Exam Details
| Subject | Thermal Engineering | |
| Paper | ||
| Exam / Course | Diploma in Mechanical Engineering (DMEVI)& B.Tech. MECHANICAL ENGINEERING 1-4 (BTMEVI) | |
| Department | School of Engineering & Technology (SOET) | |
| Organization | indira gandhi national open university | |
| Position | ||
| Exam Date | June, 2016 | |
| City, State | new delhi, |
Question Paper
What do you mean by multistage compression State its advantages and disadvantages.
A petrol engine has the brake thermal efficiency 24% and mechanical efficiency 80%. What is its indicated thermal efficiency?
A two-stage, single acting reciprocating compressor takes in air at the rate of 0·2 m^3/sec. Intake pressure and temperature are 0·1 MN/m^2 and 16°C, respectively. The air is compressed to a final pressure of 0·7 MN/m^2 . The intermediate pressure is ideal and intercooling is perfect. The compression index is 1·25 and the compressor runs at 10 rev/sec. Neglect clearance.
Determine:
The intermediate pressure
Total volume of each cylinder
An engine uses a fuel of calorific value of 42000 kJ/kg and has a specific gravity of 0·75. The engine develops a brake power of 29·44 kW. The brake thermal efficiency of the engine is 24%. Determine the volume of
the fuel consumed per second.
Explain the difference between
pre-ignition,
auto-ignition, and
detonation.
A four-stroke S.I. engine delivers a brake power of 441·6 kW with a mechanical efficiency of 85%. Determine the indicated power and frictional power of the engine.
Explain the phenomena of knocking in S.I. engines. What are the different factors which influence the knocking Describe them in brief.
What do you mean by performance of an I.C. engine? Elaborate. Discuss with a suitable sketch the brake rope dynamometer.
State the relative advantages and disadvantages of battery and systems. Describe the working of any one.
A two-stroke C.I. engine delivers a brake power of 368 kW while 73.6 kW is used to overcome the frictional losses. The engine consumes 180 kg/hr of fuel at an air-fuel ratio of 20 :1. The heating value of fuel is 42000 kJ/kg.
Determine the following:
Indicated power
Mechanical efficiency
Air consumption
Indicated thermal efficiency
Brake thermal efficiency
An engine is required to develop 100 kW, the mechanical efficiency of the engine is 86% and the engine uses 55 kg/hr of fuel. Due to improvement in the design and operating conditions, there is a reduction in engine friction to the extent of 4·8 kW. If the indicated thermal efficiency remains the same, determine the saving in fuel in kg/hr.
A 6-cylinder petrol engine has a volume compression ratio of 5 1. The clearance volume of each cylinder is 0·000115 m^3. The engine consumes 10·5 kg of fuel per hour whose calorific value is 41800 kJ/kg. The engine runs at 2500 rpm, and the efficiency ratio is 0·65. Calculate the average indicated mean effective pressure developed.
A single-cylinder four-stroke diesel engine running at 1800 rpm has a bore of 85 mm and a stroke of 110 mm. It takes 0·56 kg of air per minute and develops a brake power output of 6 kW while the air-fuel ratio is
20 1. The calorific value of the fuel used is 42550 kJ/kg, and the ambient air density is 1·18 kg/m^3.
Calculate
The volumetric efficiency
Brake specific fuel consumption
A four-cylinder four-stroke S.I. engine has a compression ratio of 8 and bore of 100 rom, with stroke equal to the bore. The volumetric efficiency of each cylinder is equal to 75%. The engine operates at a speed of 4800 rpm with an air-fuel ratio of 15.
Given that the calorific value of fuel 42 MJ/kg, ambient air density 1·12 kg/m^3 mean effective pressure in the cylinder 10 bar and mechanical efficiency of the engine 80%. Determine the indicated thermal efficiency
and the brake power.
What do you understand by 'ignition timing' Enumerate the various factors which affect ignition timings.
What are the two basic types of nozzles used in a diesel injection system Briefly explain them.
A petrol engine has the brake thermal efficiency 24% and mechanical efficiency 80%. What is its indicated thermal efficiency?
A two-stage, single acting reciprocating compressor takes in air at the rate of 0·2 m^3/sec. Intake pressure and temperature are 0·1 MN/m^2 and 16°C, respectively. The air is compressed to a final pressure of 0·7 MN/m^2 . The intermediate pressure is ideal and intercooling is perfect. The compression index is 1·25 and the compressor runs at 10 rev/sec. Neglect clearance.
Determine:
The intermediate pressure
Total volume of each cylinder
An engine uses a fuel of calorific value of 42000 kJ/kg and has a specific gravity of 0·75. The engine develops a brake power of 29·44 kW. The brake thermal efficiency of the engine is 24%. Determine the volume of
the fuel consumed per second.
Explain the difference between
pre-ignition,
auto-ignition, and
detonation.
A four-stroke S.I. engine delivers a brake power of 441·6 kW with a mechanical efficiency of 85%. Determine the indicated power and frictional power of the engine.
Explain the phenomena of knocking in S.I. engines. What are the different factors which influence the knocking Describe them in brief.
What do you mean by performance of an I.C. engine? Elaborate. Discuss with a suitable sketch the brake rope dynamometer.
State the relative advantages and disadvantages of battery and systems. Describe the working of any one.
A two-stroke C.I. engine delivers a brake power of 368 kW while 73.6 kW is used to overcome the frictional losses. The engine consumes 180 kg/hr of fuel at an air-fuel ratio of 20 :1. The heating value of fuel is 42000 kJ/kg.
Determine the following:
Indicated power
Mechanical efficiency
Air consumption
Indicated thermal efficiency
Brake thermal efficiency
An engine is required to develop 100 kW, the mechanical efficiency of the engine is 86% and the engine uses 55 kg/hr of fuel. Due to improvement in the design and operating conditions, there is a reduction in engine friction to the extent of 4·8 kW. If the indicated thermal efficiency remains the same, determine the saving in fuel in kg/hr.
A 6-cylinder petrol engine has a volume compression ratio of 5 1. The clearance volume of each cylinder is 0·000115 m^3. The engine consumes 10·5 kg of fuel per hour whose calorific value is 41800 kJ/kg. The engine runs at 2500 rpm, and the efficiency ratio is 0·65. Calculate the average indicated mean effective pressure developed.
A single-cylinder four-stroke diesel engine running at 1800 rpm has a bore of 85 mm and a stroke of 110 mm. It takes 0·56 kg of air per minute and develops a brake power output of 6 kW while the air-fuel ratio is
20 1. The calorific value of the fuel used is 42550 kJ/kg, and the ambient air density is 1·18 kg/m^3.
Calculate
The volumetric efficiency
Brake specific fuel consumption
A four-cylinder four-stroke S.I. engine has a compression ratio of 8 and bore of 100 rom, with stroke equal to the bore. The volumetric efficiency of each cylinder is equal to 75%. The engine operates at a speed of 4800 rpm with an air-fuel ratio of 15.
Given that the calorific value of fuel 42 MJ/kg, ambient air density 1·12 kg/m^3 mean effective pressure in the cylinder 10 bar and mechanical efficiency of the engine 80%. Determine the indicated thermal efficiency
and the brake power.
What do you understand by 'ignition timing' Enumerate the various factors which affect ignition timings.
What are the two basic types of nozzles used in a diesel injection system Briefly explain them.
Other Question Papers
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