Flame Laminar Velocity

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INTRODUCTION and DESCRIPTION OF EXPERIMENT The purpose of this experiment is to measure the laminar flame velocity of gaseous fuel in a lean, stoichiometric, and rich air/fuel volumetric ratio at atmospheric pressure, constant room temperature and investigate the effects of the mixture on the flame velocity. This experiment is important especially dealing with applications that have limited time for the flame to travel to the furthest part of a combustion chamber. Some of these applications are like vehicle engines, furnaces or boilers. Turbulence will enhance the flame velocity but at the wrong scale created at the wrong position and time, it will cause the flame to extinct. This is because the flame is stretched until too much heat is released. For this experiment, the main variable taken down was the time needed for the flame to reach a certain height in the Perspex tube. The apparatus consist of a burette to measure the volume of propane that should be needed for combustion as well as various valves and mixers to produce better mixing to achieve the required air/fuel ratio. After mixing, the fumes are sent to the Perspex tube to be ignited where the thermocouples which are set at known distances will measure the time taken for the flame to reach each thermocouple. Knowing the distance and time taken between each thermocouple, the velocity of the flame can then be calculated. RESULTS, DISCUSSION and CONCLUSIONS The volume of propane for the stoichiometric mixture was measured to be conducted first. This was done first so that the amount of oxygen present will burn all the combustible elements in the fuel completely. The chemical reactions for combustion are written as below: Propane + Air → Carbon dioxide + Air C3H8 + (28% O2, 79% N2) → CO2 + H2O C3H8 + a(O2 + 3.76 N2) → b CO2 + c H2O + a*3.76 N2 Balancing both sides gives a = 5, b = 3, c = 4.

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