الفهرس 
Theoretical principlesOnly 14 pages are availabe for public view
 |  | from | 121 |  |  |
| | | from | 121 | | |
Abstract
This study aims to investigate the effect of the
pulsation parameters of the combustion air on the
premixed flame behavior and local heat flux inside a
vertical water cooled combustor. The combustor is of a
cylindrical shape with 6 cm inside diameter and 90 cm
length. It is composed of thirty equal cooling jackets.
The combustion air is supplied to the combustion unit
through a mechanical pulsator which controls the
pulsation parameters. Gaseous fuel of 70% Butane and 30%
propane was continuously fed to the chamber.
The experiments were carried out for both pulsating
and steady combustion with a premixed flame at a constant
air to fuel mass ratio of 20:1. The pulsation parameters
considered in this study. are the frequency and the cycle
duty. Three values of the frequency were used 31. 101 and
136 Hz. Also. three cycle duties were applied 25%. 50%
and 75%. During each experimental run. the axial
temperature distribution along the combustor tube. the
local heat flux. the final exhaust carbon monoxide and
the flame length were measured.The output results indicated that the combustion
process with pulsation has been intensified and the flame
length was decreased with a subsequent increase in the
heat transfer to the neighbouring cooling jackets.
Oscillatory changes in heat flux were observed.
Comparison of steady and pulsed combustion operation
showed that the unit thermal efficiency increases with
pulsed combustion for only certain pulsation
otherwise it decreases or slightly be
affected. A
maximum improvement in the thermal efficiency of about
14% was achieved at a frequency of 136 Hz and a cycle
duty of 25%.
Exhaust gas analysis showed a decrease in carbon
monoxide concentration with increasing both the cycle
duty and frequency.
It can be concluded that the properly
pulsed
combustion improves the
heat transfer
rates
and
intensifies the combustion. This allows the use of a
compact heat exchanger unit for the same thermal
capacity.