te1 question paper

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QUESTION BANK

THERMAL ENGINEERING 1 (M 506)

Module 1 (Steam Engineering)

Short Questions (4 Marks)

1. Explain dryness fraction. 2004 Oct/Nov; 2005 May

2. Explain wet, dry and super heat steam. 2004 Oct/Nov

3. Draw and explain the phase equilibrium diagram for steam on T-S plot with relevant constant

property lines. 2007 Jan4. Describe the applications of Mollier diagram. 2004 Oct/Nov

5. Using Mollier diagram, determine the heat drop and final condition of steam when steam is at 700

K N/m2 at 200 o C is expanded adiabatically to a pressure of 100 K N/ m2. 2005 May

6. Calculate entropy of 1 Kg of wet steam with dryness fraction 0.9 at a pressure of 840 K N/m 2.

2005 May

7. Calculate the enthalpy of steam at 15 bar and 2500 C. Dec 2007

8. Calculate entropy of 5 kg of steam at a pressure of 15 bar and 2500 C using steam tables. 2008

May

9. Show that heat supplied is equal to the change in internal energy, when steam is expanded at

constant volume. 2005 May

10. Clearly explain the difference between isothermal and hyperbolic processes as applied to wet

steam. 2004 Oct/Nov 4 M; 2006 May/Jun11. Show the following process on T-S and h S diagram of steam; (a) Constant volume cooling. (b).

Constant pressure heating and (c) Throttling. 2005 Nov

12. Describe the Rankine cycle and show how it differs from Carnot cycle by sketching both cycles

on the same TS diagram. The steam is dry and saturated after evaporation in both cycles. 2006

May/Jun

13. Draw T-S diagram of Rankine cycle for wet, dry saturated and superheated steams. Dec 2007

14. Draw T-S diagram of Rankine cycle using dry saturated steam and develop the equation of cycle

efficiency. July/August 2007 ; Nov 2008

15. Distinguish between Water tube and Fire tube boilers and state under what conditions each type

would be desirable. 2004 Oct/Nov; 2005 May; 2005 Nov

16. Explain briefly how steam boilers are classified. 2008

17. What are boiler mountings and accessories? Briefly explain any one of them. [2005 May, July/

August 2007]; Nov 2008

18. Explain why safety valves are needed in a boiler. Draw a neat sketch of a spring loaded safety

valve and explain its working. 2007 Jan

19.

Six Mark (6) Questions

1. A vessel of 0.4 m3 capacity contains 2 Kg of wet steam at 6 bar pressure. Calculate the volume

and mass of water and of dry steam. 2005 Nov

2. Steam at 10 bar and 250 o C expands until the pressure becomes 2.75 bar. The dryness fraction of

steam at the end of expansion is 0.95 dry. Determine the change in internal energy. 2006

May/Jun

3. Calculate the internal energy of 1 Kg of steam at a pressure of 10 bar when the steam is (i) 0.9dry and (ii) dry saturated. The volume of water may be neglected. 2005 Nov

4. One Kg of steam at 1.8 MPa and 2800 C undergoes a constant pressure process until the quality

becomes 50 %. Find the work done, change in enthalpy and heat transferred if the process is non

flow. 2006 May/Jun

5.

12 Marks (12) Questions

1. 0.085 m3 drum contains saturated water and water vapour at 3340 C. Find the mass of each if

there volumes are equal. 2008 May

2. Steam at 18 bar and dryness fraction of 0.9 is heated at constant pressure until dry and saturated.

Find the increase in volume, heat supplied and work done per Kg of steam. If the volume is now

kept constant find how much heat must be extracted to reduce the pressure to 14 bar. 2005 Nov

3. Two boilers discharge equal amounts of steam. Steam from one is at 18 bar 3800

C. The other isat 18 bar and 95 % quality. Determine: (a) The equilibrium condition after mixing, (b) Loss of

entropy of high temperature steam, (c) Gain in entropy of low temperature steam, and (d) Net

increase or decrease of entropy. Dec 2007


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4. A large insulated vessel is divided in to two chambers, one containing 6 Kg. of dry saturated

steam at 0.2 MPa and the other 12 Kg. of steam, 0.8 quality at 0.5 MPa. If the partition is

removed and the steam is mixed thoroughly and allowed to settle, then find the final pressure,

steam quality and entropy changes in the process. 2007 Jan

5. Steam at a pressure of 0.5 MPa and a temperature of 200o C is expanded adiabatically to a

pressure of 0.07 MPa. Find the final condition of steam using Mollier diagram.

6. A closed vessel of 1.2 m 3 in capacity contains steam at 3 bar. absolute and 0.85 dryness. Steam at

10 bar and 0.96 dryness is supplied to the vessel until the pressure inside the vessel becomes 5

bar. Calculate the weight of steam supplied to the closed vessel and the final dryness fraction ofthe steam in the vessel. Neglect the volume of the moisture and thermal capacity of the vessel.

2006 May/Jun

7. A simple Rankine cycle operates between 2600 C and 950 C. Steam is supplied to the turbine at

dry saturated condition. If the expansion is isentropic, determine its efficiency. Show the cycle in

h-s and T-s diagrams. 2008 May

8. In a steam power plant working on Rankine cycle, Steam at 100 bar and 500 o C is expanded in a

turbine to a condenser pressure of 0.2 bar. The net power out put of the turbine is 140 MW.

Determine the thermal efficiency and mass flow rate of steam in Kg/hr. July/August 2007

9. In a Rankine cycle operating on water, superheated vapour enters the turbine at 100 bar, 5000 C.

Condenser pressure is 0.1 bar. The net power output is 150 MW. If the turbine has an isentropic

efficiency of 85 % determine (a) the thermal efficiency, and (b) the mass flow rate of steam in

kg./hr. Dec 200710. Steam at 21 bar and 350o C is expanded in a steam turbine to 0.08 bar. It then enters a condenser

where it is condensed to saturated water. The pump feeds back the water in to the boiler.

Assuming the turbine efficiency are 60 %, determine per Kg of steam, the net work, the heat

transferred to the working fluid, and the Rankine cycle efficiency. 2007 Jan

11. With the help of neat diagrams, explain the working of various boiler mountings.

12.

Module II (Steam Nozzles & Steam Turbines)


1. Explain various types of nozzles and their distinguishing features. 2004 Oct/Nov; 2005 Nov 4

M, 2008 May

2. Explain the effect of friction on the performance of steam nozzles using temperature - entropy

and enthalpy entropy diagram. [July/August 2007]; Nov 20083. Derive the expressions for velocity and mass flow through the nozzle in terms of initial pressure,

initial specific volume, area of cross section, final pressure and index n of frictionless adiabatic

expansion. 2004 Oct/Nov

4. Explain physical significance of critical pressure ratio in steam nozzles. 2005 May; 2006

May/Jun

5. Explain the effect of varying the back pressure in a convergent divergent nozzle and state when

the maximum flow occurs in the nozzle. 2007 Jan

6. Explain the steady flow energy equation as applied to a steam nozzle. Explain its use in the

calculation of steam velocity at the exit of a nozzle. 2006 May/Jun

7. Show the process of expansion of steam in nozzle in T-S diagram: (a) When expansion is

isentropic (b) when expansion is irreversible. Dec 2007

8. Explain metastable flow through nozzles.

9. Explain supersaturated flow of steam in nozzle and sketch the process on h S diagram. 2005

May; 2005 Nov; 2007 Jan

10. Steam at 3 bar with 10 o C superheat is passed through a convergent nozzle. The velocity of steam

entering the nozzle is 91.5 m/s. The back pressure is 1.5 bar. Assuming nozzle efficiency as 90

%, determine the area of the nozzle at throat. Maximum discharge through the nozzle is limited to

0. 45 Kg/s. Take Cps (superheated steam) = 2.2 KJ/Kgo C. 2004 Oct/Nov

11. Steam expands from 3 bar to 1 bar in a nozzle. The initial velocity is 90 m/s and the initial

temperature is 150 o C. The nozzle efficiency is 95 %. Determine the exit velocity. 2005 Nov

12. Steam at a pressure of 700 K N/m2 and 0.9 dry enters a nozzle with throat area 1.4 cm2. It leaves

the nozzle at a pressure of 106 K N/m2. Calculate the weight of steam discharged per second and

the dia. of the exit of the nozzle so that the discharge shall be maximum. 2005 May13. In a single stage impulse turbine the blade angles are equal and the nozzle angle is 20o. The

velocity coefficient for the blade is 0.83. Find the maximum blade efficiency possible. If the

actual blade efficiency is 90 % of maximum blade efficiency, find the possible ratio of blade

speed to steam speed. 2004 Oct/Nov


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14. Steam at 3150 K N/m2 and 370 o C is expanded in a high pressure turbine to 560 K N/m2 and is

reheated to 370 o C and is used in the low pressure turbine. Exhaust is 3.45 K N/m 2. Calculate the

gain in efficiency by reheating. 2005 May

15. Give Classifications of Steam Turbines. Briefly explain. 2004 Oct/Nov, Dec 2007

16. Differentiate between impulse and reaction turbines. Nov 2008

17. Define speed ratio, Blade velocity coefficient, blade efficiency and stage efficiency of steam

turbines.2004 Oct/Nov

18. Define (a) Blading Efficiency, (b) Stage Efficiency and (c) nozzle Efficiency 2005 May

19. Derrive an expression for maximum blade efficiency in a single stage Impulse Turbine. 2007 Jan20. Define diagram efficiency. Write down an expression for the same. Dec 2007

21. Draw the inlet and exit velocity diagrams of a Parsons reaction turbine. Dec 2007

22. Draw velocity triangles of moving blades of a reaction turbine. 2008 May

23. Define speed ratio, Blade velocity coefficient, blade efficiency and stage efficiency of steam

turbines. 2004 Oct/Nov

24. Define (a) Blading Efficiency, (b) Stage Efficiency and (c) nozzle Efficiency 2005 May

25. Define the term degree of reaction used in a reaction turbine and prove that the moving and

fixed blade should have same shape for a 50 % reaction. July/August 2007, Dec 2007

26. Deduce the expression for the work done per stage of a reaction turbine and determine the

condition for maximum efficiency. 2005 May

27. Explain the terms throttle governing and nozzle governing. 2006 May/Jun, July/August 2007

28. Why are steam turbines compounded? Explain different methods of compounding. 2007 Jan29.


1. Dry saturated steam at a pressure of 8 bar absolute enters a convergent divergent nozzle and

leaves at 1.5 bar absolute. If the flow is isentropic and corresponding expansion index is 1.135,

find the ratio of cross sectional area at exit and throat for maximum discharge. 2006 May/Jun

2. Steam at a pressure of 10 bar and 0.98 dry is passed through a convergent divergent nozzle to a

back pressure of 0.1 bar. The mass flow rate is 0.55 Kg/s. Find (i) pressure at the throat. (ii)

Number of nozzles used if each nozzle has a throat area of 0.5 cm2. The enthalpy drop used for

heating the steam by friction in divergent part is 10% of the overall enthalpy drop. The index of

expansion is 1.13. 2007 Jan

3. Dry saturated steam at 5 bar enters a convergent divergent nozzle at a velocity of 160 m/s. The

exit pressure is 1.5 bar. The throat and exit atea are 1280 mm 2 and 1600 mm2 respectively.Assuming isentropic flow up to the throat , critical pressure ratio as 0.58 and frictional heating as

10 % of the heat loss in the divergent portion, estimate the mass flow rate and the nozzle

efficiency. July/August 2007

4. In a 50 % reaction turbine stage, running at 50 revolutions per second, the exit angles are 300 and

the inlet angles are 500. The mean diameter is one meter. The steam flow rate is 10 3 Kg/min. and

the stage efficiency is 85 %. Determine (i) the power output of the stage; (ii) the specific enthalpy

drop in the stage. 2006 May/Jun

5. The data pertaining to an impulse turbine is as follows: Blade speed = 300 m/s, Isentropic

enthalpy drop in nozzle = 450 KJ/Kg., Nozzle efficiency = 90 %, Nozzle angle = 20 o , Blade

velocity coefficient = 0.85, Blade exit angle = 25 o ,. Draw the velocity diagram and calculate for

a steam flow rate of 1 Kg/s, (i) The inlet angle of moving blade. (ii) The axial thrust. (iii) The

driving force on the wheel. (iv) Diagram power. (v) Diagram efficiency. (vi) The energy lost in

blades due to friction. July/August 2007

6. A single stage impulse turbine has a diameter of 1.2 meter running at 3000 rpm. The nozzle angle

is 18o. Blade speed ratio is 0.42. The ratio of relative velocity at outlet to the relative velocity at

inlet is 0.9. The outlet angle of the blade is 3o smaller than the inlet angle. The steam flow rate is

5 Kg/s. Draw the velocity diagram and find: (i) velocity of whirl. (ii) axial thrust on the end

bearings. (iii) blade angle. (iv) power developed. 2007 Jan

7.


1. Starting from fundamentals, show that the maximum discharge through a nozzle, the ratio of

throat pressure to inlet pressure is given by [2 / (n+1)]n/(n - 1) where n is the index for isentropic

expansion through the nozzle. 2005 Nov2. Steam at 0.9 MPa, 250 0 C and flowing at the rate of 1 Kg/S passes in to a pipe carrying wet steam

at 0.8 MPa and 0.95 dry. After adiabatic mixing at 0.8 MPa the flow rate is 2.3 Kg/s. Determine

the condition of the steam after mixing. The mixture is then expanded in a friction less nozzle


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isentropically to a pressure of 0.4 MPa. Determine the velocity of the steam leaving the nozzle.

Neglect the velocity of steam in the pipeline. July/August 2007 12 M

3. Dry saturated steam at a pressure of 0.6 MPa flows through nozzles at the rate of 4.5 kg./sec. and

discharges at a pressure of 0.16 MPa. The loss due to friction in the diverging portion of the

nozzle is 15% of the total isentropic enthalpy drop. Taking isentropic expansion index as 1.135,

determine the cross-sectional area of the throat and exit of the nozzle. 2008 May

4. Dry saturated steam enters a steam nozzle at a pressure of 12 bar and is discharged at a pressure

of 1.5 bar. If the dryness fraction of discharged steam is 0.95, what will be the final velocity of

steam? Nov 20085. Steam at a pressure of 10 bar and dryness fraction of 0.98 is discharged through a convergent

divergent nozzle to a back pressure of 0.1 bar. The mass flow rate is 10 kg/kW-Hr. If the power

developed is 200 kw, determine (a) the Pressure at the throat, and (b) Number of nozzles required

if each nozzle has a throat of rectangular cross section 5 mm x 10 mm, if 10 % of overall

isentropic enthalpy drop reheats by friction in the divergent portion. Dec 2007

6. In a stage of an impulse turbine, with single row wheel, the mean dia of the blades is 1m. It runs

at 3000 rpm. The steam issues from the nozzle at a velocity of 350 m/sec and the nozzle angle is

200. The rotor blades are equiangular. The blade friction factor is 0.86. Determine the power

developed if axial thrust on the end bearing of rotor is 120 N. 2008 May

7. Discuss on Velocity and pressure compounding of steam turbines. Nov 2008

8.

Module III (Gas Turbine Plants)Short Questions (4 Marks)

1. Explain advantages and disadvantages of a closed cycle gas turbine. 2004 Oct/Nov; 2006

May/Jun; 2007 Jan

2. Differentiate between closed loop and open loop gas turbines. Dec 2007

3. What are the advantages and disadvantages of gas turbine over I C engines? What are the fields

of applications of gas turbine power plants? 2005 Nov, July/August 2007

4. Describe a gas turbine combustion chamber with the help of a neat sketch. 2004 Oct/Nov

5. Explain factors which affect the combustion efficiency of gas turbine power plant. 2007 Jan

6. Define Combustion intensity. Dec 2007

7. Define isentropic efficiency of a gas turbine. 2005 May; Dec 2007

8. Draw T-S diagram of a gas turbine showing inter-cooling, reheating and regenerative heating.Dec

20079. What are the advantages of reheating in a gas turbine? Nov 2008

10. Discuss means of improving the specific output and thermal efficiency of the simple open cycle

gas turbine plant. 2005 May ; 2005 Nov; 2007 Jan ; Dec 2007

11. Derive an expression for thermal efficiency of standard gas turbine plant working on closed

Braytons cycle. 2008 May

12. What are the uses of compressed air? 2005 May

13. Explain the phenomenon of surging and choking in centrifugal compressors. 2006 May/Jun,

July/August 2007

14. Differentiate between rotary and centrifugal compressors. Explain any one type of rotary

compressor. 2008 May

15. Discuss various classifications of rotary air compressors. 2008

16. What are the special advantages of axial compressors? Nov 2008

17.


1. Derive the expression for optimum pressure ratio for maximum specific work output in a closed

cycle gas turbine plant. 2004 Oct/Nov; 2005 May

2. In an open cycle constant pressure gas turbine, air enters the compressor at 1.02 bar and 20 o C.

The pressure of air rises to 4.08 bar. The isentropic efficiencies of compressor and turbine are 80

% and 85 % respectively. The air Fuel ratio is 80:1. Find the thermal efficiency of the cycle if the

flow rate of air is 2.5 Kg/S. Take Cp = 1 k J/kg.o K and = 1.4 for air and gas. C V of fuel used to

41720 kJ/kg. 2004Oct/Nov

3. With the help of neat sketches, explain the working of centrifugal air compressor. 2008 May

4.12 Marks (12) Questions

1. What problems are encountered in the design of gas turbine combustion chamber? Draw a neat

sketch of a combustion chamber used for an open cycle plant and name the parts.


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2006 May/Jun; 2007 Jan

2. What are the effects on the thermal efficiency and specific output of the gas turbine power plant

of the following factors. (a) load on the plant, (b) pressure ratio, (c) turbine inlet temperature, (d)

compressor inlet temperature, (e) regenerator. July/August 2007

3. Prove that for a two stage gas turbine plant with perfect inter-cooling and perfect reheating the

intermediate pressure for maximum work output is given by the geometric mean of the initial

suction pressure and the final delivery pressure. 2006 May/Jun 12 M, 2008 May

4. Explain the working of a closed cycle gas turbine. Nov 2008

5. In a gas turbine plant, air is compressed from 1 bar and 15

o

C to 5.6 bar. It is then heated to 650

o

Cin a combustion chamber and expanded back to 1 bar. Calculate the cycle efficiency. Nov 2008

6. In a gas turbine plant air is compressed from 1 bar, 15 o C through a pressure ratio of 4:1. It is

then heated to 650 o C in a combustion chamber and expanded back to atmospheric pressure of 1

bar in a turbine. Calculate the cycle efficiency and work ratio if a perfect heat exchanger is used.

The isentropic efficiencies of the turbine and compressor are 85 % and 80 % respectively. 2005

Nov; Dec 2007

7. Explain the ideal energy transfer in a centrifugal compressor and how does axial flow compressor

differ from centrifugal compressor. 2005 Nov

8.

Module IV (Solar Energy)


1. Define optical efficiency? How optical losses can be minimized? 2005 Nov2. Define the term overall loss coefficient with respect to a solar collector. Nov 2008

3. What are the various thermal losses in a solar collector? Explain. 2005 May

4. Define the term instantaneous collection efficiency. 2008 May

5. Explain the concept of Zero Energy house July/August 2007

6. Write short notes on solar pond. 2004 Oct/Nov 4 M; 2006 May/Jun 4 M; 2005 Nov

7. Explain various types of solar thermal collectors. 2004 Oct/Nov 4 M, 2008 May

8. Explain mean flat plate temperature as applied to solar energy. 2004 Oct/Nov, 2008 May

9. Explain working of a cylindrical parabolic concentrating collector. July/August 2007

10. Explain liquid flat plate collector. 2005 May

11. Explain with a neat sketch the working of Flat plate collector2007 Jan

12. Explain focusing type solar collector. 2005 May; Nov 2008

13. Explain the working of concentrator type of collector. Dec 200714. Describe the subtracting system. 2005 May

15. Explain the concept of Satellite solar power station. 2007 Jan

16. Explain the functioning of a solar water heater. 2004 Oct/Nov

17. With the sketch explain working of a solar air heater. 2006 May/Jun

18.


1. Write down an energy balance equation of a liquid flat plate collector. Explain various terms in

this equation. 2008 May

2.


1. What is the importance of Solar Power in the present energy crises in world? Also discuss recent

developments in power generation using solar energy. 2007 Jan,

2. Explain the working of a solar heater. Nov 2008

3. Explain working of a cylindrical parabolic concentrating collector. What are its advantages over a

solar air heater? 2005 Nov

4. Explain with the help of a neat sketch the solar thermal power generation system. 2004 Oct/Nov;

2005 May; Dec 2007

5. Explain the working of a solar power generation cycle using flat plate collectors. Nov 2008

6. Describe the basic principle of photovoltaic conversion and list out the merits over other systems?

What are the basis hurdles in the development of this mode of power generation? [2007 Jul/Aug]

7. Explain the low temperature Rankine cycle used for solar power generation. 2006 May/Jun

12 M; 2008 May

8. Explain any four thermal applications of solar energy with the help of neat sketches. Dec 20079. How many types of solar water collectors are generally used? Describe any two of them. Discuss

the selective coating used. 2005 Nov

10. Describe in detail the different energy storage systems used in connection with solar power. Also

state their advantages and disadvantages. 2007 Jan


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11.

Module V Thermal Power Plants


1. Draw layout of a diesel power plant. 2004 Oct/Nov; 2005 May

2. Discuss various arrangements of feed water heaters in steam power plants. Dec 2007

3. What are the functions of a condenser in a steam power plant? 2006 May/Jun

4. What are the different types of condensers? Nov 2008

5. What is the function of evaporators in a thermal power plant?Nov 2008

6. Discuss about the ash handling system in a power plant. 2004 Oct/Nov; 2005 May; 2007 Jan,July/August 2007

7. Briefly explain the advantages of forced draft over induced draft. 2004 Oct/Nov

8. Describe various stages of coal handling, preparation delivery. 2004 Oct/Nov; 2005 May;

2005 May; Dec 2007

9. Discuss various types of fuels used in thermal power plants. 2008 May

10. List operations in ash handling. Dec 2007

11. Explain necessity of dust collection system. 2008 May

12. Why mechanical handling of fuel is necessary in power plants? Dec 2007

13. Describe the different types of overfeed stockers and discuss the merits and demerits of each over

the other. 2007 Jan

14. What are the merits of mechanical draft system? 2004 Oct/Nov; 2005 May

15. Distinguish between Forced draught and Induced draught. Dec 200716. What is natural draught cooling tower? What is the reason for its hyperbolic shape? 2005 Nov;

2004 Oct/Nov; 2005 Nov

17. What are cross flow and counter flow cooling towers. 2006 May/Jun

18.


1. Give advantages and disadvantages of steam power plants. Dec 2007

2. Distinguish between forced and induced draft system. Why the balanced draft is preferred over

the forced or induced draft? 2007 Jan

3. Discuss the emitting and collecting mechanisms in Electrostatic precipitators. 2007 Jul/Aug

4. Explain the functions of a cooling tower in a modern power plant. Describe with a neat sketch the

working of a mechanical draft cooling tower. 2006 May/Jun, July/August 2007

5. Explain the working of two pass surface condenser with a schematic diagram. 2007 Jan6. Explain the working of two pass surface condenser with a schematic diagram. 2007 Jul/Aug

7.


1. Draw and explain the layout of a typical Steam power plant. 2005 May; 2006 May/Jun

2. What are the various types of condensers used in thermal power stations? Nov 2008

3. Briefly explain the emissions from thermal power plant and their effect on atmosphere and

environment. 2007 Jan, 2007 Jul/Aug

4. What are cyclone separators? Explain the principle of gas solid separator in cyclone. 2005 Nov

5. With the help of a T S diagram explain the working of a direct contact spray condenser. 2005

Nov

6. Explain the operation of an electrostatic precipitator. 2006 May/Jun 6 M; 2008 May

7. Explain the working of forced draft cooling tower. Nov 2008

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