Mechanical Engg Simple Notes ,Solved problems and Videos

Indicated power – IP = PmepLAN Where Pmep – 6 bar – mean effective pressure - 6 x 100 kN/m2 L – Length of stroke in m

Assuming CV of gas used as 21,500 kj/m3 at NTP instead of 21,500 kJ/kg at NTH Heat supplied by fuel in kJ/sec. = 0.00300 x 21,500

Specific humidity:- It is defined as the ratio of mass of vapour to the mass of dry air in a given sample of moist air.  Specific humidity ma mv  Absolute humidity:- It is defined as the actual mass of water vapour in unit volume of air. Its unit is gm/m3  Relative humidity:- It is defined as the ratio of partial pressure of water vapour in a given volume of mixture to the partial pressure of water vapour when same volume of mixture is saturated at the same temperature.

DPT – Dew point temperature tDP - It is the temperature at which air water vapour mixture starts to condense. 01 D.P.T. of mixture is defined as the temperature at which water vapours starts to condense. WBT - Wet bulb temperature - tWB 01 - It is the temperature recorded by thermometer when its bulb is covered with wet cloth known as wick and is exposed to air. DBT – Dry bulb temperature - tDB 01 - It is the temperature of air recorded by a ordinary thermometer and it is not affected by the moisture present in air. Moist Air – It is the mixture of dry air and water vapour

The compression process in reciprocating compressor may approach to low speed of compression and cylinder cooling. Therefore isothermal efficiency is used in reciprocating compressor. But in rotary compressor there is high friction and eddies formation due to high velocity air through the compressor. This causes heating of air during compression process. Therefore temperature of air leaving the impeller is higher than the isentropic compression. The compressor may be as high as 1.7 (n>t). Therefore isentropic efficiency is used in rotary compressor.

Fig. shows construction of simple catalytic converter exhaust fan as it enters the converter all three pollutions namely HC CO and NOX oxidizes and reduce is to the component which are acceptable to the environment, This occurs due to chemical reaction and at 600 to 7000 c temperature.

1) Friction Power:- The difference between indicated power and brake power.  It is the power lost in friction FP =IP -BP

Effect of Supercharging on SI and CI engine

Effect of Compression ratio in a single stage reciprocating compressor on PV diagram

Physical Significance:-