Efficiency Increasing System

2262 Words Feb 21st, 2013 10 Pages


The concept of increasing the fuel efficiency of a petrol engine in this project, is to pre-heat the intake air which is flowing through the carburetor. The humidity in the atmospheric air affects the petrol vapourisation in the carburettor. Therefore, by pre-heating the inlet air to the carburettor for a considerable amount, the vapourisation can be ease and in turn complete combustion is achieved. Moreover by reducing the water vapour to the engine, the steam formation in the engine can be reduced pitting of the engine cylinder, piston and exhaust pipe.

The pre-heating of inlet air to the engine can be achieved by fixing a heat exchanger inside the exhaust
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The air fuel ratio must change depending when maximum Economy or maximum power is required. Also required air-fuel ratio must be provided for transient conditions like starting, warm up, and acceleration. Further in all conditions the consideration of minimum exhaust emission should be kept in mind.

For automotive Engines there are three main areas of steady state operation requiring different air fuel ratios.

1. Idling and Low Load

The no load running made of the Engine is called idling. During idling the air supply is restricted by the nearly closed throttle and the suction pressure is very low. This condition of low pressure gives rise to back flow of exhaust gases and air leakage from the various parts of the Engine intake system. At idling and during part load operation back flow during the valve overlap period occurs since the exhaust pressure is higher than the intake pressure. This increases the amount of residual gases. The problem of dilution by residual gases becomes more pronounced at low loads and idling because the exhaust temperature reduces with decreasing load, i.e., the density and hence mass of the residual gases increase.

The amount of fresh charge brought in during idling is much less than that during full throttle operation. The presence of exhaust gas tends to obstruct the contact of fuel and air particles a requirement necessary for satisfactory combustion. The richening of mixtures increases