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air at the beginning of the cycle is | bar and 30°C. Heat is added during constant pressure

process upto 4% of the stroke. Take cylinder diameter as 250 mm and stroke length as 300 mm.

Determine: (i) The air standard efficiency of the cycle. (ii) The power developed. Take cp =

1.005 kJ/kg K and cy = 0.718 kJ/kg K for air. (10 marks)

6. a) What is the purpose of supercharging of I. C. engines? Mention two applications were

supercharging of engines is necessary. (4 marks)

b) Show that efficiency of stirling cycle is same as that of carnot cycle if they are operating at same
temperature limits. (6 marks)

7. A 4-cylinder four stroke petrol engine is working based on the following data: Air-fuel ratio by
weight = 15:1, calorific value of the fuel = 45000 kJ/kg, mechanical efficiency = 80%,
airstandard efficiency = 54%, relative efficiency = 70%, volumetric efficiency = 75%,
stroke/bore ratio = 1.25, suction conditions = 1 bar and 30°C, r.p.m. = 2500, brake power =
70kW. Calculate: (1) Compression ratio. (ii) Indicated thermal efficiency. (iii) Brake specific
fuel consumption. (iv) Bore and stroke.

(10 marks)

8. a) Explain how frictional power can be obtained using Morse test? (4 marks)

b) The percentage composition of a sample of liquid fuel by weight is C = 85% and H2 = 15%.
Calculate: (i) the weight of air needed for combustion of | kg of fuel. (ii) The volumetric
composition of the products of combustion, if 16% of excess air is supplied. (6 marks) Part C

Answer any four questions

9. a) What are the causes of hydrocarbon emissions? How HC emissions contributes to air
pollution? (4 marks) 0) Explain octane and cetane rating of fuels? (6 marks)

10. With the help of a practical pressure-crank angle diagram, explain the different stages of
combustion in 5.1. engines. (10 marks)

11.a) What are the advantages and disadvantages of direct injection combustion chambers for 0.1.

engines? (4 marks) 9) Write short notes on alternative fuels and biofuels. (6 marks)

12. a) How are gas turbines classified? Compare gas turbines and I. C. engines, based on speed and

mechanical efficiency. (4 marks)

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