Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January AE 3rd Sem 76400 Engineering Thermodynamics Previous Question Paper
Total No. of Pages : 03
Total No. of Questions : 18
B.Tech. (AE) (2018 Batch) (Sem.?3)
ENGINEERING THERMODYNAMICS
Subject Code : BTAE-302-18
M.Code : 76400
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
Write briefly :
1.
What are the differences between supersaturated flow and isentropic flow through steam
nozzles?
2.
What do you understand by thermal equilibrium?
3.
Define air standard cycle efficiency.
4.
Define available energy and unavailable energy.
5.
What is Rankine cycle? What are the limitations of Rankine cycle?
6.
Define latent heat of evaporation or Enthalpy of evaporation.
7.
What is the function of the throttling valve in vapour compression refrigeration system?
8.
What is humidification and dehumidification?
9.
What are the factors that affect the volumetric efficiency of a reciprocating compressor?
10. What is meant by Dry Bulb Temperature (DBT)?
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SECTION-B
11. Describe steady flow energy equation and apply the equation to a nozzle and derive an
equation for velocity at exit.
12. a) What are the conditions for reversibility?
b) Heat exchanger circulates 5000 kg/hr of water to cool oil from 150?C to 50?C The
rate of flow of oil is 2.5 kJ/kgK. the water enters the heat exchanger at 21?C.
Determine the net change in 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.
13. Draw p-T diagram and label various phases and transitions. Explain the process of
isobaric heating above triple point pressure with the help of p-T diagram.
14. Explain the working of 4-stroke cycle Diesel engine. Draw the theoretical and actual
valve- timing diagram for the engine.
15. What is sensible heat? How is the sensible heat loss from a human body affected by :
a) Skin temperature
b) Environment temperature, and
c) Air motion.
SECTION-C
16. An air conditioning system is to take in outdoor air at 263 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
process takes place at a pressure of 100 kPa.
Determine :
a) The rate of heat supply in the heating section.
b) The mass flow rate of the steam required in the humidifying section.
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17. An Engine-working on Otto cycle has a volume of 0.45 m3, pressure 1 bar and
temperature 30?C at the beginning of compression stroke. At the end of compression
stroke, the pressure is 11 bar and 210 KJ of heat is added at constant volume.
Determine :
a) Pressure, temperature and volumes at salient points in the cycle.
b) Efficiency.
18. 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.
Process
Q (kJ)
W (kJ)
U (kJ)
1-2
40
?
25
2-3
20
?10
?
3-4
?20
?
?
4-1
0
+8
?
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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This post was last modified on 26 June 2021