04-04-2012, 03:17 PM
Experimental Investigation on Effect of Various Parameters
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INTRODUCTION
Carburetors are used in petrol or similar liquid fuel engines by means of which the fuel mixed with air is supplied into the induction manifold of the engine.
The carburetor controls the required quantity of fuel and breaks it up into minute globules for being mixed with the correct quantity of air. The main purpose of carburetor is to supply the required quantity of petrol and air mixture, of the correct strength as per requirement of load conditions of the engine.
DISCUSSIONS AND CONCLUSIONS
• The density of the air at atmospheric conditions is assumed 1.2kg/m3.
• In petrol engines, at constant rpm at higher load, ṁ increases as expected. However the power value increases in quite a larger proportion. Thus bsfc (the ratio of mass flow rate to power) decreases. As throttle increases, pumping losses decrease due to the decreasing air resistance.
• At constant throttle, at moderate speeds, ṁ value increases and also simultaneously the power value decreases. Thus bsfc increases and hence the consumption of fuel is minimum at higher loads
• Thus we prefer not much higher loads and not much higher rpm.
• At constant load, as rpm increases, power increases. This is in acceptance with the anticipated trend.
• Also at constant load, the mass flow rate increases too. However the bsfc value (the ratio of mass flow rate to power) initially increases, attains maxima and then starts decreasing. Thus at constant load, consumption of the fuel is minimum at moderate rpm and therefore the engine speed must neither be too high nor too low.