STUPIDSID
1 (a)
Explain the following:
i) Enthalpy of formation
ii) Combustion efficiency
iii) Enthalpy of combustion
iv) Complete combustion
v) Incomplete combustion
i) Enthalpy of formation
ii) Combustion efficiency
iii) Enthalpy of combustion
iv) Complete combustion
v) Incomplete combustion
10 M
1 (b)
The products of combustion of hydrocarbon fuel of unknown composition have the following composition on dry basic:
CO2=8.0%, CO=0.9%, O2=8.8%, N2=82.3%
Calculate:
i) Air-fuel ratio
ii) Composition of fuel on mass basis
iii) The percentage of theoretical air on mass basis.
CO2=8.0%, CO=0.9%, O2=8.8%, N2=82.3%
Calculate:
i) Air-fuel ratio
ii) Composition of fuel on mass basis
iii) The percentage of theoretical air on mass basis.
10 M
2 (a)
Derive an expression of air standard efficiency of a dual cycle, starting the assumptions made.
10 M
2 (b)
A diesel engine operation on an air standard diesel cycle has 20 mm bore and 30 mm stroke. The clearance volume is 4.2×10-4 m3. The fuel is injected for constant pressure for 5% of the stroke, calculate the air standard efficiency. If the cut-off is delayed from 5% to 8% what will be the effect on efficiency?
10 M
3 (a)
Explain the following:
i) Motoring test method
ii) Willian's line method
i) Motoring test method
ii) Willian's line method
8 M
3 (b)
A two stroke diesel engine was motored when meter reading was 1.5 kW. Test on engine was carried for one hour and data observed were as follows: Brake torque=120 N-m.
Cp(gas)=1.05 kj/kg-k Speed=600 RPM Room temperature=27°C Fuel used=2.5 kg, A:F ratio=32:1 Calorific value=40.3 Mj/kg, Cooling water=818 kg, Rise in temperature of cooling water=10°C.
Exhaust gas temperature 347°C.
Determine brake power, indicated power, brake thermal efficiency. And draw the heat balance sheet on minute basis.
Cp(gas)=1.05 kj/kg-k Speed=600 RPM Room temperature=27°C Fuel used=2.5 kg, A:F ratio=32:1 Calorific value=40.3 Mj/kg, Cooling water=818 kg, Rise in temperature of cooling water=10°C.
Exhaust gas temperature 347°C.
Determine brake power, indicated power, brake thermal efficiency. And draw the heat balance sheet on minute basis.
12 M
4 (a)
Sketch the flow diagram and corresponding T-S diagram of a reheat vapour cycle and derive an expression for the reheat cycle efficiency. What are the advantages gained by reheating the steam in between stages?
10 M
4 (b)
A steam power station uses the following cycle steam boiler outlet: 150 bar, 550°C Reheat at 0.1 bar, using the Molier diagram and assuming the ideal process find,
i) Quality of steam at turbine exhaust.
ii) Cycle efficiency.
i) Quality of steam at turbine exhaust.
ii) Cycle efficiency.
10 M
5 (a)
Derive an expression for minimum work I/P by two stage compressor with intercooler.
10 M
5 (b)
The following data refer to a single stage double acting air compressor in which air is drawn at 1 bar and compressor in which air is drawn at 1 bar and compressed to 16 bar, according to the law PV1.25=C. Input to compressor is 50 kW. The speed of the compressor is 300 RPM. The piston speed is 180 m/min. The volumetric efficiency is 80%. Calculate the diameter and stroke of the cylinder.
10 M
6 (a)
With neat sketches, explain turbojet and ramjet propulsions.
10 M
6 (b)
A gas turbine receives air at 100 kPa and 300 K and compresses it to 620 kPa. With compressor efficiency of 88%. The fuel has a heating value of 44180 kJ/kg and fuel air ratio is 0.017 kg of fuel per kg of air. The turbine efficiency is 90%. Calculate the compressor work, turbine work and thermal efficiency.
10 M
7 (a)
Explain the effect of super heating and sub-cooling with the aid of T-S and P-H diagram.
6 M
7 (b)
Explain steam jet refrigeration.
4 M
7 (c)
A vapour compression refrigeration uses Freon-12 has its temperature -10°C and 30°C. The vapour enters the compressor dry and under cooled by 5°C in the condenser. For the capacity of 15 TO R, find
i) COP
ii) Mass of Freon
iii) Power required Cp (vapour)=0.56 kJ/kg-K and Cp (liquid)=1.003 kJ/kg-K
i) COP
ii) Mass of Freon
iii) Power required Cp (vapour)=0.56 kJ/kg-K and Cp (liquid)=1.003 kJ/kg-K
10 M
8 (a)
Define the following:
i) Wet bulb temperature
ii) Dew point temperature
iii) Relative humidity
iv) Specific humidity
v) Degree of saturation
i) Wet bulb temperature
ii) Dew point temperature
iii) Relative humidity
iv) Specific humidity
v) Degree of saturation
10 M
8 (b)
A sling thermometer reads 40°C DBT and 28°C WBT. Find the following:
i) Specific humidity
ii) Relative humidity
iii) Dew point temperature
iv) Vapour density
i) Specific humidity
ii) Relative humidity
iii) Dew point temperature
iv) Vapour density
10 M
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