CONSECUTIVE 15 ANNA UNIVERSITY QUESTION PAPER
B.E./B.Tech. DEGREE EXAMINATIONS, NOV./DEC. 2011
(Regulations 2008)
Third Semester Mechanical Engineering
ME2202 Engineering Thermodynamics
( Common to PTME 2202 Engineering Thermodynamics for B.E.(Part
-Time) Third Semester Mech - Regulations 2009; Use of approved thermodynamic tables, Mollier diagram, Psychometric chart and Refrigerant property tables are permitted in the examination.)
Time: Three Hours Maximum: 100 marks
Answer ALL Questions
Part A - (10 x 2 = 20 marks)
1. Distinguish between the terms 'state' and 'process' of thermodynamics.
2. Show that energy of an isolated system is always constant.
3. What is a cyclic heat engine?
4. What do you mean by entropy generation?
5. What is a pure substance? Give examples.
6. Why is Carnot cycle not practicable for a steam power plant?
7. What is equation of state? State the van der Waals equation for a real gas of m kg.
8. What is the partial pressure of carbon dioxide in a container that holds 5 moles of carbon dioxide, 3 moles of nitrogen and 1 mole of hydrogen and has a total pressure of 1.05 atmospheres?
9. What is a psychrometer?
10. Sketch the Cooling and Humidifying process on a skeleton Psychrometric chart.

Part B - (5 x 16 = 80 marks)
11. (a) (i) Define the following terms:
(1) Thermodynamics
(2) Macroscopic approach
(3) Continuum(6)
(ii) 25 people attended a farewellparty in a small room ofsize 10 x 8 m and have a 5 m ceiling.
Each person gives up 350 kJ ofheat per hour. Assuming that the room is completely sealed off and insulated, calculate the air temperature rise occurring in 10 minutes. Assume Cv of air
0.718 kJ/kg K and R = 0.287 kJ/kg K and each person occupies a volume of 0.05 m3. Take p
= 101.325 kPa and T = 20°C. (10)
OR
11. (b) (i) Considering a system which changes its state, prove that the internal energy is a point function. (8)
(ii) Air flows at the rateof0.5 kg/sthrough an air compressor, entering at 7 m/s,, 100 kPa and
0.95 m3/kg and leaving at 5 m/s, 700 kPa, and 0.19 m3
/kg. The internal energy of air leaving is 90 kJ/kg greater than that of the air entering. Cooling water in the compressor jackets absorbs heat from the air at the rate of 58 kW. (1) Compute the rate of shaft work input to the air in kW (2) Find the ratio of the inlet pipe diameter to outer pipe diameter. (8)
12. (a) (i) An engine is supplied with 1120 kJ/s of heat. The source and sink temperature are maintained at 560°K and 280°K. Determine whether the following cases represent the reversible, irreversible or impossible heat engines.

(1) 900 kW of heat rejected
(2) 560 kW of heat rejected
(3) 108 kW of heat rejected(8) www.chennaituitions.inwww.chennaituitions.in
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(ii) A heat pump working on the Carnot cycle takes in heat from a reservoir at 5°C and delivers heat to a reservoir at 60°C. A heat engine is driven by a source at 840°C and rejects heat to a reservoir at 60°C. The reversible heat engine, in addition to driving the heat pump, also drives a machine that absorbs 30 kW. If the heat pump extracts 17 kJ/s from the 5°C reservoir, determine (1) the rate ofheat supply from the 840°C source, and (2) the rate of heat rejection to the 60°C sink. (8)
OR
12. (b) (i) Derive an expression for the change in entropy of a perfect gas during polytropic process in terms of T1 and T2. (8)
(ii) 2 kg of water at 90°C is mixed with 3 kg of water at 10°C in an isolated system. Calculate the change of entropy due to the mixing process. (8)
13. (a) Two streams of steam, one at 2 MPa, 300°C and the other at 2 MPa, 400° C, mix in a steady flow adiabatic process. The rates of flow of the two streams are 3 kg/min and 2 kg/min respectively. Evaluate the final temperature of the emerging steam, if there is no pressure drop due to the mixing process. What would be the rate of increase in the entropy of the universe? This steam with negligible velocity now expands adiabatically in a nozzle to a pressure of 1 kPa. Determine the

exit velocity of the stream and exit area of the nozzle.(16)
OR
13. (b) (i) Define specific steam consumption, specific heat rate and work ratio. (6)
(ii) In a Rankine cycle, the steam at inlet to turbine is saturated at a pressure of 35 bar and the exhaust pressure is 0.2 bar. The flow rate of steam is 9.5 kg/s. Determine (1) the pump work (2) the turbine work (3) Rankine efficiency (4) condenser heat flow (5) work ratio and (6) specific steam consumption. (10)
14. (a)(i) A vesselofvolume 0.3 m3 contains 15 kg of air at 303 K. Determine the pressure exerted by the air using, (1) Perfect gas equation (2) van der Waals equation. Take critical temperature of air as 132.8 K. Critical pressure of air is 37.7 bar. (6)
(ii) A perfect gas mixture consists of 4 kg of N2 and 6 kg of CO2 at a pressure of 4 bar and a temperature of 25°C. For N2: Cv = 0.745 kJ/kgK and Cp = 1.041 kJ/kgK. For CO2: Cv = 0.653 kJ/kgK and Cp = 0.842 kJ/kgK. Find Cp , Cv and R of the mixture. If the mixture is heated at constant volume to 50°C, find the changes in internal energy, enthalpy and entropy of the mixture.(10)
OR
14. (b) (i) Derive and explain the Maxwell's relations. (8)
(ii) Derive the T dS equation taking T and p as independent variables. (8)
15. (a) Atmospheric air at 1.0132 bar has a DBT of 32°C and a WBT of 26°C. Find(i) the partial pressure of water vapour (ii) the specific humidity (iii) the dew point temperature (iv) the relative humidity (v) the degree of saturation (vi) the density of the air in the mixture (vii) the density

of the vapour in the mixture (viii) the enthalpy of the mixture. (8x2 = 16)
OR
15. (b) (i) Explain the process of heating with humidification of air, with the help of sketches of schematic of air duct with the elements involved as well as the representation on psychrometric chart.
(6)
(ii) 1 kg of air at 40°C DBT and 50% relative humidity is mixed with 2 kg of air at 20°C DBT and
20°C dew point temperature. Calculate the specific humidity, enthalpy and the dry bulb temperature wwof the mixture. (10) w.chennaituitions.inwww.chennaituitions.in
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B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011
Third Semester
Mechanical Engineering
ME 2202 — ENGINEERING THERMODYNAMICS (Regulation 2008)
(Common to PTME 2202 Engineering Thermodynamics for B.E (Part-Time) Mechanical
Engineering Third Semester - Regulation 2009)
Time : Three hours Maximum : 100 marks
Answer ALL questions
PART A — (10 x 2 = 20 marks)
1.Calculate the actual pressure of air in the tank if the pressure of compressed air measured by manometer is 30 cm of mercury and atmospheric pressure is 101 kPa. (Take g
= 9.78 m/s2
)
2. What is meant by 'Hyperbolic Process'?

3. List out the generic types of irreversibilities.
4. State : Carnot Theorem and Its Corollaries.
5. What do you understand from the word 'Dryness fraction'?
6. What are the ways by which Rankine cycle efficiency may be improved?
7. State : Dalton's law of partial pressures.
8. What do you mean by ‘‘Compressibility factor’’?
9. Define : Relative humidity.
10. What do you understand from the ‘‘Dew point temperature’’?
PART B — (5 x 16 = 80 marks)
11. (a) A gas contained in a cylinder is compressed from 1 MPa and 0.05 m3 to
2 MPa. Compression is governed by pF" constant. Internal energy of gas is given by; U =7.5 PV
-425, kJ. where P is pressure in kPa and V is volume in m3
. Determine heat, work and change in internal energy assuming compression process to be quasistatic. Also find out work interaction, if the
180 kJ of heat is transferred to system between same states.Also explain why it is different from above? (16)
Or
(b) In a gas turbine installation air is heated inside heat exchanger up to 750 °C from ambient temperature of27 °C. Hot air then enters into gasturbine with the velocity of50 m/s and leaves at 600
°C. Air leaving turbine enters a nozzle at 60 m/s velocity and leaves nozzle at temperature of
500 °C
For unit mass flow rate of air determine the following assuming adiabatic expansion in turbine and

nozzle, (16)
(i) Heat transfer to air in heat exchanger (ii) Poweroutput from turbine (iii) Velocity at exit of nozzle. Take up for air as 1.005 kJ/kg° K.
12. (a) A reversible heat engine operates between two reservoirs at 827 °C and 27°C.
Engine drives a Carnot refrigerator maintaining -13°C and rejecting heat to reservoir at 27°C.
Heat input to the engine is 2000 kJ and the net work available is 300 kJ. How much heat is transferred to refrigerant and total heat rejected to reservoir at 27 °C? (16)
Or
(b) (i) How do you differentiate the Exergy (Availability) and energy based upon their characteristics? (4)
(ii) Determine the rate of power loss due to irreversibility in a heat engine operating between temperatures of 1800 K and 300 K. Engine delivers 2 MW of power when heat is added at the rate of
5MW. (12) www.chennaituitions.inwww.chennaituitions.in
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13. (a) In a closed vessel the 100 kg of steam at 100 kPa, 0.5 dry is to be brought to a pressure of 1000 kPa inside vessel. Determine the mass of dry saturated steam admitted at
2000 kPa for raising pressure. Also determine the final quality.
Or
(b) A steam power plant running on Rankine cycle has steam entering HP turbine at 20 MPa,
500
°C and leaving LP turbine at 90% dryness. Considering condenser pressure of 0.005 MPa and

reheating occurring up to the temperature of 500 °C determine, (16)
(i) The pressure at which steam leaves HP turbine (ii) The thermal efficiency, (iii)
Work done.
14.(a)In 5 kg mixture of gases at 1.013 bar and 300 K the various constituent gases are as follows, 80% N2, 18% O2, 2% CO2. Determine the specific heat at constant pressure, gas constant for the constituents and mixture and also molar mass of mixture taking y = \A for N2 and
O2 and γ = 3.1 for CO2. Universal gas constant =8314J/kg.K. (16)
Or
(b) Derive the Clausius Clapeyron equations and Vander Waal's equations.(16)
15.(a) For the atmospheric air at room temperature of 30 °C and relative humidity of 60% determine partial pressure of air, humidity ratio, dew point temperature, density and enthalpy of air.
(16)
Or
(b) Two streams of moist air, one having flow rate of 3 kg/s at30 °C and 30% relative humidity, other having flow rate of2 kg/s at 35°Cand 85% relative humidityget mixed adiabatically.
Determine specific humidity and partial pressure of water vapour after mixing. Take CP, Stream = 1.86 kJ/kg.K.
(16) www.chennaituitions.inwww.chennaituitions.in
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B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010
Third Semester
Mechanical Engineering

ME 2202 — ENGINEERING THERMODYNAMICS (Regulation 2008)
(Common to PTME 2202- Engineering Thermodynamics for B.E. (Part-Time) Third Semester
Mechanical Engineering Regulation 2009)
Time : Three hours Maximum : 100 Marks
(Use of Standard Thermodynamic tables, Mollier diagram,
Psychrometric Chart and Refrigerant Property Tables is permitted)
Answer ALL questions
PART A — (10 x 2 = 20 Marks)
1. What are point and path functions? Give some examples.
2. Distinguish between stored energies and interaction energies.
3. What is the difference between a refrigerator and a heat pump?
4. How do the values of the integrals compare for a reversible and irreversible process between the same end states?
5. Why are the temperature and pressure dependent properties in the saturated mixture region?
6. What are the four processes that make up the simple ideal Rankine cycle?
7. Using the definitions of mass and mole fractions derive a relation between them.
8. What does Joule —Thomson coefficient represent?
9. How do constant-enthalpy and constant wet bulb temperature lines compare on the psychrometric chart?
10. Moist air is passed through a cooling section where it is cooled and dehumidified. How do the specific humidity and the relative humidity of air change during this process?
PART B — (5 x 16 = 80 Marks)

11. (a) A rigid tank containing 0.4 m3 of air at 400 kPa and 30°C is connected by a valve to a piston cylinder device with zero clearance. The mass of the piston is such that a pressure of200 kPa is required to raise the piston. The valve is opened slightly and air is allowed to flow into the cylinder until the pressure of the tank drops to 200 kPa. During this process, heat is exchanged with the surrounding such that the entire air remains at 30°C at all times. Determine the heat transfer for this process. (16)
Or
(b) The electric heating system used in many houses consists of simple duct with resistance wire.
Air is heated as it flows over resistance wires. Consider a 15 kW electric heating system. Air enters the heating section at 100 kPa and 17°C with a volume flow rateof150 m3
/min. Ifheat is lost from the air in the duct to the surroundings at a rate of 200 W. determine the exit temperature of air.(16)
12. (a) Air is compressed by an adiabatic compressor from 100 kPa and 12 °C to a pressure of 800 kPa at a steady rate of 0.2 kg/s. If the isentropic efficiency of the compressor is
80 percent, determine the exit temperature of air and the required power input to the compressor.(16)
Or
(b) A 200 m3 rigid tank initially contains atmospheric air at 100 kPa and 300 K and is to be used as

storage vessel for compressed air at 1 Mpa and 300 K. Compressed air is to be supplied by a compressor that takes in atmospheric air at Po = 100 kPa and To = 300 K. Determine the minimum work required for this process. (16)
13. (a) (i)A 0.5 m3 vessel contains 10 kg refrigerant 134a at -20°C. Determine the pressure, the www.chennaituitions.inwww.chennaituitions.in
Page 6 of 31 total internal energy and the volume occupied by the liquid phase. (6)
(ii) A rigid tank with a volume of 2.5 m3 contains 15 kg of saturated liquid vapour mixture of water at 75°C. Now the water is slowly heated. Determine the temperature at which the liquid in the tank is completely vaporized. Also, show the processes on T-v diagram with respect to saturation lines. (10)
Or
(b) Consider a steam power plant that operates on a reheat Rankine cycle and has a net power output of 80 MW. Steam enters the high-pressure turbine at 10 MPa and 500°C and the lowpressure turbine at 1 MPa and 500°C. Steam leaves the condenser as a saturated liquid at a pressure of
10 kPa.
The isentropic efficiency of the turbine is 80 percent, and that of the pump is 95 percent. Show the cycle on a T-s diagram with respect to saturation lines, and determine
(i) the quality (or temperature, if superheated) of the steam at the turbine exit,

(ii) the thermal efficiency of the cycle, and
(iii) the mass flow rate of the steam. (16)
14. (a) (i)A rigid tank contains 2 kmol of N2 and 6 kmol of CO2 gases at 300 K and 15 MPa.
Estimate the volume of the tank on the basis of
(1) the ideal-gas equation of state,
(2) compressibility factors and Amagat's law, and
(3) compressibility factors and Dalton's law. (8)
(ii) An insulated rigid tank is divided into two compartments by a partition. One compartment contains 7 kg of oxygen gas at 40°C and 100 kPa, and the other compartment contains 4 kg of nitrogen gas at 20°C and 150 kPa. Now the partition is removed, and the two gases are allowed to mix. Determine
(1) the mixture temperature and
(2) the mixture pressure after equilibrium has been established.(8)
Or
(b) (i) Using the ideal-gas equation of state, verify
(1) the cyclic relation and (2) the reciprocity relation at constant P. (4)
(ii) Show that the internal energy of an ideal gas and an incompressible substance is a function of temperature only, u = u(T). (6)
(iii) Derive expressions [puloP)T and {phiov)T in terms of P, v, and T only (6)
15. (a) (i) A 5 m x 5 m x 3 m room contains air at 25°C and 100 kPa at a relative humidity of 75 percent. Determine
(1) the partial pressure of dry air,
(2) the specific humidity,

(3) the enthalpy per unit mass of the dry air, and
(4) the masses of the dry air and water vapour in the room. (8)
(ii) The dryand the wet-bulb temperatures of atmospheric air at 1 atm (101. 325 kPa) pressure are measured with a sling psychrometer and determined to be 25°C and 15°C respectively.
Determine
(1) the specific humidity,
(2) the relative humidity, and
(3) the enthalpy of the air using thermodynamic relations. (8)
Or
(b) (i)What is sensible heat? How is the sensible heat loss from a human body affected by the
(1) skin temperature,(2) environment temperature, and (3)air motion? (6)
(ii) Saturated air leaving the cooling section of an air-conditioning system at 14°C at a rate of 50 m
3
/min is mixed adiabatically with the outside air at 32°C and 60 percent relative humidity at a rate of
20 m3
/min. Assuming that the mixing process occurs at a pressure of 1 atm, determine the specific humidity, the relative humidity, the dry bulb temperature, and the volume flow rate of the mixture.
(10) www.chennaituitions.inwww.chennaituitions.in
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B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010 ,

Third Semester
Mechanical Engineering
ME2202 — ENGINEERING THERMODYNAMICS
(Regulation 2008)
Time: Three hours Maximum: 100 Marks
(Use of Standard Thermodynamic Tables, Mollier Diagram, Psychometric Chart and
Refrigerant Property Tables is permitted)
Answer ALL Questions
PART A — (10 x 2 = 20 Marks)
1. What do you understand by flow work? Is it different from displacement work?
2. Which property of a system increases when heat is transferred:
(a) At constant volume
(b) At constant pressure?
3. What do you understand by dissipative effects? When work is said, to be dissipated?
4. Isentropic process need not be necessarily an adiabatic process - Justify.
5. What is.critical state? Define the term critical pressure, critical temperature and critical volume of water.
6. Why is Carnot Cycle not practicable for a steam power plant?
7. Write down the Vender Waals equation of state. How does it differ from the ideal gas equation of state?
8. Define Joule - Kelvin effect. What is inversion temperature?
9. Define specific humidity. How does it differ from relative humidity?
10. What is evaporative cooling? Will it work in humid climates?
PART B — (5 x 16 = 80 Marks)

11. (a) (i) The resistance of the windings in a certain motor is found to be 75 ohms at room temperature (25°C). When operating under full load under steady state conditions, the motor is switched off and the resistance of the windings is immediately measured again and found to be 90 ohms. The windings are made of copper whose resistance at temperature at t °C is given by Rt = R0 [1+0.00393t] where Ro is the resistance at
0°C. Find the temperature by the coil during full load. (8)
(ii) At the beginning of the compression strode of a two-cylinder internal combustion engine the air is at a pressure of 101.325 kPa. Compression reduces the volume by 1/5 of its original volume, and the law of compression is given by pv1.2
= constant. If the bore andstroke of each cylinder is 0.15 m and 0.25 m respectively, determine the power absorbed in kW by compression strokes when the engine speed is such that each cylinder undergoes 500 compression strokes per minute. '
(8)
Or www.chennaituitions.inwww.chennaituitions.in
Page 8 of 31
(b) (i) The properties of a system, during a reversible constant pressure non-flow process at
P = 1.6 bar changed from v1=0.3m3
/kg,T1 =20°C to v2 = 0.55m3
/kg, T2 =260°C. The specific heat of the fluid is given by Cp = [1.5+(75/T+45)] kJ/kg°C where T is in °C.
Determine, the heat added, work done, change in internal energy and change inenthalpy per kg of fluid. (8)

(ii) A nozzle is a device for increasing the velocity of a steadily flowing stream. At the inlet to a certain nozzle, the enthalpy of the fluid passing is 3000 kJ/kg and the velocity is 60 m/s. At the discharge end, the enthalpy is 2762 kJ/kg. The nozzle is horizontal and there is negligible heat loss from it.
(1) Find the velocity at exit from the nozzle.
(2) If the inlet area is 0.1 m2 and the specific volume at the inlet 4 is 0.187 m3
/kg, find the mass flow rate.
(3) If the specific volume at the nozzle exit is 0.498 m3
/kg, find the exit area of the nozzle. (8)
12. (a) (i) Show that the efficiency of a reversible engine operating between two given constant temperatures is the maximum. (8)
(ii) A heat pump working on the Carnot cycle takes in heat from a reservoir at 5°C and delivers heat to a reservoir at 60°C. The heat pump is driven by u reversible heat engine which takes heat from reservoir at 840°C and rejects heat to a reservoir at 60°C. The reversible heat engine also drives a machine that absorbs 30 kW. If the heat pump extracts 17 kJ/s from the reservoir at 5°C, determine
(1) The rate of heat supply from 840°C source, and
(2) The rate of heat rejection to 60°C sink. (8)
Or
(b) (i) Determine the maximum workobtainable by using one finite bodyat temperature T and a thermal energy reservoir at temperature To, T>T0. (8)

(ii) An aluminium block (cp =400J/kgK) with a mass of 5 kg is initially at 40°C in room air at 20°C. It is cooled reversibly by transferring heat to a completely reversible cyclic heat engine until the block reaches 20°C. The 20°C room air serves as a constant temperature sink for the engine. Compute
(1) The change in entropy for the block,
(2) The change in entropy for the room air,
(3) The work done by the engine. (8)
13. (a) (i) Steam flows through a small turbine at the rate of5000 kg/h entering at 15 bar 300°C and leaving at 0.1 bar with 4% moisture. The steam enters at 80 m/s at a point 2 m above the discharge and leaves at 40 m/s. Compute the shaft power assuming that the device is adiabatic but considering kinetic and potential energy changes. Calculate the diameter of the inlet and discharge tubes (8)
(ii) Steam expands isentropically in a nozzle from 1 MPa, 250°C to 10 kPa.The steam flow rate is 1 kg/s. Find the velocity of steam at the exit from the nozzle, and the exit area of the nozzle-. Neglect the velocity of steam at inlet to the nozzle. The exhaust steam from the nozzle flows into a condenser and flows out as saturated water. The cooling water enters the condenser at 25°C and leaves at 35°C. Determine the mass flow rate. (8) www.chennaituitions.inwww.chennaituitions.in
Page 9 of 31
Or
(b) (i) With a neat diagram explain the regenerative Rankine cycle with open feedwater heater
(ii) In a thermal plant operating on a Rankine cycle, superheated steam at 50 bar and 500°C enters a turbine, the isentropic efficiency of which is 0.8. The condenser pressure is 0.05 bar and it delivers saturated liquid to a feed pump, the isentropic

efficiency of which is 0.7. Determine the thermal efficiency of the power plant and the mass flow rate of steam required for 50 MW net power generation. (8)
14. (a) (i)Explain how real gases deviate from an ideal gas behaviour? (4)
(ii) Why does isothermal compression need minimum work and adiabatic compression need maximum work?
(iii)A certain quantity of air initially at a pressure of 8bar and 280°C has a volume of
0.035 m3
. It undergoes a cycle consisting of the following processes:
(1) Expands at constant pressure to 0.1 m3
.
(2) Follows polytropic process with n = 1.4
(3) A constant temperature process which completes the cycle.
Evaluate the heat received and rejected in the cycle and cycle efficiency. (8)
Or
(b) (i) Derive the Clapeyron equation. (8)
(ii) Over a certain range of pressures and temperatures the equation of a certain substance is given by, the relation
V = (RT/p) - (C/T3
) where C is constant. Derive an expression for:
(1) The change of enthalpy.
(2) The change of entropy of this substance in an isothermal Process
15. (a) (i) Explain the process of cooling and dehumidification. (8)
(ii) Explain with an example evaporative cooling. (8)

Or
(b) (i) Two streams of air 25°C, 50% RH and 25°C, 60% RH are mixe adiabatically to obtain 0.3 kg/s of dry air at 30°C. Calculate the amounts of air drawn from both the streams, and humidity ratio of the mixed air. (6)
(ii) An air-conditioned room requires 30 m3
/min of air at 1.013 bar, 20°C, 52.5%
RH. The steady flow conditioner takes in air at 1.013 bar, 77%RH, which it cools to adjust the moisture content and reheats to room temperature. Find the temperature to which the air is cooled and thermal loading on both the cooler and heater. Assume that a fan before the cooler absorbs 0.5 kW, and that the , condensate is discharged at the temperature to which the air is cooled. (10) www.chennaituitions.inwww.chennaituitions.in
Page 10 of 31
B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2009
Third Semester
Mechanical Engineering
ME 2202 — ENGINEERING THERMODYNAMICS
(Regulation 2008)
Time: Three hours Maximum:100 Marks
(Use of Standard Thermodynamic Tables, Mollier Diagram, Psychometric
Chart and Refrigerant Property Tables is permitted)
Answer ALL Questions
PART – A
1. What is the difference between the classical and the statistical approaches to

thermodynamics?
2. State the zeroth law of thermodynamics
3. What is the Kelvin-Planck expression of the second law of thermodynamics?
4. Why is the second law, called a directional law of nature?
5. Why is excessive moisture in steam undesirable in steam turbines?
6. Why is the Carnot cycle not a realistic model for steam power plants?
7. What does the Joule Thomson coefficient represent?
8. In a gas mixture , which component will have the higher partial pressure-the one with the higher mole number or the one with the larger molar mass?
9. What is the difference between dry air and atmospheric air?
10. When are the dry bulb and dew bulb temperature identical?
PART B — (5 x 16 = 80 Marks)
11. (a)A reciprocating air compressor takes in 2 m3
/min air at 0.11 MPa, 293 K which it delivers at 1.5 MPa, 384 K to an after cooler where the air is cooled at constant pressure to 298 K. The power absorbed by the compressor is 4.15 kW. Determine the heat transfer in (i)the compressor (ii) the cooler. State your assumptions
(16)
Or b) In a turbo machine handling an incompressible fluid .with a density of 1000 kg/m3 the conditions of the fluid at the rotor entry and exit are as given below :
Inlet Exit
Pressure 1.15 MPa 0.05
Velocity 30 m/sec 15.5 m/sec

Height above datum 10 m 2 m
If the volume flow rate of the fluid is 40m3
/s, estimate the net energy transfer from the fluid as work. (16) www.chennaituitions.inwww.chennaituitions.in
Page 11 of 31
12. (a) The interior lighting of refrigerators is provided by incandescent lamps whose switches are actuated by the opening of the refrigerator door. Consider a refrigerator whose 40W.light bulb remains on continuously as a result of a malfunction the switch. If the refrigerator has a coefficient ofperformance of1.3 and the cost of electricity is Rs. 8 per kWh, determine the increase in the energy consumption of the refrigerator and its cost per year if the switch is not fixed. (16)
Or
(b) (i) A Carnot heat engine receives 650 kJ of heat from a source of unknown temperature and rejects 250 kJ of it to a sink at 297 K. Determine the temperature of the source and the thermal efficiency of the heat engine.
` (6)
(ii) A Carnot heat engine receives heat from a reservoir at 1173 K at a rate of 800 kJ/min and rejects the waste heat to the ambient air at 300 K. The entire work output of the heat engine is used to drive a refrigerator that removes heat from the refrigerated space at 268
K and transfers it to the same ambient air at 300 K. Determine the maximum rate of heat removal from the refrigerated space and the total rate of heat rejection to the ambient air (8)
13. (a) Consider a steam power plant operating on the ideal Rankine cycle Steam enters the turbine at 3 MPa and 623 K and is condensed in the condenser at a pressure of 10 kPa.

Determine (i) the thermal efficiency of this power plant, (ii) the thermal efficiency if steam is superheated to 873 K instead of 623 K, and (iii) the thermal efficiency if the boiler pressure is raised to 15 MPa while the turbine inlet temperature js maintained at 873 K. (16)
Or
(b) Consider a steam power plant operating on the ideal reheat Rankine cycle. Steam enters the high-pressure turbine at 15 MPa and 873K and is condensed in the condenser at a pressure of 10 kPa If the moisture content of the steam at the exit of the low-pressure turbine is not to exceed 10.4 percent, determine (i) the pressure at which the steam should be reheated and (ii) the thermal efficiency of the cycle. Assume the steam is reheated to the inlet temperature of the high-pressure turbine. (16)
14. (a)(i)Using the Clapeyron equation, estimate the value of the enthalpy of vaporization of refrigerant R —134a at 293 K, and compare it with the tabulated value.
(10)
(ii) Show that Cp - Cv = R for an ideal gas. (8)
Or
(b) (i) Show that the Joule-Thomson coefficient of an ideal gas is zero. (6)
(ii) Using the cyclic relation , and the first Maxwell relation, derive the other three Maxwell relations (10)
15. (a) (i) What is the lowest Temperature that air can attain in an
Evaporative cooler if it enters at 1 atm, 302 K, and 40 percent relative humidity? (4)
(ii) Consider a room that contains air at 1 atm, 308 K. and 40 percent relative humidity. Using the psychrometric chart, determine: the specific humidity, the enthalpy, the wet-bulb temperature, the dew-point temperature and the specific volume of the air. (12)

Or
(b) An air-conditioning system is to take in outdoor air at 283 K and 30 percent relative humidity at a steady rate of 45 m3
/min and to condition it to 298 K and 60 percent relative humidity. The outdoor air is first heated to 295 K in the heating section and then humidified by the injection of hot steam in the humidifying section. Assuming the entire processtakes place at a pressure of100 kPa, determine (i) the rateofheat supply in the heating section and (ii) the mass flow rate of the steam required in the humidifying section. www.chennaituitions.inwww.chennaituitions.in
Page 12 of 31
B.E/B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010.
Third Semester Mechanical Engineering
ME 1201 — ENGINEERING THERMODYNAMICS (Common to B.E. Production
Engineering) , (Regulation 2004)
(Common to B.E. (Part-Time) Second Semester Mechanical Engineering -Regulation 2005)
Time : Three hours Maximum marks : 100 marks
Answer ALL questions.
(Use of Steam Tables, Mollier diagram and Fsychrometric charts permitted).
PART A — (10 x 2 = 20 marks)
1. What are point functions and path functions? Given examples.
2. State the zeroth law of thermodynamics. Also give the thermodynamic definition of work.
3. Enunciate the Kelvin-Planck statement of second law of thermodynamics.
4. Give the expression for the COP of a heat pump in terms of source and sink temperatures.

5. Define a pure substance.
6. One kg ice melts at constant atmospheric pressure and at 0°C to form liquid water. If the latent heat of fusion of ice is 333.3 kJ/kg, calculate the entropychange during thisprocess.
7. What is the use of generalised compressibility chart?
8. State any two applications of Clausius-Clapeyron equation. -
9. Sketch the adiabatic saturation process on T-s diagram.
10. Sketch the evaporative cooling process on a skeleton psychrometric chart.
PART B — (5 x 16 = 80 marks)
11. (a) (i) State the first law of thermodynamics for a cycle and apply the same to reversible cycles to prove that property energy exists. (8)
(ii) A gas of mass 1.5 kg undergoes a quasistatic expansion which follows the relationship, p = a + bV where a and b are constants.The initial and final pressures are 1000 kPa and 200 kPa respectively and the corresponding volumes are 0.2 m3 and 1.2 m3
. The specific internal energy of the gas is given by, u = l.5pv -85 kJ/kg where p is in kPa and v is in m3
/kg.
Calculate the work done during the process. (8)
Or
(b) Air flows steadily at the rate of 0.5 kg/s through an air compressor entering at 7 m/s velocity,
100 kPa pressure, and 0.95 m3
/kg specific volume, and leaving at 5 m/s, 700 kPa, and 0.19 m3
/kg. The

internal energy of air leaving is 90 kJ/kg greater than that of the air entering. .Cooling water in the compressor jackets absorb heat at the rate of 58 kW. Calculate the rate of shaft work input to the compressor. (16)
12. (a) (i) Prove that the Kelvin-Planck statement and Clausius statement of second law of thermodynamics are equivalent. (8)
(ii) Represent the Carnot cycle on p-V and T-s planes and deduce an expression for www.chennaituitions.inwww.chennaituitions.in
Page 13 of 31 thermal efficiency in terms of temperature. (8)
Or
(b) (i) Prove that the change in entropy during a polytropic process is givenby S2-S1 =Cv(n-k/n-l)loge(T2/T1). Where k is the ratio of specific heats and n is the index of compression or expansion. (8)
(ii) A closed system consists of 1 kg of air which is initially at 1.5 bar and 67°C The volume doubles as the system undergoes a process according to the law PV1.2
= C.
Find the work done, heat transfer and change in entropy. (8)
13. (a) In a steam generator compressed liquid water at 10 MPa, 30°C enters a
30 mm diameter tube at the rate of3 litres/sec. Steam at 9 MPa, 400°C exits the tube. Find the rate of heat transfer to the water. (16)
Or
(b) (i) Explain the factors which affect the thermal efficiency and quality of turbine exhaust of

Rankine cycle. Justify your discussion using T-s diagrams. (8)
(ii) Sketchthe Rankine regenerative cycle with one feed heater as schematic and T-s diagrams and deduce the; expression for the thermal efficiency. (8)
14. (a) (i) Deduce the Maxwell's relations (8)
(ii) From the third relation of Maxwell deduce the Clausius-Clapeyron equation. (8)
. Or
(b) A mixture of2 kg oxygen and 2 kg Argon is in an insulated piston cylinder arrangement at
100 kPa, 300 K. The piston compresses the mixture to half its initial volume. Find the final pressure, temperature and piston work. Molecular weight of oxygen is 32 and argon is 40. Ratio of specific heats for oxygen is 1.39 and for Argon, is 1.667. (16)
15. (a) (i) Define the Terms. Dew point, specific humidity, relative humidity, wet bulb temperature. (4)
(ii) Describe how a psychrometric chart is constructed. Explain using pertinent equations for all properties represented on it. (12)
Or
(b) Air at 40°C DBT and 27°C WBT is to be cooled and dehumidified by passing it over a refrigerant coil to give a final condition of 15°C and 90% RH. Find the amounts of heat and moisture removed per kg of dry air. (16) www.chennaituitions.inwww.chennaituitions.in
Page 14 of 31
B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2009.
Third Semester
Mechanical Engineering

ME 1201 — ENGINEERING THERMODYNAMICS (Common to Production Engineering)
(Common to B.E. (Part-Time) - Second Semester - Mechanical Engineering
- Regulation 2005)
(Regulation 2004) Time : Three hours
Maximum : 100 marks
(Use of standard thermodynamic tables, Mollier diagram, Psychrometric chart and Refrigerant property tables permitted)
Answer ALL questions.
PART A — (10 x, 2 = 20 marks)
1. What is meant by Continuum? Identify its importance.
2. What is the requirement for the thermal equilibrium? Which law governs it?
3. Classify the following as point or path function: Heat, Enthalpy, Displacement work,
Entropy.
4. Why is the COP of an heat pump is higher than that of a refrigerator, if they both operate between the same temperature limits?
5. What is the triple point of water? Give the values of properties at that point.
6. What is meant by latent heat of vaporization?
7. Is water vapour an ideal gas? Why?
8. If atmospheric air (at 101325 Pa) contains 21% oxygen and 79% nitrogen (vol. %), what is the partial pressure of oxygen?
9. If the vapour pressure in the open atmosphere is 2.38 kPa atmospheric pressure is 100 kPa, calculate the specific humidity.
10. How do relative humidity, specific humidity, dew point temperature and wet bulb temperature change during sensible cooling?

PART B — (5 x 16 = 80 marks)
11. (a) (i) Distinguish between the reversible process and the cyclic process. (4)
(ii) Air contained in the cylinder and piston arrangement comprises the system. A cycle is completed by four process 1-2, 2-3, 3-4 and 4-1. The energy transfers are listed below.
Complete the table and determine the network in kJ. Also check the validity of the first law of thermodynamics. (8 + 2 + 2)
Process Q (kJ) W (kJ) ΔU (kJ)
1-2 40 ? 25
2-3 20 -10 ?
3-4 -20 ? ?
4-1 0 +8 ?
Or
(b) (i) Derive the suitable expression for the ideal compressor from the steady flow energy equation and specify the assumptions under which such equation is applicable. (4)
(ii) Calculate the power developed and diameter of the inlet pipe, if a gas enters into the gas turbine at 5 kg/s, 50 m/s with an enthalpy of 0.9 MJ/kg and leaves at 150 m/s with an enthalpy of
0.4 MJ/kg. The heat loss to the surrounding is 0.025 MJ/kg. Assume 100 kPa and 300 K at the inlet. (8 + 4) www.chennaituitions.inwww.chennaituitions.in
Page 15 of 31
12. (a) (i) Deduce the efficiency of Carnot cycle in terms of temperature fromits p-V diagram.
(4)

(ii) Air is compressed from 100 kPa and 300 K to 5 bar isothermally and then it receives heat at constant pressure. It is finally returns to its initial condition by a constant volume path. Plot the
Cycle on p-V and T-s diagram and calculate the net heat and work transfer.
(2 + 2 + 4 + 4)
Or
(b) (i)Bring out the concept of the Entropy and importance of T-s diagram.
(4)
(ii) Five kg of water at 303 K is mixed with one kg of ice at 0°C. The system is open to atmosphere. Find the temperature of the mixture and the change of entropy for both ice and water.
Assume Cp of water as 4.18 kJ/kg-K and Latent heat of ice as 334.5 kJ/kg. Comment on the result based on the principle of increase in entropy (4 + 4 + 4)
13. (a) (i) What is dryness fraction and degree of superheat (4)
(ii) Wet steam of 0.5 MPa and 95 % dry occupies 500 litres of volume. What is its internal energy? If this steam is heated in a closed rigid vessel till the pressure becomes 1 MPa, find the heat added. Plot the process on the Mollier chart. (5 + 5 + 2)
Or
(b) A regenerative cycle with three open feed water heaters works between 3 MPa, 450°C and 4 kPa. Assuming that the bleed temperatures are chosen at equal temperature ranges, plot the process on h-s diagram and determine the efficiency of the cycle.
14. (a) (i) State the equation of state for van der wall's gas and explain the importance of each term; Also bring out the limitations of the equation (3 + 3 + 2)

(ii) A gas mixture consists of 12 kg of methane, 5 kg of nitrogen and 3 kg of oxygen. Determine the molecular mass and gas constant of the mixture. If the total pressure is 100 kPa, calculate their partial pressures. (3 + 3 + 2)
Or
(b) (i) What is compressibility factor? Explain its significance. (2 + 2)
(ii) Deduce the expression for the Joule Thomson coefficient and hence plot the variation of temperature with pressure for various enthalpies, marking all zones and boundaries. (8 + 4)
15. (a) (i) Deduce the relationship for specific humidity in terms of total pressure and vapour pressure. (4)
(ii) If a room of 75 m3 contains air at 25°C and 100 kPa at 75% relative humidity, determine the partial pressure of dry air, specific humidity, enthalpy, mass of dry air and water vapour in the room.
(3 + 3 + 3 + 3)
Or
(b) (i) How is the ratio of dry air flows related to specific humidity and enthalpy in an adiabatic mixing? (4)
(ii) In a power plant, cooling water leaves the condenser and enters a wet cooling tower at 35°C at a rate of 100 kg/s. water is cooled to 22.8°C in the cooling tower by air that enters the tower at
101.325 kPa and 20°C and 60% relative humidity and leaves saturated at 30°C. Neglecting the fan power, determine the volume flow rate of air in to the cooling tower and mass flow rate of the wwrequired make up water. (8+4) w.chennaituitions.inwww.chennaituitions.in

Page 16 of 31
B.E./B.Tech. DEGREE EXAMINATION, MAY/JUNE 2009.
Third Semester Mechanical Engineering
ME 1201 — ENGINEERING THERMODYNAMICS (Common to B.E. Production
Engineering)
(Regulation 2004)
(Common to B.E. (Part-Time) Second Semester Mechanical Engineering) Time : Three hours Maximum: 100 marks
(Use of standard thermodynamic tables, Mollier diagram, Psychometric chart are permitted)
Answer ALL questions. PART A — (10 x 2 = 20 marks)
1. What do you understand by flow work? Is it different from displacement work?
2. What is PMM 1 ?
3. Give the criteria of reversibility, irreversibility and impossibility of a thermodynamic cycle.
4. What is meant by availability?
5. Draw the phase equilibrium diagram for a pure substance on T-S plot with relevant constant property line.
6. What is the effect of regeneration of a steam power plant?
7. What is "Compressibility Factor"?
8. State Dalton's law of partial pressures.
9. Define dew point temperature.
10. What is adiabatic saturation process?
PART B — (5 x 16 = 80 marks)

11. (a) A gas of mass 1.5 kg 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 kPa and 200 kPa respectively and the corresponding volumes are 0.20 m3 and 1.20 m3
. The specific internal energy of the gas is given by the relation: u = 1.5 pv — 85 kJ/kg, where p is in kPa and v is in m3
/kg. Calculate the net heat transfer and the maximum internal energy of the gas attained during expansion.
Or
(b) A nozzle velocity is a device for increasing the velocity of a steadily flowing stream. At the inlet to a certain nozzle, the enthalpy of the fluid passing is 3000 kJ/kg and the velocity is 60 m/s. At the discharge end, the enthalpy is 2762 kJ/kg. The nozzle is horizontal and there is negligible heat loss from it. (i) Find the velocity at exit from the nozzle. (ii) If the inlet area is 0.1m2 and the specific volume at inlet is 0.187 m3
/kg, find the mass flow rate, (iii) If the specific volume at the nozzle exit is
0.498 m3
/kg, find the exit area of the nozzle.
12. (a) (i) What are the causes of irreversibility of a process? (4)
(ii) A reversible heat engine operates between two reservoirs at temperatures of 600°C and
40°C.

The engine drives a reversible refrigerator which operates between reservoirs at temperatures of40°C and - 20°C. The heat transfer to the engine is 2000 kJ and the net work output of the combined engine refrigerator plant is 360 kJ. (1) Evaluate the heat transfer to the refrigerant and the net heat transfer to the reservoir at 40°C. (2) Reconsider (1) given that the efficiency of the heat engine and the COP of the refrigerator are each 40% of their maximum possible values. (12)
Or
(b) (i) Ten grams of water at 20°C is converted into ice at -10°C at constant atmospheric pressure.
Assuming the specific heat of liquid water to remain constant at 4.2 J/gK and that of ice to be half of this value, and taking the latent heat of fusion of ice at 0°C to be 335 J/g, Calculate the total entropy change of the system. (14)
(ii) Why is entropy transfer associated with heat transfer and not with work transfer? (2) www.chennaituitions.inwww.chennaituitions.in
Page 17 of 31
13. (a) (i) Why do the isobars on Mollier diagram diverge from one another? (4)
(ii) A large insulated vessel is divided into two chambers, one containing 5 kg of dry saturated steam at 0.2 MPa and the other 10 kg of steam, 0.8 quality at 0.5 MPa. If the partition between the chambers is removed and the steam is mixed thoroughly and allowed to settle, find the final pressure, steam quality and entropy change in the process (12)

Or
(b) In a reheat cycle, the initial steam pressure and the maximum temperature are 150 bar and
550°C respectively. If the condenser pressure is 0.1 bar and the moisture at the condenser inlet is 5%, and assuming ideal processes, determine (i) the reheat pressure, (ii) the cycle efficiency, and
(iii) the steam rate.
14. (a) Two vessel, A and B, both containing nitrogen, are connected by a valve which is opened to allow the contents to mix and achieve an equilibrium, temperature of 27°C.
Before mixing the following information is known about the gases in two vessels.
Vessel-A Vessel -B p = 1.5 MPa p = 0.6 MPa t = 50°C t = 20°C
Contents = 0.5 kg mol Contents = 2.5 kg mol
Calculate the final equilibrium process, and the amount of heat transferred to the surroundings.
If the vessel had been perfectly insulated, calculate the final temperature and pressure which would have been reached. Take γ = 1.4.
Or
(b) Derive the Maxwell's equations.
15. (a) (i) . Explain the process of cooling and dehumidification. (4)
(ii) Air at 20°C, 40% RH is mixed adiabatically with air at 40°C, 40% RH in the ratio of 1 kg of the former with 2 kg of the latter (on dry basis). Find the final condition of air (12)
(b) For a hall to be air-conditioned, the following conditions are given:
Outdoor condition - 40°C dbt, 20°C wbt

Required comfort conditions - 20°C dbt, 60% RH
Seating capacity of hall - 1500
Amount of outdoor air supply - 0.3 m3/min/person
If the required condition is achieved first by adiabatic humidification and then by cooling, estimate (i) the capacity of the cooling coil in tonnes, and (ii) the capacity of the humidifier in kg/h. www.chennaituitions.inwww.chennaituitions.in
Page 18 of 31
B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2008.
Third Semester
(Regulation 2004)
Mechanical Engineering
ME 1201 — ENGINEERING THERMODYNAMICS
(Common to Production Engineering)
(Common to B.E. (Part-Time) - Second Semester - Regulation 2005) Time: Three hours
. Maximum: 100 marks
(Use of standard thermodynamic tables, Mollier diagram, Psychrometric chart and Refrigerant property tables permitted)
Answer ALL questions.
PART A — (10 x 2 = 20 marks)
1. Define a thermodynamic system. Classify the following systems as open/closed/isolated : (a) Mixture of ice and water in a metal container (b) A wind mill.
2. Define heat and thermodynamic definition of work. ,

3. Give Clausius statement of Second Law of Thermodynamics.
4. What is the principle of increase of Entropy?
5. Define quality of steam. What are the methods of determining quality of steam?
6. Give the flow and T-s diagrams of the regenerative Rankine cycle with single open feed water heater.
7. Explain the following terms : (a) Mole fraction, (b) Mass fraction.
8. Write the Maxwell's equations and also give the basic relations from which these are derived.
9. What do you understand by dry bulb and wet bulb temperatures?
10. Draw a psychrometric chart and show the following processes on it :
(a) sensible cooling, (b) latent heating, (c) heating and dehumidification and (d) cooling and humidification.
PART B — (5 x 16 = 80 marks)
11. (a) (i) A van der Waal gas is compressed reversibly at constant temperature from volume V1 to V2. The equation of state is given by
P =(RT/V-b)-(a/V2
) . Determine the work done per mole of the gas. (8)
(ii) Define a new thermodynamic scale saydegree N, in which the freezing point and boiling point of water are 100°N and 300°N respectively. Correlate this temperature scale with centigrade scale.
(8)
Or
(b) (i) Apply steady flow energy equation for a nozzle. State the

assumptions made. (6)
(ii) A gas occupies 0.3 m3 at 2 bar. It executes a cycle consisting of processes : (1) 1-2; constant pressure with work interaction of 15 kJ. (2) 2-3; compression process which follows the law
PV = Constant, and U3 = U2 (3) 3-1; constant volume process, and change in internal energy is
40 kJ. Neglect change in KE and PE. Draw PV diagram for the process and determine network transfer for the cycle. Also . show that first law is obeyed by the cycle. (10)
12. (a) (i) Derive Clausius inequality and mention the criteria for reversibility of a cycle.
(6)
(ii) A reversible heat engine operates between two reservoirs at 820°C and 27°C. Engine drives a www.chennaituitions.inwww.chennaituitions.in
Page 19 of 31 reversible refrigerator which operates between reservoirs at temperatures of 27°C and -15°C.
The heat transfer to the engine is 2000 kJ and network available for the combined cycle is 300 kJ. (1)
How much heat is transferred to the refrigerant and also determine the total heat rejected to the reservoir at
27 °C. (2) If the efficiency of the heat engine and COP of the refrigerator are each 40% of their maximum values, determine heat transfer to the refrigerator and also heat rejected to the reservoir at
27°C. (10)
Or
(b) (i) Show that there is a decrease in available energy when heat is transferred through

a finite temperature difference. (6)
(ii) In a closed system air is at a pressure of 1 bar, temperature of 300 K and volume of 0.025 m3
.
The system executes the following processes during the completion of thermodynamic cycle :
1-2; constant volume heat addition till pressure reaches 3.8 bar, 2-3; constant pressure cooling of air; 3-1; isothermal heating to initial state. Determine the change in entropy in each process. Take Cv =
0.718 kJ/kgK. R = 287 J/kgK.
(10)
13. (a) (i) Draw and explain phase equilibrium diagram for a pure substance on P-T coordinate. Also indicate different regions on the diagram. (8)
(ii) Steam at a pressure of15 bar and 250°C expands according to the law PV1.25 = C to a pressure of 1.5 bar. Evaluate the final conditions, work done, heat transfer and change in entropy. The mass of the system is 0.8 kg. (8)
Or
(b) (i) Why is Carnot cycle not practicable for a steam power plant? (4)
(ii) In a steam power plant the condition of steam at inlet to the steam turbine is 20 bar and
300°C and the condenser pressure is 0.1 bar. Two feed water heaters operate at optimum temperatures.
Determine: (1) The quality of steam at turbine exhaust; (2) network per kg of steam, (3) cycle efficiency, and (4) the steam rate. Neglect pump work (12)

14. (a) (i) Write a short note on Generalized Compressibility chart. (6)
(ii) A mixture of Ideal gases consists of 2.5 kg of N2 and 4.5 kg of CO2 at a pressure of 4 bar and a temperature of 25°C. Determine :
(1) Mole fraction of each constituent,
(2) Equivalent molecular weight of the mixture,
(3) Equivalent gas constant of the mixture,
(4) The partial pressure and partial volumes,
(5) The volume and density of the mixture. (10)
Or
(b) (i) Derive van der Waal's equation in terms of reduce parameters. (8)
(ii) Derive TdS equations taking Temperature, volume and temperature, pressure as independent properties (8)
15. (a) Atmospheric air at 1.0132 bar has a DBT of 32°C and a WBT of 26°C. Compute (i) the partial pressure of water vapor, (ii) the specific humidity, (iii) the dew point temperature (iv) the relative humidity, (v) the degree ofsaturation, (vi) the density of air in the mixture, (vii) the densityof vapour in the mixture and (viii) the enthalpy of the mixture. Use thermodynamic table only.
(16)
Or
(b) (i) Explain the process of cooling dehumidification of air. (8).
(ii) 30 m3
/min of moist air at 15°C DBT and 13°C WBT are mixed with 12 m3
/min of moist air at
25°C DBT and 18°C WBT. Determine DBT and WBT of the mixture assuming the barometric

pressure is one atmospheric. (8)
B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2008. www.chennaituitions.inwww.chennaituitions.in
Page 20 of 31
Third Semester
(Regulation 2004)
Mechanical Engineering
• ME 1201 — ENGINEERING THERMODYNAMICS
(Common to Production Engineering)
(Common to B.E. (Part-Time) - Second Semester - Regulation 2005) Time : Three hours
Maximum : 100 marks
(Use of standard thermodynamic tables, Mollier diagram, Prychrometric chart and
Refrigerant property tables permitted)
Answer ALL questions.
PART A — (10 x 2 = 20 marks)
1. Define 'process' and 'cycle' with one example each.
2. Distinguish between heat and temperature.
3. What do you understand by the concept of entropy?
4. What is loss of availability? How is it related to entropy of universe?
5. If water is at 65°C at 1 atm, what is the state of water? What is its specific enthalpy?
6. Plot the standard Rankine cycle on T-s diagram and label all the processes assuming the steam to be dry and saturated at the end of expansion.
7. Have you ever encountered any ideal gas? If so, where?
8. What is coefficient of expansion?

9. If the relative humidity of air is 60% at 30°C, what is the partial pressure of water vapour?
10. What is thermodynamic wet bulb temperature?
PART B — (5 x 16 = 80 marks)
11. (a) (i) Derive an expression for the work transfer in an isothermal process. (2 + 2)
(ii) Identify any four reasons for irreversibility in a process. (4)
(iii) A Work done by substance in a reversible non-flow manner is in accordance with
V = (15/p) m3
, where p is in bar. Evaluate the work done on or bythe systemas pressure increases from 10 to 100 bar. Indicate whether it is a compression process or expansion process. If the change in internal energy is 500 kJ, calculate the direction and magnitude of heat transfer. (6 + 2)
Or
(b) (i) Define internal energy and prove that it is a point function. (3 + 4)
(ii) Establish the relationship between the specific heat at constant pressure and specific heat at constant volume. (3)
(iii) In a Gas turbine installation, the gases enter the turbine at the rate of 5 kg/sec with a velocity of 50 m/sec and enthalpy of 900 kJ/kg and leave the turbine with 150 m/sec. and enthalpy of
400 kJ/kg. The loss of heat from the gases to the surroundings is 25 kJ/kg. Assume R = 0.285 kJ/kg
°K,
Cp = 1.004 kJ/kg °K and inlet conditions to be at 100 kPa and 27°C. Determine the diameter of the inlet pipe. (6)
12. (a) (i) State Carnot theorem (3)

(ii) An inventor claims to have developed an engine which receives 1000 kJ at a temperature of
160°C. It rejects heat at a temperature of 5°C and delivers 0.12 kWh of mechanical work. Is this a valid claim? Justify your answer through Classius inequality. (3 + 2)
(iii) A refrigeratoroperating between two identical bodies cools one of the bodies to a temperature
T2. Initially both the bodies are at temperature T1. Deduce the expression for the minimum specific work input, taking their specific heat as c. (8)
Or www.chennaituitions.inwww.chennaituitions.in
Page 21 of 31
(b) (i) Deduce the expression for the Entropy change in terms of pressure and temperature.
(6)
(ii) One kg of ice at -10°C is allowed to melt in atmosphere at 30°C. The ice melts and the water so formed rises in temperature to that of atmosphere. Determine the entropy change of ice, the entropy change of surrounding, the entropy change of universe and write your comment based on principle of increase in entropy. The specific heat of ice is 2 kJ/kg-K and its latent heat is 335 kJ/kg.
(3 + 3 + 3 + 1)
13. (a) (i) Draw p-V-T surface for any substance that contracts on freezing and get p-T plot out of them. (4 + 2)
(ii) 3 kg of steam at 18 bar occupy a volume of 0.2550 m3
. During a constant volume process, the

heat rejected is 1320 kJ. Determine final internal energy. Find dryness fraction and pressure, change in entropy and work done. (10)
Or
(b) (i) Briefly explain the process of super-heated steam formation with the help of T-s diagram. (6)
(ii) A steam power plant runs on a single regenerative heating process. The steam enters the turbine at 30 bar and 400°C and steam fraction is withdrawn at 5 bar. The remaining steam exhausts at
0.10 bar to the condenser. Calculate the efficiency, steam fraction and steam rate of the power plant.
Neglect pump work. (6 + 2 + 2)
14. (a) (i) Prove that the total pressure is a sum of partial pressures. (4)
(ii) A closed vessel has a capacity of 0.5 m3
. It contains 20% nitrogen and 20% oxygen 60% carbon dioxide by volume at 20°C and 1 MPa. Calculate the molecular mass, gas constant, mass percentages and the mass of mixture (12)
Or
(b) (i) Derive Tds relations in terms of temperature & pressure changes and temperature
& volume changes. (10)
(ii) Describe Joule Kelvin effect with the help of T-p diagram. (6)
15. (a) (i) Describe the adiabatic cooling process and deduce the expression for its enthalpy. (4 + 4)
(ii) Air at 20°C, 40% relative humidity is missed adiabatically with air at 40°C, 40% RH in the ratio of 1 kg of former with 2 kg of latter (on dry basis). Find the final condition (humidity and

enthalpy) of air (8)
Or
(b) (i) Draw the cooling and dehumidification process and explain Sensible Heat Factor, Bypass
Factor and effectiveness of coil with respect to it. (6)
(ii) A steam of air at 101.32 kPa. 18°C, and a relative humidity of 30% is flowing at the rate of
14.15 m3
/min. A second stream at 101.32 kPa. 38°C and a relative humidity of 50% is flowing at the rate of 8.5 m3
/min. The two streams are mixed adiabatically to form a third stream at 101.32 kPa.
Determine the specific humidity, the relative humidity and the temperature of the third stream.
(4 + 3 + 3) www.chennaituitions.inwww.chennaituitions.in
Page 22 of 31
B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2007.
Third Semester
(Regulation 2004)
Mechanical Engineering
ME 1201 — ENGINEERING THERMODYNAMICS
(Common to Production Engineering)
(Common to B.E. (Part-Time) - Second Semester - Regulation 2005) Time : Three hours
Maximum : 100 marks
(Use of standard thermodynamic tables, Mollier diagram, Psychrometric chart and
Refrigerant property tables permitted)
Answer ALL questions.
PART A — (10 x 2 = 20 marks)

1. What is a PMM1? Why is it impossible?
2. Is it correct to say 'total heat' or 'heat content' of a closed system?
3. Why the second law of thermodynamics is called a directional law of nature?
4. The coefficient of Performance (COP) of a heat pump is 5. Find the COP of a refrigerator if both are reversible devices interacting between same source temperature and sink temperature.
5. Define saturation state of a system.
6. Why Carnot cycle is not practicable for a steam power plant?
7. What do you mean by equation of state?
8. State the Dalton's law of partial pressure.
9. Define dew point temperature
10. What is sensible heating?
PART B — (5 x 16 = 80 marks)
11. (a) (i) A blower handles 1 kg/sec of air at 293 K and consumes a power of
15 kW. The inlet and outlet velocities of air are 100 m/sec and 150 m/sec respectively.
Find the exit air temperature, assuming adiabatic conditions. Take Cp of air as 1.005 kJ/kg-K. (9)
(ii) A room for four persons has two fans, each consuming 0.18 kW power and three 100
W lamps. Ventilation. air at the rate of 0.0222 kg/sec enters with an enthalpy of 84 kJ/kg and leaves with an enthalpy of 59 kJ/kg. If each person puts out heat at the rate of 0.175 kJ/sec, determine the rate at which heat is to be removed by a room cooler, so that a steady state is maintained in the room. (7)
Or b. (i) One litre of hydrogen at 273 K is adiabatically compressed to one-half of its initial

volume. Find the change in temperature of the gas, if the ratio of two specific heats for hydrogen is 1.4 (4)
(ii) The velocity and enthalpy of fluid at the inlet of a certain nozzle are 50 m/sec and
2800 kJ/kg respectively. The enthalpy at the exit of nozzle is 2600 kJ/kg. The nozzle is horizontal and insulated so that no heat transfer takes place from it. Find i. Velocity of the fluid at exit of the nozzle ii. Mass flow rate, if the area at inlet of nozzle is 0.09 m2 iii. Exit area of the nozzle, if the specific volume at the exit of the nozzle is 0.495 m
3
/kg. (12)
12. (a) (i) Give the Clausius statement of second law (3)
(ii) A house hold refrigerator is maintained at a temperature of 275 K. Every time the www.chennaituitions.inwww.chennaituitions.in
Page 23 of 31 door is opened, warm material is placed inside, introducing an average of 420 kJ, but making only a small change in the temperature of the refrigerator. The door is opened 20 times a day, and the refrigerator operates at 15% of the ideal COP. The cost of work is
Rs 2.50 per kWhr. What is the bill for the month of April for this refrigerator? The atmosphere is at 303 K. (13)
Or
(b) (i) What is a thermal energy reservoir (3)
(ii) Establish the inequality of Clausius (13)
13. a. A cyclic steam power plant is to be designed for a steam temperature at

turbine inlet of 633 K and an exhaust pressure of 8 kPa. After isentropic expansion of steam in the turbine, the moisture content at the turbine exhaust is not to exceed 15%.
Determine the greatest allowable steam pressure at the turbine inlet, and calculate the
Rankine cycle efficiency for these steam conditions. Estimate also the mean temperature of heat addition (16)
Or b. In a reheat steam cycle, the maximum steam temperature is limited to 773 K. The condenser pressure is 10 kPa and the quality at turbine exhaust is 0.8778. Had there been no reheat, the exhaust quality would have been 0.7592. Assuming ideal processes, determine (i) reheat pressure (ii) the boiler pressure (iii) the cycle efficiency (iv) the steam rate (16)
14. (a) (i) A certain gas has CP = 0.913 and Cv = 0.653 kJ/kg K. Find the molecular weight and the specific gas constant R of the gas. (4)
(ii) Derive the Clausius- Clapreyon equation. (12)
Or
(b) (i) Derive Maxwell's equations (11)
(ii) Prove Tds =CvdT +T (∂p/∂T)v dV . (5)
15. (a) In a laboratory test, a sling psychrometer recorded dry bulb and wet bulb temperatures as 303 K and 298 K respectively. Calculate (i) vapour pressure (ii) relative humidity (iii) specific humidity (iv) degree of saturation (v) dew point temperature (vi) enthalpy of the mixture. (16)
Or
(b) (i) 1 kg of air at 313 K dry bulb temperature and 50% relative humidity is mixed with
2 kg of air at 293 K dry bulb temperature and 293 K dew point temperature. Calculate the

temperature and specific humidity of the mixture. (10)
(ii) Show the following processes on a skeleton psychrometric chart a. dehumidification and cooling b. heating and humidification (6) www.chennaituitions.inwww.chennaituitions.in
Page 24 of 31
BE./B.Tech. DEGREE EXAMINATION, MAY/JUNE 2007.
Third Semester
(Regulation 2004)
Mechanical Engineering
ME 1201 — ENGINEERING THERMODYNAMICS
(Common to Production Engineering)
(Common to BE. (Part-Time) Second Semester)
(Regulation 2005)
Time : Three hours
Maximum : 100 marks
Use of Steam Tables, Mollier Chart, Psychrometric Chart permitted.
Answer ALL questions.
PART A — (10 x 2 = 20 marks)
1. What is meant by internal energy?
2. A rigid tank is insulated around both its sides and ends. It is separated initially into two equal volumes by a partition. When one side contains 1 kg of gas at 100 kPa and 345°C, the other side remains evacuated. If the partition is removed, find final pressure and temperature.
3. What do you understand by a reversible process?

4. What are the two major conclusions deduced from the Carnot principles?
5. Define triple point and identify the triple point of water.
6. Steam in a pipeline with a pressure of 1000 kPa flows through a throttling calorimeter where pressure is 100 kPa and temperature is 120°C. What is the initial quality of steam if enthalpy remains constant during throttling?
7. What is equation of state? Write the same for an ideal gas.
8. What is the significance of compressibility factor?
9. What is specific humidity and how do you calculate it?
10. What is meant by adiabatic saturation temperature?
PART B — (5 x 16 = 80 marks)
11. (a) (i) Deduce the expression for the displacement work in an isothermal process (4)
(ii) Three grams of nitrogen gas at 6 atm and 160°C is expanded adiabatically to double its initial volume, then compressed at constant pressure to its initial volume and then compressed again at constant volume to its initial state. Calculate the net work done on the gas. Draw the p-V diagram for the process. Specific heat ratio of nitrogen is 1.4. (10 + 2)
Or
(b) (i) Describe steady flow energy equation and deduce suitable expression for the expansion of gas in a gas turbine with suitable assumptions (8)
(ii) Air expands by isentropic process through a nozzle from 784 kPa and 220°C to an exit pressure of 98 kPa. Determine the exit velocity and the mass flow rate, if the exit area is 0.0006 m2
. (8)
12. (a) (i) What are the conditions for reversibility? Explain. (4)

(ii) An heat exchanger circulates 5000 kg/hr of water to cool oil from 150°C to 50°C.
The rate of flow of oil is 2500 kg/hr. The average specific heat of oil is 2.5 kJ/kgK.
The water enters the heat exchanger at 21°C. Determine the net change in the entropy due to heat exchange process, and the amount of work obtained if cooling of oil is done by using the heat to run a Carnot engine with sink temperature of 21°C. (8 + 4) www.chennaituitions.inwww.chennaituitions.in
Page 25 of 31
Or
(b) (i) Deduce Clausius inequality and interpret it. (4 + 2)
(ii) An ideal gas of 0.12 m3 is allowed to expand isentropically from 300 kPa and
120°C to 100 kPa. 5 kJ of heat is then transferred to the gas at constant pressure.
Calculate the change in entropy for each process. Assume γ = 1.4 and
Cp =1.0035 kJ/kg-K. If these two processes are replaced by a reversible polytropic expansion, find the index of expansion between original and final states. What will be the total changes in entropy? (4 + 4 + 2)
13. (a) (i) Draw p-T diagram and label various phases and Transitions.
Explain the process of isobaric heating above triple point pressure with the help ofp-T diagram. (4 + 4)
(ii) 2 kg of water at 200°C are contained in a 20 m3 vessel. Determine the pressure, enthalpy, mass and volume of vapour within the vessel (8)
Or
(i) Draw Rankine cycle with one open type feed water heater. Assume the condition of

the steam before entering the turbine to be superheated. Sketch the cycle on T-s diagram. (6)
(ii) In an ideal reheat cycle, the steam enters the turbine at 30 bar and 500°C. After expansion to 5 bar, the steam is reheated to 500°C and then expanded to the condenser pressure of 0.1 bar. Determine the cycle thermal efficiency, mass flow rate of steam.
Take power output as 100 MW. (6 + 4)
14. (a) (i) Deduce Maxwell's relations (6)
(ii) Explain the Joule Thomson effect with the help of T-p diagram and derive the expression for Joule Thomson coefficient. Show that the value of this coefficient for an ideal gas is zero. (4 + 4 + 2)
Or
(b) (i) What are the differences between real and ideal gases (4)
(ii) Write down the van der Waal's equation of state for real gases and how is it obtained from ideal gas equation by incorporating real gas corrections? (2 + 4)
(iii) A tank contains 0.2 m3 of gas mixture composed of 4 kg of nitrogen, 1 kg of oxygen and 0.5 kg of carbon-di-oxide. If the temperature is 20°C, determine the total pressure, gas constant and molar mass of the mixture (6)
15. (a) (i) Draw the psychrometric chart and show any two psychrometric processes on it. (6)
(ii) A sample of moist air at 1 atm and 25°C has a moisture content of 0.01% by volume. Determine the humidity ratio, the partial pressure of water vapour, the degree of saturation, the relative humidity and the dew point temperature. (10)
Or

(b) (i) Describe the process of adiabatic mixing of two streams and deduce the ratio of masses of two streams in terms of humidity and/or enthalpy (10)
(ii) The temperature of the windows in a house on a day in winter is 5°C. When the temperature in the room is 23°C, and the barometric pressure is 74.88 cm Hg, what would be the maximum relative humidity that could be maintained in the room without condensation on the window panes? Under these conditions, find the partial pressure of the water vapour and air, the specific humidity and the density of the mixture. (6) www.chennaituitions.inwww.chennaituitions.in
Page 26 of 31
B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2006.
Third Semester Mechanical Engineering
ME 1201 — ENGINEERING THERMODYNAMICS
(Common to Production Engineering and B.E. (Part-Time) -Second Semester - Regulation
2005)(Regulation 2004)
Time : Three hours
Maximum : 100 marks
Standard steam table, Mollier chart, Psychometric-charts are permitted.
Answer ALL questions.
PART A — (10 x 2 = 20 marks)
1.What is the convention for positive and negative work?
2.What are the corollaries to the first law of Thermodynamics?
3. Given Kelvin-Planck statement of the second Law of Thermodynamics.
4.What is a process involved in a Carnot cycle, sketch the same in P-V and T-S diagram.

5. Define critical pressure and temperature for water.
6. Sketch the Rankine cycle on a P-V plane and name the various process.
7. State the Avagodro's law and state its significance.
8.Write the Maxwell's questions and its significance.
9.Explain the terms (a) Specific humidity (b) Dew point temperature.
10. What is adiabatic mixing and write the equation for that?
PART B — (5 x 16 = 80 marks)
11. (a) In an isentropic flow through nozzle, air flows at the rate of 600 kg/hr. At inlet to the nozzle, pressure is 2 MPa and temperature is 127°C. The exit pressure is 0.5 MPa. Initial air velocity is 300 m/s .Determines (i) Exit velocity of air (ii) Inlet and exit area of nozzle.
Or
(b) A centrifugal pump delivers 2750 kg of water per minute from initial pressure of 0.8 bar absolute to a finalpressure of2.8 bar absolute. The suction is 2 m below and the delivery is 5 m above the centre of pump. If the suction and delivery pipes are of 15 cm and 10 cm diameter respectively, make calculation for power required to run the pump.
12. (a) A heat engine operating between two reservoirs at 100 K and 300 K is used to drive heat pump which extracts heat from the reservoir at 300 K at a rate twice that at which engine rejects heat to it. If the efficiency of the engine is 40% of the maximum possible and the coefficient of performance of the heat pump is 50% of the maximum possible, make calculations for the temperature of the reservoir to which the heat pump rejects heat. Also work out the rate of heat rejection from the heat pump if the rate of supply of heat to the engine is 50 kW.

Or
(b) One kg of air is contained in a piston cylinder assembly at 10 bar pressure and 500 K temperature. The piston moves outwards and the air expands to 2 bar pressure and 350 K temperature.
Determine the maximum work obtainable. Assume the environmental conditions to be 1 bar and
290 K.Also make calculations for the availability in the initial and final states.
13. (a) 1 kg ofsteam initially dry saturated at 1.1 MPa expands in a cylinder following the law PV1.13
= C. The pressure at the end of expansion is 0.1 MPa. Determine
(i) The final volume
(ii) Final dryness fraction
(iii) Work done
(iv) The change in internal energy www.chennaituitions.inwww.chennaituitions.in
Page 27 of 31
(v) The heat transferred.
Or
(b) Steam at a pressure of 2.5 MPa and 500°C is expanded in a steam turbine to a condenser pressure of 0.05 MPa. Determine for Rankine cycle (i) The thermal efficiency of Rankine cycle
(ii)
Specific steam consumption. If the steam pressure is reduced to 1 MPa and the temperature is kept same 500°C. Determine the thermal efficiency and the specific steam consumption. Neglect feed pump work.

14. (a) Derive Tds Equation when
(i) T and V independent
(ii) T and P independent
(iii) P and V independent.
Or
(b) Explain and derive the
(i) Joules Thompson co-efficient (ii) Clausius Clapeyron equation.
15. (a) A room 7m x 4m x 4m is occupied by an air water vapour mixture at 38°C. The atmospheric pressure is 1 bar and the relative humidity is 70%. Determine humidity ratio, dew point temperature mass of dry air and mass of water vapour. If the mixture of air-water vapour is further cooled at constant pressure until the temperature is l0°C. Find the amount of water vapour condensed.
Or
(b) Air at 20°C, 40% RH is mixed adiabatically with air at 40°C 40% RH in the ratio of1 kg of the former with 2 kg of later. Find the final condition of air. Draw the process in chart also as diagram. www.chennaituitions.inwww.chennaituitions.in
Page 28 of 31
B.E./B.Tech. DEGREE EXAMINATION, MAY/JUNE 2006.
Third Semester ,Mechanical Engineering
ME 1201 — ENGINEERING THERMODYNAMICS
(Common to Production Engineering)
(Regulation 2004)
Time : Three hours Maximum : 100 marks

Standard Steam Table, Mollier chart, Psychrometric charts are permitted.
Answer ALL questions.
PART A — (10 x 2 = 20 marks)
1. What is the relationship between a system and its environment when the system is (a)
Adiabatic (b) Isolated?
2. What is meant by enthalpy'?
3. State the Clausius statement of Second Law of Thermodynamics.
4. State few examples of irreversible process.
5. What is a pure substance? Give examples.
6. How evaporation differs from boiling?
7. State Dalton's law of partial pressures. On what assumptions this law is based?
8. What is an equation of state?
9. Define the Carnot cycle with P-V and T-S diagram.
10. What is specific humidity? When does it become maximum?
PART B — (5 x 16 = 80 marks)
11. (i)Derive the general energy equation for a steady flow system and apply the equation to a nozzle and derive an equation for velocity at exit. (8)
(ii) In an air compressor, air flows steadily at the rate of 0.5 kg/sec. At entry to the compressor, air has a pressure of 105 kPa and specific volume of 0.86 m3
/kg and at exit of the compressor those corresponding values are 705 kPa and 0.16 m3/kg. Neglect Kinetic and Potential energy change. The Internal energy of air leaking the compressor is
95 kJ/kg greater than that of air entering. The cooling water in the compressor absorbs
60 kJ/sec. of heat from the air. Find power required to derive the compressor. (8)

12. (a) Two kg of air at 500 kPa, 80°C expands adiabatically in a closed system until its volume is doubled and its temperature becomes equal to that of the surroundings which is at 100 kPa, 5°C for this process, determine i. The maximum work ii. The change in availability and iii. The irreversibility.
For air taken, Cv 0= 0.718 kJ/kg K, u = Cv T Where Cv is constant and PV = mRT where P is pressure in kPa, V volume in m3
, m mass in kg, R a constant equal to 0.287 kJ/kg
K and T temperature in K. (16)
Or b. Establish the inequality of Clausius and express Entropy change in irreversible process. (16)
13. (a) In a single heater regenerative cycle the steam enters the turbine at
30 bar, 400°C and the exhaust pressure is 0.10 bar. The feed water heater is a direct
- contact type, which operates at 5 bar. Find i. the efficiency and the steam rate of the cycle, and www.chennaituitions.inwww.chennaituitions.in
Page 29 of 31 ii. the increase in mean temperature of heat addition, efficiency and steam rate as compared to the Rankine cycle (with out regeneration) Neglect pump work. (16)
Or
(b) One kg of steam is contained in an elastic balloon of spherical shape which

supports an internal pressure proportional to its diameter. The initial condition of steam is saturated vapour at 110°C. Heat is transferred to steam until pressure reaches 200 kPa. Determine: i. Final temperature ii. Heat transferred. Take Cps = 2.25 kJ/kg K (16)
14. (a) Entropy is a function of any two properties like P and V, P and T etc., for a pure substance with the help of Maxwell's Equation. Prove i. Tds =Cy.dT + T[β/k].dv ii. Tds = Cp.dT-V.βdp.T iii. Tds = [KCy /β] .dp+ [Cp/vβ] .dv. (16)
OR
(b) Determine change of Internal Energy and change of entropy when the gas obeys Vander
Waal's equation. (16)
15. (a) The atmospheric air at 30°C DBT and 75% RH enters a cooling coil at the rate of
200 m3
/rmn. The coil dew point temperature. is 14°C and the by-pass factor is 0.1 determine i. The temperature of air leaving the coil ii. Capacity of the cooling coil in TR iii. The amount of water vapour removed iv. Sensible heat factor for the process. (16)
Or
(b) The volume flow rate of air is 800 m3
/min of re-circulated at 22°C DBT

and 10°C dew point temperature is to be mixed with 300 m3
/min of fresh air at 30°C DBT and 50% RH. Determine the enthalpy, Specific volume,
Humidity ratio and dew point temperature of the mixture. (16) www.chennaituitions.inwww.chennaituitions.in
Page 30 of 31
B.E/E.TECH. DEGREE EXAMINATIONS, NOVEMBER/DECEMBER 2005
ME 1201- ENGINEERING THERMODYNAMICS
Third semester,Mechanical engineering
(Common to Production engineering)
Time: three hours maximum: 100marks
ANSWER ALL QUESTIONS.
PART A- (10X2=20MARKS)
1. What is heat?
2. Prove that cp-c v=R.
3. State zeroth law of thermodynamics. What is its application?
4. Deduce the relation between the COP of heat pump and refrigerator.
5. What is meant by thermodynamic temperature scale? How do you device such scale?
6. What do you understand by pure substance? Give some typical e.g.
7. What is critical point? What are the properties of water at critical point?
8. What are the unique features of Vander Waal’s equation of state?
9. What is compressibility factor? What does it signify? What is its value for van der
Waal’s gas at critical point?

10. What is dew point temperature? How is it related to dry bulb and wet bulb temperature at the saturation condition?
Part B – (5x6=80 marks)
11. i) Prove that internal energy is a property. (4) ii) 1 kg of gas at 1.1 bar, 27oC is compressed to 6.6 bar as per the law pv1.3
= const.
Calculate work and heat transfer, if
(1)When the gas is ethane (C2H6) with molar mass of 30 kg/ k mol and cp of 2.1 KJ/kg k..
(2)When the gas is Argon(Ar) with molar mass of 40 kg/ k mol and cp of 0.52 KJ/kg k.. (12)
12. a) i) “ Two reversible adiabatic lines cannot intersect”. Is this statement true or false?
Justify the answer. (4) ii) A reversible engine operates between a source at 972 oC and two sinks,one at 127o C and another at 27 oC . The energy rejected is same at both the sinks. What is the ratio of heat supplied to the heat rejected? Also calculate the efficiency. (12)
(Or) b. i) What are the conditions for reversibility? (2) ii) Differentiate between heat pump and refrigerator. (2) iii)50kg of water is at 313K and enough ice -5 o c is mixed with water in an adiabatic vessel such that at the end of the process all the ice melts and water at 0 o C is obtained . Find the mass of ice required and the entropy change of water and the ice.Given Cp of water = 4.2
KJ/kg k, cp of ice = 2.1 K J/kg k and latent heat of ice= 335 KJ/kg . (12)
13. a) i) Draw the p-T diagram of a pure substance and label all the phases and phase changes.
(4) ii) What do you understand by dryness fraction? What is its importance? (2)

iii)A rigid tank of .003 m3 capacity contains wet vapour at 80 k pa. If the wet vapour mass is
12kg, calculate the heat added and the quality of the mixture when the pressure inside the tank reaches 7 M pa. (10)
(Or) b . i) What are the major problems of Carnot vapour cycle? (2) ii) What are the methods for improving the performances of Rankine cycle? (2) www.chennaituitions.inwww.chennaituitions.in
Page 31 of 31 iii) Steam enters the turbine at 3 M pa and 400 o C and is condensed at 10 kpa. Some quantity of steam leaves the turbine at 0.6 Mpa and enters open feed water heater. Compute the fraction of the steam extracted per kg of steam and cycle thermal efficiency.
(12)
14. a) i) Write down the Dalton’s law of partial pressure and explain its importance. (6) ii) 0.45kg of CO and 1kg of air is contained in a vessel of volume 0.4 m3 at 15 o C . Air has 23.3% of O 2 and 76.7% of N2 by mass. Calculate the partial pressure in vessel.
Molar masses of CO, O2 and N2 are 28,32 and 28 kg/kmol. (10)
OR
(b) (i) What is the use of clapeyron equation? And write it down for liquidVapour region. (6)
(ii) Explain the flow process of a real gas through a throttle valve. Derive the expression for the joule Thomson coefficient and deduce its value for an ideal gas. (10)
15. (a) (i) Differentiate between i. Dry bulb temperature and wet bulb temperature. (4) ii. Wet bulb depression and dew point expression. (4)

ii. Air at 16 o C and 25% relative humidity passes through a heater and then through a humidifier to reach and final dry bulb temperature of 30 o C and 50% relative humidity.
Calculate the heat and moisture added to the air. What is the sensible heat factor?.
(Or) b .i) In an adiabatic missing of two streams, drive the relationship among the ratio of masses of streams, ratio of enthalpy change and ratio of specific humidity change. (8) ii) Saturated air at 20o c at a rate of 1.167 m3
/sec is mixed adiabatically with the outside air at 35 oC and 50% relative humidity at a rate 0.5 m3
/sec. Assuming adiabatic mixing condition at 1 atm, determine specific humidity, relative humidity, and dry bulb temperature and volume flow rate of the mixture. (8) www.chennaituitions.in