GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER-V (NEW) EXAMINATION - WINTER 2020
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Subject Code:3150210 Date:03/02/2021
Subject Name:Automobile Engines
Time:10:30 AM TO 12:30 PM Total Marks: 56
Instructions:
- Attempt any FOUR questions out of EIGHT questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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Q.1 (a) Define (1) Swept volume with SI Unit 03
(2) Clearance Volume with SI Unit
(3) Compression ratio with expression
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(b) Describe factors influencing firing order of SI engine. 04
(c) Explain valve timing diagram of SI and CI 4-stroke engine with neat. 07
Q.2 (a) Give assumptions are made for analysis of single jet carburetor. 03
(b) Explain in brief working principle of venture in context to carburetor. 04
(c) Explain A/F ratio in various operation ranges of carburetor for SI 07
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engine during transient operation.Q.3 (a) Give objectives of injection system of CI engine. 03
(b) Explain terms atomization and turbulence in context to CI engine 04
injection system.
(c) Give type of solid injection system. Explain common rail injection 07
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system with suitable sketch.Q.4 (a) Describe in brief knocking phenomenon. 03
(b) Explain the role of Ethylene glycol in the coolant. 04
(c) Describe with neat sketch water cooling system with thermostat valve. 07
Q.5 (a) Give the function of lubrication system. 03
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(b) Explain parameters viscosity, pour point, oxidation stability, oiliness 04
in context to lubricating oil.
(c) A single cylinder 4 stroke cycle oil engine works on diesel. The 07
following reading were taken when the engine was running at full load
Mean effective pressure = 7.5 bar
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Speed of the engine = 400 rpmBrake Power = 8 kj/s
Fuel consumption= 2.8 kg/hr
Calorific value of fuel = 42000 kj/kg
Diameter of the cylinder = 16 cm
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Stroke length =20 cmEstimate: Friction power, Mechanical efficiency, Brake thermal
efficiency, Brake mean effective pressure.
Q.6 (a) What is scavenging? 03
(b) Describe concept of supercharging. 04
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Q.7 (a) What is valve overlapping? Give significance of it. 03
(b) Compare brake power, friction power and indicated power of an IC 04
engine.
(c) Explain combustion phenomenon of SI using pressure-theta (Crank 07
angle) diagram with stages.
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Q.8 (a) Define (1) Volumetric efficiency with expression 03
(2) Friction power with SI Unit
(b) Explain turbocharger with neat sketch. 04
(c) Explain heat balance in details. 07
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