HEAT POWER ENGINEERING II
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Chapter 1:-
PROPERTIES OF STEAM (3x3=9, 1x8-8, total 17 marks)
Short answer questions
1. Define the dryness fraction and write the formula.
2. Draw Moiler diagram and show the label the lines
3. Define (a) sensible heat, and (b) latent heat of vaporization.
4. What are the different methods of measurement of quality of steam?
5. Draw the p-v and T-S diagrams of isothermal, reversible adiabatic process constant volume and polytrophic process
6. Determine the specific enthalpy of wet steam with dryness fraction 0.85 and a pressure of 9bar.
7. Determine the enthalpy of 4 kg of wet steam which is 20% wet at a pressure of 10 bar using steam tables.
8. Find the mass of 2 m³ of steam under the pressure of 40 bar and temperature 450 °C.
9. A closed vessel contains 1200 liters of saturated steam. Determine the mass of steam and final condition of steam if it is cooled from 8 bars pressure to 2 bars pressure.
Essay answer questions
1. 5 kg of steam at a pressure of 12 bar and temperature 250 °C expands polytropically in a cylinder to 1.5 bar as per law PV 1.3 =C. Determine,(a) Final dryness fraction, (c) Work done, and(b) Final volume, (d) Change in internal energy.
2. One kg of steam having a pressure of 8.4 bar abs and dryness fraction 0.9 is expanded in a cylinder to a pressure of 0.35 bar abs. If the expansion is hyperbolic, determine the quantity of the heat which passes through the cylinder walls into the steam.
3. A piston cylinder arrangement contains 10 kg of 100 % dry steam at 1-8 MPa and its expands to a pressure of 0.13 MPa. If the index of expansion is 1.25, determine (a) Final dryness fraction (b)Work done during expansion (c) Heat transferred.
4. A vessel of 1200 litres capacity contains steam at a pressure of 18 bar and at a temperature of 270° C. It is expanded to a pressure of 1.4 bar according to PV1.3= constant. Determine:
(a) The final condition of steam (c) Total work done
(b) The total change in internal energy (d) The total change in entropy
5. 5. One kg of steam having a pressure of 8.4 bar abs and dryness fraction 0.9 is expanded in a cylinder to a pressure of 0.35 bar abs. If the expansion is hyperbolic, determine the quantity of heat which passes through the cylinder walls into the steam.
6. A pressure vessel contains 4 kg of wet steam which is 85% dry at a pressure of 660 KPa. Determine its entropy, enthalpy and internal energy using steam tables.
7. Calculate the enthalpy and entropy of steam at 12 bar when it is, (a) saturated, (b) dry with 0.9,(c) superheated at 330 °C. Take Cps =2.09 kJ/kgK.
8. Calculate the specific entropy of steam at a pressure of 20 bar under the following conditions: (a)Wet steam with 0.95 dryness fraction (b) Steam is dry and saturated (c) Steam is superheated
with degree of superheat 40 °C.
Chapter 2:-
STEAM BOILERS (2x3=6, 1×8=8, total 14 marks)
Short answer questions
1. State the difference between induced draught and forced draught
2. Distinguish between water tube and fire-tube boilers
3. List out different boiler mountings
4. List out different boiler accessories
5. What are the factors which govern the selection of a boiler?
6. State the need of high pressure modern boilers
7. Define the terms (a) Equivalent evaporation (b) Factor of evaporation (c) Boiler efficiency
Essay answer questions
1. Explain the working principle of Benson Boilers with diagrams.
2. Explain the working principle of Lamount Boiler with diagrams
3. Draw the line diagram of Babcock Wilcox Boiler and explain them.
4. During test on a boiler the following data were collected.
Steam pressure: 9.487 bar gauge , Feed water temperature: 35°C, Steam condition: dry and saturated ,Rate of evaporation: 12kg/kg of coal
Calorific value: 37500 KJ/Kg
Determine (a) thermal efficiency
(b) factor of evaporation
(c)equivalent evaporation
Chapter 3:-
STEAM NOZZLES (2×3=6, 1x8-8, total 14 marks)
Short answer questions
1. What are the applications of the nozzles?
2. What is steam nozzle? And list the different types of steam nozzles
3. State Effect of friction in nozzles
4. Steam enters an insulated nozzle at 10 bar and 200 °C with a Velocity of 50 m/s and leaves a 3 bar. Find the exit velocity of steam. Assume expansion as isentropic.
5. Steam enters a steam nozzle at a pressure of 1.8 Mpa and at a temperature of 350 °0 C and expands to a pressure of 0.12 Mpa with 95% dry. Calculate the exit velocity of the steam.
6. Steam enters the nozzle at 15 bar and 300°C and expands to 2bar and a quality of 85% dry. Determine velocity at exit.
Essay answer questions
1. Explain the working of the steam injector with legible sketch.
2. Dry saturated steam at a pressure of 8 bar enters a convergent divergent nozzle and leaves at a pressure of 1 bar. Find the ratio of diameters at exit and throat for maximum discharge. Assume The flow is isentropic and take expansion index n=1.135.
3. Dry saturated steam enters a steam nozzle of a pressure of 10 bar expands isentropically to 1 bar pressure. Determine (a)Quality of steam at exit and (b) Exit velocity. Assume the inlet velocity to nozzle is zero.
4. A convergent-divergent nozzle receives wet steam of 2% wet at a pressure of 26 bar with an approach velocity of 100 m/s and expands it to a back pressure of 0.3 bar. Nozzle efficiency is 85% and all the frictional losses take place in the divergent portion only. Determine: (a) The critical throat pressure(b) The discharge of steam (c) The area of cross section of the nozzle at its exit.
5. A nozzle is to be supplied with steam at 10 bar and 2000C and is to discharge 180 kg/hr into a turbine wheel chamber where the pressure is 1 bar. The efficiency of the nozzle may be taken as 85%. Calculate the throat and exit diameters of the nozzle for maximum discharge.
6. Find the mass flow rate of steam in a nozzle having inlet pressure and temperature are 12 bar and 250°C, back pressure is 1 bar. The throat diameter is 15 mm.
Chapter 4:-
STEAM TURBINES (1x3=3, 1x8-8, total 11 marks)
Short answer questions
1. Differentiate the impulse turbines from reaction turbine?
2. State the necessity of governing a turbine?
3. State the necessity of compounding a turbine
4. Define bleeding in a steam turbine and its effect.
5. Define the terms reheating of turbine
6. What are jet condensers and surface condensers?
Essay answer questions
1. Classification of steam Turbines with examples
2. Describe the methods of reducing rotor speeds with the help of diagrams (3 compounding methods)
3. The absolute steam entry velocity of a single-stage impulse turbine is 600 m/s, nozzle angle is 20°,ratio of blade speed to whirl component of steam speed is 0.5, blade velocity coefficient is 0.85. Find (a) The blade angles at inlet and outlet if the steam enters without shock and leaves the blade in an axial direction, (b)Power developed if the steam flow rate is 5 kg/sec, (C) Blade or diagram efficiency and (d)Axial thrust.
4. 2 kg/sec steam is supplied to a simple impulse steam turbine from a set of nozzles whose pressure range is 10 bar to 0-2 bar. The nozzle angle is 22° and blade exit angle is 30°, the mean blade speed is 250 m/sec. If the nozzle efficiency is 80%, find the (a) Power developed, (b) blade efficiency, and (c) inlet angle of blade.
5. 5. In an impulse turbine the nozzles are inclined at 18° and deliver 30 kg/s of steam at a velocity of 900 m/s while the blade velocity is 350 m/s. Calculate (a)Power developed (b) Blade angles (c) Diagram efficiency neglecting friction
6. In a De-lavel steam turbine the blade angles are 350 at inlet and exit. The steam leaves the nozzle at 500 m/s and the blade speed 100 m/s. If the relative velocity of steam is reduced by 15% during its passage through the blades. Draw the inlet and outlet velocity diagrams and find (a) nozzle angles at inlet and outlet (b) the power developed per unit mass (c) the blade efficiency.
Chapter 5:-
STEAM CONDENSORS (2x3=6, 1x8=8, total 14 marks)
Short answer questions
1. State function of steam condenser.
2. How do you classify the condensers?
3. State the difference between jet condenser and surface condenser.
4. List the three advantages and disadvantages of high level jet condenser.
5. What are the effects of air leakage into the condenser?
6. Define the terms (a) condenser efficiency (b)vacuum efficiency
7. State the difference between down flow and central flow surface condenser.
8. List out the elements of the steam condensing plant.
Essay answer questions
1. Explain the working principle shell and tube surface condenser with neat sketch
2. Explain the working principle of high level jet condenser with neat sketch
3. Explain the working principle of evaporative condenser with neat sketch
4. Data from the trail of a surface condenser is as follows:
Barometer reading = 764 mm Hg, Condenser vacuum = 680 mm Hg, Condenser mean temperature = 36.2°C,Hot well temperature = 30°C, Cooling water inlet temperature = 20°C,Temperature rise of cooling water = 12°C.
Evaluate a) corrected vacuum to standard barometer reading, b) Vacuum efficiency, c) condenser efficiency.
5. The following observations were recorded during a test on a surface condense Mean condenser temperature = 350 C; Hot well temperature = 300C; Condenser vacuum =700 mm of Hg; Barometer reading = 760 mm of Hg; Condensate collected = 16.75 kg/min; Cooling water = 660 kg/min; Inlet temperature of cooling water = 200C; Outlet temperature of cooling water = 340C; Determine (i) Mass of air present per m3 of condensate (ii) Dryness fraction of steam as it enters The Condensate (iii) Vacuum efficiency
6. A surface condenser deals with 12000 kg of steam per hour. Air leakage into the condenser is found to be 4 kg/hr. The vacuum and temperature at the air pump suction are 700 mm of Hg and 360C respectively. The barometric pressure is 760 mm of Hg. Compute the volumetric capacity in m³/min of wet air pump.
NOTE- 10 Marks question will be come in 2nd or 3rd or 4th lesson