Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 3rd Sem New 2131905 Engineering Thermodynamics Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER?III (New) EXAMINATION ? WINTER 2018
Subject Code: 2131905 Date: 05/12/2018
Subject Name: Engineering Thermodynamics
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of steam table with Mollier chart is allowed.
Q.1 (a) Define heat, thermodynamic work and critical point. 03
(b) What is thermodynamic system? Explain its all types with suitable examples. 04
(c) Derive the general energy equation and deduce it for steady flow energy
equation. Apply the same to nozzle.
07
Q.2 (a) Write down statement of first law of thermodynamics for 1) an isolated
system, 2) a system undergoing a cycle and 3) a system undergone a specific
process.
03
(b) What is entropy? Prove that it is a point function and hence property of the
system.
04
(c) Steam is leaving a 4 litre Pressure cooker whose operating pressure is 150
kPa. It is observed that the amount of liquid water in the cooker has decreased
by 0.6 litre in 40min. after the steady operating conditions are established.
And the cross section area of the exit opening is 8 mm
2
. Determine (a)
Temperature and other properties of steam, (b) mass of water decreased (c)
mass flow rate of steam (d) exit velocity of steam (e, f) the total and flow
energies of the steam per unit mass and (g) The rate at which energy leaves
the cooker by steam.
07
OR
(c) Prove the Carnot theorem applied to reversible heat engine. Also write down
statements of its corollaries.
07
Q.3 (a) Prove the equivalency of Kelvin Plank and Clausius statements of second
law of thermodynamics.
03
(b) Explain the Clausius inequality. 04
(c) 4 kg of ice at -4
O
C is exposed to the atmosphere which is at 20
O
C. The ice
melts and comes into equilibrium with the atmosphere. Draw T-s plot for the
system, determine the entropy increase of the universe and comment about
the process.
Can water convert back into ice at -4
O
C naturally? Why? If it happened, what
will be the change in entropy of system for this case?
For ice, specific heat = 2.09 kJ/ kg K and latent heat of fusion =333 kJ/kg.
For water, specific heat = 4.18 kJ/ kg K.
07
OR
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER?III (New) EXAMINATION ? WINTER 2018
Subject Code: 2131905 Date: 05/12/2018
Subject Name: Engineering Thermodynamics
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of steam table with Mollier chart is allowed.
Q.1 (a) Define heat, thermodynamic work and critical point. 03
(b) What is thermodynamic system? Explain its all types with suitable examples. 04
(c) Derive the general energy equation and deduce it for steady flow energy
equation. Apply the same to nozzle.
07
Q.2 (a) Write down statement of first law of thermodynamics for 1) an isolated
system, 2) a system undergoing a cycle and 3) a system undergone a specific
process.
03
(b) What is entropy? Prove that it is a point function and hence property of the
system.
04
(c) Steam is leaving a 4 litre Pressure cooker whose operating pressure is 150
kPa. It is observed that the amount of liquid water in the cooker has decreased
by 0.6 litre in 40min. after the steady operating conditions are established.
And the cross section area of the exit opening is 8 mm
2
. Determine (a)
Temperature and other properties of steam, (b) mass of water decreased (c)
mass flow rate of steam (d) exit velocity of steam (e, f) the total and flow
energies of the steam per unit mass and (g) The rate at which energy leaves
the cooker by steam.
07
OR
(c) Prove the Carnot theorem applied to reversible heat engine. Also write down
statements of its corollaries.
07
Q.3 (a) Prove the equivalency of Kelvin Plank and Clausius statements of second
law of thermodynamics.
03
(b) Explain the Clausius inequality. 04
(c) 4 kg of ice at -4
O
C is exposed to the atmosphere which is at 20
O
C. The ice
melts and comes into equilibrium with the atmosphere. Draw T-s plot for the
system, determine the entropy increase of the universe and comment about
the process.
Can water convert back into ice at -4
O
C naturally? Why? If it happened, what
will be the change in entropy of system for this case?
For ice, specific heat = 2.09 kJ/ kg K and latent heat of fusion =333 kJ/kg.
For water, specific heat = 4.18 kJ/ kg K.
07
OR
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2
Q.3 (a) Define following terms: 1) dead state 2) high grade energy 3) irreversibility. 03
(b) Two Carnot engines work in series between source and sink temperature of
1200K and 300K. Find out the intermediate temperature if 1) Both engines
having same efficiency 2) Both engines develop equal power.
04
(c) By burning a fuel, the rate of heat release is 500 kW at 2000 K. What would
be the first law and second law efficiencies if 1) energy is absorbed in a
metallurgical furnace at the rate of 480 kW at 1000 K 2) energy is absorbed
at the rate of 450 kW for generation of steam at 500 K and 3) energy is
absorbed in a chemical process at the rate of 300 kW at 320 K. Take ambient
temperature 300 K. What is the inference that you can draw from this
example?
07
Q.4 (a) Draw P-v, T-s plot of Carnot vapor cycle indicating all the processes. Also
state its limitations.
03
(b) Draw neat schematic and explain the working of simple Brayton cycle. 04
(c) A Thermal power plant operates on ideal reheat type Rankine cycle with inlet
of steam to high pressure turbine at 150 bar and 550
O
C. The dry steam at exit
is being reheated at 40 bar to 550
O
C and supplied to low pressure turbine.
Condenser works at 0.1 bar. Draw the T-s and h-s plot for the same and
determine 1) quality at outlet of low pressure turbine 2) cycle efficiency 3)
steam rate 4) heat rate and 5) work ratio.
07
OR
Q.4 (a) Draw the P-v and T-s plot for the Diesel cycle indicating all the processes
and write down formula for its thermal efficiency.
03
(b) What is the mean temperature of heat addition? Explain its significance. 04
(c) In an air standard Otto cycle, the temperatures at the beginning and end of
the isentropic compression are 316K and 596K respectively. Determine the
air standard efficiency and compression ratio. Also calculate the heat
supplied, heat rejected and net power produced, if the maximum temperature
during cycle is 3 times that of after isentropic compression.
07
Q.5 (a) Define effectiveness of regeneration, mole fraction and characteristic gas
constant.
03
(b)
Draw the P-v, T-s plot and compare Otto, Diesel and Dual cycle for same
compression ratio and heat rejection.
04
(c) Explain Dalton?s law of partial pressure and Gibbs-Dalton law applied to
mixture of gases.
07
OR
Q.5 (a) Draw the neat schematic of regeneration type Rankine cycle with two feed
water heaters indicating clearly all components and mass flow of steam.
03
(b) Explain in brief reduced properties of gas and critical compressibility factor. 04
(c) Explain Vander Waal?s equation of state. 07
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This post was last modified on 20 February 2020