1(a) Explain with suitable
sketches, the working of a four-stroke spark-ignition engine. (6 Marks)
(b) Define mean effective
pressure. What is its relevance in reciprocating engines? (4 Marks)
(c) What are the characteristics
of constant volume fuel-air cycle? (6 Marks)
(d) A diesel engine develops 5
kW. Its indicated thermal efficiency is 30% and mechanical efficiency 57%.
Estimate the fuel consumption of engine in (a) kg/hr, (b) litres/hr, (c)
indicated specific fuel consumption, and (d) brake specific fuel consumption.
(4 Marks)
2(a) Explain the term ‘burning
time loss’ with the help of p-V diagram. (4 Marks)
(b) Discuss the general
principles of SI engine combustion chamber design. (6 Marks)
(c) Discuss the variables
affecting the delay period. (4 Marks)
(d) In a bomb calorimeter test on
petrol, the HCV was determined and found to be 46900 kJ/kg. If the fuel
contains 14.4% H2 by mass, calculate the LCV. Given ufg
at 250C for H2O = 2304.4 kJ/kg. (4 Marks)
3(a) What are the factors which
affect the process of carburetion? (4 Marks)
(b) Distinguish between
continuous injection system and timed injection system. (6 Marks)
(c) Compare the burning rates in
petrol and diesel engines. (4 Marks)
(d) A 6-cylinder 4-stroke S.I.
engine having a piston displacement of 700 cm3 per cylinder
developed 78 kW at 3200 r.p.m and consumed 27 kg of petrol per hour. The
calorific value of petrol is 44 MJ/kg. Estimate the volumetric efficiency of
the engine if the air-fuel ratio is 12 and the intake air is 0.9 bar, 320C.
Also determine the brake thermal
efficiency and the brake torque. (6 Marks)
4(a) Describe a battery ignition
system with the help of a sketch. (6 Marks)
(b) What is a Texaco ignition
system? Mention its advantages. (4 Marks)
(c) What is the significance of
flash and fire points of a lubricant. (6 Marks)
(d) A petrol engine with
indicated thermal efficiency of 30% has an fp of 18 at 1500 rev/min and 45 kW
at 2500 rev/min. If the bhp required at each speed is 75 kw and the calorific
value of the fuel is 44000 kJ/kg, calculate the bsfc at both speeds, assuming
indicated thermal efficiency to be same at both speeds. (4 Marks)
5 (a) Why is over-cooling in an
engine harmful? (4 Marks)
(b) Describe with a sketch the
construction and working of a thermostat. (6 Marks)
(c) Explain the scavenging
process in two-stroke engine. What is meant by blowdown? (6 Marks)
(d) Explain pulse turbocharging.
(4 Marks)
6 (a) Describe with a sketch, the
principle of eddy current dynamometer. (6 Marks)
(b) What are reduction mechanisms
for taking indicator diagrams? Describe with sketches the important types of
reduction mechanisms. (6 Marks)
(c) What is a flame ionization
detector? (4 Marks)
(d) A test on a two-stroke single
cylinder oil engine gave the following results: Cylinder bore=200 mm, engine
stroke=250 mm, indicated mean effective pressure=4.5×102 N/m2,
fuel consumption=7kg/h, calorific value of fuel=43500 kJ/kg, engine speed=180
rev/min. Calculate the indicated power and indicated thermal efficiency. (4
Marks)
7 (a) Describe with a sketch, a
dual-fuel engine and comment on its performance. (6 Marks)
(b) Discuss the performance of
multi-fuel engine on various fuels. (4 Maks)
(c) What is meant by crankcase
blowby? How it can be controlled? (6 Marks)
(d) Compare diesel engine and
gasoline engine emissions. (4 Marks)
8 (a) What are the important
methods of charge stratification? (4 Marks)
(b) Discuss with the help of a
sketch, the governance of Stirling engine. (6 Marks)
(c) Discuss some applications of
Wankel RC engine. (4 Marks)
(d) A gas turbine cycle takes in
air at 250C and atmospheric pressure. The compression pressure ratio
is 4. The compressor efficiency is 75%. The inlet temperature to turbine is
limited to 7500C. What turbine efficiency would give overall cycle
efficiency 0%. (4 Marks)
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