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10 a)
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13

14 a)

b)

D1038 Pages: 2
PART (^
Answer any four full questions, each carries 10marks.
What are the basic requirements of a good combustion chamber (4)
“Factors tending to increase detonation in 5 1 Engine tend to reduce knock in C I (6)
Engine”. Explain the validity of the above statement.
Write a short note on alternate fuels for IC engines. (5)
What is EGR? Explain how EGR reduces NOx emission. (5)
Write a short note about the pollutants from SI and CI engines. (4)
Explain the stages of combustion in C I Engine. (6)

At the design speed the following data apply to a gas turbine set employing 2 (10)
heat exchanger: Isentropic efficiency of compressor = 75%, Isentropic efficiency

of turbine = 85%, Combustion efficiency = 98%, Mechanical Transmission
efficiency = 99%, Mass rate of air = 22.7 kg/sec, Pressure ratio = 6:1, Heat
exchanger effectiveness = 75%, Maximum cycle temperature = 1000 K. The
ambient air pressure and temperature are 15°C and 1.013 bar respectively.
Assuming no pressure loss in heat exchanger and combustion chamber, calculate

the net power output, specific fuel consumption and thermal efficiency of the
cycle. Take calorific value of fuel as 43125 kJ/kg, cp = 1.005 kJ/kg K and Y =

1.4 during compression and cp = 1.147kJ/kg K and Y = 1.33 during heating and
expansion.

In an open cycle constant pressure gas turbine, air enters the compressor at 1.02 (10)
bar and 27°C. The pressure of air after the compression is 4.08 bar. The
isentropic efficiencies of the turbine and compressor are 80% and 85%
respectively. The air fuel ratio used is 80:1. Find the power output and thermal
efficiency of the cycle if the flow rate of air is 2.5 kg/sec. Take cp = 1 kj/kg K

and Y = 1.4 for air and gases. Calorific value of fuel used is 41720 kJ/kg.

Derive an expression for thermal efficiency of Brayton cycle. Represent Brayton (5)
cycle in Pv and Ts diagrams.
Discuss the means of improving the specific output and thermal efficiency of the simple (5)

open cycle gas turbine plant.
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