What are the main energy losses in engines b Discuss three m

What are the main energy losses in engines? (b) Discuss three methods of improving engine performance using schematic diagrams.

Solution

The main energy losses in the engine are

1.) Direct Frictional losses

In Engines there are many parts like piston rings , main bearings, cam shafts etc. Since there are many moving parts due to their relative motion there is large amount of loss due to friction.

2.) Heat losses

In engines it is to be noted that large amount of the available energy is lost in the non usable form which is called as heat losses. Nearly 1/3 rd parts of the total energy of the engine is lost in the form of heat from the exhaust gasses.

3.) Pumping losses

In 4 stroke engines, a considerable amount of of energy is spent during intake and exhaust process. The pumping loss is the net power spent by the engine on the working medium during intake and exhaust strokes. In case of two stroke engines this is negligible since the incoming fresh mixture is used to scavenge the exhaust gasses.

Methods to improve engine performance

Using It is possible to take advantage of the kinetic energy in the exhaust gasses to drive a turbine which is connected to the crankshaft to increase the engine output. Engines with this type of power booster is called turbo compound engines

Performance can be increased by increasig the mass of the charge entering which can increase the power, this can be done by using the supercharger.

The use of high compression ratio will increase the efficiency of conversion of the energy in the fuel into useful mechanical energy. This requires the development of economically feisible higher antiknock quality fuels.However there will be limited advantage in increasing the compression ratio