Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 4th Sem New 2140106 Basic Engineering Thermodynamics Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? IV (New) EXAMINATION ? WINTER 2019
Subject Code: 2140106 Date: 13/12/2019
Subject Name: Basic 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.
MARKS
Q.1 (a) Define open system, closed system and isolated system with example. 03
(b) Explain the concept of thermodynamic equilibrium. State zeroth law of
thermodynamics and explain how it leads to the concept of temperature?
04
(c) Explain the followings
1.Microscopic and macroscopic point of view
2.Control volume and control surface
3.Intensive and extensive properties
4.Continum
07
Q.2 (a) Define point function and path function with example. 03
(b) Prove that work is a path function. 04
(c) Derive any two T-ds relations and explain their importance in
thermodynamics.
07
OR
(c) Derive the expression for efficiency and mean effective pressure for dual
cycle.
07
Q.3 (a) Define available energy and unavailable energy for a nonflow process. 03
(b) In a gas turbine unit, the gas flow through the turbine is 15 kg/s and the
power developed by the turbine is 12000 kW. The enthalpies of the gases
at inlet and outlet are 1260 kJ/kg and 400 kJ/kg respectively and the
velocity of gases at inlet and outlet are 50 m/s and 110 m/s respectively.
Calculate: the rate at which the heat is rejected from the turbine and the
area of inlet pipe given the specific volume of gases at the inlet is 0.45
m
3
/kg
04
(c) In a Carnot cycle, the steam at inlet to the turbine is saturated at pressure
of 30 bar and exhaust pressure is 0.04 bar. Determine: 1) the compressor
work, 2) the turbine work, 3) Carnot efficiency, 4) the quality of steam at
the end of expansion. Use of steam table is permitted.
07
OR
Q.3 (a) Derive an expression for pdV work for isothermal process. 03
(b) Define irreversibility and discuss the causes of same. 04
(c) Compare the Otto, Diesel and Dual cycle for
(1) same compression ratio and heat supplied
(2) constant maximum pressure and heat supplied
07
Q.4 (a) Define Air standard efficiency, thermal efficiency and work ratio. 03
(b) Discuss air standard Otto cycle. 04
(c) Derive general energy equation for steady flow process (SFEE) and
simplify it when applied for the nozzle and gas turbine.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? IV (New) EXAMINATION ? WINTER 2019
Subject Code: 2140106 Date: 13/12/2019
Subject Name: Basic 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.
MARKS
Q.1 (a) Define open system, closed system and isolated system with example. 03
(b) Explain the concept of thermodynamic equilibrium. State zeroth law of
thermodynamics and explain how it leads to the concept of temperature?
04
(c) Explain the followings
1.Microscopic and macroscopic point of view
2.Control volume and control surface
3.Intensive and extensive properties
4.Continum
07
Q.2 (a) Define point function and path function with example. 03
(b) Prove that work is a path function. 04
(c) Derive any two T-ds relations and explain their importance in
thermodynamics.
07
OR
(c) Derive the expression for efficiency and mean effective pressure for dual
cycle.
07
Q.3 (a) Define available energy and unavailable energy for a nonflow process. 03
(b) In a gas turbine unit, the gas flow through the turbine is 15 kg/s and the
power developed by the turbine is 12000 kW. The enthalpies of the gases
at inlet and outlet are 1260 kJ/kg and 400 kJ/kg respectively and the
velocity of gases at inlet and outlet are 50 m/s and 110 m/s respectively.
Calculate: the rate at which the heat is rejected from the turbine and the
area of inlet pipe given the specific volume of gases at the inlet is 0.45
m
3
/kg
04
(c) In a Carnot cycle, the steam at inlet to the turbine is saturated at pressure
of 30 bar and exhaust pressure is 0.04 bar. Determine: 1) the compressor
work, 2) the turbine work, 3) Carnot efficiency, 4) the quality of steam at
the end of expansion. Use of steam table is permitted.
07
OR
Q.3 (a) Derive an expression for pdV work for isothermal process. 03
(b) Define irreversibility and discuss the causes of same. 04
(c) Compare the Otto, Diesel and Dual cycle for
(1) same compression ratio and heat supplied
(2) constant maximum pressure and heat supplied
07
Q.4 (a) Define Air standard efficiency, thermal efficiency and work ratio. 03
(b) Discuss air standard Otto cycle. 04
(c) Derive general energy equation for steady flow process (SFEE) and
simplify it when applied for the nozzle and gas turbine.
07
2
OR
Q.4 (a) Derive the expressions for coefficient of volume expansion and
coefficient of isothermal compressibility for a perfect gas.
03
(b) Prove that, Cp-Cv = R 04
(c) An engine working on an Otto cycle has a volume of 0.45 m
3
, pressure 1
bar and temperature 30?C at the beginning of compression stroke. At the
end of compression stroke, the pressure is 11 bar. 210 kJ of heat is added
at constant volume. Determine pressure, temperature and volume at
salient points in the cycle, % clearance, efficiency, net work per cycle and
power developed if Revolution speed is 210 RPM.
07
Q.5 (a) State and explain the second law of thermodynamics. 03
(b) Discuss perpetual motion machine of the second kind. 04
(c) A Carnot engine operates as refrigerator. Define the COP and derive its
expression for refrigerator. If the refrigerator has refrigerating capacity
of 100 kJ/s while operating between temperature limits of -20?C and
35?C. determine power input and COP.
07
OR
Q.5 (a) State and explain Boyle?s law and Charles law. 03
(b) Prove that all reversible engines working between the two constant
temperature reservoirs have the same efficiency.
04
(c) Explain the effect of following variables on the performance of Rankine
cycle with help of p-h and T-s diagram.
1.Effect of increase in boiler pressure
2.Effect of decrease in condenser pressure
3.Effect of superheating the steam
07
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This post was last modified on 20 February 2020