UKPSC AE 2013: Uttarakhand Assistant Engineer (AE) Exam, AE Mechanical Engineering (Paper-Il)
Text of page 2
Mechanical Engineering (Paper-I!)
Triple point and critical point pressure of carbon dioxide are:-
(a) 4.5 8mm Hg and 221.2 bar respectively
(b) 5.18 bar and 221.2 bar respectively
(c) I bar and 50 bar respectively
(d) 5.18 bar and 73.8 bar respectively
2. In winter air conditioning, the inside design conditions are given by the following:-
(a) 25°C DBT, 50% RH (b) 25°C DBT, 60% RH
(c) 21°C DBT, 50% RH (d) 21°C DBT, 60% RH
3. Effective temperature in respect of air conditioning is the temperature of:-
(a) Unsaturated air (b) Saturated air
(c) Dry air (d) Either (b) or (c) above
4. Normal boiling point of different refrigerants are given below. Which pairs are correct?
(1) NH3 —40.8°C (2) R-12 —29.8°C
(3) R-22 —33.3°C (4) R-134a —26.2°C
(a) (1) and (2) are correct (b) (3) and (4) are correct
(c) (2) and (4) are correct (d) (1) and (4) are correct
5. Actual expansion process in a throttling device is:-
(a) Reversible adiabatic expansion (b) Isenthalpic expansion
(c) Fanno - line expansion (d) Isothermal expansion
6. What will be the depth of a point below water surface in sea, where pressure intensity is
1.006 MN/rn2? (Specific gravity of sea water = 1.025)
(a) lOm (b) lOOm
(c) 1000rn (d) irn
7. Which of the following expression correctly defines the relationship between internal pressure
intensity (p) and the radius of spherical droplet (r)?
(a) pcc (b) pocr
1
(c) poc (d) pocr2
r
ESE-07 (2) Series-B
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8. In case of multi-stage vapour compression system, flash intercooling is beneficial in case of
those refrigerants only for which:-
(a) Latent heat of vapourization is more (b) Latent heat of vapourization is less
(c) Thermal conductivity is high (d) Thermal conductivity is low
9. For an incompressible flow, which of the following is correct?
ôu v Ott *3v
—+—=0 Ik\ -+->
a1 ox Oy ) Ox Oy
Ou Ov Ou Ov
—+--< td' —+—=1
Ox 0)' '' Ox Oy
10. The velocity components in a two dimensional flow field for an incompressible fluid are
expressed as
U = + 2x - x2y
3
3
v=xy2 -2y---
These functions represent:-
(a) Rotational flow (b) Irrotational flow
(c) Either rotational or irrotational flow (d) Neither rotational nor irrotational flow
11. Constant volume cycle is also known as:-
(a) Otto cycle (b) Joule cycle
(c) Rankin cycle (d) Atkinson cycle
12. An engine working on stirling cycle between the same temperature limits as that of Carnot
cycle, has air standard efficiency:-
(a) More than Carnot cycle (b) Equal to Carnot cycle
(c) Less than Carnot cycle (d) Depends upon other factor also
13. The frictional resistance in case of turbulent flow is independent of :-
(a) Pressure of flow (b) Density of fluid
(c) Temperature of fluid (d) Area of surface in contact
14. The velocity at which the flow changes from laminar to turbulent for a given fluid at a given
temperature is known as:-
(a) Maximum velocity•. (b) Minimum velocity
(c) Average velocity (d) Critical velocity
ESE-07 (4) Series-B
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15. The head loss due to turbulent flow as compared to laminar flow is:-
(a) More (b) Less
(c) Equal (d) Unpredictable
16. In a laminar flow, the velocity at any point is:-
(a) Constant in magnitude but varying in direction
(b) Constant in magnitude as well as in direction
(c) Constant in direction but varying in magnitude
(d) Variable in magnitude as well as in direction
17. The similarity of shape between the model and prototype is known as:-
(a) Dynamic similarity (b) Kinematic similarity
(c) Geometric similarity (d) None of the above
18. The thickness of boundary layer is proportional to:-
(a) Its distance from the leading edge
(b) Square of its distance from the leading edge
(c) Four times its distance from the leading edge
(d) Square root of its distance from the leading edge
19. The flow within the boundary layer is:-
(a) Only turbulent (b) Only laminar
(c) Either (a) or (b) (d) None of the above
20. The total drag on a plate held normal to the flow is equal to:-
(a) Pressure drag (b) Viscous drag
Viscous drag
(c) Pressure drag x viscous drag (d) Pressure drag
21. The coefficient of drag and lift are functions of:-
(a) Frouds number (b) Reynolds number
(c) Weber number (d) Euler number
22. The aspect ratio of a wing is expressed as:-
(a) i/A (b) i/A2
(c) 12/A (d) 12/A2
23. Beyond. the stall point, the drag coefficient:-
(a) Decreases rapidly (b) Increases rapidly
(c) Remains same (d) None of the above
24. The process in which heat energy is transmitted by means of electromagnetic waves is known
as:-
(a) Heat conduction (b) Heat convection
(c) Heat radiation (d) None of the above
(6) Series-B
ESE-07
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25. Heat conduction in gases is due to:-
(a) The elastic impacts of molecules
(b) The motion of electrons
(c) The mixing motion of different parts of a fluid
(d) The electromagnetic waves
26. In which case the medium is not required for the transfer of heat energy:-
(a) Conduction (b) Convection
(c) Radiation (d) None of the above
27. According to Fourier's law, thequantity of heat flow through a surface area 'A' and thickness
'x' is given by the relation:-
(a) Q = - KA (dt/dx) (b) Q = - A/k (dt/dx)
(c) Q = - A (dx/dt) (d) Q = - KA (dx/dt)
28. According to Newton's law of cooling, the rate of heat transfer from a solid surface of area A,
at a temperature t1 , to a fluid at temperature t2 is given by:-
(a) Q=hA(t1 +t2) (b) Q=hA(t1 t2)
(c) Q=h/A(t1-t2) (d) Q=A/h(t1 +t2)
29. The opaque body is that which:-
(a) Absorbs all radiations
(b) Reflects all radiations
(c) Transmits all radiations
(d) Partly reflects and partly absorbs the radiation
30. According to Stefan Boltzman law the relation between the total emission from a black body
per unit area and per unit time (Eb) and the absolute temperature (T) is given as:-
(a) Eb oc T4 (b) Eb oc i
(c) Eb ocT2 (d) ET
31. If a body is at thermal equilibrium, then:-
(a) Emissivity <absorptivity (b) Emissivity> absorptivity
(c) Emissivity = absorptivity (d) None of the above
32. The heat transfer by conduction through a pipe is given by the relation:-
7t1k(T1 .z-T2 ) 2irlk(T1 1'2)
(a) Q log(A2/A1) Q log(A2/A1)
27t1k(T1 T) lk(T1 —T2)
(c) Q= log(AxA) 'Q 2itlog(A2/A1)
ESE-07 Series-B
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33. With the help of fins, the heat transfer can be increased by about:-
(a) 4 times (b) 6 times
(c) 8 times (d) 10 times
34. In a low speed S.1. engine, the inlet valve closes approximately:-
(a) 40° after BDC (b) 30° before BDC
(c) 100 after BDC (d) 100 before BDC
35. The function of fuel injector, is to:-
(a) Pump the fuel at high pressure (b) Mix diesel with air
(c) Atmoise the fuel (d) Ignite the fuel
36. The function of carburettor is to:-
(a) Refining the fuel
(b) Increase the. pressure of fuel vapours
(c) Inject petrol in cylinder
(d) Atomise and vapourise the fuel and to mix it with air in proper ratio
37. In S.I. engine, the throttle valve of carburettor controls the quantity of:-
(a) Fuel (b) Air
(c) Fuel and air mixture (d) Lubricating oil
38. The function of a hydraulic turbine is to convert water energy into:-
• (a) Heat energy (b) Electrical energy
(c) Atomic Energy (d) Mechanical energy
39. The specific speed of a turbine is:-
(a) Its maximum speed
(b) Its minimum speed
(c) Its speed at maximum output
(d) The speed of a geometrically similar turbine that would develop one metric horse
power under a head of one meter
40. The type of turbine recommended for a head of 10 meter is:-
(a) Francis turbine (b) Kaplan turbine
(c) Pelton turbine (d) None of the above
41. The vanes of a centrifugal pump move due to:-
(a) Pressure energy of water
(b) Kinetic energy of water
(c) Both pressure and kinetic energy of water
(d) Power supplied by prime mover
ESE-07 (10) Series-B
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42. The specific speed of a centrifugal pump is given as:-
(a) Nj/h' (b) N/h
(c) Nj/h (d) Nf/h
43. Which of the following compressors has highest capacity?
(a) Reciprocating (b) Centrifugal
(c) Axial flow (d) Fan
44. The volumetric efficiency of a reciprocating compressor is equal to:-
(a) 1+K-K(p2/p1 ) (b) 1+K-K(p2/p1 )fl
(c) 1+K+K(p2/p1 )' (d) 1+K-K(p2/p1 )1'
45. The thermal efficiency of an open cycle gas turbine increases with the:-
(a) Increase in inlet temperature of atmospheric air
(b) Decrease in inlet temperature of atmospheric air
(c) Remain same for all temperatures of inlet air
(d) None of the above
46. Constant volume gas turbine works on:-
(a) Joule cycle (b) Carnot cycle
(c) Otto cycle (d) Atkinson cycle
47. The capacity of boiler is defined as:-
(a) The volume of feed water inside the shell
(b) The volume of the steam space inside the shell
(c) The maximum pressure at which steam can be generated
(d) Amount of water converted into steam from 100°C to 110°C in one hour
48. The type of safety valve recommended for high pressure boiler is:-
(a) Dead weight safety valve (b) Lever safety valve
(c) Spring loaded safety valve (d) None of the above
49. Blade efficiency of steam turbine is equal to:-
(a) V(V 1 -V2) / 2g (b) 2V(V 1 -V 2) / V1 2
(c) V(V 1 -V 2) / V1 2 (d) V2(V 1 -V 2) / 2V1
ESE-07 (12) Series-B
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50. The gas which is used as a coolant in a nuclear power plant is:-
(a) Freon (b) Ammonia
(c) Helium (d) Chlorine
51. The function of a reflector in nuclear power plant is to:-
(a) Reflect heat
(b) Reflect light
(c) Reflect the escaping neutrons back into the core
(d) None of the above
52. If the capacity of a refrigerating machine is one ton, than the rateof heat abstraction is equal
to: -
(a) 50 kcal/min (b) 100 kcal/min
(c) 150 kcal/min (d) 500 kcal/min
53. The refrigeration system works on:-
(a) Zeroth law of thermodynamics (b) First law of thermodynamics
(c) Second law of thermodynamics (d) None of the above
54 Which of the refrigerant is more toxic?
(a) Carbon dioxide (b) Ammonia
(c) Freon- 12 (d) Freon-22
55. Which of the following refrigerant is more costly?
(a) Ammonia (b) Carbon dioxide
(c) Methyl chloride (d) Freon- 12
56. Pick up the correct statement:-
(a) The refrigerant should have high thermal conductivity and low freezing temperature
(b) The refrigerant should have low heat transfer coefficient and high latent heat
(c) The refrigerant should have high specific volume and high latent heat
(d) The refrigerant should have high specific volume and low latent heat
57. Which of the following refrigerant has maximum latent heat?
(a) Sulphur dioxide (b) Carbon dioxide
(c) Ammonia (d) Dichioro-difloro-methane
58. A refrigerant should have the following property:-
(a) High boiling point (b) High latent heat
(c) High specific heat (d) High specific volume
ESE-07 (14) Series-B
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59. The necessary data required for the design of the air conditioning apparatus is/are:-
(a) Grand total heat (b) Dehumidified air quantity
(c) Apparatus dew point (d) All of the above
au
60. If A u B V andC = V then momentum equation of the boundary layer can be
given as follows:-
(a) A+B+C=0 (b) A+B-C=0
(c) A+B-C2=0 (d) A.B=C
61. For non-flow closed system the value of net energy transferred as heat and work equals
change in:-
(a) Enthalpy (b) Entropy
(c) Internal energy (d) None of the above
62. During throttling process the following holds good:-
(a) Enthalpy does not change (b) Entropy does not change
(c) Internal energy does not change (d) Volume change is negligible
63. For an adiabatic process, the temperature and pressure are related as under:-
r-I
(a) iRa (b)
T(pr
T1 'j'i T1 P1)
r+I
1 prI I '\
2_ p21r
(c) (d)
T1
p11 TI \\PI )
64. An engine operates between temperature limits 900 K and T2 and another between T2 and
400 K. For both engines to be equally efficient T2 should be:-
(a) 600 K (b) 700 K
(c) 625 K (d) 650 K
65. For a process, the value of (8Q-8W) is:-
(a) Positive (b) Negative
(c) Zero (d) Unpredictable
66. Area under the curve of a T-S diagram represents:-
(a) Heat transfer for a reversible process
(b) Heat transfer for an irreversible process
(c) Heat transfer for all processes
(d) None of the above
ESE-07 (16) Series-B
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67. A heat engine developes 60 kW work having an efficiency of 60%, Amount of heat rejected
will be:-
(a) 400 kW (b) 10 kW
(c) 40 kW (d) 20 kW
68. In Carnot cycle, addition and rejection of heat takes place at:-
(a) Constant pressure (b) Constant temperature
(c) Constant volume (d) Constant speed
69. For same value of compression ratio and heat input, the order of thermal efficiency of Otto,
Diesel and Dual cycles will be as under:-
(a) n >n >77
Otto Diesel Dual
(b) 7 Otto > 7 Dual> 77Diesel
(c) fl
Diesel
>t7
Dual
>77 Otto (d) 17> 77
Dual Diesel > 7 Otto
70. A heat engine receives 1120 kJ of heat and rejects 840 kJ of heat while operating between
two temperature limits of 560 K and 280 K. It indicates that the engine operates on the
following cycle:-
(a) Reversible cycle (b) Irreversible cycle
(c) Impossible cycle (d) Unpredictable cycle
71. Change in entropy for a natural process will always be:-
(a) Zero (b) Positive
(c) Negative (d)
72. The thermal efficiency of an ideal Otto cycle:-
(a) Increases with compression ratio
(b) Increases with specific heat ratio
(c) Increases with compression ratio and specific heat ratio
(d) Increases with compression ratio but decreases with specific heat ratio
73. Critical radius of insulation for sphere is equal to:-
(a) 2k.h (b) h / 2k
(c) 2k/h (d) k.h
74. If the ratio of emission of a body to that of a black body at a given temperature is constant for
all wavelengths, the body is called:-
(a) Black body (b) Gray body
(c) White body (d) Opaque body
75. The thickness of thermal boundary layer is equal to hydrodynamic boundary layer when
Prandtl number is equal to:-
(a) 0 (b) 0.1
(c) 1.0 (d) 10
ESE-07 (18) Series-B
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76. A composite wall consists of three different materials having thermal conductivities K, 2K
and 4K respectively. The ratio of temperature drop across different materials will be:-
(a) 1: 1: 1 (b) 1: 2: 4
(c) 4:2:1 (d) 2:4:1
77. A body cools from 90°C to 70°C in 5 minutes. The time required by body for further cooling
to 50°C will be:-
(a) 5 minutes (b) Less than 5 minutes
(c) More than 5 minutes (d) 10 minutes
78. The value of Stanton number for value of Nusselt number 400, Reynolds number 40 and
Prandtl number 20 will be:-
(a) 800 (b) 200
(c) 2 (d) 0.5
79. Assuming the Sun to be a black body emitting radiation with maximum intensity at
2 = 0.491um, the surface temperature of the sun will be:-
(a) 491.4 K (b) 4914 K
(c) 49140 K (d) 491.4° C
80. According to Wien's law, the wavelength corresponding to maximum energy is proportional
to:-
(a) T' (1) T
(c) T 3 (d) T 4
81. LMTD in case of counter flow heat exchanger as compared to parallel flow heat exchanger
is:-
(a) Lower (b) Higher
(c) Same (d) Unpredictable
82. For radiation between two large parallel plates having emissivities , and E,, the effective
emissivity will be:-
(a) (b) E1 E2
1
1
(c) 1 1
(d) —+-1
E1 +E2 -1 E1 E2
83. In turbulent filmwise condensation on a vertical surface, the critical value of Reynolds number
recommended for use is:-
(a) 2300 (b) 1800
(c) 5x105 (d) 1000
ESE-07 (20) Series-B
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84. The intensity of solar radiation on earth is of the order of :-
(a) 1 kW/m2 (b) 2 kW/m2
(c) 3 kW/m2 (d) 4 kW/m2
85. Free convection heat transfer is significantly affected by:-
(a) Reynolds number (b) Grashof number
(c) Prandtl number (d) Stanton number
86. In a counterfiow heat exchanger, the hot fluid is cooled from 110°C to 80°C by a cold fluid
which is heated from 30°C to 60°C. LMTD for the heat exchanger will be:-
(a) 80°C (b) 50°C
(c) 30°C (d) 20°C
87. Fouling factor in the design of heat exchanger is used considering the fact that:-
(a) It is used when a liquid exchanges heat with gas
(b) It is used in case of Newtonian fluids
(c) It is used as a dimensionless factor
(d) It is a factor of safety in design
88. Which dimensionless number has the significant role in forced convection:-
(a) Mach number (b) Reynold number
(c) Prandtl number (d) Pecklet number
89. Air standard efficiency of an Otto cycle having compression ratio 4 and adiabatic exponent
for airr=1.5 will be:-
(a) 50% (b) 75%
(c) 25% (d) 5.0%
90. Thermal efficiency of a Carnot engine is 30%. If the engine is reversed to operate as heat
pump with same operating conditions, what will be the COP of the heat pump?
(a) 0.3 (b) 1.33
(c) 2.33 (d) 3.33
91. An oil having kinematic viscosity 0.25 stokes flows through a pipe of 10cm diameter. The
flow will be critical at a velocity of about:-
(a) 0.5 mIs (b) 1.5mls
(c) 1.8mls (d) 4.6mls
92. Unit of kinematic viscosity is:-
(a) m2/s (b) N.s/m2
(c) kgls.m2 (d) mlkg.s
93. Navier — Stoke's equation is concerned with:-
(a) Turbulence (b) Viscosity
(c) Buoyancy (d) Compressibility
ESE-07 (22) Series-B
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94. When a fluid flows through a pipeline under viscous flow conditions, the ratio of velocity at
the axis of the pipe to the mean velocity of flow is:-
(a) 0.5 (b) 1.0
(c) 1.67 (d) 2.0
95. In a turbulent flow through a pipe, the shear stress is:-
(a) Maximum at the centre and decreases linearly towards the wall
(b) Maximum at the centre and decreases logarithmically towards the wall
(c) Maximum mid—way between the centre line and the wall
(d) Maximum at the wall and decreases linearly to zero at the centre
96. At what distance (r) from the centre of a pipe of radius (R) does the average velocity occur in
laminar flow:-
(a) r = 0.33 (b) r = 0.707
(c) r = 0.50 (d) r = 0.59
97. The loss of head due to friction in a pipe of uniform diameter in which a viscous flow is
taking place is given in terms of Reynolds number, Re as:-
(a) 1/Re (b) 4/Re
(c) 16/Re (d) 64/Re
98. Hydraulic radius is equal to:-
(a) Area divided by the square of wetted perimeter
(b) Area divided by the wetted perimeter
(c) Wetted perimeter divided by area
(d) Square root of area
99. An oil with specific gravity 0.85 and viscosity 3.8 poise flows in a 5cm diameter horizontal
pipe at 2.0 mIs. The Reynolds number will be approximately:-
(a) 224 (b) 2240
(c) 22.4 (d) 22400
100. The nominal thickness of boundary layer represents the distance from the surface to a point
where:-
(a) Flow ceases to be laminar
(b) The shear stress becomes maximum
(c) Velocity is 99% of its asymptotic limit
(d) None of the above
101. In a laminar boundary over a flat plate, what would be the ratio of wall shear stresses r and
at two sections which lie at distances X1 2 units and X2 10 units from the leading edge
of the plate:-
- 0.5
(a) T 5.0 (b) z- 1 /r 2 - (5)
I/ 2=
- 0.25
(c) (d) T I /T,(S)
ESE-07 (24) Series-B
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102. The height of water column corresponding to a pressure equivalent of 60 cm of mercury
column will be:-
(a) 816 cm (b) 8160 cm
(c) 81.6 cm (d) 7996.0 cm
103. Loss of head due to friction to maintain 0.05 m3/s of discharge of petrol (sp. gravity 0.7)
through a steel pipe 0.2 m diameter and 1000 m long, taking coefficient of friction 0.0025
will be
(a) 0.644 m (b) 6.44 m
(c) 64.4 m (d) 644 m
104. If the compression ratio is increased in S.I. engine, the knocking tendency will:-
(a) Increase (b) Decrease
(c) Not be affected (d) Cannot be predicted
105. Anti knock property of C.I. engine fuel can be improved by adding:-
(a) Tetra — ethyl lead (b) Amylnitrate
(c) Hexadecane (d) Trimethyl pentane
106. The injection pressure in diesel engine is of the order of:-
(a) 30-4Obar (b) 100—ISObar
(c) 200 — 300 bar (d) 400 — 600 bar
107. Carbon deposit on the cylinder head of an I.C. engine tend to increase:-
(a) Clearance volume (b) Compression ratio
(c) Swept volume (d) None of the above
108. An impulse turbine is used for:-
(a) Low head of water (b) High head of water
(c) Medium head of water (d) High discharge
109. If the jet ratio in a Pelton turbine wheel is 18, the number of buckets will be about:-
(a) 24 (b) 21
(c) 26 (d) 18
110. A low value of time constant for a thermocouple can be achieved by:-
(a) Decreasing the wire diameter
(b) Using metals of high density and high specific heat
(c) Increasing the heat transfer coefficient
(d) (a) and (c) above
ESE-07 (26) Series-B
Text of page 28
Ill. In order to avoid cavitation in centrifugal pumps:-
(a) The suction pressure should be high
(b) The delivery pressure should be high
(c) The suction pressure should be low
(d) The delivery pressure should be low
112. Thermal efficiency of closed cycle gas turbine plant is increased by the following:-
(a) Reheating (b) Intercooling
(c) Regenerator (d) None of the above
113. Most of the terrestrial solar radiations (received on the earth) lie within wavelength range:-
(a) 0.101um to 0.29pm (b) 0.29pm to 2.5wn
(c) 3.81um to 7.81wn (d) 1021u,n to 10'°/Dn
114. Flat plate solar collectors are used for temperature applications above ambient of about:-
(a) 20°C (b) 50°C
(c) 100°C (d) 1000°C
115. A Carnot refrigerator operates between 300.3 K and 273 K. The fraction of cooling effect
required as work input is:-
(a) 20% (b) 10%
(c) 50% (d) Cannot be calculated
116. A Carnot refrigeration cycle has a COP of 4. The ratio of higher temperature to lower
temperature will be:-
(a) 2.5 (b) 2.0
(c) 1.5 (d) 1.25
117. Vapour compression cycle using R- 12 gives maximum COP when:-
(a) Suction state to compressor is in wet region
(b) Suction state to compressor is in superheat region
(c) Suction state to compressor is dry saturated
(d) None of the above
118. In a simple saturated vapour compression refrigeration cycle, the heat rejected in condenser
is 160 kJ/kg and compressor work is 32 kJ/kg, then the COP will be:-
(a) 4 (b) 5
(c) 6 (d) None of the above
ESE-07 (28) Series-B
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119. In aqua—ammonia and LiBr—Water absorption refrigeration system, the refrigerants are
respectively:-
(a) Water and LiBr (b) Water and Water
(c) Ammonia and LiBr (d) Ammonia and Water
120. Room sensible heat factor is defined as (RSH: Room sensible heat, RLH: Room Latent heat):-
(a) RSH / (RSH+RLH) (b) RLH / (RSH+RLH)
(c) RSH/RLH (d) None of the above
121. The surrounding air temperature in summer is 45°C in a locality. The refrigeration temperature
is 5°C. Assume 10°C temperature difference in the heat exchanger that exchanges heat with
surroundings. The COP of the Carnot refrigerator under these conditions, will be:-
(a) 6.95 (b) 7.95
(c) 6.56 (d) 5.56
122. In an ammonia vapour compression system, wet compression process is used instead of dry
compression. The C.O.P.
(a) Will increase (b) Will decrease
(c) Can increase or decrease (d) Remains unaffected
123. A regenerative liquid — vapour heat exchanger is used in a vapour compression system operating
on ammonia refrigerant, the COP:-
(a) Will increase (b) Will decrease
(c) Can increase or decrease (d) Remains unaffected
124. The refrigerant C,1-14 is designated as:-
(a) R24 (b) R1S
(c) R1150 (d) R150
125. External equalizer in thermostatic expansion valve (TEV) is used so that the TEV senses the
pressure of evaporator:-
(a) At the outlet (b) At the inlet
(c) In the middle (d) At outlet as well as inlet
126. If COP of a vapour compression system is 4, the heat rejection ratio of its condenser will be:-
(a) 0.25 (b) 5.0
(c) 1.25 (d) 0.20
127. Aircraft refrigeration system is based upon:-
(a) Joule cycle (b) Brayton cycle
(c) Carnot cycle (reversed) (d) Vapour compression cycle
ESE-07 (30) Series-B
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128. 1fF is mass handled by a pump and D is refrigerant vapour distilled in a vapour absorption
system, specific weak solution circulation is given by:-
F F—D
(a) (b)
D
F—D D
(c) (d)
F
129. The system used for cooling of supersonic aircraft is:-
(a) Simple system (b) Bootstrap system
(c) Reduced ambient system (d) Regenerative system
130. Lewis number is given by the following relation: (J= heat transfer coefficient, K is mass
transfer coefficient and C is specific heat):-
,
Cp K
(a) (b) fg.Cp
fg.K w
fg fg
(c) (d)
C-K
131. A sample of moist air is at a dry bulb temperature of 21°C and dew point temperature of
15°C. Specific humidity of air is 0.0 11 kg w.v./kg d.a. What will be the enthalpy of moist air?
(a) 59.4 kJ/kg d.a. (b) 323.4 kJ/kg d.a.
(c) 52.5 kJ/kg d.a. (d) 49.0 kJ/kg d.a.
132. During adiabatic saturation process of air in air washer, the water is sprinkled at a surface
temperature equal to of incoming air:-
(a) DBT (b) WBT
(c) DPT (d) None of the above
133. When steam is injected into the incoming air, the following changes occur in the condition of
air:-
(a) Temperature increases significantly but specific humidity increases negligibly.
(b) Temperature increases negligibly but specific humidity increases appreciably.
(c) Both temperature and sp. humidity increase appreciably.
(d) Both temperature and sp. humidity increase negligibly.
134. In the concept of effective temperature, the relative humidity of air is considered to be:-
(a) 0% (b) 50%
(c) 75% (d) 100%
ESE-07 (32) Series-B
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135. For atmospheric air, following conditions are given:-
DBT = 3 5°C, DPT = 23°C and barometer reads 750 mm Hg. Saturation pressure at 23°C and
35°C is 21.06 mm Hg and 42.4 mm Hg respectively. The relative humidity and partial pressure
of water vapour will be:-
(a) 49.7% and 21.06 mm Hg respectively
(b) 35.5% and 42.4 mm Hg respectively
(c) 3 5.5% and 15.06 mm Hg respectively
(d) Impossible to calculate
136. Some qualities of C.I. engine fuels are given below. Select the quality which is not desirable:-
(a) Good ignition quality (b) High volatility
(c) High viscosity (d) Low flash point
137. In C.!. engines, ignition delay can be reduced by:-
(a) Decreasing compression ratio
(b) Increase in air inlet temperature
(c) Decrease in coolant temperature
(d) Decreasing the engine speed
138. A Pelton turbine works under a head of 405 m and runs at 400 rpm. What will be diameter of
its runner? (k = 0.45):-
(a) 1.93m (b) 3.80m
(c) 2.I0m (d) None of the above
139. A Kaplan turbine develops 3000 kW power under a head of 5m and a discharge of 75 m3/s.
Determine the overall efficiency:-
(a) 0.79 (b) 0.82
0.90 (d) None of the above
(c)
140. A centrifugal pump lifts 0.0 13 m3 /s water from a depth of 32 m. if the pump motor consumes
6 kW, what is the overall efficiency of pump. Given density of water = 1000 kg/rn3:-
(a) 88% (b) 75%
69% (d) None of the above
(c)
141. Run away speed for Francis turbine ranges:-
(a) 1.8 to 1.9 times normal speed (b) 2.5 to 3 times normal speed
3 to 3.5 times normal speed (d) 2 to 2,2 times normal speed
(c)
142. In centrifugal compressors, pressure ratio may be increased:-
By decreasing slip factor (b) By increasing slip factor
(a)
By making rough blades (d) By none of the above
(c)
(34) Series-B
ESE-07
Text of page 36
143. If B is magnetic field strength, the theoretical power output of MHD generator is proportional
to:-
(a) B (b) B2
(c) B3 (d)
144. Absorption of energy in solar collectors can be increased to a maximum value by coating the
absorber surface by:-
(a) Black paint (b) Lamp black
(c) Rough black coating (d) Selective coating
145. On increasing the temperature of absorber plate of solar collector the efficiency of collector:-
(a) Increases
(b) Decreases
(c) May increase or decrease depending upon atmospheric temperature
(d) Does not depend on absorber plate temperature
146. Solar photovoltaic cell is made up of semiconductor materials. The efficiency of conversion
of solar energy into electrical energy is of the order of:-
(a) 7% (b) 21%
(c) 70% (d) 90%
147. The following boiler operates in supercritical range of pressure:-
(a) Benson (b) Babcock and Wilcox
(c) Loeffler (d) Cornish
148. Pressure compounding can be done in the following type of turbines:-
(a) Impulse turbines (b) Reaction turbines
(c) Both impulse and reaction turbines (d) None of the above
149. The first law of thermodynamics was given by:-
(a) Obert (b) Keenan
(c) Joule (d) Newton
150. Gas A at 1 MPa, 100°C and Gas B at 5 MPa, 100°C are mixed such that final temperature
after mixing remains 100°C. The process is adiabatic. The entropy of the gases after mixing:-
(a) Will increase (b) Will remain same
(c) Will decrease (d) Cannot be calculated
151. T1 is high and T, is low temperature of a Carnot heat engine. Which is the most efficient way
to increase efficiency?
(a) To increase T1 (b) To decrease T2
(c) To increase T1 and T2 both (d) To decrease T1 and T2 both
ESE-07 (36) Series-B
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152. A refrigerator (COP=2.5) removes energy by heat transfer from freezer at 0°C at a rate of
9000 kJ/hr and rejects energy to the surroundings. Determine power input to the refrigerator:-
(a) 614.3 kJ/hr (b) 3600 kW
(c) 659.3 kJ/hr (d) 1 kW
153. A machine produces 100 kJ work by consuming 100 kJ heat. This machine will be called:-
(a) PMM - I (b) PMM - II
(c) PMM - III (d) None of the above
154. For a steady flow system (where kinetic and potential energies are negligible), the first law of
thermodynamics can be expressed as:-
(a) dQ—dW=dU (b) Q—W=AE
(c) _ \; = AU (d) _ \' = AH
155. A gas turbine plant operates between 27°C, minimum temperature and 927°C maximum
temperature. Calculate the cycle efficiency:-
(a) 25% (b) 50%
(c) 75% (d) None of the above
156. The effect of regeneration on efficiency and work output of Brayton cycle is that its:-
(a) Efficiency decreases but work output increases
(b) Efficiency as well as work output increases
(c) Efficiency increases but work output remains same
(d) Efficiency remains same but work output increases
157. Which cycle consists of three processes?
(a) Ericsson cycle (b) Stirling cycle
(c) Atkinson cycle (d) Lenoir cycle
158. Third law of thermodynamics is:-
(a) An extension of second law (b) An extension of first law
(c) An independent law of nature (d) An extension of zeroth law
159. A 20 cm diameter pipe of 30 km length transports oil at 0.01 m3/s. The power required to
maintain flow will be [i.' = 0.1N — s/rn 2 , density = 900kg/rn3 ]
(a) 76.32kW (b) 7.632W
(c) 763.2 W (d) 0.7632 kW
ESE-07 (38) Series-B
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160. A small air bubble of diameter 1.0 mm rises with a steady velocity of 1.5 cm/s through an oil
of specific gravity 0.9. The viscosity of oil will be:-
(a) 3.24x10 3 N-s/m2 (b) 32.4x10 3 N-s/rn2
(c) 32.4x10 6 N-s/rn2 (d) None of the above
161. The flow in the capillary tube is laminar because:-
(a) The capillary tube is made of glass
(b) The surface tension and capilarity promotes laminarisation
(c) Only inviscid liquid can flow through capillary tube
(d) The diameter of capillary tube is very small
162. Flow separation is caused by:-
(a) Reduction of pressure in the direction of flow
(b) Reduction of the boundary layer thickness
(c) Presence of adverse pressure gradient
(d) Presence of favourable pressure gradient
163. In case of flow over a flat plate, the Reynold number at which flow becomes turbulent is:-
(a) 2300 (b) 3.2x105
(c) 7.5x105 (d) 2000
164. The critical angle of attack of an aerofoil is that where:-
(a) The lift becomes zero
(b) The drag becomes zero
(c) The drag begins to rise
(d) The lift begins to drop
165. A normal shock can occur only when:-
(a) Flow changes from supersonic to subsonic
(b) Flow changes from sonic to subsonic
(c) Flow changes from subsonic to sonic
(d) The flow is Trans-sonic
166. Flow over an elliptical body may be idealized by superimposing a free stream and:-
(a) A source (b) A doublet
(c) A source and sink (d) A free vortex
167. Impingement ofajet on a flat plate may be expressed by:-
(a) xy (b) =x2 -y2
(c) x3 +y3 (d) i=x/y
ESE-07 (40) Series-B
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168. Euler number is given as the ratio of:-
(a) Inertia force / Gravity force (b) Pressure force / inertia force
(c) Inertia force / Surface tension (d) Gravity force / Inertia force
169. With the increase in the length of fin, fin efficiency:-
(a) Decreases (b) Increases
(c) Remains unaffected (d) First increases and then decreases
170. Consider a cylinder of radius R with uniformly distributed heat source of heat generation rate
and constant thermal conductivity K. Assume temperature as a function of radius (r) only.
The boundary conditions are; T = T at r R and heat generated equals heat lost at surface.
The temperature distribution in the cylinder is given by:-
q r2 q r
(a) T=T + (l-) (b) T=T + (1- 2)
'2K R W4K R
(c) T=T +_9_.(R2 - r2) (d) T=TW+-9-(R2 - r2)
W2K 4K
171. In transient heat conduction, lumped capacity analysis is applicable with good accuracy when
Biot number (Bi):-
(a) is equal to 1 (b) is less than 0.1
(c) is greater than 0.1 (d) is less than I
172. General conduction equation in its simple form, v2 T=0 (where T is temperature), is called:-
(a) Poisson's equation (b) Fourier's equation
(c) Laplace equation (d) Kirchoff's equation
173. Air at 300 °C and 7 bar is expanded isentropically until the velocity is 300 rn/s. Calculate the
static temperature of the air at high velocity condition if C of air is 1.00 kJ/kg-°C:-
(a) 255 °C (b) 295 °C
(c) 300 °C (d) None of the above
174. Prandtl number is connecting link between:-
(a) Velocity field and temperature field (b) Gravity field and temperature field
(c) Gravity field and velocity field (d) None of the above
175. The significance of Reynold analogy is that it:-
(a) Tells whether flow is laminar or turbulent
(b) Relates heat transfer to momentum transfer
(c) Relates heat transfer and mass transfer
(d) Relates heat transfer and frictional loss
ESE-07 (42) Series-B
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176. For mixed (free and forced) convection in horizontal tubes of diameter d and length L, Graetz
number (Gz) is defined as:-
d d
(a) Re. Pr. (b) Gr. Pr. Re.
L
d d
(c) Gr. Re. (d) Gr. Pr. L
177. Radiations are incident from a small area dA1 to a disc A2 of diameter D kept at a distance R.
The shape factor FdA1 -~ A2 will be:-
D2 D2
(a) (b)
R 2 +D2 4R2 + D2
D2
(c) (d)
(R2 +D2 / 4) R2 + 4D2
178. Three radiation shields are placed between two infinite parallel plates. The emissivities of
plates and shields are same. As compared to heat transfer without shields, the heat transfer
with shield will become:-
I I
(a) - (b) -
3 9
(c) (d) None of the above
179. For a double pipe, counter flow heat exchanger with C = I (C = Cmm / Cmax) the effectiveness
.
is equal to:-
NTU (b) li-l/NTU
(a)
NTU-1
NTU NTU+l
(c) (d)
NTU + I NTU—1
180. Dittus Boelter equation for heating of a fluid in a tube is given as follows:-
-
(a) Nu0.023 Re08 Pr04
(b) Nu0.023 Re08 Pr03
(c) NuC Re' (where C is a constant and n is a real number)
(d) NuC 1og Re"
ESE-07 (44) Series-B
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Space For Rough Work/tl cpii ESE-07 (46) Series-B
Official key not published for this paper.
Page 1 of 46
Source: Uttarakhand Public Service Commission. Question paper published by Uttarakhand Public Service Commission.