STUPIDSID
Solve any one question from Q.1(a,b) &Q.2(a,b)
1(a)
Define a thermodynamic system and surroundings. Give classification of system with example.
6 M
1(b)
A fluid system, contained in a piston and cylinder machine, passes through a complete cycle of four processes. The sum of all heat transferred during a cycle is-340 kJ. The system completes 200 cycles per min. Complete the following table showing the method for each item, and compute the net rate of work output in kW.
| Process | Q(kJ/min) | W(kJ/min) | ΔE(kJ/min) |
| 1-2 | 0 | 4340 | - |
| 2-3 | 42000 | 0 | - |
| 3-4 | -4200 | - | -73200 |
| 4-1 | - | - | - |
6 M
2(a)
Show that CP - CV = R. Derive the relation for heat transfer and work transfer for constant pressure process.
6 M
2(b)
An iron cube at a temperature of 400°C is dropped into an insulated bath containing 10 kg water at 25°C. The water finally reaches a temperature of 50°C at steady state. Given that the specific heat of water is equal to 4186 J/kg K. Find the entropy changes for the iron cube and the water. Is the process reversible? If so why?
6 M
Solve any one question from Q.3(a,b) &Q.4(a,b)
3(a)
What is a available energy? Define dead state, useful work and unavailable work.
6 M
3(b)
An engine working on Otto cycle, air has t pressure of 1 bar and temperature of 27 deg. C. Air is compressed adiabatically with a compression ratio of 7 and then heat is added at constant volume till the temperature rises to 2000 K. Find the air standard efficiency, pressure at the end of compression and heat addition in process and the mean effective pressure of the cycle. Assume, CV = 0.718kJ/kgK, γ=1.4 and R = 287 Nm/kgK.
6 M
4(a)
Discuss the principle of separating calorimeter with a neat labeled diagram.
6 M
4(b)
A thermal power plant works on Rankine cycle has a boiler pressure of 120 bar and condenser pressure of 5kPa. Steam is superheated in the super heater to 400 deg.C. Find per kg of steam generated by boiler:
i) Net work output
ii) Rankine efficiency
iii) Specific steam consumption.
i) Net work output
ii) Rankine efficiency
iii) Specific steam consumption.
6 M
Solve any three question from Q.3 (i, ii, iii, iv) Solve any one question from Q.5(a,b) &Q.6(a,b)
5(a)(i)
Give the function and location of any 3 of the following: i) Super heater
2 M
5(a)(ii)
Air preheater
2 M
5(a)(iii)
Water level indicator
2 M
5(a)(iv)
Spring loaded safety valve.
2 M
5(b)
The following results were obtained in a boiler trial
i) Feed water per hour = 700 kg at 27 deg. C
ii) Steam produced at 8 bar and 0.97 dry.
iii) Coal used = 100 kg/hr having CV of coal = 25000 kJ/kg
iv) Ash and unburnt coal collected = 7.5 kg/hr having CV = 2000 kJ/kg
v) Mass of flue gases produced per kg of fuel burnt = 17.3 kg
vi) Flue gas temperature = 327 deg.C
vii) Room termperature 16 deg.C
viii) Specific heat of flue gases = 1.025 kJ/kgK
Dra the energy balance on minute basis.
i) Feed water per hour = 700 kg at 27 deg. C
ii) Steam produced at 8 bar and 0.97 dry.
iii) Coal used = 100 kg/hr having CV of coal = 25000 kJ/kg
iv) Ash and unburnt coal collected = 7.5 kg/hr having CV = 2000 kJ/kg
v) Mass of flue gases produced per kg of fuel burnt = 17.3 kg
vi) Flue gas temperature = 327 deg.C
vii) Room termperature 16 deg.C
viii) Specific heat of flue gases = 1.025 kJ/kgK
Dra the energy balance on minute basis.
7 M
6(a)
Derivde the formula for:
i) Equivalent evaporation and
ii) Boiler efficiency.
i) Equivalent evaporation and
ii) Boiler efficiency.
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6(b)
The following readings were recorded during a boiler trial of 6 hrs duration:
Mean steam pressure = 12 bar; Mass of steam generated = 40000kg
Mean dryness fraction = 0.85; mean feed water temperature = 30°C
Coal used = 4000 kg; Calorific value of coal = 33400 kJ/kg Calculate:
i) Factor of equivalent evaporation
ii) Heat rate of boiler in kJ/kg
iii) Equivalent evaporation form and 100°C
iv) Efficiency of boiler.
Mean steam pressure = 12 bar; Mass of steam generated = 40000kg
Mean dryness fraction = 0.85; mean feed water temperature = 30°C
Coal used = 4000 kg; Calorific value of coal = 33400 kJ/kg Calculate:
i) Factor of equivalent evaporation
ii) Heat rate of boiler in kJ/kg
iii) Equivalent evaporation form and 100°C
iv) Efficiency of boiler.
7 M
Solve any one question from Q.7(a,b) &Q.8
7(a)
What are the factors affecting Human Comfort? Discuss in detail.
6 M
7(b)
Atmospheric air at 30 deg. C DBT and 18 deg. C WBT is cooled to 20 deg. C DBT without changing its moisture content. Find:
i) Initial enthalpy and specific humidity of air
ii) Final relative humidity air and WBT
iii) Sensible heat removed per kg of air.
i) Initial enthalpy and specific humidity of air
ii) Final relative humidity air and WBT
iii) Sensible heat removed per kg of air.
7 M
8(a)
Define and discuss the significance of the following:
i) Wet Bulb temeperature
ii) Dew point temperature
iii) Humidity ratio.
i) Wet Bulb temeperature
ii) Dew point temperature
iii) Humidity ratio.
6 M
8(b)
Air enters a window air conditioner at 1 atm and 30° C and 80% RH at a rate of 10m3 min and leaves as saturated at 14°C. A part of moisture which condenses during the process is also removed at 14°C. Determine the heat flow rate and moisture removed from the air. Show the process on psychrometric diagram.
7 M
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