Applied Thermodynamics - Dec 2016

Mechanical Engg (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

Solve any one question fromQ.1(a,b) and Q.2(a,b)

1(a) Draw and expalin actual valve timing diagram for four stroke C.I. Engine.(6 marks) 1(b) Draw and explain with neat sketch simple carburetor.(6 marks) 2(a) Explain pumping and friction losses and their effects on the power output of the engine.(6 marks) 2(b) Explain stage of combustion in SI engine with the help of P-Theta diagram.(6 marks)

Solve any one question fromQ3(a,b) and Q.4(a,b)

3(a) Draw and explain working of automatic injector.(6 marks) 3(b) The following data were recorded in a test one hour duration on a single cylinder oil engine working on a 4-stroke cycle:
Bore = 300 mm
Stroke = 450 mm
Average speed = 200 rpm
Brake friction load = 1860 N
Fuel used = 8.8 kg
Calorific value of fuel = 41800 kJ/kg
Mean effective pressure (m.e.p.) = 5.8 bar
Quantity of cooling water = 650 kg
Temperature rise = 22°C
Diameter of the brake wheel = 1.22m Determine:
i) Mechanical efficiency
ii) Brake thermal efficiency
iii) Draw heat balance sheet on kW basis.(6 marks) 4(a) Compare abnormal combustion in SI and CI engine.(6 marks) 4(b) The following details were in a test on a four-cylinder, four stroke engine, diameter =100 mm, stroke = 120 mm, speed of the engine = 1600 rpm, fuel consumption = 0.2 kg/ min, calorific value of fuel is 44000kJ/kg, difference in tension on either side of the brake pulley = 40 kg, brake circumference is 300 cm, If the mechanical efficiency is 80% calculate:
i) Brake thermal efficiency
ii) Indicated thermal efficiency
iii) Indicated mean effective pressure
iv) Brake specific fuel consumption.(6 marks)

Solve any one question fromQ5(a,b) and Q.6(a,b)

5(a) Enlist and discuss briefly various types of exhaust emissions from an automobile.(6 marks) 5(b) Enlist tyes of lubrication system and explain with neat sketch dry sump lubrication system(7 marks) 6(a) Explain catalytic converter used in S.I. engines.(6 marks) 6(b) What is thermostat? Draw a neat sketch of Thermostat cooling system and explain its working.(7 marks)

Solve any one question fromQ.7(a,b) and Q.8(a,b)

7(a) Explain Vane type compressor with a neat sketch.(6 marks) 7(b) A single cylinder, single acting air compressor delivers 10 kg of air per minute. The air is compressed from 1 bar and 27 deg. C to 6 bars. The compression process follows the law PV^1.25=C. Find:
i) Work done
ii) Brake power required if mechanical efficiency is 80%.(7 marks) 8(a) Write down the advantages of Multi staging in reciprocating air compressor.(6 marks) 8(b) A 2-stage single acting air compressor takes in air at 1 bar and 300 K. Air is discharged at 10 bar. The intermediate pressure is ideal and intercooling is perfect. The law of compression is PV^1.3= C Rate of discharge is 0.1 kg/sec, find:
i) Power required to drive the compressor
ii) Saving in work compared to single-stage
iii) Isothermal efficiency for single and multistage. Take CP = 1kJ/kgK, R = 0.287kgK.(7 marks)