correlations of the
inlet air and the exhaust gas velocities were determined as a
function of the temperature difference between the fire
temperature and the ambient temperature. The inlet air velocity
is evaluated to be ug, in = 0.0488 (ΔT) 0.234. The exhaust gas
velocity is determined to be ug, out = (3ug, 1+ug, 2)/4 where ug, 1
= 0.0329 (ΔT) 0.419 and ug, 2 = 0.0053 (ΔT) 0.787.
The experimental study of the performance of a charcoal cook
stove was carried out using the water boiling test to investigate
the effect of internal parameters (physical dimension) of the
stove. These internal parameters consist of the gap or gas
exhaust area, the wall thickness, air inlet area, grate hole
area, and grate to pot distance. The results of this study show
that when one of the internal parameters is changed, the fire
temperature in the combustion chamber, the water temperature, the
consumption rate of charcoal, the boiling rate of water, and the
efficiency of the stove will be altered. The smaller the gap
area is the higher the fire temperature, the consumption rate of
charcoal, and the efficiency of the stove. The thick walled
stove in general shows higher performance than the thin walled
stove. The distance between the grate and the pot also has an
effect on the stove. The shorter the grate to pot distance the
higher is the efficiency of the stove. Reduction of the grate
hole area reduces the stove efficiency. The effect of the air
inlet area on efficiency is similar to that of the gap area.
A model for simulating a charcoal cook stove has been
proposed. Mass and energy balances have been developed to
simulate the cooking and combustion occurring in the stove. The
model simulation illustrates the effects of the internal
parameters and also their interaction on the stove performance in
terms of variations of temperature in the combustion zone with
time, boiling rate of water, consumption rate of charcoal,
quantity of water evaporated with time, and the efficiency of the
stove.
The stove modelling predicted that increase in wall
thickness and decrease in gap area, grate hole area, and grate to
pot distance would increase the fire temperature, the water
temperature, the charcoal consumption rate, the quantity of water
evaporated, and the efficiency of the stove. The predictions showed good agreement with the experiments. |