Diploma Thermal Engineering 2 Important Questions
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- The following questions are extracted from Previous year board exam question papers.
Diploma Thermal Engineering 2 Important Questions
Unit 1 Formation and Properties of Steam & Thermodynamic
Processes of Vapour
1.One kg of steam at a pressure of 1 bar absolute and 0.85 dry is compressed according to the law p.v 1.25 = constant. The final pressure is 2 bar. Find the final condition of steam and heat which passes through the cylinder walls.
2.Explain the method of finding dryness fraction of steam using separating and throttling calorimeter with a neat sketch.
3.A rigid vessel is divided into two parts A and B by a partition. Part A contains 1 kg of dry saturated steam at 3.5 bar. Part B contains 2 kg of wet steam at 7 bar with dryness 0.8. The partition is removed and the pressure in the vessel after sometime is measured as 5 bar. Calculate (a) Volume of the vessel (b) quality of steam at 5 bar and (c) heat interchange between steam and surround walls of the vessel.
4.In a combined and throttling calorimeter the following readings were taken
Total Quantity of steam passed = 24 kg
Water drained in the separator = 1.23 kg
Steam pressure before throttling = 9 bar
Steam pressure after throttling = 1.2 bar
Temperature of the steam = 120 0 C
Specific heat of super heated steam = 2.0 KJ/kgK
Determine 1. Dryness Fraction by separating calorimeter 2. Dryness fraction by throttling calorimeter and 3 . Dryness fraction of the steam in the main
5.One kg of water at 95oC is heated under a constant pressure of 17.5 bar absolute until it is converted into steam with dryness fraction 0.98. Calculate the change in volume, work done, heat supplied, change in internal energy and the change in entropy.
6.Steam at 10 bar and 0.925 dry is contained in a vessel of volume 1 m3. The delivery valve is opened and the steam is blown off. The period of blowing is so regulated that the total heat per kg of steam in vessel remains constant during the blowing off period and pressure drops to 5 bar. Estimate the mass of steam blown off
7.A sample of 1 kg of steam at a pressure of 15 bar exists in the following conditions (i) Wet steam with dryness fraction 0.8 and (ii) Super heated with temperature 2150 C. Take the specific heat of super heated steam os 2.3 kJ/kgK AND NEGLECT COLUME OF WATER. Determine the following properties in each case (1) Volume (2) Enthalpy (3) Entropy (4) External work of evaporation and (5) Internal Energy
8.One kg of dry and saturated steam at 250oC isothermally expands to 6 bar. Determine (a) change in entropy, (b) change in enthalpy, (c) change in internal energy, (d) heat transferred. Also determine the work done for the non-flow process.
9. Write short notes on mollier diagram. (or) What are the uses of mollier chart and indicated the
various line included in mollier chart with their region.
10. Explain the various process in with graph connecting the temperature and enthalpy, temperature and entropy, temperature and volume process.
11. How do you determine the dryness fraction of a steam by using barrel calorimeter?
12. How do you determine the dryness fraction of a steam by using combined separating and throttling calorimeters?
1.During a test of an oil fired water tube boiler, the following data were obtained :
Steam pressure = 16 bar abs; water evaporated per minute = 282.85 kg; feed water temperature = 75oC; quality of steam = 99% dry; fuel oil burnt per minute = 22.45 kg; heating value of fuel oil = 44996 kJ/kg. Calculate (a) the actual evaporation, (b) the equivalent evaporation from and at 100oC, (c) the factor of evaporation, (d) boiler efficiency and (e) boiler power.
2.The following results were obtained in a boiler trail
Feed Water per hour = 1520 kg at 300C
Steam produced = 0.95 dry at 9 bar
Coal per hour 200 kg of calorific value = 27500 kJ/kg
Ash and Unburnt coal collected from beneath fire bars
16 kg per hour of calorific value = 2720 kJ/kg
Mass of dry flue gases per kg of coal burnt = 17.3 kg
Flue gas temperature = 3300C
Air temperature = 170C
Specific heat of flue gas = 1.00 kJ/kgK
Loss due to incomplete combustion is 1 % of the coal. Draw up a heat balance sheet per kg of coal and also determine the equivalent evaporation from and at 100 0C per kg of coal
3.A boiler generates 750 kg of steam per hour at 11 bar absolute and 500C super heat. The coal supplied is 100 kg per hour and calorific value of coal is 29300 kJ/kg. The feed water temperature is 450C and specific heat of super heated steam is 2.09 kJ/kgK. Calculate (i) Actual evaportation (ii) Factor of evaporation (iii) Equivalent evaporation from and at 1000C (iv) Boiler efficiency and (v) Boiler power.
4.A boiler plant consist of an economiser, boiler and superheater. The feed water leaves the economiser at 77oC and 97% dry steam and steam leaves the boiler drum at 21 bar. The steam gets superheated to 270oC on the superheater. If feed water supplied to the economiser at 38oC is 10 kg/kg of coal fired, determine : 1) Equivalent evaporation in kg/kg of coal 2) The efficiency of the plant, if the calorific value of coal is 32.6 3 ×10 kJ/kg. 3) The percentage of heat received in economiser and superheater. Take Specific heat of Super heated steam Cps = 2.1 kJ/kgK.
5.Explain with a neat sketch the working of Lamont boiler and state its demerits
6.In a boiler trail, the following observations were made
Pressure of steam – 10 bar absolute
Steam generated – 540 kg per hr.
Fuel Used – 65 kg per hour
Moisture in fuel – 2% by weight
Mass of flue gases – 9 Kj/KG OF FUEL
Temperature of the flue gases – 3250C
Temperature of the boiler house – 280C
Feed Water Temperature – 500C
Dryness fraction of steam – 0.95
Mean specific heat of flue gases – 1.005 kJ/kgK
Calorific value of fuel – 34000 kJ/kgK
Determine the equivalent evaporation from and at 1000C and draw up a heat balance sheet for the boiler.
7.A boiler produces 2267 kg of dry saturated steam per hour at a pressure of 11.5 bar absolute from feed water which is at a temperature of 121oC. The coal fired in 3 hours is 750 kg and has calorific value of 32000 kJ/kg. It is found that 10% of the coal is unburnt. Calculate: 1) Equivalent evaporation from and at 100oC per kg of coal fired, 2) Efficiency of the boiler, 3) Efficiency of the boiler and grate combined.
8.The following observations were made during a test on a steam boiler:
Furnace oil used per hour – 1666 litres
Specific gravity of furnace oil – 0.83
Steam supplied by boiler – 20,800 kg/hr
Steam pressure – 24 bar
Steam temperature – 3000C
Mean temperature of feed water – 125 0C
Boiler room temperature – 350C
Flue gas temperature – 2400 C
Specific heat of dry flue gases – 1.005 kJ/kgK
Specific heat of superheated steam – 2.1 kJ/kgK
Calorific value of furnace oil – 52000 kJ/kg
Air supplied is 21 times the quantity of furnace oil used. Loss due to incomplete combustion is 1% of the fuel. Draw up a heat balance sheet for the boiler for unit mass of the oil and workout the thermal efficiency
9. State the function of the following
a) Safety valves b) Water level indicator (c) Fusible plug (d) Pressure gauge (e) Steam stop valve (f) Feed check valve (g) Economiser (h) Super heater (i) Air pre heater
10. List the main features of the modern high pressure boilers.
11. With line sketch explain the working of BHEL high pressure boiler. (or) Explain with neat sketch B.H.E.L high pressure boilers with specification and advantages (or) Explain with neat sketch Bharat Heavy Electrical Limited boilers with specification and advantages high pressure boilers.
10. State the main clauses of Indian boiler act and Mention the safety precaution to he followed in boiler operation.
11. What are the effects of impurities present in the feed water?
12. Why the boiler feed water treatment is needed?
13. Explain the internal and external treatment of boiler feed water
14. What are the procedure to he followed to start the boiler from cold conditions?
15. With neat sketch explain the working of Lamont boiler.
16. With neat sketch, explain the function, location and working of any two boiler mountings.
17. With neat sketch, explain the functions, location and working of any two boiler accessories.
18. State the functions of electrostatic precipitator
Unit -3 THERMAL POWER PLANT & STEAM TURBINES AND CONDENSERS
1. Explain and drew the layout of thermal power plant.
2. Explain the fuel and ash circuit of a thermal power plant with a line diagram.
3. Explain the water and steam circuit of a thermal power plant with a line diagram.
4. Explain the air and flue gas circuit of a thermal power plant with a line diagram
5. Explain the cooling water circuit of a thermal power plant with a line diagram.
6. List the major pollutants and their effects and how SO2, and NO2, pollutants are controlled?
7. Explain with neat sketch three types of pollution control
8. Write notes on
a) Fluidised bed combustion b) Thermal pollution
c) Noise pollution
9. What is the necessity of compounding and state the types of compounding adopted in the turbine? Explain any two with neat sketches.
10. Draw P-V and T-S diagram of modified rankine cycle and indicate various processes.
11. Explain the working of the following with suitable sketches.
1) Back pressure turbine ii) Exhaust turbine iii) Pass out turbine
12. Draw and explain P-V and T-S diagram of carnot cycle and derive an expression for efficiency of carnot cycle using steam as working fluid.
13. What is the necessity of compounding? Explain pressure compounding in a steam turbine with a
14. Explain velocity and pressure velocity compounding in a steam turbine with a neat sketch.
15. Explain the working of condensing plant with line diagram.
16. Explain the working of any two types of Jet condenser.
17. Explain the working of any two types of surface condenser with suitable sketch.
18. Explain the working of evaporative condenser.
19. Compare the Jet condensers with surface condenser Explain the working of cooling tower with
Unit 4 CONVENTIONAL SOURCES OF ENERGY AND NUCLEAR POWER PLANT
1. Draw the layout of hydroelectric (Hydel) power plant and explain in detail. State its merits and
2. With suitable line diagram explain the diesel power plant. State its merits and demerits.
3. Explain the chain reaction.
4. Draw the layout of nuclear power plant and explain. State its merits and demerits
5. Draw the outline of nuclear reactor and lable the components.
6. What are the desirable properties of nuclear fuels?
7. With a neat sketch explain the working of PWR? State its merits and demerits.
8. With a neat sketch explain the working of BWR? State its merits and demerits
9. With a neat sketch explain the working of CANDU type reactor. State its merits and demerits.
10. With a neat sketch explain the working of fast breeder reactor. State its merits and demerits.
11. What are the effects of nuclear radiation?
12. Explain nuclear fuel cycle and what are the factors to be considered while selecting the site for
nuclear power plant. Explain.
13. Explain in detail about any three methods of Uranium enrichment.
14. Discuss in details about disposal of nuclear wastes.
15. What are the differences between nuclear power plant and thermal power plant?
16. Discuss in details about nuclear power plant in India
Unit 5 AIR COMPRESSORS & GAS TURBINES
1. Explain with a neat sketch the working of vane blower and root blower.
2. Describe the working of a centrifugal compressor and axial compressor with a neat sketch.
3. Explain the working of single stage single acting reciprocating compressor with neat sketch.
4. Explain the working of constant pressure open cycle gas turbine
5. Explain the working of gas turbine with intercooler
6. Explain the working of gas turbine with reheater
7. Explain the working of gas turbine with regenerator (or) heat exchanger
8. Explain the working of open gas turbine cycle with intercooler, heat exchanger and reheater and
closed cycle gas turbine
9. Explain the working of turbo jet turbo propeller and ram jet