ChettinadCollege Of Engineering &

Technology

NH-67, KARUR - TRICHY HIGHWAYS, PULIYUR CF, KARUR.

TAMIL NADU. PIN:639114 INDIA.

DEPARTMENT OF MECHANICAL ENGINEERING

ME6301 – ENGINEERING THERMODYNAMICS Question Bank

Prepared By

A.AKBAR ALI.ME., Assistant Professor – Mechanical Department

Chettinad College Of Engineering & Technology

NH-67, Karur - Trichy Highways,

Puliyur CF, Karur.

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Tamil Nadu. Pin:639114 India.

ChettinadCollege Of Engineering &

Technology

DEPARTMENT OF MECHANICAL ENGINEERING

ME6301 – ENGINEERING THERMODYNAMICSQUESTION-BANK

TWO MARKS PART-AUNIT – I BASIC CONCEPT AND FIRST LAW OF THERMODYNAMICS

1. Define the term Thermodynamics?

2. What is meant by Thermodynamics system? How do you classify it?

3. What is meant by closed system? Give an example?

4. Define open system? Give an example?

5. Distinguish between open & closed system?

6. Define isolated system?

7. Define specific heat capacity at constant pressure?

8. Define specific heat capacity at constant volume?

9. What is meant by surroundings?

10. What is boundary?

11. What is Thermodynamic property?

12. Distinguish between Heat & Temperature?

13. Define A following system are in open/closed/isolated

(a) Boiler (b) Mixture of ice and water in a metal container (c) Wind mill

14. How do you classify the property?

15. Define extensive and intensive property?

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16. Differentiate extensive and intensive property?

17. What do you understand by equilibrium of a system?

18. When a system is said to be in “Thermodynamic Equilibrium”?

19. State first law of thermodynamics and give any two corollaries?

20. What is meant by perpetual motion of machine first kind?

21. Prove that for an isolated system, there is no change in internal energy?

22. Determine the molecular volume of any perfect gas at 600 N/m2and 300C. Universal gas constant may be taken as 8314J/kg mole0K

23. Define the term Process?

24. Define the term Cycle?

25. What is meant by open and closed cycle?

26. What is meant by reversible and irreversible process?

27. What is point and path function?

28. What is Quasi-static process?

29. Define the term enthalpy?

30. Define the term Internal energy?

31. What is meant by thermodynamics work?

32. Sketch isothermal expansion on p-V Diagram and state the property remain constant?

33. Prove the difference in specific heat capacities equal to Cp- Cv = R?

34. Define Zeroth law of Thermodynamics?

35. Differentiate Ideal and Real gas?

36. What are the limitations of first law of Thermodynamics?

37. Define the term Enthalpy?

38. Define hyperbolic process?

39. Define free expansion process?

40. Define Throttling process? What is NTP & STP?

41. A liquid mass18 kg is heated from 250Cto850C.How much heat transfer is required?Take Cp=4.2kJ/kgK. 42. A Closed system receives an input of heat is 450 kJ. Determine the work done by the system?

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UNIT – II SECOND LAW AND AVAILABILITY ANALYSIS

1. State the Kelvin – Planck statement of second law of Thermodynamics?

2. State the Clausius statement of second law of Thermodynamics?

3. State Carnot’s theorem?

4. What are the Corollaries of Carnot theorems?

5. Define PMM of second kind?

6. What are the difference between a Heat pump and Refrigerator?

7. What is meant by Heat Engine?

8. Define the term COP?

9. Write the expression for COP of a heat pump and a refrigerator?

10. Why the Carnot cycle cannot be realized in practice?

11. Why the Carnot cycle efficiency will be maximum?

12. What are the processes involved in Carnot cycle?

13. Sketch the PV & TS diagram of Carnot cycle?

14. Is the second law independent of first law? How?

15. Define Entropy?

16. Write the expression for efficiency of Carnot cycle?

17. Define change of Entropy. How is entropy compared with heat transfer and absolute temperature?

18. Define the term source, sink and reservoir?

19. Why the performance of refrigerator and heat pump are given in terms of COP and not in terms of efficiency?

20. Comments on the statements “The entropy of universe tends to be maximum”

21. What is meant by principles in increase in entropy?

22. What do you meant by “clausius inequality”

23. Write down the equation for Carnot COP of a heat pump which works between two heat reservoirs of temperature T1 and T2 temperature?

24. Explain briefly clausius inequality?

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25. For compression process between same and states which work will be more reversible orirreversible?

26. A heat pump pumps 10MJ/KW.hr to the high temperature reservoir. What is the COP?

27. Find the entropy of universe when 1000KJ of heat is transferred from 8000K to 5000K?

28. Give the expression to find change in entropy during constant pressure and polytropic process. Show on T-s diagram?

29. Explain the term Reversibility?

30. Can entropy of universe ever decrease? Why?

31. What is essence of second law of thermodynamics?

32. If the Carnot engine efficiency is 50%. Find the COP of refrigerator working between same temperatures?

33. Define the term Absolute Entropy?

34. What are the causes of Irreversibility?

35. Write the Corollaries of Carnot theorem?

36. What is thermodynamics temperature scale?

37. List out the applications of entropy?

38. Define the term Availability?

39. What is available energy?

40. What is unavailable energy?

UNIT – III PROPERTIES OF PURE SUBSTANCE AND STEAM POWER CYCLE

1. Define latent heat of Ice?

2. What is pure substance?

3. What is saturation pressure and temperature?

4. Define latent heat of evaporation?

5. Find the saturation temperature & latent heat of evaporation of steam at 1Mpa?

6. Define the terms ‘Boiling point’ and ‘Melting point’

7. What is meant by superheated steam?

8. What are the uses of superheated steam?

9. Define: Sensible heat of water?5

10. Differentiate Wet steam and Dry Steam?

11. State phase rule of pure substances?

12. Define: Super heat enthalpy?

13. Define dryness fraction of steam?

14. What is degree of under cooling & Degree of sub cooling?

15. Define triple point and critical point for pure substance?

16. When saturation pressure increases, what happen to saturation temperature and freezing point?

17. Draw the change of phase of water in T-V diagram?

18. Draw the h-s diagram for steam and show a throttling process on it?

19. Draw the skeleton p-V diagram of water?

20. Draw the p-V-T surface of water?

21. Write the formula for calculating entropy change from saturated water to superheated water to superheat condition?

22. Determine the condition of steam of 2bar whose entropy is 6.27kJ/kg?

23. Determine specific enthalpy and entropy of 1200C saturated steam?

24. Find the mass of 0.1m3 of wet steam at a temperature of 1600C and 0.94 dry?

25. One kg of 10bar has an enthalpy of 2500kJ/kg. Find its quality?

26. What is meant by steam power cycle?

27. Define the term efficiency ratio?

28. What is meant by isentropic efficiency?

29. Define specific steam consumption of an ideal Rankine’s cycle?

30. What is meant by work ratio?

31. What is the importance of work ratio in vapour cycles?

32. Name the different process of Rankine’s cycle T-s diagram?

33. What are the effects of condenser pressure on the cycle?

34. A vapour cycle inherently has two advantages over gas power cycle?

35. What are the limits of maximum and minimum temperature in a steam power cycle?

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36. Mention the improvements made to increase the ideal cycle efficiency of Rankine’s cycle?

37. Sketch the diagram of Rankine’s cycle indicating the main components?

38. What are the effects of condenser pressure in Rankine’s cycle?

39. Why Carnot cycle cannot be realized in practice for vapour cycle?

40. What are the disadvantages of Reheating?

41. List the advantages of Reheating?

UNIT – IV IDEAL AND REAL GASES ,THERMODYNAMIC RELATIONS

1) Determine the molecular volume of any perfect gas at 600N/m2 and 300C. Universal gas constant may be taken as 8314J/kg mole K?

2) State Boyle’s law?

3) State Joule’s law?

4) State Renault’s law?

5) State Avogadro’s law?

6) State Dalton’s law of partial pressure?

7) How does the Vander waals equation differ from the ideal gas equation of state?

8) What is meant by virtual expansion

9) Distinguish between ideal and real gas?

10) What is Maxwell relation?

11) Define joule-Thomson co-efficient?

12) Define co-efficient of volume expansion and isothermal compressibility?

13) What is compressibility factor?

14) Draw the generalized compressibility chart?

15) What does compressibility chart signify? And what is its value for an ideal gas at a critical point?

16) Why joule-Thomson co-efficient is it Zero for an ideal gas?

17) What is clapeyron Equation?

18) State Tds equation?

19) State the assumption made in kinetic energy theory of gases?7

20) State the Helmholtz function?

21) State Gibbs function?

22) What is mass fraction?

23) What is Molar fraction?

24) What is partial pressure and volume?

25) What is pure substance?

26) State Amagat’s law of partial pressure?

27) What are the properties of gas mixtures?

28) List the assumption are made for mixing of ideal gas?

29) What is real gas?

30) List properties of real gas?

31) Air contains 21% of O2 and 79% of nitrogen by volume. Determine molecular weight of air, R and density at S.T.P?

32) Differentiate STP & NTP?

33) List properties of ideal gas?

34) What is specific heat of an ideal gas?

35) Write the enthalpy value of an ideal gas?

36) What is equation state of ideal gas?

37) What is intermolecular force?

38) What is Shape factor?

39) Write the Vendar Waal’s equation?

40) What is Beattie-bridgeman equation of state?41) What is Benedict-Webb-Rubin equation of state?

42)What is Virial equation of state?

UNIT – V GAS MIXTURES AND PSYCHROMETRY

1. What is the difference between air conditioning and refrigeration?

2. Define psychrometry?

3. Name some psychrometric processes and represent them on the psychrometric chart?

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4. Define dry bulb temperature (DBT)?

5. Define wet bulb temperature?

6. Define dew point temperature?

7. Define Relative Humidity (RH) AND Specific humidity?

8. Differentiate between absolute and relative humidity.

9. Define DPT and degree of saturation?.

10. What is dew point temperature?

11. On a psychometric chart, show all the property lines?

12. Show the dew point and adiabatic saturation process n a skeleton T-s diagram ofWater?

13. State Dalton’s law of partial pressure?

14. Define Apparatus Dew Point (ADP) of cooling coil?

15. List down the psychrometric processes?

16. Define Bypass factor of a coil?

17. Define the humidification process?

18. State the effects of very high and a very low bypass factor?

19. What factors affect by pass factor?

20. What are the assumptions made while mixing two air streams?

21. Represent the following psychrometric processes using a skeleton psychrometric Chart?

21. What is dew point Depression?

22. What is adiabatic saturation temperature?

23. What are the substances used in chemical dehumidification?

24. What is sensible heat?

25. What is latent heat?

26. How does humidity affect human comfort?27. What is meant by adiabatic mixing?

28. Define sensible heat factor?

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29. Show the dew point and adiabatic saturation process on T-s diagram of water?

30. What is Wet bulb Depression?

31. What is meant by apparatus dew point temperature?

32. Define RSHF?

33. What is psychrometric?

34. Define GSHF?

35. Define chemical dehumidification?

36. What is adiabatic evaporative cooling?

37. Define adiabatic mixing of two streams?

38. What is infiltration air load?

39. What is equipment load?

40. What is fresh air load?

PART-BUNIT – I BASIC CONCEPT AND FIRST LAW OF THERMODYNAMICS

1. Mass of 15 kg of air in a piston cylinder device is heated from 250C to 900C by passing current through a resistance heater inside the cylinder. The pressure inside thecylinder is held constant at 300Kpaduring the process and the heat loss of 60KJ occurs. Determine the Electrical energy supplied in kW-hr and change in internal energy?

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2. Calculate the distance moved by a locomotive from consuming 2 tones of coal if 10% of the heat generated by coal is converted into coal gas then into mechanical work. The tractive effort required is 30tonne of dead mass of locomotive is 2500 tones. Assume 1kg of coal librates 35000 kJ of heat on burning.

3. The following data refers to a closed system, which undergoes a thermodynamics cycle consisting of four processes.Process Heat transfer kJ/min Work transfer kJ/mina-b 50,000 -b-c -5,000 34,200c-d -16,000 -2,200d-a - -3,000Show that the data is consistent with the first law of thermodynamics and calculate (a) Net rate of work output in MW (b) Efficiency of the cycle

4. A paddle wheel fixed to a shaft of an engine revolves in a closed hollow vessel containing water. This closed vessel is connected freely on the shaft and restraint to its turning moment is proved by mass attached to its side. Find the temperature rise for the following observations.Engine rpm = 650, Load applied = 60 kg at a leverage of 1.2m,Quantity of water = 200 kgDuration of test

5. During the summer season a room measuring 10 x 13 x 6 m3is cooled electrically from initial temperature 280O C to 200 OC. The air pressure inside the room is same as that of surroundings and is equal to 72 cm of Hg. The pressure remains constant during the cooling process. The cooling capacity of furniture and wall is 35kJ/k. The specific heat of air 1.005kJ/kg0k. Calculate the amount of electrical energy needed for cooling the room. How much air comes through gaps and windows during cooling period?

6. 25 Peoples attended the farewell party in small size room10 x 8m and has a 5m ceiling. Each person gives up about 350 kJ of heat / hour. Assuming that the room is completely sealed off and insulated, calculate the air temperature rise occurring within 10 minutes. Assume Cp, Cv and R and each person occupies a volume of 0.05m3

7. Prepare the chart for non-flow process and derive the formula for PV& T relations, work done, internal energy, heat transfer, enthalpy & entropy

8. Mass of 15kg of air in a piston cylinder device is heated from 250C to 900C by passing current through a resistance heater inside the cylinder. The pressure inside the cylinder is held constant at 300 kPa during the process and a heat loss of 60 kJ occurs. Determine the electrical energy supplied in kW – hr and change in internal energy.

9. Derive the steady flow energy equation with its application?

10. In a vessel of 10 kg of O2 is heated in a reversible non flow constant volume process, so that pressure of O2 is increased two times that of initial value. The initial temperature is 200C. Calculate the final temperature, change in internal energy, change in enthalpy, heat transfer & entropy. Take R = 0.259kJ/kgkCv = 0.625kJ/kgk for Oxygen

11. 5 kg of air at 400C and 1 bar is heated in a reversible non flow constant pressure process until the volume is doubled. Find (a) change in volume (b) work done (c) Change in internal energy (d) Change in enthalpy

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12. 0.25 kg of air at a pressure of 1 bar occupies the volume of 0.3m3. If this air expands isothermally to a volume of 0.09m3. Find the initial air temperature and final temperature, external work done, heat observed by the air, change in internal energy.

13. 1.5 kg of certain gas at pressure of 8bar and 200C occupies a volume of 0.05m3 it expands adiabatically to a pressure of 0.9 bar and volume 0.73 m3 Determine the work done during the process, gas constant, ratio of specific heats, value of two specific heats, change in internal energy and change in enthalpy.

14. A 1 kg of ideal gas of molecular weight 30 and specific heat ratio 1.4 is compressed according to law of PV1.25 = C from 1bar absolute and 270C to pressure of 16bar Absolute. Calculate the temperature at the end of compression, heat rejected, work done on the gas duringtheprocess, change in enthalpy

15. A turbine operates under steady flow condition receives steam at the following state pressure = 1.2Mpa, Temperature =1880C, Enthalpy = 2785 kJ/kg, velocity = 33.3m/sec and elevation = 3m. The steam leaves the turbine at the following state: pressure = 20Kpa, Enthalpy = 2512 kJ/kg, velocity = 100m/sec and elevation = 0m. Heat is lost to the surrounding at the rate of 0.29kJ/sec. If the rate steam flow to the turbine is 0.42kg/sec what is the power output of the turbine in KWM.

16. air at temperature of 150C , passes through a heat exchanger at velocity of 30m/s , where as its temperature is raised 8000C. it then enters a turbine with the same velocity of 30 m/s and expands until the temperature falls to 6500C. On leaving the turbine, the air is taken at velocity of 60m/s to nozzle were it expands until the temperature has fallen to 5000 C. if the air flow rate is 2 kg/s Calculate: the rate of heat transfer to the air in the heat exchanger, the power output from the turbine assuming no heat loss the velocity at exit from the nozzle Assuming no heat loss. take the enthalpy of air as h = Cpt, where Cp is the specific heat equals to 1.005kJ/kg k and ‘t’ the temperature.

17. A mass of air is initially at 2600C and 700Kpa and occupies 0.028m3. The air is expanded at constant pressure to 0.084m3. A polytropic process with n = 1.5 is then carried out, following by constant temperature process all process are reversible (a) Sketch the cycle pV& Ts planes.(b) Find the heat received and rejected in the cycle.(c) Find the efficiency of cycle.

18. A gas of mass 1.5kg undergoes a Quasi-Static expansion which follows a relationship p=a+bV, where ‘a’ and ‘b’ are constants. The initial and final pressures are 1000 & 200Kpa and the corresponding volumes are 0.2 & 1.2m3. The specific internal energy of the gas is given by the relation u = 1.5pV-85 kJ/kg where p is Kpa and V is in m 3. Calculate the net heat transfer and the maximum internal energy of the gas attain during expansion.

19. Air flows steadily at the rate of 0.5kg/sec through an air compressor, entering at 7m/sec velocity, 100 kPa pressure and 0.95 m3/kg, volume leaving at 5m/sec, 700kPa and 0.19 m3/kg. The internal energy of the rate leaving is 90kJ/kg greater than that of the air entering. Cooling water in compressor jackets absorbs heat from the air at the rate of

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58kW (a) Compute the rate of shaft work input to air in kW. (b) Find the ratio of the inlet pipe diameter to the outlet pipe diameter.

20. Define internal energy and prove that its point functions? And establish relationship between the specific heat at constant pressure and specific heat at constant volume?

UNIT – II SECOND LAW AND AVAILABILITY ANALYSIS

1. Derive the expression for thermal efficiency of a Carnot cycle with its p-V and Ts Diagram?

2. Explain the Clasius inequality with its p-V diagram?

3. Derive the expression for change in entropy for the following process (i)Isochoric (ii) Isobaric (iii) Isothermal (iv) Isentropic (v) Polytropic

4. Explain the absolute entropy, absolute enthalpy and absolute internal energy?

5. An inventor claims to have developed a refrigerating unit which maintains the refrigerated space at -60C while operating in a room where temperature is 270C and has COP 8.5. Find out whether his claim is correct or not?

6. A heat engine is used to drive a heat pump. The heat transfer from a heat engine and from the heat pump is used to heat the water?

7. A Carnot engine takes heat from an infinite reservoir at 5500C and rejects it to a sink2750C. Half of the work delivered by the engine is used to run generator and the other half is used to run heat pump which takes heat at 2750C and rejects it at 4400C. Express the heat rejected at 4400C by the heat pump as % of heat supplied to the engine at 5500C. If the operation of the generator is 500W, Find the heat rejected/hour by the heat pump at 4400C?

8. A Heat engine operates between a source at 6000C and a sink at 600C. Determine the least rate of heat rejection/ kW net output of the engine?

9. 0.2kg of air at 1.5bar and 270C is compressed to a pressure of 15bar according to the law of PV1.25=C. Determine work done on or by air, heat flow to or from the air, increase or decrease in entropy?

10. A reversible heat engine operates between a source at 8000C and a sink 300C. What are least rate of heat rejection / kW network output of the engine?

11. 1 kg of ice melts at constant atmospheric pressure and at 00C to form liquid water. If the latent heat of fusion of ice is 333.3kJ/kg, Calculate the entropy change during process?

12. Explain the corollaries of second law of thermodynamics with suitable example?

13. Three identical bodies of A, B & C constant heat capacity are at temperature of 300, 300 & 100K. a heat engine is operated between A and B and a heat pump working as refrigerator is operated between B and C. The heat pump is operated by the output of the

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engine. If the work or heat supplied from outside, find the highest temperature to which any one of body can be raised by the operation of the heat engine or refrigerator?

14. Explain reversibility?

15. Find the change in entropy of 1kg of ice which is heated from -50C to 00C. Cp ice = 2.093 kJ/kg0K. The pressure during heating is maintained at 1 atm constant. Latent heat of fusion of ice=334.96 kJ/kg

16. Give the expression to find change in entropy during constant pressure?

17. A domestic food freezer maintains a temperature of -150C. The ambient air is 300C. If the leaks into freezer at a continuous rate of 1.75kg/sec, What is the least power necessary to pump the heat out continuously?

18. Derive absolute entropy for closed cycle processes?

19. 5kg of air at 2bar and 300C is compressed to 24bar pressure according to the law of PV1.2=C. After compression air is cooled at constant volume to 300C. Determine the volume and temperature at the end of compression, Change in entropy during compression, Change in entropy during constant volume of cooling Take Cp=1.005kJ/kgK, Cv=0.715kJ/kg0K.

20. Derive the availability analysis to open cycle processes?

UNIT – III PROPERTIES OF PURE SUBSTANCE AND STEAM POWER CYCLE

1. Explain the process of steam formation with help of T-H diagram?

2. Calculate the state of a steam using steam table.(a) Steam has a pressure of 15bar and specific volume of 0.12m3/kg (b) Steam has a pressure of 10bar and temperature of 2000C.(c) Steam has a pressure of 30bar and Enthalpy 2700kJ/kg.

3. Explain the Phase rule?

4. Draw the p-V diagram of pure substance and explain its various regions of the diagram in details?

5. In a steam power plant operating on an ideal reheat Rankine’s cycle, the steam enters the high pressure turbine at 3Mpa and 4000C. After expansion to 0.6Mpa, the steam is reheated to 4000C and then expanded the low pressure turbine to the condenser pressure of 10kPa. Determine the thermal efficiency of the cycle and the quality of the steam at the outlet of low pressure turbine?

6. Draw the p-T diagram of pure substance and explain its various regions of the diagram in details?

7. Explain the p-v-T surfaces of water and CO2?

8. Explain mollier diagram with neat sketch and give advantages?

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9. A reheat cycle operating between 30bar to 0.04bar has a superheat and reheats temperature of 4500C. The first expansion takes place till the steam is dry saturated and then reheat is given. Neglecting feed pump work determines the ideal cycle efficiency?

10. With help of T-s diagram explain the various process of ideal Rankine’s cycle and derive the efficiency in terms of enthalpy?

11. Why the Rankine’s cycle used as a standard reference for the steam power cycle rather than Carnot cycle?

12. How can be the Rankine’s cycle modified for reciprocating steam engine plants? why?

13. What is the effect of Rankine’s cycle efficiency when the steam is supplied at the inlet of the turbine is (a) Dry saturated (a) wet with dryness fraction ‘x’ and (c) Superheated?

14. Explain process of reheating with help of T-s diagram in the Rankine’s cycle? Why it is used?

15. A steam power plant uses steam at boiler pressure of 150bar and temperature 5000C at condenser pressure of 0.1bar.find the quality of steam at turbine exhaust, cycle efficiency and steam rate?

16. Explain the ideal regenerative Rankine’s cycle with help of T-s & diagram? What arethe effects of regeneration on efficiency of the cycle?

17. Why the ideal regenerative cycle is not practical and how to modify it for practical purpose?

18. Draw the schematic and T-s diagram for regenerative Rankine’s cycle with two feed water heater, and obtain the expression for mass of steam extracted for each heater?

19. In a single regenerative cycle the steam enters the turbine at 30bar and 4000C and the exhaust pressure is 0.1bar. The condensate is heated in a direct contact type heater which operates at 5bar. Find the efficiency and the steam rate of the cycle and the increase in mean temperature of heat addition, efficiency and steam rate as compared to the rankine’s cycle. Neglect the pump work?

20. A steam boiler generates steam at 30bar; 3000C t the rate of 2kg/sec. the steam is expanded isentropically in a turbine to a condenser pressure of 0.05bar, condensed at constant pressure and pumped back to boiler.(a) Draw the schematic arrangement of the above plant T-s diagram of Rankine’s cycle.(b) Find heat supplied in the boiler/hr.(c) Determine the quality of steam after expansion(d) What is power generated by the turbine(e) Estimate the Rankine’s efficiency considering pump work?

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UNIT – IV IDEAL AND REAL GASES ,THERMODYNAMIC RELATIONS

1. State anyone equation of state for real gas and show how the deviation from ideal gas behavior is accounted for?

2. Prove the difference in specific heat capacities equal to Cp-Cv=R and Cp-Cv=TVβ2/ kT

3. Deduce the Maxwell relations from thermodynamic property relations?

4. Using Maxwell relations Cp-Cv=TVβ2/ kT where β is the volume of expansivity and kT is the isothermal compressibility?

5. Explain the construction and give the use of generalized compressibility chart?

6. Explain the flow process of a real gas through a throttle valve. Derive the expression for joule Thomson coefficient and deduce its value for an ideal gas?

7. Methane at 1.013bar and 300C enters an insulated mixing chamber at rate of 5kg/sec. It is mixed with air at 1bar in an air/methane mass ratio of 18. The flow is stead and kinetic energy changes are negligible. Ambient pressure and temperature are 1.013bar and 300C, determine (a) the temperature of the mixing /kg of methane. Take Cv and Cp of methane as 1.7354kJ/kg/k and 2.2537 kJ/kg/k respectively.

8. Find the increase in entropy when 7.5kg of O2 at 700C are mixed with 8kg of nitrogen at the same temperature. The initial pressure of each constituent is 103kPa and is the same as that of mixture?

9. Explain the Dalton’s law of partial pressure?

10. A mixture of perfect gases at 250C contains 65% of N2, 20% O2 and 25% CH4 by volume. If the partial pressure of CH4 is 65kPa, determine (a) The partial of N2 and O2(b) Mass proportion of mixture (c) gas constant for the mixture and (d) Volume/mole of mixture.

11. Compute the specific volume of steam at 1bar and 5500K using Vander waals equation. Take critical temperature of steam is 647.30K and critical pressure is 220.9bar.

12. Explain the Clapeyron equation of partial pressure?

13. Prove that Cp of ideal gas is a function of temperature only?

14. A mixture of 2kg O2 and 2kg of Argon is in insulated piston cylinder arrangement at 100kPa, 3000K. The piston now compresses the mixture to half its initial volume. Molecular weight of O2 is 32 and for argon are 40. ratio of specific heats for O2 is 1.39 and for argon is 1.667.

15. A mixture of Ideal gases consists of 3kg pf N2 and 5kg of CO2 at a pressure of 300kPa and a temperature of 200C. Find (a) The mole fraction of each constituents (b) the

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equivalent Molecular weight of mixture (c) The equivalent gas constant of the mixture (d) The partial pressures and the partial volumes?

16. 0.45kg of CO and 1kg of air is contained in a vessel of volume 0.4m3at 150C. Air has 23.3% of O2 and 76.7% of N2 by mass. Calculate the partial pressure of each constituents and total pressure in the vessel. Molar volume of CO, CO2 and N2 are 28, 32 and 28kg/kmol.

17. Obtain the expression for ds in terms of dT and dp?

18. The equation of state in the range of pressure and temperature by v=RT/p – C/T: where C is constant. Derive the expression for the change of enthalpy and entropy for this substance during an isothermal process?

19. Using Clausius Cleperyon’s equation, Estimate the enthalpy of vaporization at 2200C saturation temperature. Take the following data Ts = 2200C; vg = 0.08603m3/kg; vf =0.00119m3/kg.

20. Explain the Joule’s Thomson Co-efficient detailly?

UNIT – V GAS MIXTURES AND PSYCHROMETRY

1. Give short notes on following (a) Specific humidity (b) Relative humidity (c) Dew point temperature (d) Wet bulb depression

2. Explain adiabatic saturation process?

3. Explain bypass factor of cooling coil and state its effects?

4. In an adiabatic mixing of two streams, derive the relationship among the ratio of enthalpy change and ratio of specific humidity change?

5. Air has a dry bulb temperature of 250C and wet bulb temperature of 150C. If the barometer reads 1bar, Calculate(a) Vapour pressure(b) Specific humidity (c) Saturation ratio(d) Relative humidity(e) Dew point temperature(f) Vapour density(g) Enthalpy of mixture.

6. An air water mixture at 200C and 1 bar has relative humidity 80% Calculate(a) Partial pressure of the vapour and the air(b) Specific humidity (c) Saturation ratio(d) Dew point temperature(e) Density of air(f) If the mixture is cooled at constant pressure to a temperature of 100C, find the amount of water – vapour condensed / kg of dry air?

7. The atm air has a dry bulb temperature of 200C and the specific humidity of 0.0095kg/kg of dry air. If the barometer reads 760mm of Hg, determine(a) Partial pressure of the vapour (b) Relative humidity(c) Dew point temperature.

8. The sling psychrometer in a laboratory test recorded the following readingsDry bulb temperature = 250C, Wet bulb temperature = 150C, 15Barometer readings = 760 mm of Hg, Partial pressure = 10 mm of Hg,Determine the specific humidity and saturation ratio?

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9. A mixture of air and water vapour possesses a volume of 700m3at 1 pressure and temperature 350C. Its relative humidity is 75%. Find the specific humidity, dew point temperature, mass of air and mass of vapour in the mixture?

10. Atmospheric air at 76cm of Hg has 250C dry bulb temperature and 150C wet bulb temperature using Psychrometric chart Calculate the following(a) Relative humidity(b) Humidity ratio(c) Dew point temperature(d) Enthalpy(e) Partial pressure of water (f) Specific volume of air(g) Saturation pressure corresponding to dry bulb temperature.(h) Saturation pressure corresponding to wet bulb temperature.

11. Atmospheric air at 1bar pressure has 300C dry bulb temperature and 50% relative humidity. Using psychrometric chart calculate the dew point temp, enthalpy and vapour pressure?

12. An air conditioning system is designed under the following condition: Outdoor condition - 350C DBT and 70% RH Required indoor condition – 250C DBT and 75% RH Amount of fee air circulated – 250m3/min Coil dew point temperature – 150CThe required condition is achieved by first cooling and dehumidification. Calculate the Capacity of cooling coil in TOR, Capacity of heating in kW, Mass of water vapour removed in kg/sec.

13. 2kg of air at 300C, 65% RH is mixed adiabatically with 5kg of air at 200C, 10%RH. Determine final condition of the mixture?

14. Air at 20 0C, 40% RH is mixed with adiabatically with air 400C, 40% RH in the ratio of 1kg of the former with 2kg of the later (on the dry basis) Find the final condition?

15. An air water vapour mixture at 0.1Mpa, 300C, 80% RH has a volume of 50m3.Calculate the specific humidity, dew point temp, Mass of dry air and mass of water vapour?

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