STUPIDSID
Answer any one question from Q1 and Q2
1 (a)
Explain with the help of a P-V diagram the loss due to variation of specific heats in an Otto cycle.
6 M
1 (b)
With a neat sketch explain the working principle of simple carburettor.
6 M
2 (a)
Draw ideal and actual valve timing diagram for four stroke S.I. engine.
6 M
2 (b)
Explain the different stages of combustion in S.I. engine.
6 M
Answer any one question from Q3 and Q4
3 (a)
Explain the various factors that influence the delay period in C.I. engine.
6 M
3 (b)
In a test of a four-cylinder four-stroke petrol engine of 75
mm bore and 100 mm stroke, the following results were obtained at full throttle at a constant speed and with a fixed setting of the fuel supply of 0.082 kg/min:
BP with all cylinders working = 15.24 kW
BP with cylinder No. 1 cut-off = 10.45 kW
BP with cylinder No. 2 cut-off = 10.38 kW
BP with cylinder No. 3 cut-off = 10.23 kW
BP with cylinder No. 4 cut-off = 10.45 kW
Estimate: (1) Total indicated power of the engine
(2) Total friction power,
(3) Indicated thermal efficiency of the engine
If the calorific value of the fuel is 44 MJ/kg.
BP with all cylinders working = 15.24 kW
BP with cylinder No. 1 cut-off = 10.45 kW
BP with cylinder No. 2 cut-off = 10.38 kW
BP with cylinder No. 3 cut-off = 10.23 kW
BP with cylinder No. 4 cut-off = 10.45 kW
Estimate: (1) Total indicated power of the engine
(2) Total friction power,
(3) Indicated thermal efficiency of the engine
If the calorific value of the fuel is 44 MJ/kg.
7 M
4 (a)
Explain with figures various types of combustion chambers used in CI engines.
6 M
4 (b)
During the trial of a single cylinder, four-stroke oil engine, the following results were obtained:
Find IP, BP and draw heat balance sheet for the test.
| Cylinder diameter | =20 cm |
| Stroke | =40 cm |
| Mean effective pressure | =6 bar |
| Torque | = 407 Nm |
| Speed | =250 r.p.m. |
| Fuel consumption | = 4 kg/h |
| Calorific value of fuel | = 43 MJ/kg |
| Cooling water flow rate | = 4.5 kg/min |
| Air used per kg of fuel | = 30 kg of air/kg of fuel |
| Rise in cooling water temperature | = 45oC |
| Temperature of exhaust gases | = 420oC |
| Room temperature | = 20oC |
| Mean specific heat of exhaust gas | = 1 kJ/ kgK |
| Specific heat of water | = 4/18 kJ/kgK |
Find IP, BP and draw heat balance sheet for the test.
7 M
Answer any one question from Q5 and Q6
5 (a)
Explain with neat sketch pressurized dry sump lubrication system.
6 M
5 (b)
Discuss the effect of A:F ratio on emission of:
i) Unburnt HC
ii) CO
iii) NOx.
i) Unburnt HC
ii) CO
iii) NOx.
6 M
6 (a)
Explain battery ignition system with neat diagram.
6 M
6 (b)
Explain exhaust gas recirculation method used to control NOx emissions.
6 M
Answer any one question from Q7 and Q8
7 (a)
What are the advantages of multi-staging in reciprocating air compressor?
6 M
7 (b)
During an experiment on reciprocating air compressor the following observations are being taken:
Determine the volume of free air handled by compressor in m3/min.
| Barometer reading | = 75.6 cm Hg |
| Manometer reading across orifice | = 13 cm Hg |
| Atmospheric temperature | = 25oC |
| Diameter of orifice | = 15 mm |
| Coefficient of discharge across the orifice | =0.65 |
| Take density of Hg | = 0.0135951 kg/cm3 |
Determine the volume of free air handled by compressor in m3/min.
7 M
8 (a)
Draw isothermal, polytrophic and isentropic compression on P-V and T-s diagram and compare the three works.
6 M
8 (b)
Determine the minimum number of stages required in an air compressor which admits air at 1 bar 27°C and delivers at 180 bar. The maximum discharge temperature at any stage is limited to 150°C. Consider the index for polytropic compression as 1.25 and perfect and optimum inter-cooling in between the stages. Neglect the effect of clearance.
7 M
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