UNIT
– 1
GAS POWER CYCLES
2
MARKS
1. What
are gas power cycles?
2. Define
air standard cycle efficiency.
3. Name
any four “gas power cycles".
4. What
is a thermodynamic cycle?
5. Define
mean effective pressure.
6. Define
compression ratio.
7. What
is cutoff ratio?
8. What
do you mean by expansion ratio.
9. Mention
the various processes of otto cycle.
10. Give
any two differences between otto and diesel cycle.
11. Which
cycle is more efficient with respect to the same compression ratio?
12. What
is the compression ratio range for otto cycle and diesel cycle?
13. Name
the factors that affect the air standard efficiency of diesel cycle.
14. State
any two assumptions made in gas power cycles.
15. List
out the various processes of Diesel cycle.
16. What
are the various processes of Dual cycle?
17. Mention
the various processes of Brayton cycle.
18. Define
isentropic efficiency of a compressor.
19. Sketch
the schematic arrangement of open gas turbine power plant.
20. Explain
about isentropic efficiency of a turbine.
6 Marks
21. What
are the assumptions made in the analysis of gas power cycles?
22. Explain
the working of otto cycle with the help of p-V & T-s diagram.
23. Brief
the working of Diesel cycle with the help of p-V & T-s diagram.
24. Describe
the working of Dual cycle with the help of p-V & T-s diagram.
25. Explain
the working of Brayton cycle with the help of p-V & T-s diagram.
26. Draw
the schematic arrangement, p-V and T-s diagram of a Brayton cycle with reheater.
27. Sketch
the schematic arrangement of a gas turbine power plant with reheater,
regenerator and intercooler with T-s diagram
28. Compare
Otto, Diesel and Dual cycles.
29. Sketch
the schematic arrangement, p-V and T-s diagram of a Brayton cycle with
intercooler
30. During
an Otto cycle the pressure at the beginning and end of the compression stroke
are 1 bar and 6.75 bar respectively. Find the air standard efficiency of the
cycle.
31. Calculate
the air standard efficiency of the cycle which is working on constant volume
cycle, if the compression ratio is 6. Assume ᵞ = 1.4.
32. Compare
the theoretical and actual brayton cycle with the help of p-V and T-s diagram.
33. A
diesel engine operating on an air standard diesel cycle has 20 cm bore and 30
cm stroke. The clearance volume is 420 cm3. Find the compression
ratio of the engine.
34. What
are the effects of introducing intercooling and regeneration in basic turbine
cycle?
35. In
a gas turbine power plant working on a Brayton cycle, the inlet air temperature
is 30°C and 1 bar. The pressure ratio is 6.25 and the maximum temperature is
827°C. Find the
(i)
Compressor work
(ii)
Turbine work
(iii)
Work ratio
10 Marks
36.
Brief the working of Otto cycle with the
help of p-V diagram, T-s diagram and derive the air standard efficiency of the
cycle.
37.
Explain the working of Diesel cycle with
the help of p-V diagram, T-s diagram and derive the air standard efficiency of
the cycle.
38.
Describe the working of Brayton cycle
with the help of p-V diagram, T-s diagram and derive the air standard
efficiency of the cycle.
39.
A
Dual combustion air standard cycle has a compression ratio of 10. The constant
pressure part of combustion takes place at 40 bar. The highest and the lowest
temperature of the cycle are 1727°C and 27°C respectively. The pressure at the
beginning of compression is 1 bar. Calculate,
(i)
The
pressure and temperature at key points of the cycle.
(ii)
The
heat supplied at constant volume,
(iii)
The
heat supplied at constant pressure,
(iv)
The
heat rejected,
(v)
The
Work output,
(vi)
The
cycle efficiency. Take CP = 1.005 kJ/kg K, CV = 0.718
kJ/kg K
40.
A
gas turbine works on an air standard Brayton cycle. The initial condition of
the air is 25°C and 1 bar. The maximum pressure and temperature are limited to
3 bar and 650°C. Determine the following:
(i) Cycle
efficiency
(ii) Heat
supplied and heat rejected per kg of air
(iii)Work output
(iv) Exhaust temperature. Take CP
= 1.005 kJ/kg K, CV = 0.718 kJ/kg K.
41. An
Engine-working on Otto cycle has a volume of 0.45 m3, pressure 1 bar
and temperature 30°C at the beginning of compression stroke. At the end of
compression stroke, the pressure is 11 bar and 210 kJ of heat is added at
constant volume. Determine (i) Pressure, temperature and volumes at salient
points in the cycle,
(ii) Cycle Efficiency. Take
CP = 1.005 kJ/kg K, CV = 0.718 kJ/kg K.
UNIT-2
INTERNAL
COMBUSTION ENGINES
2
MARKS
1.
What do you
mean by an IC engine?
2.
List any four
components of an IC engine.
3.
Name the rings
present in the piston of an engine.
4.
What is the
use of a connecting rod?
5.
List out the
use of a flywheel?
6.
What are all
the processes taking place in an IC engine?
7.
Mention the
use of a camshaft?
8.
Define brake
power
9.
What is indicated
power?
10. What do you mean by brake thermal efficiency?
11. Define indicated thermal efficiency
12. What are the different methods of cooling system
employed in cooling IC engines?
13. What do you mean by stroke volume and clearance volume?
14. Mention the use of a carburettor?
15. Name the stages of combustion of a SI engine
16. What are the methods of ignition system used in IC
engines?
17. Name the stages of combustion of a CI engine.
18. What is the purpose of lubricating IC engines?
19. List out the different methods of lubrication system
used in IC engines?
20. Mention the various parts of a spark plug.
6 marks
21. Differentiate between a two stroke and a four stroke
engine.
22. Distinguish between a petrol engine and a diesel
engine.
23. Explain the phenomenon of knocking in petrol engines
24. Brief the phenomenon of knocking in diesel engines.
25. Explain scavenging and its significance in IC
engines.
26. Draw and add a short note on the pressure – crank
angle diagram depicting the stages of combustion of a SI engine.
27. Explain pressure – crank angle diagram depicting the
stages of combustion of a CI engine.
28. Differentiate between a simple carburettor and a
complete carburettor.
29. Compare the theoretical and actual p-V diagram of a
four stroke petrol engine.
30. Distinguish battery coil and magneto coil ignition
system.
31. Compare the theoretical and actual p-V diagram of a
four stroke diesel engine.
32. Explain about splash and mist lubrication system
used in IC engines.
33. Sketch schematic layout of MPFI system.
34. What is likely to happen if petrol is used in diesel
engines and if diesel is used in petrol engines?
35. Draw and explain the port timing diagram of a two
stroke diesel engine.
10 marks
36. Describe
the working of a four stroke diesel engine with neat sketches.
37. Explain
the working of a four stroke petrol engine with neat sketches.
38. Brief
the working of a battery coil ignition system with neat sketch.
39. Explain in detail about the pressure – crank angle
diagram depicting the stages of combustion of a CI engine.
40. Compare the theoretical and actual valve timing
diagram of a four stroke diesel engine.
41. Explain necessity of cooling in an IC engine. With a
neat sketch describe the working of pump circulation liquid cooling system used
for multi-cylinder engine.
Unit-3
Steam nozzles and
turbines
2marks
1.
What do you mean by a nozzle?
2.
What are the various types of nozzles
and their function?
3.
Write down the expression for velocity
at exit from steam nozzle.
4.
Define nozzle efficiency.
5.
What is meta stable flow?
6.
Differentiate isentropic flow and
supersaturated flow.
7.
Define critical pressure ratio.
8.
List out the use of large size and small
size turbines.
9.
What do you mean my carry over loss?
10.
Mention the different methods of
compounding turbines?
11.
What do you mean by governing of
turbines?
12.
What are the different methods of
governing steam turbines?
13.
Mention any four losses which occur in a
steam turbine.
14.
Explain the function of moving blades
15.
List out the function of fixed blades.
16.
What are the reasons due to which
pressure drop is reduced in a nozzle?
17.
What do you mean by degree of reaction
of a turbine?
18.
What are the assumptions made in the deriving
the condition for maximum efficiency of a turbine?
19.
What do you mean by pressure compounding
of a turbine?
20.
What is velocity compounding of a
turbine?
6marks
21.
Explain about the different types of
nozzles with neat sketches
22.
Derive an expression for the velocity of
steam flowing through a nozzle
23.
Explain in detail about the effects of
friction in a nozzle.
24.
Explain the phenomenon of
supersaturation and its effects in nozzles.
25.
Give a brief classification on steam
turbines.
26.
Differentiate between impulse turbine
and reaction turbine.
27.
Explain the working of impulse turbines
with neat sketch.
28.
Explain the working of reaction turbines
with neat sketch.
29.
Brief about throttle governing with neat
sketch.
30.
Discuss about nozzle governing with neat
sketch.
31.
Describe bypass governing with neat
sketch.
32.
What do you mean by critical pressure
ratio? What is the critical pressure ratio of saturated steam, superheated
steam and for gases?
33.
Explain in detail about the various
losses that takes place in a turbine.
34.
Draw the velocity diagram for a simple
impulse turbine.
35.
Sketch the velocity diagram for a
reaction turbine.
10 Marks
36.
Dry saturated steam at a pressure of 11
bar enters a convergent-divergent nozzle and leaves at a pressure of 2 bar. If
the flow is adiabatic and frictionless, determine,
(i)
The exit velocity of the steam,
(ii)
Ratio of cross section at exit and that
at throat. Assume the index of adiabatic expansion to be 1.135
37. Dry saturated
steam at 2.8 bar is expanded through a convergent nozzle to 1.7 bar. The exit
area is 3 cm2. Calculate the exit velocity and mass flow rate for,
(i) Isentropic expansion,
(ii) Super
saturated flow.
38. Dry saturated
steam enters a steam nozzle at a pressure of 15 bar and is discharged at a
pressure of 2.0 bar. If the dryness fraction of discharge steam is
0.96, what will be the final velocity of
steam. Neglect initial velocity of steam. If
10% of heat drop
is lost in friction; find the
percentage reduction in the final velocity.
39. In a steam nozzle, the steam expands from 4 bar
to 1 bar. The initial velocity is 60 m/s and initial temperature is 200°C.
Determine the exit velocity if nozzle efficiency is 92 %.
40. Explain in
detail about pressure – velocity compounding of turbines with neat sketch.
41. In a de-laval
turbine, the steam enters the wheel through a nozzle with velocity of 350 m/s
and at an angle of 20° to the direction of the motion of the blade. The blade
speed is 250 m/s and exit angle of the moving blade is 35°. Find the inlet
angle of the moving blade, exit velocity of the steam and its direction.
Unit-4
Air Compressors
2marks
1.
What
is an air-compressor?
2.
List
a few applications of air compressors.
3.
How
will you classify compressors based upon design and principle of operation?
4.
Classify
compressors according to capacity.
5.
Define
volumetric efficiency of a compressor.
6.
What
is meant by free air delivered?
7.
Define
Mechanical efficiency of a compressor.
8.
Explain
how the flow of air is controlled in a reciprocating compressor.
9.
Define
clearance ratio.
10.
What
are the factors that limit the delivery pressure in a reciprocating compressor?
11.
Define
isothermal efficiency of a compressor.
12.
Why
clearance is necessary in a reciprocating compressor?
13.
Give
the expression for intercooler pressure.
14.
What
is the purpose of intercooler?
15.
What
do you mean by single stage compression?
16.
What
is multistage compression?
17.
Give
two merits of rotary compressor over reciprocating compressor.
18.
What
are factors that affect the volumetric efficiency of a reciprocating
compressor?
19.
Give
examples of positive displacement compressors.
20.
List
out any two advantages of multistage compression.
6marks
21.
Give
a brief classification of compressors.
22.
Differentiate
between reciprocating and rotary compressor.
23.
Discuss
about the working of single acting reciprocating compressor.
24.
Sketch
the p-V diagram of a two stage reciprocating compressor
25.
What
are the advantages of multistage compression over single stage compression?
26.
Derive
an expression for work done during isothermal compression for a single acting
reciprocating compressor without clearance volume.
27.
Deduce
an expression for work done during isentropic compression for a single acting
reciprocating compressor without clearance volume.
28.
Derive
an expression for work done during polytropic compression for a single acting
reciprocating compressor without clearance volume.
29.
Find
an expression for the work done by a two stage reciprocating air compressor
with intercooler.
30.
A
single cylinder, single acting air compressor compresses 30 m3 of
air at a pressure of 1 bar and 27°C to 700kPa. Calculate the power required for
the compressor if the compression is
(i)
isothermal,
(ii)
polytropic
(iii)
adiabatic.
31.
Differentiate
between positive displacement and non positive displacement compressors.
32.
Derive
an expression for work done by a single acting reciprocating compressor with
clearance volume.
33.
Compare
rotary compressor and reciprocating compressor.
34.
What
are the assumptions made in multistage compression?
35.
A
single stage double acting air compressor of 150 kW power takes air in it at 1
bar and delivers at 6 bar. The compression follows the law pV1.35 =
C. The compressor runs at 160 rpm with average piston speed of 150 m/min.
Determine the size of the cylinder.
10Marks
36.
A single stage single acting air
compressor delivers 0.6 kg of air per minute at 6 bar. The temperature and
pressure at the end of suction stroke are 30°C and 1 bar. The bore and stroke
of the compressor are 100 mm and 150 mm respectively. The clearance is 3 % of
the swept volume. Assuming index of compression and expansion to be 1.3, find,
(i)
Volumetric efficiency of the compressor,
(ii)
Power required if the mechanical efficiency is 85%.
37.
A single stage single acting compressor
delivers 14m3 of free air per minute from 1 bar to 7 bar. The speed
of the compressor is 310 rpm. Assuming that compression and expansion follow
the law pV1.35=constant and clearance is 5% of the swept volume,
find the diameter and stroke of the compressor. Take L=1.5D. The temperature
and pressure of air at the suction are same as atmospheric air.
38.
A single – stage double - acting air
compressor is required to deliver 14 m3 of air per minute measured
at 1.013 bar and 15°C. The delivery pressure is 7 bar and the speed is 300 rpm.
Take the clearance volume as 5 % of the swept volume with the compression and
expansion index of n=1.3. Calculate,
(i)
Swept volume of the cylinder,
(ii)
The delivery temperature,
(iii)
Indicated power.
39.
Explain in detail the working of a
multistage compressor with help of p-V diagram.
40.
A two stage single acting reciprocating
air compressor takes 6m3 of air at 1.1 bar and 23°C and compresses
into 20 bar. The intermediate receiver cools the air to 25°C and 8.5 bar
pressure. The law of compression is pV1.35=constant. Calculate the
work done.
41.
A two stage single acting reciprocating
air compressor compresses air from 1 bar and 20°C to 42 bar. If the law of
compression is pV1.3=constant and the inter cooling is perfect, find
per kg of air
(i)
the work done in compression,
(ii)
the mass of cooling water necessary for abstracting the heat in the
intercooler, if the temperature rise of the cooling water is 25°C.
Unit-5
Refrigeration
& Air-conditioning
2Marks
1.
Define COP
2.
What are the components of a vapour
compression system?
3.
Define tonnege of refrigeration
4.
What do you mean by refrigeration?
5.
Name any four commonly used refrigerants
6.
What is a refrigerant?
7.
What do you mean by refrigerating
effect?
8.
Define psychrometry.
9.
Define dry bulb and wet bulb temperature.
10.
What are the two main types of
refrigeration system?
11.
Define dew point temperature
12.
What do you mean by saturation capacity
of air?
13.
State Dalton’s law of partial pressure.
14.
Define bypass factor of a coil.
15.
Name the different types of
air-conditioning systems?
16.
Define apparatus dew point of a coil.
17.
What are the factors that affect the
bypass factor of a coil?
18.
What are the functions of a throttle
valve?
19.
List out the refrigerant and absorbent
that is being used in the Lithium Bromide Refrigeration system.
20.
How does humidity affect human comfort?
6Marks
21.
Differentiate between vapour compression
and vapour absorption refrigeration systems.
22.
List out the properties of a good
refrigerant.
23.
Explain about subcooling and
superheating in vapour compression systems with help of a T-s diagram.
24.
What are the effects of very high and
very low by pass factor?
25.
Compare summer and winter
air-conditioning systems.
26.
Discuss about specific humidity,
relative humidity and degree of saturation.
27.
What is meant by sensible heating,
sensible cooling and dehumidification?
28.
Define SHF, RSHF & ERSHF
29.
What is the function of analyzer and
rectifier in simple vapour absorption system?
30.
Define dry bulb depression, wet bulb
depression and dew point temperature.
31.
List out the various psychrometric
processes and represent them on the psychromentric chart.
32.
Draw and explain vapour compression
cycle with p-h and T-s diagram for a dry saturated vapour at the end of
compression.(no subcooling takes place)
33.
Explain in detail about different types
of air conditioning systems
34.
Enumerate the components of cooling load
estimate.
35.
List out requirements of a comfort
air-conditioning system.
10Marks
36. Explain
the working of a vapour compression refrigeration system with neat sketch
37. Discuss
in detail about the working of an Ammonia absorption refrigeration system with
neat sketch.
38. Describe
the working of a Lithium Bromide vapour absorption refrigeration system with
neat sketch.
39.
A vapour compression refrigerator works
between the pressure limits of 60 bar and 25 bar. The working fluid is just dry
at the end of compression and there is no under cooling of the refrigerant
before expansion valve. Determine,
(i)
COP of the cycle,
(ii)
Capacity of the refrigerator, if the working fluid is flowing at a rate of 5
kg/min.
The
properties of the refrigerant are given in the following table,
|
Pressure
(bar)
|
Saturation
Temperature, (K)
|
Enthalpy (kJ/kg)
|
Entropy (kJ/kg K)
|
||
|
Liquid
|
Vapour
|
Liquid
|
Vapour
|
||
|
60
|
295
|
61.9
|
208.1
|
0.197
|
0.703
|
|
25
|
261
|
-18.4
|
234.5
|
-0.075
|
0.896
|
40. In
a laboratory test, a sling psychrometer recorded dry bulb and wet bulb
temperatures as 303K and 298K respectively. Calculate
a. Vapour
pressure,
b. Relative
humidity,
c. Specific
humidity,
d. Degree
of saturation,
e. Dew
point temperature,
f. Enthalpy
of the mixture.
41. An
ammonia refrigerator produces 30 tonnes of ice from and at 0°C in a day of 24
hours.
The temperature range in the compressor is from 25°C to 15°C. The vapour is dry saturated at the end of compression
and an expansion valve is used.
Calculate the coefficient of performance. The properties of the
refrigerant are given in the following table:
|
Temperature
°C
|
Enthalpy
KJ/kg
|
Entropy
KJ/kg-K
|
||
|
Liquid
|
Vapour
|
Liquid
|
Vapour
|
|
|
25
|
100.04
|
1319.22
|
0.3473
|
4.4852
|
|
-15
|
-54.56
|
1304.99
|
-2.1338
|
5.0585
|
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