Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 3rd Sem New 2131404 Food Engineering Thermodynamics Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? III (New) EXAMINATION ? WINTER 2019
Subject Code: 2131404 Date: 03/12/2019
Subject Name: Food Engineering Thermodynamics
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Standard Steam Tables and normal range Psychrometric Chart can be used
Q.1 (a) Why gases deviate from ideal behavior? A 50 liters capacity vessel contains
CO2 gas at 77
o
C and 3 bar pressure. Calculate the mass of CO2 in kilogram.
03
(b) Two kilogram of methane gas was injected into a 100 liter vessel containing
nitrogen at 0.9 bar absolute pressure and 27
o
C under isothermal conditions.
Calculate the partial pressure of methane gas and the total pressure in the
container in bar. [M = 16 g/mol]
04
(c) Answer the following:
i. Explain the law of corresponding states.
ii. Write Van der Waal?s gas equation and give SI units.
iii. Define open system.
iv. If vacuum is 600 mmHg, calculate absolute pressure in kPa.
v. Calculate the specific gas constant for a gas mixture containing 80% N2
and 20% O2 by weight.
vi. Name different types of thermometers.
vii. Show that Cp ? Cv =
_
R for ideal gases.
07
Q.2 (a) State Zero
th
law of thermodynamics. Discuss different temperature scales and
their interrelationships.
03
(b) Ten kilogram of O2 gas is heated reversibly at constant pressure from an
initial state of [T = 330 K, P= 1.6 bar] until its volume doubles. Calculate
(i) The expanded work in kJ
(ii) Change in internal energy and enthalpy in kJ.
[Take Cp = 35J/mol K, R = 8.314 J/mol k]
04
(c) State first law of thermodynamics for a closed system. Ten kilogram of an
ideal gas at 113
o
C and 8 bar pressure expands isentropically four times its
initial volume. Calculate the work done during the process in kJ.
[Cp = 1.005 kJ/kgK, Cv = 0.715 kJ/kgK]
07
OR
(c) Derive SFEE for a fluid stream entering and leaving a turbine in terms of
work and energy transfer per unit mass. Specify the assumptions made.
07
Q.3 (a) What is Gibb?s phase rule? Calculate the degrees of freedom of water at its
triple point.
03
(b) Calculate the approximate pressure at which water would boil at 180
o
C. It is
known that water boils at 100
o
C at 1.01325 bar. [Take R = 8.314 J/mol K,
hfg (at 100
o
C) = 2258 kJ/kg]
04
(c) Explain Joule-Kelvin effect with the help of a T-P diagram. 07
OR
Q.3 (a) What is Gibb?s phase rule? Calculate the degrees of freedom of water at its
critical point.
03
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? III (New) EXAMINATION ? WINTER 2019
Subject Code: 2131404 Date: 03/12/2019
Subject Name: Food Engineering Thermodynamics
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Standard Steam Tables and normal range Psychrometric Chart can be used
Q.1 (a) Why gases deviate from ideal behavior? A 50 liters capacity vessel contains
CO2 gas at 77
o
C and 3 bar pressure. Calculate the mass of CO2 in kilogram.
03
(b) Two kilogram of methane gas was injected into a 100 liter vessel containing
nitrogen at 0.9 bar absolute pressure and 27
o
C under isothermal conditions.
Calculate the partial pressure of methane gas and the total pressure in the
container in bar. [M = 16 g/mol]
04
(c) Answer the following:
i. Explain the law of corresponding states.
ii. Write Van der Waal?s gas equation and give SI units.
iii. Define open system.
iv. If vacuum is 600 mmHg, calculate absolute pressure in kPa.
v. Calculate the specific gas constant for a gas mixture containing 80% N2
and 20% O2 by weight.
vi. Name different types of thermometers.
vii. Show that Cp ? Cv =
_
R for ideal gases.
07
Q.2 (a) State Zero
th
law of thermodynamics. Discuss different temperature scales and
their interrelationships.
03
(b) Ten kilogram of O2 gas is heated reversibly at constant pressure from an
initial state of [T = 330 K, P= 1.6 bar] until its volume doubles. Calculate
(i) The expanded work in kJ
(ii) Change in internal energy and enthalpy in kJ.
[Take Cp = 35J/mol K, R = 8.314 J/mol k]
04
(c) State first law of thermodynamics for a closed system. Ten kilogram of an
ideal gas at 113
o
C and 8 bar pressure expands isentropically four times its
initial volume. Calculate the work done during the process in kJ.
[Cp = 1.005 kJ/kgK, Cv = 0.715 kJ/kgK]
07
OR
(c) Derive SFEE for a fluid stream entering and leaving a turbine in terms of
work and energy transfer per unit mass. Specify the assumptions made.
07
Q.3 (a) What is Gibb?s phase rule? Calculate the degrees of freedom of water at its
triple point.
03
(b) Calculate the approximate pressure at which water would boil at 180
o
C. It is
known that water boils at 100
o
C at 1.01325 bar. [Take R = 8.314 J/mol K,
hfg (at 100
o
C) = 2258 kJ/kg]
04
(c) Explain Joule-Kelvin effect with the help of a T-P diagram. 07
OR
Q.3 (a) What is Gibb?s phase rule? Calculate the degrees of freedom of water at its
critical point.
03
2
(b) Show that for a reversible process
P S
S
V
P
T
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
04
(c) Prove that for any gas undergoing a throttling process, the Joule-Kelvin
coefficient is given by
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
? v
T
v
T
C
P P
T j
1
,
?
07
Q.4 (a) Explain Carnot cycle showing all the state points and explain the significance
of this cycle.
03
(b) Explain the following:
(i) Clausius inequality.
(ii) Thermal reservoirs
04
(c) Explain Kelvin-Plank and Clausius statements of second law of
thermodynamics & prove that they are in fact equivalent.
07
OR
Q.4 (a) Explain the concept and importance of available and unavailable energy
03
(b)
Prove that
) (
?
T
dQ
< 0; for any cyclic irreversible process.
04
(c) Explain Clausius statement of second law of thermodynamics. A heat pump
is operating between ? 5
o
C and 25
o
C. It delivers a COP which is 50% of the
maximum possible COP. If it is delivering 5kW of heat into the warm room,
calculate the power requirement to drive the unit.
07
Q.5 (a)
Prove that specific humidity of moist air is given by
?
?
?
?
?
?
?
?
?
?
w o
w
p p
p
622 . 0 ?
03
(b) The weather report on a certain date was recorded as given below:
A. Atmospheric pressure = 760 mm Hg
B. Ambient Temperature = 38
o
C
C. RH = 60%
Using Psychrometric Chart, calculate the DPT, WBT, Specific enthalpy and
absolute humidity of the atmospheric air.
04
(c) Explain P-V and T-s phase diagram of a pure substance (water). Using Steam
Tables determine the following for saturated steam at 2MPa pressure:
(i) Saturation temperature in
o
C
(ii) Entropy in kJ/kg K
(iii) Latent heat of vaporization in kJ/kg
(iv) Specific volume in m
3
/kg
07
OR
Q.5 (a) Define the following terms for moist air:
(i) Wet bulb temperature
(ii) Relative humidity
(iii) Dry bulb temperature
03
(b) Air at a certain place is at 40
o
C abd has a barometric pressure of 1 bar. If pw
of water vapours present in the air is 20 mm Hg, calculate the following:
i. DBT
ii. Specific humidity
iii. Relative humidity
iv. DPT
04
(c) Explain phase diagram of a pure substance (water) on a P-v diagram. Ten kg
of wet steam at 120
o
C containing 80% of dry steam is allowed to completely
condense to water at 92
o
C. Calculate the amount of heat released in kJ.
07
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This post was last modified on 20 February 2020