Monday, July 23, 2012


Anna University November/December 2011 
(Regulation 2010)
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A — (10 ´ 2 = 20 marks)

1. Explain the following terms :
(a) Process (b) cycle.
2. Define internal energy.
3. What do you mean by the term ‘entropy’?
4. What is a temperature entropy diagram?
5. Draw a p-T (pressure-temperature) diagram for a pure substance.
6. Explain comparison between Rankine cycle and Carnot cycle.
7. Explain compressibility factor.
8. Write the Maxwell’s equation.
9. Define dry bulb temperature.
10. Explain adiabatic mixing of two substances.

PART B — (5 ´ 16 = 80 marks)
11. (a) 10 kg of fluid per minute goes through a reversible steady flow process. The properties of fluid at the inlet are 1 P = 1.5 bar, 1 r = 26 kg/m3, 1 v = 110 m/s and 1 u = 910 kJ/kg and at the exit are 2 P = 5.5 bar, 2 r = 5.5 kg/m3 2 v = 190 m/s and 2 k = 710 kJ/kg. During the passage, the fluid rejects 55 kJ/s and rises through 55 m. Determine : (i) the change in enthalpy (h) (ii) work done during the process (w).
(b) A system contain 0.2 m3 of a gas at a pressure of 4 bar and 150°C. It is expanded adiabatically till the pressure falls to 1 bar. The gas is then heated at a constant pressure till its enthalpy increases by 100 kJ. Determine the total work done. Take p c = 1 kJ/kgK and v c = 0.714 kJ/kgK. (16)

12. (a) A reversible heat pump is used to maintain a temperature of 0°C in a refrigerator when it rejects the heat to the surroundings at 27°C . If the heat removal rate from the refrigerator is 1500 kJ/min. Determine the C.O.P of the machine and work input required. If the required input to
run the pump is developed by a reversible engine which receives heat at 400°C and rejects heat to atmosphere, then determine the over all C.O.P of the system. (16)

(b) A reversible engine is supplied with heat from two constant temperature sources at 900K and 600K and rejects heat to a constant temperature sink at 300K. If the engine executes a numbers of complete cycles while developing 100 kW, and rejecting 3600 kJ of heat per minute. Determine
the heat supplied by each source per minute and efficiency of the engine. (16)

13. (a) One kg of steam at 10 bar exists at the following conditions (i) wet and 0.8 dry (ii) dry and saturated and (iii) at a temperature of 199.9°C. Determine the enthalpy, specific volume, density, internal energy and entropy in each case. Take ps c = 2.25 kJ/kg. (16)
(b) A Rankine cycle works between 40 bar and 0.2 bar with saturated steam at turbine inlet. Determine the cycle efficiency and the ratio of pump work and turbine work. (16)

14. (a) A certain ideal gas has R = 290 J/kg k and g = 1.35 (i) Determine the values of p c and v c . (ii) The mass of the gas it is filled in a vessel of 0.5 m3 capacity till the pressure inside becomes 4 bar gauge and the temperature is 27°C (iii) if 40 kJ of heat is given to the vessel when the vessel is closed, determine the resulting temperature and pressure. Take the atmospheric pressure = 100 kPa. (16)
(b) A container of 3m3 capacity contains 10 kg of CO2 at 27°C. Estimate the pressure exerted by CO2 by using.
(i) Perfect gas equation.
(ii) Vander Waal’s equation.
(iii) Beattie Bridgeman equation. (16)

15. (a) It is required to design an air conditioning plant for a small office room for following winter conditions. Outdoor conditions = 14°C DBT and 10°C WBT Required conditions = 20° C DBT and 60% R.H Amount of air circulation 0.30 m3/min/person. Seating capacity of office = 60 The required condition is achieved first by heating and then by adiabatic humidifying.
Determine the following :
(i) Heating capacity of the coil in kW and the surface temperature required if the by pass factor of coil is 0.4.
(ii) The capacity of the humidifier. (16)
(b) Saturated air at 20°C at a rate of 70 m3/min is mixed adiabatically with the outside air at 35°C and 50% relative humidity at a rate 30 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. (16)


PART –A (2 marks)
1. Define the term thermal engineering.
2. What is meant by thermodynamics system? How do you classify it?
3. What is meant by closed system? Give an example.
4. Define an open system Give an example.
5. Distinguish between Open and Closed system
6. Define an 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 meant by thermodynamic property
12. How do you classify the property?
13. Define Intensive and Extensive properties.
14. What do you understand by equilibrium of a system?
15. Differentiate Intensive and Extensive properties


1. one kg of gas expands at CO&11stant pressure from 0.085 m3 to 0.13 Ill).if the initial
temperature of the gas is 22.5 °c. find the final. Temperatures, net heat transfer, change in
internal energy, pressure of gas. (16)
2. A certain quantity of gas is head at constant pressure from 35 °0 to 185°c. Estimate the
amount of hem transferred, ideal work done, change in internal energy, when the initial volume of
the gas is 0.6 m3. (16)
3. Explain and derive Isothermal process (16)
4. Explain and derive Isobaric process. (16)
5. 2kg of gas at a pressure of 1.5 bar. Occupies a volume of 2.5 m3. If this gas compresses
isothermally to 1/3 times the initial volume. Find initial. Final temperature, work done, heat
transfer. (16)
6. one kg of air is compressed polytropically (n=1.3) from 1 bar and 27 deg Celsius
to 3 bar. Find I. work transfer , 2.Heat transfer,3. Change in internal energy (16)
PART –A (2 marks)
1. State the Kelvin - Planck statement of second law of thermodynamics.
2. State Clausius statement of second law of thermodynamics.
3. Write the two statements of the Second law of thermodynamics.
4. State Carnot's theorem.
5. What are the Corollaries of Carnot theorems?
6. Define - PMM of second kind.
7. What is difference between a heat pump and refrigerator?
8.What is mean by heat engine?
9. Define the term COP.
10. Why Carnot cycle cannot be realized in practice?
11. Name two alternative methods by which the efficiency of a Carnot cycle can be increased.
12. Why a heat engine cannot have 100% efficiency
13. When the Carnot cycle efficiency will be maximum?
14. What are the processes involved in Carnot cycle
1. Air flows through an adiabatic compressor at 3 kg/s the inlet conditions are 2 bar and 310k
and exit conditions are 20 bar and 560 k. compute the net rate of availability transfer and
irreversibility. (16)
2. Air in a closed vessel of fixed volume of 0.15 m 3, exerts pressure of 12 bar at 250 °c ,if the
vessel is cooled so that the pressure falls to 3.5 bar, determine the final temperature, heat
transfer and change of entropy. (16)
3. Explain Carnot engine cycle and its efficiency. (16)
4. Explain the term availability and unavailability. (16)
5. A heat engine operates between a source a 600 °c and a sink at 60 c Determine the least rate
of heat rejection per KW net output of the engine. (16)
6. 0.2 kg of air at 1.5 bar and 27 "c is compressed to a pressure of 15 bar according to the law
pv (l.25) =c. determine work done heat flow to or from the air, increase or decrease in entropy
PART –A (2 marks)
1.Define latent heat of ice.
2. What is pure substance?
3. What is saturation temperature and saturation pressure?
4. Define latent Heat of vaporization.
5. Find the saturation temp and latent heat of vaporization of steam at 1 Mpa.
6. Define the terms 'Boiling point' and 'Melting point .
7. What is meant by super heated steam and indicate its use.
8. Define: sensible heat of water.
9. Define the term "Super heat enthalpy".
10. What are wet and dry steam?
11 State phase rule of pure substances.
12. Define dryness fraction of steam (or) What is quality of steam?
13. Explain the terms: Degree of super heat, Degree of sub cooling.
14. Define triple point and critical point for pure substance.
1. Find the specific volume and enthalpy of steam at 9 bar when the condition of steam is
a) Wet with dryness fraction 0.95 b) dry saturated c) super heated temperature of 240° (16)
2. Steam initially at 400 Kpa and 0.6 dry is heated in a rigid vessel of 0.1m3 volume. The final
condition is 600 Kpa. Find the amount of heat added and mass of steam. (16)
3. Explain P-V diagram and P-V-T surface. (16)
4. 2 kg of steam initially at 5 bar and 0.6 dry is heated at constant pressure until the temperature
becomes 350 c.find the change in entropy and internal energy. (16)
5.A steam plant working on a simple rankine cycle operated between the temperature of 260°c
and 95°c .the steam is dry and saturated when it enters the turbine and expanded isentropic ally.
Find rankine efficiency. (16)
6) 2.5 kg of steam is heated at constant pressure of 250 kpa and 100°c, until temperature is
250°c. Find the amount of heat added and change in entropy. (16)
(Use mollier chart)
UNIT – 4
PART –A (2 marks)\
1. Determine the molecular volume of any perfect gas at 600N/m2 and 300 C. Universal gas
constant may be taken as 8314J/kg mole-K.
2. State Boyle's law.
3. State Charle's law.
4. State Joule's law.
5. State Regnault's law.
6. State Avogadro's law.
7. State Dalton's law of partial pressure

8. How does the Vander Waals equation differ from the ideal gas equation of state?
9. What is meant by virtual expansion?
10. Distinguish between ideal and real gas.
11. Define Joule-Thomson Co-efficient.
12. Define Co-efficient of volume expansion and Isothermal compressibility.
13. What is compressibility factor?
14. What is compressibility factor? What does it signify? What is its value for an ideal gas at
critical point?
.1. Derive Dalton’s law of partial pressure. Define amagats law of partial volume. (16)
2. Derive vandar Waals equation. (16)
3. Derive Maxwell’s equation (16)
4. Derive clausius-clapeyron equation. (16)
5. Derive Joule-Thomson coefficient equation. (16)
6. A mixture of gases contains 50%nitrogen,40% oxygen and 10% carbon di oxide by mass. 2
kg of mixture is compressed from 200 kpa and 293k to 400 kpa polytropically which follows
the PV(I.25)=C. Determine the work done, heat transferred and change in entropy.
(Take (cp)n2=1.04 (cp)o2= 0.918 kj / kg k, (cp)co2=O.846 k/k (16)
UNIT – 5
PART –A (2 marks)

1. What is the difference between air conditioning and refrigeration?
2. Define psychrometry.
3. 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? How is it related to dry bulb and wet bulb temperature at the
saturation condition?
11. Define Apparatus Dew Point (ADP) of cooling coil.
12. List down the psychrometirc processes.
13. Define bypass factor (BPF) of a coil.
14. State the effects of very high and a very low bypass factor.
15. What are the assumptions made while mixing two air streams
I. Dry bulb and wet temperatures of 1 atmospheric air stream are 40°0 and 30°c
respectively. Determine
(a)Humidity (b) Relative humidity (c) Specific humidity. (16)
2. Atmospheric air with barometric pressure of 1.013 bar has 38°c dry bulb temperature
and 28°c wet bulb temperature. Determine (a) Humidity ratio (b) Relative humidity (c) dew
point temperature. (16)
3. Atmospheric air at 760 mm of Hg has 45°c DBT and 30°c WBT, using psychometric
chart calculate R.H, Humidity ratio, DPT, enthalpy, specific volume of air. (16)
4.Atmospheric air at 1 bar pressure has 2.5°0 DBT and 75% RH using psychometric chart,
calculate DBT, enthalpy, vapour pressure. (16)
5. Explain sensible heating process, sensible cooling, and humidification process. (16)
6. An air water vapour mixture at 0.1 Mpa, 30°0, 80% RH. Has a volume of 50 m3
Calculate the specific humidity, dew point, wet bulb temperature, mass of dry air and mass of
water vapour. (16)
7.Calculate the specific humidity, dew point, wet bulb temperature, mass of dry air and mass of

water vapour. (16)