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Theory

Explain how the heat balance sheet for an IC engine is prepared............

i) Heat Balance Sheet :-The complete record of heat supplied and heat rejected during a certain time(Say one minute)by an IC engine is entered in a tabulated form called as heat balance sheet. i) Heat supplied by the fuel= Mf x C  where Mf= mass of fuel supplied in Kg/min C = Lower calorific value of fuel kj/kg  

Explain with sketch working of screw compressor.

A rotary-screw compressor is a type of gas compressor that uses a rotary-type positivedisplacement mechanism. They are commonly used to replace piston compressors where large volumes of high-pressure air are needed, either for large industrial applications or to operate highpower air tools. Rotary-screw compressors use two meshing helical screws, known as rotors, to compress the gas. In a dry-running rotary-screw compressor, timing gears ensure that the male and female rotors maintain precise alignment.

a) Define : i) Stroke ii) Bore

a) i) Stroke – Distance travelled by piston from one dead Centre to other dead Centre (Say TDC to BDC). ii) Bore:- The nominal Inner diameter of engine cylinder is called cylinder bore. iii) Piston Speed- Distance traveled by piston in one minute.(= 2LN m/min.) iv) The Mean Effective Pressure (MEP) :-It is a fictitious pressure that, if it operated on the piston during the entire power stroke, would produce the same amount of net work as that produced during the actual cycle.

Explain the effect of superheating and subcooling on the performance of vapour compression cycle......

Effect of superheating: As shown in the figure a & b the effect of superheating is to increase the refrigerating effect, but this increase in the refrigerating effect is at the cost of increase in amount of work spent to attain upper pressure limit. Since the increase in work is more as compared to increase in refrigerating effect, therefore overall effect of superheating is to give a low value of C.O.P.

Explain with neat sketch two way catalytic converter.

C) Catalytic Convertor: -. A catalytic converter is cylindrical unit about the size of small silencer and is installed into exhaust system of vehicle. It converts the harmful gases from the engine into harmless gases and escapes them into atmosphere. Inside converter there is honeycomb structure of ceramic or metal which is coated with alumina base material and therefore a second coating of precious metal platinum, palladium or rhodium or combination of same.

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