Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 3rd Sem New 3131404 Food Engineering Thermodynamics Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? III (New) EXAMINATION ? WINTER 2019
Subject Code: 3131404 Date: 26/11/2019
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) Define ideal and real gases. Why do real gases deviate from ideal behaviour?
A sealed container contains air at 87
o
C and 1 bar. The container was
evacuated using a vacuum pump so that the vacuum inside the container is
recorded as 18 kPa. Calculate the final temperature & absolute pressure inside
the container.
03
(b) Write down Van der Waal?s equation of state for real gases. Two hundred
moles of CO2 gas is stored in a 2 liter closed container at ? 13
o
C. Calculate
the pressure of the gas in kPa using Van der Waal?s gas equation.
Take a = 0.360Pa (m
3
/mole)
2
, b = 4.28 x 10
-5
m
3
/mole, R = 8.314 J/mole K
04
(c) Match Column-I with most appropriate entity from Column-II and reconstruct
a matched table.
Column-I Column-II
Vacuum of 380 mm Hg equals (i) Van der Waal?s gas equation
(ii) Cp ? Cv is > 0
(iii) NkT (iv) 14 g
(v) 77
o
F
(vi) 56 g (vii) T R
_
(viii)
< 0 for real gases
(ix) Sublimation (x) 14.67kPa
(xi) 259.8 J/kg K
Ideal gases
Real gases
Specific gas constant for O2 gas
is
For ideal gases PV is equal to
Mass of 2 mole N2 gas at NTP is
25
o
C is equal to
Freeze drying
07
Q.2 (a) Explain Zeroth law of thermodynamics. List different types of thermometers. 03
(b) A gas at 5 bar and 177
o
C kept in a container of 200 liter volume. It is cooled
isobarically to 27
o
C. Calculate the following in kJ:
(a) Heat transferred.
(b) Change in internal energy.
[Take Cp = 40 J/mol K, R = 8.314 J/mol k]
04
(c) Derive SFEE for a fluid stream entering and leaving a thermodynamic system
in terms of work and energy transfer per unit mass. Specify the assumptions
made.
07
OR
(c) Explain how first law of thermodynamics can be applied for closed systems
operating in a cyclic and non-cyclic process. Prove that ?TV
?-1
= constant? for
an ideal gas undergoing a reversible process.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? III (New) EXAMINATION ? WINTER 2019
Subject Code: 3131404 Date: 26/11/2019
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) Define ideal and real gases. Why do real gases deviate from ideal behaviour?
A sealed container contains air at 87
o
C and 1 bar. The container was
evacuated using a vacuum pump so that the vacuum inside the container is
recorded as 18 kPa. Calculate the final temperature & absolute pressure inside
the container.
03
(b) Write down Van der Waal?s equation of state for real gases. Two hundred
moles of CO2 gas is stored in a 2 liter closed container at ? 13
o
C. Calculate
the pressure of the gas in kPa using Van der Waal?s gas equation.
Take a = 0.360Pa (m
3
/mole)
2
, b = 4.28 x 10
-5
m
3
/mole, R = 8.314 J/mole K
04
(c) Match Column-I with most appropriate entity from Column-II and reconstruct
a matched table.
Column-I Column-II
Vacuum of 380 mm Hg equals (i) Van der Waal?s gas equation
(ii) Cp ? Cv is > 0
(iii) NkT (iv) 14 g
(v) 77
o
F
(vi) 56 g (vii) T R
_
(viii)
< 0 for real gases
(ix) Sublimation (x) 14.67kPa
(xi) 259.8 J/kg K
Ideal gases
Real gases
Specific gas constant for O2 gas
is
For ideal gases PV is equal to
Mass of 2 mole N2 gas at NTP is
25
o
C is equal to
Freeze drying
07
Q.2 (a) Explain Zeroth law of thermodynamics. List different types of thermometers. 03
(b) A gas at 5 bar and 177
o
C kept in a container of 200 liter volume. It is cooled
isobarically to 27
o
C. Calculate the following in kJ:
(a) Heat transferred.
(b) Change in internal energy.
[Take Cp = 40 J/mol K, R = 8.314 J/mol k]
04
(c) Derive SFEE for a fluid stream entering and leaving a thermodynamic system
in terms of work and energy transfer per unit mass. Specify the assumptions
made.
07
OR
(c) Explain how first law of thermodynamics can be applied for closed systems
operating in a cyclic and non-cyclic process. Prove that ?TV
?-1
= constant? for
an ideal gas undergoing a reversible process.
07
2
Q.3 (a) Draw and show the following processes on a psychrometric chart:
(i) Sensible heating
(ii) Dehumidification
(iii) Humidification
03
(b) Atmospheric air for Anand city on a certain day in October records the
following:
Temperature = 32
o
C
Barometric Pressure = 760 mm Hg
WBT = 27
o
C
Using Psychrometric Chart determine:
(i) DPT in
o
C
(ii) % RH
(iii) DBT in
o
C
(iv) Specific humidity in kg/kg d.a
04
(c) Draw a labeled ?P-V diagram? of pure water showing zones of thermodynamic
interest. Determine the following using Steam Tables for saturated steam at
10 bar pressure:
(i) Saturation temperature in Kelvin
(ii) Specific Entropy in kJ/kg K
(iii) Latent heat of vaporization in kJ/kg
(iv) Enthalpy of saturated vapours in kJkg.
07
OR
Q.3 (a) Indicate the following processes on psychrometric chart for moist air:
i. Sensible cooling
ii. Dehumidification and heating
iii. Cooling and dehumidification
03
(b) Atmospheric air on a certain day has the following parameters:
Temperature = 40
o
C
Barometric Pressure = 760 mm Hg
Relative humidity = 80%.
Using Psychrometric Chart determine:
(i) DPT in
o
C
(ii) WBT in
o
C
(iii) Absolute humidity in kg/kg d.a
(iv) Enthalpy in kJ/kgd.a
04
(c) Show state points of water on a ?T-S phase diagram?. Explain sub-cooling,
superheating, critical point & triple point of water. Using Steam Tables, for
saturated steam at 180
o
C, determine
(i) Saturation pressure in bar
(ii) Specific Entropy in kJ/kg K
(iii) Enthalpy of saturated vapours in kJkg.
07
Q.4 (a)
Prove that for any thermodynamically feasible cyclic process
0 ?
?
T
dQ
.
03
(b) What is Joule-Kelvin effect? Show that for ideal gases, 0
T , j
? ? 04
(c) State first law of thermodynamics for a closed system undergoing a state
change process. An ideal gas is allowed to expand isothermally in a reversible
manner. Establish that the work done per mole of gas is given by
1
2
ln
V
V
nRT W ?
.
07
OR
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? III (New) EXAMINATION ? WINTER 2019
Subject Code: 3131404 Date: 26/11/2019
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) Define ideal and real gases. Why do real gases deviate from ideal behaviour?
A sealed container contains air at 87
o
C and 1 bar. The container was
evacuated using a vacuum pump so that the vacuum inside the container is
recorded as 18 kPa. Calculate the final temperature & absolute pressure inside
the container.
03
(b) Write down Van der Waal?s equation of state for real gases. Two hundred
moles of CO2 gas is stored in a 2 liter closed container at ? 13
o
C. Calculate
the pressure of the gas in kPa using Van der Waal?s gas equation.
Take a = 0.360Pa (m
3
/mole)
2
, b = 4.28 x 10
-5
m
3
/mole, R = 8.314 J/mole K
04
(c) Match Column-I with most appropriate entity from Column-II and reconstruct
a matched table.
Column-I Column-II
Vacuum of 380 mm Hg equals (i) Van der Waal?s gas equation
(ii) Cp ? Cv is > 0
(iii) NkT (iv) 14 g
(v) 77
o
F
(vi) 56 g (vii) T R
_
(viii)
< 0 for real gases
(ix) Sublimation (x) 14.67kPa
(xi) 259.8 J/kg K
Ideal gases
Real gases
Specific gas constant for O2 gas
is
For ideal gases PV is equal to
Mass of 2 mole N2 gas at NTP is
25
o
C is equal to
Freeze drying
07
Q.2 (a) Explain Zeroth law of thermodynamics. List different types of thermometers. 03
(b) A gas at 5 bar and 177
o
C kept in a container of 200 liter volume. It is cooled
isobarically to 27
o
C. Calculate the following in kJ:
(a) Heat transferred.
(b) Change in internal energy.
[Take Cp = 40 J/mol K, R = 8.314 J/mol k]
04
(c) Derive SFEE for a fluid stream entering and leaving a thermodynamic system
in terms of work and energy transfer per unit mass. Specify the assumptions
made.
07
OR
(c) Explain how first law of thermodynamics can be applied for closed systems
operating in a cyclic and non-cyclic process. Prove that ?TV
?-1
= constant? for
an ideal gas undergoing a reversible process.
07
2
Q.3 (a) Draw and show the following processes on a psychrometric chart:
(i) Sensible heating
(ii) Dehumidification
(iii) Humidification
03
(b) Atmospheric air for Anand city on a certain day in October records the
following:
Temperature = 32
o
C
Barometric Pressure = 760 mm Hg
WBT = 27
o
C
Using Psychrometric Chart determine:
(i) DPT in
o
C
(ii) % RH
(iii) DBT in
o
C
(iv) Specific humidity in kg/kg d.a
04
(c) Draw a labeled ?P-V diagram? of pure water showing zones of thermodynamic
interest. Determine the following using Steam Tables for saturated steam at
10 bar pressure:
(i) Saturation temperature in Kelvin
(ii) Specific Entropy in kJ/kg K
(iii) Latent heat of vaporization in kJ/kg
(iv) Enthalpy of saturated vapours in kJkg.
07
OR
Q.3 (a) Indicate the following processes on psychrometric chart for moist air:
i. Sensible cooling
ii. Dehumidification and heating
iii. Cooling and dehumidification
03
(b) Atmospheric air on a certain day has the following parameters:
Temperature = 40
o
C
Barometric Pressure = 760 mm Hg
Relative humidity = 80%.
Using Psychrometric Chart determine:
(i) DPT in
o
C
(ii) WBT in
o
C
(iii) Absolute humidity in kg/kg d.a
(iv) Enthalpy in kJ/kgd.a
04
(c) Show state points of water on a ?T-S phase diagram?. Explain sub-cooling,
superheating, critical point & triple point of water. Using Steam Tables, for
saturated steam at 180
o
C, determine
(i) Saturation pressure in bar
(ii) Specific Entropy in kJ/kg K
(iii) Enthalpy of saturated vapours in kJkg.
07
Q.4 (a)
Prove that for any thermodynamically feasible cyclic process
0 ?
?
T
dQ
.
03
(b) What is Joule-Kelvin effect? Show that for ideal gases, 0
T , j
? ? 04
(c) State first law of thermodynamics for a closed system undergoing a state
change process. An ideal gas is allowed to expand isothermally in a reversible
manner. Establish that the work done per mole of gas is given by
1
2
ln
V
V
nRT W ?
.
07
OR
3
Q.4 (a) Define Specific heat and enthalpy. Prove that
R C C
v p
? ?
for ideal
gases.
03
(b) An insulated rigid tank of 0.2 m
3
volume contains 25 kg of nitrogen gas at 4
bar pressure. A paddle wheel is rotated inside the tank so that its pressure
increases to 5 bar. Calculate the following:
(i) Net heat transfer (ii) Change in internal energy
(iii) Work done (iv) Entropy change.
[Take Cp = 1.04 kJ/kgK, R = 8.314 J/mol K]
04
(c) Differentiate between steady and non-steady flow processes with examples.
Write down SFEE for a fluid stream entering and exiting a turbine. For a
steady flow of steam through a turbine the following data are available:
Inlet Condition Outlet Condition
P1 = 50 bar
t1 = 500
0
C
h1 = 3600 kJ/kg
v1= 0.072 m
3
/kg
P1 = 38 bar
t1 = 470
0
C
h1 = 3500 kJ/kg
v1= 0.082 m
3
/kg
A heat loss of 12kJ/kg occurs through the turbine due to poor insulation.
Calculate the inlet and outlet velocities of steam. Assume that inlet and outlet
cross-sectional areas and elevations are same.
07
Q.5 (a) What is Gibb?s phase rule? Calculate the degrees of freedom of liquid water
at 25
0
C and 1 atmosphere pressure and at its critical point.
03
(b) Prove the following for a pure substance undergoing an infinitesimally
reversible process:
(i) dU = TdS ? PdV
(ii) dH = TdS + VdP
(iii) dA = - (PdV + sdT)
(iv) dG = VdP ? sdT
04
(c) State second law of thermodynamics. Draw a block diagram of a heat engine
indicating work-energy flow directions and write energy balance equations.
How will you express its Carnot and actual thermal efficiency? A heat engine
operating on Carnot cycle produces 200 kW of power while operating
between temperature limits of 750?C and 50
o
C. Determine the engine
efficiency and the amount of heat input to the engine.
07
OR
Q.5 (a) Explain types of thermodynamic equilibrium for a system and conditions for
its stability.
03
(b)
Using first principles, prove that
V S
S
P
V
T
?
?
?
?
?
?
?
?
? ? ?
?
?
?
?
?
?
?
04
(c) State Kelvin-Plank statement of second law of thermodynamics and explain
the equivalence of Kelvin ?Planck and Clausius statements with neat diagram.
07
*************
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This post was last modified on 20 February 2020