INTERNATIONAL INSTITUTE FOR AEROSPACE
ENGINEERING AND MANAGEMENT
Global Campus
Jakkasandra Post, Kanakapura Taluk, Ramanagara District - Pin Code: 562 112
Department of Aerospace Engineering
USN
B.Tech. Sem 4th
TEST - II
Subject Name: Thermal Science Session: Jan – June 2021
Subject Code: 18AS41 (Common for ASE & ANE) Duration: 90 Minutes
rd
Date of Examination: 3 May 2021 Max Marks: 9 X 10 = 90
Note:
✓ Answer all questions and each question carries 10 Marks.
✓ Provide neat diagrams, assumptions and units & conversions wherever applicable.
Q. Bloom’s
Question Marks COs
No Level
1. To increase the thermal efficiency of a reversible power cycle operating between
reservoirs at TH and TC, would you increase TH while keeping TC constant, or 10 CO1 L3
decrease TC while keeping TH constant? Are there any natural limits on the
increase in thermal efficiency that might be achieved by such means?
2. During January, at a location in Seattle winds at -45oC can be observed,
However, several meters below ground the temperature remains at 13oC. An
inventor claims to have devised a power cycle working between these 10 CO3 L3, L4
temperatures having a thermal efficiency of 5%. Investigate this claim, whether
the power cycle lies within these temperatures. Explain it as an engineering
model.
3. Water is the working fluid in an ideal Rankine cycle. Steam enters the turbine at
1400 lbf/in2 and 1000oF. The condenser pressure is 2 lbf/in.2 The net power
output of the cycle is 1 * 109 Btu/h. Cooling water experiences a temperature
increase from 60oF to 76oF, with negligible pressure drop, as it passes through
the condenser. Determine for the cycle
(a) the mass flow rate of steam, in lb/h. 10 CO4 L4, L5
(b) the rate of heat transfer, in Btu/h, to the working fluid
passing through the steam generator.
(c) the thermal efficiency.
(d) the mass flow rate of cooling water, in lb/h.
Plot each of the quantities calculated in Problem versus condenser pressure
ranging from 0.3 lbf/in.2 to 14.7 lbf/in.2 . Maintain constant net power output.
4. At steady state, a power cycle develops a power output of 10 kW while receiving
energy by heat transfer at the rate of 10 kJ per cycle of operation from a source CO3,
at temperature T. The cycle rejects energy by heat transfer to cooling water at a 10 L3
4
lower temperature of 300 K. If there
are 100 cycles per minute, what is the minimum theoretical value for T, in K?
5. An inventor has developed a refrigerator capable of maintaining its freezer
compartment at 20oF while operating in a kitchen at 70oF, and claims the device 10 CO4 L4, L5
has a coefficient of performance of (a) 10, (b) 9.6, (c) 4. Evaluate the claim in
each of the three cases.
6. A gas within a piston-cylinder assembly executes a Carnot power cycle during
which the isothermal expansion occurs at TH = 600 K and the isothermal
compression occurs at TC = 300 K. Determine
(a) the thermal efficiency.
(b) the percent change in thermal efficiency if TH increases by 15% while TC 10
CO2 L4
remains the same.
(c) the percent change in thermal efficiency if T C decreases by 15% while TH
remains the same.
(d) the percent change in thermal efficiency if TH increases by 15% and TC
decreases by 15%.
7. Consider a house with a floor space of 200 m2 and an average height of 3 m at 10 CO1 L3
sea level, where the standard atmospheric pressure is 101.3 kPa. Initially the
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ENGINEERING AND MANAGEMENT
Global Campus
Jakkasandra Post, Kanakapura Taluk, Ramanagara District - Pin Code: 562 112
Department of Aerospace Engineering
USN
B.Tech. Sem 4th
TEST - II
Subject Name: Thermal Science Session: Jan – June 2021
Subject Code: 18AS41 (Common for ASE & ANE) Duration: 90 Minutes
rd
Date of Examination: 3 May 2021 Max Marks: 9 X 10 = 90
Note:
✓ Answer all questions and each question carries 10 Marks.
✓ Provide neat diagrams, assumptions and units & conversions wherever applicable.
Q. Bloom’s
Question Marks COs
No Level
1. To increase the thermal efficiency of a reversible power cycle operating between
reservoirs at TH and TC, would you increase TH while keeping TC constant, or 10 CO1 L3
decrease TC while keeping TH constant? Are there any natural limits on the
increase in thermal efficiency that might be achieved by such means?
2. During January, at a location in Seattle winds at -45oC can be observed,
However, several meters below ground the temperature remains at 13oC. An
inventor claims to have devised a power cycle working between these 10 CO3 L3, L4
temperatures having a thermal efficiency of 5%. Investigate this claim, whether
the power cycle lies within these temperatures. Explain it as an engineering
model.
3. Water is the working fluid in an ideal Rankine cycle. Steam enters the turbine at
1400 lbf/in2 and 1000oF. The condenser pressure is 2 lbf/in.2 The net power
output of the cycle is 1 * 109 Btu/h. Cooling water experiences a temperature
increase from 60oF to 76oF, with negligible pressure drop, as it passes through
the condenser. Determine for the cycle
(a) the mass flow rate of steam, in lb/h. 10 CO4 L4, L5
(b) the rate of heat transfer, in Btu/h, to the working fluid
passing through the steam generator.
(c) the thermal efficiency.
(d) the mass flow rate of cooling water, in lb/h.
Plot each of the quantities calculated in Problem versus condenser pressure
ranging from 0.3 lbf/in.2 to 14.7 lbf/in.2 . Maintain constant net power output.
4. At steady state, a power cycle develops a power output of 10 kW while receiving
energy by heat transfer at the rate of 10 kJ per cycle of operation from a source CO3,
at temperature T. The cycle rejects energy by heat transfer to cooling water at a 10 L3
4
lower temperature of 300 K. If there
are 100 cycles per minute, what is the minimum theoretical value for T, in K?
5. An inventor has developed a refrigerator capable of maintaining its freezer
compartment at 20oF while operating in a kitchen at 70oF, and claims the device 10 CO4 L4, L5
has a coefficient of performance of (a) 10, (b) 9.6, (c) 4. Evaluate the claim in
each of the three cases.
6. A gas within a piston-cylinder assembly executes a Carnot power cycle during
which the isothermal expansion occurs at TH = 600 K and the isothermal
compression occurs at TC = 300 K. Determine
(a) the thermal efficiency.
(b) the percent change in thermal efficiency if TH increases by 15% while TC 10
CO2 L4
remains the same.
(c) the percent change in thermal efficiency if T C decreases by 15% while TH
remains the same.
(d) the percent change in thermal efficiency if TH increases by 15% and TC
decreases by 15%.
7. Consider a house with a floor space of 200 m2 and an average height of 3 m at 10 CO1 L3
sea level, where the standard atmospheric pressure is 101.3 kPa. Initially the
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