STUPIDSID
Answer any one question from Q1 and Q2
1 (a)
State and prove the equivalency of Kelvin Planck and Clausius statement.
6 M
1 (b)
Prove: S2-S1=Cvlm(T2/T1)+R ln(V2/V1).
6 M
1 (c)
State the limitations of First law of thermodynamics. How does the second law of thermodynamic overcome these limitations.
4 M
2 (a)
State and prove the Clausius Inequality.
8 M
2 (b)
5 kg of air is expanded at a constant pressure to four times its initial volume. The initial temperature of air is 400°C. It is then brought to its original temp, by a constant volume change. Calculate the entropy change.
8 M
Answer any one question from Q3 and Q4
3 (a)
Explain the following:
i) Available and unavailable energy
ii) Principal reasons for irreversibility
iii) Helmholtz and Gibbs function.
i) Available and unavailable energy
ii) Principal reasons for irreversibility
iii) Helmholtz and Gibbs function.
9 M
3 (b)
Calculate the decrease in available energy when 20kg of water at 90°C mixes with 30 kg of water at 30°C, the pressure being taken as constant and the temperature of surrounding is 10°C (Cp for water 4.18 kJ/kgK).
7 M
4 (a)
Derive an expression for work transfer in reversible adiabatic process.
7 M
4 (b)
1 kg of air at pressure of 8 bars and temp. of 100°C undergoes a reversible polytropic process following the law pv1.2=C. If the final pressure is 1.8 bars, determine:
i) Final specific volume, temperature and increase of entropy.
ii) The work done and heat transfer.
Assume R=0.287 kJ/kgK.
i) Final specific volume, temperature and increase of entropy.
ii) The work done and heat transfer.
Assume R=0.287 kJ/kgK.
9 M
Answer any one question from Q5 and Q6
5 (a)
With the help of T-S diagram, explain the effect of the following parameters on the performance of Rankine cycle:
i) Effect of superheat
ii) Condenser pressure.
i) Effect of superheat
ii) Condenser pressure.
8 M
5 (b)
A steam turbine receives superheated steam at a pressure of 17 bar and having degree of superheat of 110°C. The exhaust pressure is 0.07 bar and expansion of steam takes place isentropically.
Calculate:
i) The heat supplied and heat rejected
ii) Network output
iii) Thermal efficiency
iv) Specific steam consumption.
Neglect pump work.
Calculate:
i) The heat supplied and heat rejected
ii) Network output
iii) Thermal efficiency
iv) Specific steam consumption.
Neglect pump work.
10 M
6 (a)
Explain the following terms:
i) Critical point
ii) Dryness fraction.
i) Critical point
ii) Dryness fraction.
4 M
6 (b)
With the help of a neat sketch explain the working of separating and throttling calorimeter.
6 M
6 (c)
Steam at 7 bar and 250°C has a volume of 0.5046 m3. In a frictionless constant volume process the pressure changes to 3.5 bars. Find the final temperature and heat transfer. Also determine the change in entropy.
8 M
Answer any one question from Q7 and Q8
7 (a)
Write a short note on calorific value of a fuel.
5 M
7 (b)
A coal sample gave the following analysis by weight, Carbon 85%, Hydrogen 6%, Oxygen 6%, the remainder being incombustible. Determine minimum weight of air required per kg of coal for chemically correct composition.
6 M
7 (c)
Explain NDIR method of gas analysis in brief.
5 M
8 (a)
Write a note on theoretical and excess air.
5 M
8 (b)
The following particulars refer to an experimental determination of the calorific value of a sample of coal containing 88% C and 4.2% H2. Weight of coal =0.848 gm, weight of fuse wire 0.027 gm, of calorific value 6700 J/gm, weight of water in the calorimeter=1950 gm, water equivalent of calorimeter=380 gm, observed temperature rise=3.06°C, cooling correction = +0.017°C. Find the higher and lower calorific values of the coal.
6 M
8 (c)
With the help of neat sketch discuss the method of determining calorific value of gaseous fuel.
5 M
Answer any one question from Q9 and Q10
9 (a)
What are the advantages and disadvantages of multistage reciprocating air compressor?
6 M
9 (b)
A single stage reciprocating compressor takes 1 m3 of air per minute at 1.013 bar and 157deg;C and delivers it at 7 bar. Assuming that the law of compression is pV1.35=constant, and the clearance is negligible, calculate the indicate power.
10 M
10 (a)
Discuss the factors those influence the volumetric efficiency of a reciprocating air compressor.
6 M
10 (b)
A two stage single acting reciprocating compressor takes in air at the rate of 0.2 m3/s. The intake pressure and temperature of air are at 0.1 Mpa and 16°C. The air compressed to a final pressure of 0.7 Mpa. The intermediate pressure is ideal and inter-cooling is perfect. The compression index in both the stages is 1.25 and the compressor runs at 600 RPM. Neglecting clearance, determine:
i) The intermediate pressure
ii) The total volume of each cylinder
iii) The power required to drive the compressor
iv) The rate of heat rejection in the intercooler.
Take:
Cp=1.005 kJ/kgK and R=0.287 kJ/kgK.
i) The intermediate pressure
ii) The total volume of each cylinder
iii) The power required to drive the compressor
iv) The rate of heat rejection in the intercooler.
Take:
Cp=1.005 kJ/kgK and R=0.287 kJ/kgK.
10 M
Answer any one question from Q11 and Q12
11 (a)
Differentiate between mountings and accessories of the boiler. Give at least two examples of each.
8 M
11 (b)
In a boiler test 1250 kg of coal are consumed in 24 hours. The mass of water evaporated is 13000 kg and mean effective pressure is 7 bar. The feed water temperature was 40°C, heating value of coal is 30000 kJ/kg. The enthalpy of 1 kg of steam at 7 bar is 2570 kJ. Determine:
i) Equivalent evaporation per kg of coal
ii) Efficiency of the boiler.
i) Equivalent evaporation per kg of coal
ii) Efficiency of the boiler.
10 M
12 (a)
Explain the following terms:
i) Boiler efficiency
ii) Equivalent evaporation.
i) Boiler efficiency
ii) Equivalent evaporation.
8 M
12 (b)
A boiler produces 200 kg of dry saturated steam per hour at 10 bar and feed water is heated by an economizer to a temperature of 100°C. 225 kg of coal of a calorific value 30100 kJ/kg are fired per hour. If 10% of coal remains unburnt, find the thermal efficiency of the boiler and the boiler grate combined.
10 M
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