UKPSC AE 2022: Uttarakhand Combined State Engineering Service Examination, MECHANICAL ENGINEERING (PAPER II)
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1. Nusselt number for a fully developed flow in a pipe of diameter D having constant flux is
equal to
(a) 1.250 (b) 3.220 (c) 3.660 (d) 4.364
2. For a given heat flow and for the same thickness, the temperature drop across the material
will be maximum for
(a) Copper (b) Steel (c) Glass wool (d) Refractory brick
3. The shape factor of a hemispherical body placed on a flat surface with respect to itself is
(a) zero (b) 0.25 (c) 0.5 (d) 1.0
4. In a counter flow heat exchanger, the product of specific heat and mass flow rate is same
for hot and cold fluids. If NTU is equal to 0.5, then the effectiveness of the heat exchanger
is
(a) 1.0 (b) 0.50 (c) 0.33 (d) 0.2
5. Which of the following is having highest thermal conductivity ?
(a) Steam (b) Solid ice (c) Melting ice (d) Boiling water
6. The curve for unsteady state cooling or heating of bodies is
(a) parabolic curve asymptotic to time axis
(b) exponential curve asymptotic to both time and temperature axes
(c) exponential curve asymptotic to time axis
(d) hyperbolic curve asymptotic to both time and temperature axes
7. In a heat exchanger, the hot liquid enters with a temperature of 180 °C and leaves at
160 °C. The cooling fluid enters at 30 °C and leaves at 110 °C. The capacity ratio of the
heat exchanger is
(a) 0.25 (b) 1.50 (c) 0.33 (d) 0.20
8. The steady state temperature distribution in a very large thin plate with uniform surface
temperature will be
(a) linear (b) parabolic (c) hyperbolic (d) logarithmic
9. A satellite in space exchanges heat with the surroundings essentially by
(a) Conduction (b) Convection
(c) Radiation (d) Conduction and Convection put together
10. The relation 2 t = 0 is referred to as
(a) Fourier heat conduction equation
(b) Laplace’s equation
(c) Poisson’s equation
(d) Lumped parameter solution for transient conduction
11. If a material possess thermal conductivity k, density and specific heat CP, its thermal
diffusivity is equal to
k Cp kCp
(a) (b) (c) (d)
Cp k kCp
Series-A 2 CES-07
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1. D
(a) 1.250 (b) 3.220 (c) 3.660 (d) 4.364
2. ,
(a) (b)
(c) ( ) (d)
3. ,
(a) (b) 0.25 (c) 0.5 (d) 1.0
4. ,
NTU 0.5 ,
(a) 1.0 (b) 0.50 (c) 0.33 (d) 0.2
5. ?
(a) (b) (c) (d)
6.
(a)
(b)
(c)
(d)
7. , 180 °C 160 °C
30 °C 110 °C
(a) 0.25 (b) 1.50 (c) 0.33 (d) 0.20
8.
(a) (b) (c) (d)
9. -
(a) (b)
(c) (d)
10. 2 t = 0
(a) (b)
(c) (d) ()
11. k, () CP ,
k Cp kCp
(a) (b) (c) (d)
Cp k kCp
CES-07 3 Series-A
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12. Transient conduction means
(a) very little heat transfer
(b) heat transfer for a short period
(c) heat transfer with a very small temperature difference
(d) conduction when the temperature at a point varies with time
13. The sun with an effective surface temperature of 5600 K emits most of its radiations in the
spectrum of frequency range
(a) 0.1 to 4 micron (b) 1 to 10 micron
(c) 0.01 to 0.1 micron (d) at all the wavelength
14. Gases have poor property
(a) absorptivity (b) reflectivity
(c) transmissivity (d) absorptivity as well as transmissivity
15. For a hemisphere, the solids angle is measured in
(a) radian and its maximum value is pi()
(b) degree and its maximum value is 180
(c) steradian and its maximum value is two pi(2)
(d) steradian and its maximum value is pi()
16. The reciprocity theorem states that
(a) F12 = F21 (b) A1F12 = A2F21 (c) A1A2 = F12F21 (d) A2F12 = A1F21
17. Which one of the following number represents the ratio of kinematic viscosity to thermal
diffusivity ?
(a) Grasshoff number (b) Prandtl number
(c) Mach number (d) Nusselt number
18. Reynold’s analogy states that St =
(where St is the Stanton number and C fx is the skin friction coefficient)
Cfx Cfx
(a) (b) Cfx (c) (d) 2 Cfx
4 2
19. Which one of the following non-dimensional number is used to determine the transition
from laminar to turbulent flow in free convection ?
(a) Reynold’s Number (b) Grasshoff Number
(c) Peclet Number (d) Rayleigh Number
20. For a finned surface, it is considered appropriate that area of cross-section be
(a) maintained constant along the length
(b) increased along the length
(c) reduced along the length
(d) it is better to vary the convection coefficient than the area
Series-A 4 CES-07
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21. Two insulating material (put over each other) are used to insulate a steam pipe, best result
would be if
(a) inferior insulation is put over pipe and better one over it
(b) better insulation is put over pipe and inferior one over it
(c) Both may be put in any order
(d) None of the above
22. In which of the following case most unsteady heat flow occurs ?
(a) through the walls of a furnace (b) through the lagged pipes carrying steam
(c) through the wall of a refrigerator (d) during annealing of castings
23. Extended surfaces in heat transfer are often used to
(a) reduce thermal resistance at a surface.
(b) increase thermal resistance at a surface.
(c) increase heat transfer coefficient.
(d) increase temperature difference between surface and surroundings fluid.
24. A body in which the absorptivity of the surface does not vary with temperature and
wavelength of incident radiation is known as
(a) white body (b) black body (c) gray body (d) none of above
25. A flat plate consists of two layers of material A and material B (one layer each) such that
its total thermal resistance is 0.12 k/W. The plate A is in contact with a hot gas at
temperature of 150° C and plate B is in contact with cold fluid at temperature 30 C. The
overall heat transfer coefficient and rate of heat transfer through 1 m 2 surface area
respectively :
(a) 1000 W and 8.33 W/m2K (b) 1036 W and 8.63 W/m2K
(c) 1050 W and 8.50 W/m2K (d) 1080 W and 7.5 W/m2K
26. The shape factor of one surface with respect to another surface will always be between
(a) 1 and 2 (b) 0 and 1 (c) 0 and 2 (d) 1 and 3
27. The equation of effectiveness = 1 – e–NTU for a heat exchanger is valid in case of
(a) boiler and condenser for parallel flow
(b) boiler and condenser for counter flow
(c) boiler and condenser for both parallel and counter flow
(d) gas turbine for both parallel and counter flow
28. While steam expands in turbines, theoretically the entropy
(a) remains constant (b) increases
(c) decreases (d) behaves unpredictably
29. The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal
conductivities as K1 = 2K2 will be
(a) 2 (b) 1 (c) 0.50 (d) 0.25
Series-A 6 CES-07
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21. (- )
(a)
(b)
(c)
(d)
22. ?
(a) (b)
(c) (d)
23. :
(a)
(b)
(c)
(d) /
24.
,
(a) (b) (c) (d)
25. A B ( )
0.12 k/W A 150 °C B, 30 C
:
(a) 1000 W 8.33 W/m2K (b) 1036 W 8.63 W/m2K
(c) 1050 W 8.50 W/m2K (d) 1080 W 7.5 W/m2K
26.
(a) 1 2 (b) 0 1
(c) 0 2 (d) 1 3
27. = 1 – e–NTU
(a)
(b)
(c)
(d)
28. ,
(a) (b)
(c) (d)
29. Q1/Q2 K1 = 2K2
,
(a) 2 (b) 1 (c) 0.50 (d) 0.25
CES-07 7 Series-A
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30. The working fluid used in an MHD system coupled to a fast breeder reactor is a
(a) hot flue gas (b) seeded inert gas
(c) liquid metal – inert gas mixture (d) liquid metal only
31. A solar cell is basically
(a) a voltage source, controlled by flux of radiation
(b) a current source, controlled by flux of radiation
(c) an uncontrolled current source
(d) an uncontrolled voltage source
32. The range of wind speed suitable for wind power generation is
(a) 0 to 5 m/sec. (b) 5 to 20 m/sec. (c) 25 to 50 m/sec. (d) 50 to 75 m/sec.
33. A Pelton wheel is ideally suited for
(a) high head and low discharge (b) high head and high discharge
(c) low head and low discharge (d) medium head and medium discharge
34. Cavitation in a hydraulic turbine may occur in all likelihood
(a) in the spiral casing (b) at the inlet to draft tube
(c) at the inlet to runner (d) in the guide passages
35. In general, the vanes of the centrifugal pump are
(a) radial (b) curved forward (c) curved backward (d) twisted
36. The minimum net positive suction head (NPSH) required for a hydraulic pump is to
(a) increase discharge (b) increase efficiency
(c) increase suction head (d) prevent cavitation
37. Compounding of a steam turbine is done to
(a) balance the rotor
(b) reduce the blade friction
(c) reduce the rotor speed
(d) connect the shaft of one turbine to that of another
38. In a single stage impulse turbine, the maximum blading efficiency is obtained when
cos (1 + cos )
(a) = cos (b) = (c) = cos2 (d) =
2 2
39. Increasing the number of reheating stages in a gas turbine to infinity makes the expansion
(a) reversible adiabatic (b) isothermal
(c) isobaric (d) adiabatic
40. The source of energy which keeps the sun shining for billions of year is
(a) combustion of hydrogen
(b) nuclear fusion of light elements
(c) nuclear fission of heavy elements
(d) intersection of currents in the interior of the sun with the galactic magnetic field.
Series-A 8 CES-07
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30. MHD , :
(a) (b)
(c) - (d)
31. :
(a) ,
(b) ,
(c)
(d)
32. :
(a) 0 5 /. (b) 5 20 /. (c) 25 50 /. (d) 50 75 /.
33. :
(a) (b)
(c) (d)
34. :
(a) (b)
(c) (d)
35. , :
(a) (b) (c) (d)
36. (NPSH)
(a) (b)
(c) (d)
37. ()
(a)
(b)
(c) ()
(d) ()
38. - , ,
cos (1 + cos )
(a) = cos (b) = (c) = cos2 (d) =
2 2
39. :
(a) (b) (c) (d)
40.
(a)
(b)
(c)
(d) :
CES-07 9 Series-A
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41. An engine operates between temperature of 900 °K and T 2 and another engine between T2
and 400 °K. For both to do equal work, the value of T 2 will be
(a) 600 °K (b) 625 °K (c) 650 °K (d) 675 °K
42. The most common popular firing order in case of four cylinder inline I.C. engines is
(a) 1 – 3 – 4 – 2 (b) 1 – 2 – 3 – 4 (c) 1 – 3 – 2 – 4 (d) 1 – 2 – 4 – 3
43. In a four stroke cycle S.I. engine the camshaft runs
(a) at the same speed as crank shaft
(b) at the half speed as crank shaft
(c) at twice the speed of crank shaft
(d) at any speed irrespective of crank shaft speed
44. If hm and hf be the enthalpy drops in moving and fixed blades, then the degree of
reaction is defined as
hm hf hf hf
(a) (b) (c) (d)
hf hm (hf + hm) (hm + hf)
45. Lancashire boiler is of
(a) stationary fire tube boiler (b) horizontal type
(c) natural circulation type (d) all of the above type
46. The angle of beam radiation does not depend upon this factor :
(a) latitude (b) declination (c) zenith angle (d) time of day
47. Following is not used in MHD systems :
(a) ionized gas (b) liquid metal (c) electrolyte (d) magnetic field
48. In a power and efficiency versus flow at constant speed curve of a compressor, power
increases with flow rate. This is valid for
(a) axial compressor
(b) centrifugal compressor
(c) axial as well as centrifugal compressor
(d) centrifugal compressor but not for axial compressor
49. As a result of detonation in an I.C. engine following parameters attain very high value
(a) peak pressure (b) rate of rise of pressure
(c) rate of rise of temperature (d) peak temperature
50. The water tubes in Babcock and Wilcox boiler are
(a) horizontal (b) vertical
(c) inclined (d) horizontal and inclined
51. Morse test in multicylinder engine is used to determine
(a) Air flow to engine (b) B.H.P.
(c) I.H.P. (d) Mechanical efficiency
Series-A 10 CES-07
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41. 900 °K T2 T2 400 °K
, , T2
(a) 600 °K (b) 625 °K (c) 650 °K (d) 675 °K
42. - (I.C.) :
(a) 1 – 3 – 4 – 2 (b) 1–2–3–4 (c) 1–3–2–4 (d) 1–2–4–3
43. ..
(a) (b)
(c) (d)
44. hm hf : ,
hm hf hf hf
(a) (b) (c) (d)
hf hm (hf + hm) (hm + hf)
45.
(a) (b)
(c) (d)
46. :
(a) (b) ()
(c) (d)
47. MHD :
(a) (b) (c) - (d)
48. , ,
:
(a)
(b)
(c)
(d)
49. .. ()
(a) (b)
(c) (d)
50.
(a) (b) (c) (d)
51.
(a) (b) ...
(c) ... (d)
CES-07 11 Series-A
Text of page 12
52. Volumetric efficiency of air compressor is in the range of
(a) 20 – 30% (b) 40 – 50% (c) 60 – 70% (d) 70 – 90%
53. The inlet valve of a four stroke cycle I.C. engine remains open for nearly
(a) 180° (b) 125° (c) 235° (d) 200°
54. The specific speed of a centrifugal pump is given
(a) N Q / H3/4 (b) N P / H5/4 (c) N Q / H5/4 (d) N H / Q3/4
55. Once – through boiler is named as such because
(a) flue gas passes only in one direction
(b) steam is sent out only in one direction
(c) air is sent through the same direction
(d) there is no recirculation of water
56. De-Laval turbine is
(a) single rotor impulse turbine (b) velocity-compounded impulse turbine
(c) pressure – compounded impulse turbine (d) impulse – reaction turbine
57. If D is the diameter of Pelton wheel and d is the diameter of the jet, then number of
buckets on the periphery of a Pelton wheel is equal to
D
(a) D/2d (b) + 10 (c) D/2d + 20 (d) D/2d + 15
2d
58. Planck’s law holds good for
(a) Polished bodies (b) Black bodies
(c) All coloured bodies (d) All of the above
59. When solar radiation passes through a flat body, the transmittance (a) dependent on
absorptance () depends upon :
[K is extinction coefficient, n is refractive index and L is path length of radiation through
body]
(a) absorptivity and follows relation : a = e–L
(b) absorptivity and follows relation : a = e–L/2
(c) extinction coefficient and follows relation : a = e–KL
(d) refractive index and follows relation : a = e–nL
60. In a centrifugal pump, the liquid enters the pump
(a) at the top (b) at the bottom (c) at the centre (d) from sides
61. Specific speed of a turbine depends upon
(a) discharge and power (b) speed and head
(c) speed, discharge and head (d) speed, power and head
62. Reheating of steam under ideal conditions takes place at constant
(a) entropy (b) enthalpy (c) pressure (d) temperature
Series-A 12 CES-07
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52.
(a) 20 – 30% (b) 40 – 50% (c) 60 – 70% (d) 70 – 90%
53. ..
(a) 180° (b) 125° (c) 235° (d) 200°
54.
(a) N Q / H3/4 (b) N P / H5/4 (c) N Q / H5/4 (d) N H / Q3/4
55. - ( ) -
(a) (b)
(c) (d) :
56. -
(a) (b) -
(c) - (d) -
57. D d
:
(a) D/2d (b) D/2D + 10 (c) D/2d + 20 (d) D/2d + 15
58. :
(a) (b)
(c) (d)
59. () (a)
:
[K = , n L ]
(a) a = e–L
(b) a = e–L/2
(c) a = e–KL
(d) a = e–nL
60.
(a) (b) (c) (d)
61.
(a) (b)
(c) , (d) ,
62. : ______
(a) (b) (c) (d)
CES-07 13 Series-A
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63. The angle of taper on draft tube is
(a) greater than 15° (b) greater than 8°
(c) greater than 5° (d) less than 8°
64. Bio gas is predominantly
(a) hydrogen (b) carbon mono-oxide (c) carbon dioxide (d) methane
65. The specific speed of a water turbine is defined as the speed of a member of the same
homologous series of such a size that
(a) delivers unit discharge at unit head (b) delivers unit discharge at unit power
(c) delivers unit power at unit speed (d) produces unit power under unit head
66. What identifies the antiknock quality of diesel fuel ?
(a) Octane number (b) Cetane number
(c) SAE number (d) API gravity
67. The value of critical pressure ratio for superheated steam in steam nozzle is
(a) 0.640 (b) 0.454 (c) 0.546 (d) 0.500
68. In an ideal vapour compression refrigeration cycle, the refrigerant vapour enters the
compressor with enthalpy 172 kJ/kg. The refrigerant leaves the condenser as saturated
liquid with enthalpy 76 kJ/kg. The flow rate of refrigerant is 0.05 kg/sec. The capacity of
the refrigerator is
(a) 4.0 kW (b) 4.8 kW (c) 5.0 kW (d) 5.4 kW
69. In a vapour compression refrigeration system, energy transferred as heat from condenser is
found to be 300 kJ/min while the capacity of refrigerator is 1 ton. The refrigerant vapour
leaves the evaporator in the saturated state. The energy input to compressor and coefficient
of performance of system are
(a) 1 kW and 2 respectively (b) 1.2 kW and 2 respectively
(c) 1.5 kW and 2.33 respectively (d) 1.6 kW and 3.0 respectively
70. An air-water vapour mixture has a relative humidity of 60% at total pressure of 101.325
kPa at 30 °C (saturation pressure of water 4.2 kPa). Partial pressure of air is
(a) 98.805 kPa (b) 98.501 kPa (c) 95.251 kPa (d) 97.625 kPa
71. If an air water vapour mixture is passed through porous pad soaked in water, then
(a) energy transfer occurs between surroundings and humidifier.
(b) the mixture leaves in near saturated state.
(c) the process is not adiabatic.
(d) the mixture leaves at a higher temperature.
72. Pelton wheels are used for minimum of following heads
(a) 20 m (b) 100 m (c) 125 m (d) 180 m and above
Series-A 14 CES-07
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73. The throttling of certain gases may be used for getting the refrigeration effects. For such a
throttling process, the value of Joule – Thomson coefficient () is
(a) > 1 (b) < 1 (c) = 0 (d) = 1
74. The refrigerating system of passenger aircraft works on
(a) Reversed Brayton cycle (b) Reversed Atkinson cycle
(c) Reversed Ericsson cycle (d) Reversed Carnot cycle
75. During refrigeration cycle based on vapour compression system, the refrigerant exists as
high pressure liquid at exit from
(a) condenser (b) throttle valve (c) evaporator (d) compressor
76. Which of the following components in a vapour absorption plant is a substitute for the
compressor of the vapour compression system ?
(a) absorber (b) heat exchanger and generator
(c) aqua pump and generator (d) absorber, aqua pump and generator
77. Which of the following is not a desirable property of a good refrigerant ?
(a) low specific heat (b) high specific volume of vapour
(c) high critical temperature (d) large latent heat at evaporation pressure
78. In the window air conditioner the expansion device usually used is
(a) float valve (b) capillary tube
(c) thermostatic expansion valve (d) automatic expansion valve
79. Atmospheric air from 38 °C and 60% relative humidity can be brought to 18 °C and 60%
relative humidity by
(a) sensible cooling process (b) adiabatic saturation process
(c) cooling and humidification process (d) cooling and dehumidification process
80. The chemical formula of refrigerant R11 is
(a) CCl3F (b) CCl F3 (c) CCl HF (d) CHF
81. Indication of amount of moisture in air is given by
(a) dry bulb temperature (b) wet bulb temperature
(c) saturation temperature (d) dew point temperature
82. Density of water is maximum at
(a) 0 °C (b) 0 °K (c) 4 °C (d) 4 °K
83. In the ejector of a steam jet refrigerator, a section is provided after mixing chamber to
stabilize the shock. This section is of
(a) converging type (b) diverging type
(c) constant cross-section (d) hyperbolic cross-section
84. For all practical purposes, the adiabatic saturation temperature of air water vapour mixture
depends on
(a) make up water temperature only
(b) specific humidity only
(c) temperature of entering air only
(d) specific humidity and temperature of entering air
Series-A 16 CES-07
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73. , ,
- () :
(a) >1 (b) <1 (c) =0 (d) =1
74. :
(a) (b)
(c) (d)
75. , _____
(a) (b) (c) (d)
76. , , ?
(a) (b)
(c) (d) ,
77. ?
(a) (b)
(c) (d)
78. :
(a) (b)
(c) - (d)
79. 38 °C 60% 18 °C 60%
(a) (b)
(c) (d)
80. R11
(a) CCl3F (b) CCl F3 (c) CCl HF (d) CHF
81.
(a) (b) (c) (d)
82. :
(a) 0 °C (b) 0 °K (c) 4 °C (d) 4 °K
83.
(a) (b)
(c) - (d) -
84. -
(a)
(b)
(c)
(d)
CES-07 17 Series-A
Text of page 18
85. One ton of refrigeration is equivalent to :
(a) 1.0 kW (b) 2.52 kW (c) 3.52 kW (d) 5.0 kW
86. A capillary tube is used in a small refrigerator to serve the purpose of
(a) thermostat (b) expansion valve (c) drier (d) evaporator
87. Solar energy can directly be used in
(a) air refrigeration system
(b) jet refrigeration system
(c) vapour compression refrigeration system
(d) vapour absorption refrigeration system
88. In the air-water vapour mixture, the partial pressure of water vapour corresponds to the
saturation temperature is called
(a) dew point temperature (b) wet bulb temperature
(c) dry bulb temperature (d) adiabatic saturation temperature
89. Effective temperature depends upon dry bulb temperature and
(a) Wet bulb temperature (b) Relative humidity
(c) Specific humidity (d) Wet bulb temperature and air motion
90. The conventional, continuously operating single stage vapour absorption refrigeration
system
(a) requires only thermal energy as input (b) does not requires a condenser
(c) consists of two expansion valves (d) consists of one expansion valve
91. Which of the following refrigerant is not phased out due to Montreal Protocol on ozone
layer depletion ?
(a) R11 (b) R21 (c) R12 (d) R32
92. Which of the following refrigerant is suggested as replacement for R22 in large air
conditioning systems ?
(a) R134a (b) R21 (c) R410a (d) None of the above
93. Which of the following statement is true ?
(a) The maximum amount of moisture air can hold depends upon its temperature and
barometric pressure.
(b) Perfect gas model can be applied to air-water mixtures when the total pressure is
high.
(c) The minimum number of independent properties to be specified for fixing the state
of moist air is two.
(d) None of the above
94. If specific humidity of moist air is 0.011 kg w.v./kg d.a. then percentage of dry air in moist
air is about : (w.v. – water vapour, d.a. – dry air)
(a) 99% (b) 98% (c) 97% (d) 96%
Series-A 18 CES-07
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95. Water is sprayed into air and this process is plotted on the psychometric chart. This process
takes place nearly along
(a) constant D.B.T. line (b) constant R.H. line
(c) constant specific humidity line (d) constant W.B.T. line
96. In summer air conditioning the supply air quantity is 100 cmm when bypass factor is zero.
If bypass factor is 0.10, the supply air quantity will become
(a) 90 cmm (b) 111 cmm (c) 9 cmm (d) none of these
97. If 10 normal persons sitting at rest in an air conditioned theater, then cooling load added by
them in room will be
(a) 1150 W (b) 1523 W (c) 1600 W (d) 2650 W
98. In some situations latent heat load is very high such that GSHF line does not intersect
saturation curve. In this situation, following is required :
(a) dehumidification of air (b) reheating of air
(c) sub-cooling of air (d) none of the above
99. In an air refrigeration system based on open cycle, the number of heat exchangers are
(a) 1 (b) 2 (c) 3 (d) 4
100. In a vapour absorption system, if F is mass flow rate of rich solution and D is the mass
F
flow rate of vapour distilled, then specific rich solution circulation ‘f’ is given by ratio .
D
The specific weak solution circulation is expressed by
1 f (f – 1)
(a) (b) (f – 1) (c) (d)
f (f – 1) f
101. DART stands for
(a) Dry air reduced temperature (b) Dry air rated temperature
(c) Dehumidified air rated temperature (d) Dehumidified air reduced temperature
102. The HFC refrigerant R134a, which is used in domestic refrigerators
(a) is not flammable (b) is flammable
(c) is slightly flammable (d) is flammable at high temperatures
103. The relative humidity during sensible cooling process
(a) increases (b) decreases (c) remains same (d) none of these
104. Dew point temperature is always an indication of
(a) dryness of air (b) latent heat
(c) moisture content of air (d) coolness of the air
105. Which of the following statement is true ?
(a) When dry bulb temperature is equal to dew point temperature, the relative humidity
of air-water mixture is 1.0.
(b) All specific psychometric properties of moist air are based on unit mass of water
vapour.
(c) Both (a) and (b)
(d) None of the above
Series-A 20 CES-07
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106. An absorption system consisting of only two closed vessels
(a) can provide continuous refrigeration (b) provides refrigeration intermittently
(c) has no practical application (d) cannot work on solar energy alone
107. An electric cable 1.4 cm in diameter has to be insulated with rubber (thermal conductivity
W W
0.174 ). The cable is located in air where heat transfer coefficient is 8.7 2 . The
mK mK
critical thickness of insulation is
(a) 2 cm (b) 1.724 cm (c) 1.3 cm (d) 1.4 cm
108. A Kaplan Turbine is
(a) low head, high discharge, axial flow turbine
(b) high head, mixed flow turbine
(c) an inward flow impulse turbine
(d) medium head, medium discharge turbine
109. Fanno and Rayleigh lines are generally drawn on
(a) p – diagram (b) h – s diagram (c) – T diagram (d) p – h diagram
110. Normal Shock
(a) wave can only arise in a subsonic flow.
(b) is a compression process.
(c) is an expansion process.
(d) wave is a slow change of state.
111. Laminar sub-layer can develop during flow over a flat plate. It exists in
(a) Laminar zone (b) Transition zone
(c) Turbulent zone (d) Laminar and transition zone
112. Which one of the following is dimensionless ? (Notations used have usual meanings)
P D4 P D3 P D4 P NQ
(a) • 2 (b) • (c) • (d) •
x NQ x NQ x NQ x D4
113. The buoyant force acting on a floating body passes through the
(a) meta centre of the body (b) centre of gravity of the body
(c) centroid of volume of the body (d) centroid of the displaced volume
114. In supersonic flow, a diverging passage results in
(a) increase in velocity and pressure (b) decrease in pressure and density
(c) increase in velocity and density (d) decrease in velocity and pressure
115. The direction of lift force on an immersed body is
(a) in the vertically upward direction
(b) normal to the direction of motion of the body
(c) normal to the zero lift axis
(d) normal to the longitudinal axis of the body
116. A house requires 60 Mcal/hr in winter for heating. Heat pump absorbs heat from cold air
outside and requires 8 Mcal/hr of work. The COP will be
(a) 10 (b) 7.5 (c) 6.5 (d) 0.75
Series-A 22 CES-07
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106.
(a) (b) -
(c) (d)
W
107. 1.4 ( 0.174 )
mK
W
8.7 m2K
(a) 2 (b) 1.724 (c) 1.3 (d) 1.4
108.
(a) , , (b) ,
(c) (d) ,
109.
(a) p – (b) h – s (c) – T (d) p – h
110.
(a)
(b)
(c)
(d)
111.
(a) (b)
(c) (d)
112. ? ( )
P D4 P D3 P D4 P NQ
(a) • 2 (b) • (c) • (d) •
x NQ x NQ x NQ x D4
113.
(a) (b)
(c) (d)
114. ,
(a) (b)
(c) (d)
115.
(a) (b)
(c) (d)
116. 60 Mcal/hr
8 Mcal/hr COP
(a) 10 (b) 7.5 (c) 6.5 (d) 0.75
CES-07 23 Series-A
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117. Oil flows through a 200 mm diameter horizontal cast iron pipe (friction factor 4f = 0.0225)
of length 500 m. The volumetric flow rate is 0.2 m3/sec. The head loss (in m) due to
friction is (assume g = 9.81 m/sec2)
(a) 116.18 (b) 0.116 (c) 18.22 (d) 232.36
118. The maximum velocity of a one dimensional incompressible fully developed viscous flow,
between two fixed parallel plates, is 6m/sec. The mean velocity (in m/sec) of the flow is
(a) 2 (b) 3 (c) 4 (d) 5
119. The pressure gauges G1 and G2 installed on the system show pressure of PG1 = 5.0 bar and
PG2 = 1.0 bar
The value of unknown pressure P is
(a) 1.01 bar (b) 2.01 bar (c) 5.00 bar (d) 7.01 bar
120. A large concrete slab 1.0 m thick has one dimensional temperature distribution T = 4 –
10 x + 20 x2 + 10 x3, where T is temperature and x is distance from one face towards other
face of wall. If the slab material has thermal diffusivity of 2 × 10–30 m2/hr. What is the rate
of change of temperature at the other face of the wall ?
(a) 0.1 °C/hr. (b) 0.2 °C/hr. (c) 0.3 °C/hr. (d) 0.4 °C/hr.
121. Two spheres A and B of the same material have radii 1 m and 4 m and temperature 4000 K
and 2000 K respectively. The energy radiated by sphere A is
(a) greater than that of sphere B (b) less than that of sphere B
(c) equal to that of sphere B (d) equal to double that of sphere B
122. Rayleigh line makes use of
(a) continuity equation and energy equation
(b) energy equation and momentum equation
(c) continuity equation and momentum equation
(d) perfect gas equation and energy equation
123. The Reynolds number is defined as the ratio of
(a) gravity force to viscous force (b) viscous force to inertia force
(c) inertia force to viscous force (d) gravity force to inertia force
124. In which of the following case must separation of boundary layer occurs ?
dP
(a) < 0
dx
dP
(b) = 0
dx
dP
(c) >0
dx
dP
(d) > 0 and the velocity profile has a point of inflextion
dx
Series-A 24 CES-07
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u y
125. A laminar boundary layer has the velocity distribution =
U
Where u is local velocity at any distance y above the plate and U is free stream velocity.
The displacement thickness for this boundary layer will be
(a) (b) (c) (d)
2 4 6
126. A rectangular flat plate (1.20 m 0.5 m) has been set at right angle to the flow of water
(density 1000 kg/m3) in the river. If the velocity of flow is 2.5 m/sec. and drag coefficient
is 1.2, the force required to hold the plate at rest is
(a) 1.44 kN (b) 0.86 kN (c) 1.62 kN (d) 1.76 kN
127. Lines of constant velocity potential
(a) are parallel streamlines (b) are normal to streamlines
(c) can intersect each other (d) are defined for real fluid
128. The limiting case of source approaching a sink of equal strength (while keeping constant
the product of their strength and distance between them) is known as
(a) half body (b) doublet (c) Rankine body (d) flow net
129. Outward flow is more suitable for
(a) roto dynamic pump (b) mixed flow hydraulic turbine
(c) axial flow hydraulic turbine (d) none of the above
130. Effect of compressibility of fluid becomes important when Mach number is
(a) zero (b) 0.01 (c) 0.02 (d) more than 0.4
131. A hydraulic turbine develops 8000 kW when rotating at 100 revolutions per minute. The
head on the turbine is 40 m. If the head becomes 10 m, the speed and power developed by
turbine are
(a) 60 rpm, 1100 kW (b) 50 rpm, 1000 kW
(c) 65 rpm, 1700 kW (d) 70 rpm, 2100 kW
Ty
132. The temperature ratio across a normal shock is
Tx
(v = ratio of specific heats, M = Mach Number)
1 1 2
1 Mx 1 Mx
(a) 2 (b) 2
1 1 2
1 My 1 My
2 2
1 2 1 2
1 Mx 1 Mx
(c) 2 (d) 2
1 2 1 2
1 My 1 My
2 2
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133. Principle of similitude works on the basis of
(a) hydraulic design
(b) mechanical design
(c) comparing similarity between design and actual equipment
(d) similarity between model and prototype
134. For the case of laminar boundary layer developed over a flat plate where free stream
velocity U is constant, the boundary condition is
(a) at the plate, shear stress is zero (b) at the plate, y = 0, u = 0 and = 0
(c) at the plate, pressure gradient is positive (d) at the plate, y = 0, u = U
135. In a fluid flow, a continuous line is so drawn that it is tangential to the velocity vector at
every point. It is known as
(a) Streak line (b) Path line (c) Stream line (d) Natural line
136. The flow of an ideal fluid is necessarily
(a) irrotational (b) rotational
(c) unsteady and rotational (d) uniform and rotational
137. No change in static pressure across runner is found in
(a) Kaplan turbine (b) Francis turbine
(c) Pelton turbine (d) Propeller turbine
138. In centrifugal pump, the theoretical work done per unit weight is known as
(a) overall head (b) manometric head (c) Euler head (d) velocity head
139. Weber number is
Interia force Interia force
(a) (b)
Viscous force Surface tension force
Interia force Viscous force
(c) (d)
Gravitational force Surface tension force
140. If two similar rotadynamic pumps are connected in series, then
(a) the discharge will not change
(b) the discharge will change
(c) the head will change
(d) discharge will change but head will not change
141. A centrifugal pump is started with its delivery valve kept
(a) fully shut (b) fully open (c) partially open (d) none of the above
142. The critical Reynolds number for viscous flow over a flat plate is about
(a) 5 × 105 (b) 5 × 10–5 (c) 4000 (d) 2300
143. The velocity distribution at any section of a pipe for steady laminar flow is
(a) linear (b) exponential (c) parabolic (d) hyperbolic
Series-A 28 CES-07
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133. ?
(a)
(b)
(c)
(d)
134. U ,
(a) , (b) , y = 0, u = 0 = 0
(c) , (d) , y = 0, u = U
135. ,
(a) (b) (c) (d)
136.
(a) (b) (c) (d)
137. -
(a) (b)
(c) (d)
138. ,
(a) (b) (c) (d)
139.
(a) (b)
(c) (d)
140. ,
(a) (b)
(c) (d)
141.
(a) (b) (c) (d)
142.
(a) 5 × 105 (b) 5 × 10–5 (c) 4000 (d) 2300
143.
(a) (b) (c) (d)
CES-07 29 Series-A
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144. In a bottle, there is a compressed helium gas and this gas is used to inflate an inelastic
flexible balloon (which was originally folded in a completely flat state) to a volume of 0.5
m3. The atmosphere pressure is 1.013 bar. The amount of work done upon atmosphere by
balloon is :
(a) 45.60 kJ (b) 50.65 kJ (c) 52.75 kJ (d) 54.25 kJ
145. Which out of the following does not show the similarity between heat and work ?
(a) Energy interaction (b) Boundary phenomena
(c) Transient phenomena (d) All energy transfer
146. Eight kilogram of a gas is heated in a reversible non-flow constant volume process, so that
its temperature is raised from 21°C to 321°C. If specific heat at constant volume for gas in
0.6 kJ/kg K, then the change in internal energy and heat transfer for gas are respectively
(a) 1440 kJ and 1440 kJ (b) 1710 kJ and 1360 kJ
(c) 1500 kJ and 1440 kJ (d) 1560 kJ and 1710 kJ
147. The heat transfer occurs during a cycle made up of four processes as given below :
120 kJ, – 20 kJ, 16 kJ and 24 kJ. Hence, the work done during the cycle is :
(a) 100 kJ (b) 120 kJ (c) 130 kJ (d) 140 kJ
148. The following processes may be reversible in
(a) free expansion and adiabatic (b) free expansion and isothermal
(c) adiabatic and isothermal (d) free expansion and polytropic
149. A steady stream of gas at some pressure and temperature flows through porous plug
contained in a horizontal tube which is thermally insulated. The slope of constant enthalpy
curve in pressure – temperature diagram at a particular state :
(a) is always positive (b) is always zero
(c) is always negative (d) may be positive, zero or negative in value
150. The thermal efficiency and rate of heat rejection of a heat engine which receives heat at the
rate of 2100 kJ/min and develops 10.5 kW are
(a) 28.8%, 1424 kJ/min (b) 36%, 1472 kJ/min
(c) 30%, 1470 kJ/min (d) 32.5%, 1450 kJ/min
151. An actual refrigerator removes 430 kJ/kg of heat from water available at 21.8 °C to form
ice at –5 °C. The minimum work input necessary to achieve this is
(a) 40 kJ/kg (b) 42 kJ/kg (c) 43 kJ/kg (d) 46 kJ/kg
152. In an air standard diesel cycle, clearance volume is 12.5 percent of stroke volume. The
compression ratio is
(a) 9 (b) 13 (c) 14 (d) 16
153. Which of the following sets has all open systems ?
(a) Boiler, gas turbine, compressor, condenser
(b) Pump, thermos flask, petrol engine, steam turbine
(c) Fluid stored in pressure vessel, jet engine, diesel engine
(d) Window air conditioner, nozzle, pump, thermos flask
Series-A 30 CES-07
Text of page 32
154. Which is true for reversible polytropic process ?
(a) temperature remains constant. (b) entropy remains constant.
(c) internal energy remains constant. (d) some heat transfer takes place.
155. First law of thermodynamics furnishes the relationship between :
(a) heat and work (b) heat, work and properties of the system
(c) heat and internal energy (d) various properties of the system
156. A system of 100 kg mass undergoes a process in which its specific energy increases from
0.3 kJ/kg K to 0.4 kJ/kg K. At the same time, the entropy of the surroundings decreases
80 kJ/K to 75 kJ/K. The process is
(a) reversible and isothermal (b) irreversible
(c) reversible (d) impossible
157. In a polytropic expansion ratio of work to heat transfer is
n–1 n n –1
(a) (b) (c) (d)
–1 –1 n–1
158. Joule – Thomson coefficient is denoted by
S T T T
(a) (b) (c) (d)
P
T P h VP VS
159. A heat engine having an efficiency of 70% is used to drive a refrigerator having a
coefficient of performance of 5. The energy absorbed from low temperature reservoir by
the refrigerator for each kJ of energy absorbed from high temperature source by the engine
is :
(a) 0.14 kJ (b) 0.71 kJ (c) 3.5 kJ (d) 7.1 kJ
160. Which of the following parameter remains constant in a throttling process ?
(a) Temperature (b) Pressure (c) Enthalpy (d) Entropy
161. Which of the following processes can approach reversibility ?
(a) Mixing of different substances
(b) Controlled or restricted expansion or compression
(c) Chemical reactions
(d) Action of brakes in stopping a vehicle
162. A steel ball of mass 1.2 kg of specific heat 0.50 kJ/kg C is at 60 C. It is dropped into
1.2 kg of water at 20 C. The final steady state temperature of water is :
(a) 23.5 °C (b) 30 °C (c) 35 °C (d) 24.3 °C
163. The mean effective pressure in air standard Otto cycle for a fixed inlet pressure is a
function of
(a) compression ratio only
(b) compression ratio and pressure ratio during heat addition process
(c) compression ratio and exhaust pressure
(d) compression ratio, exhaust pressure and pressure ratio during heat addition
Series-A 32 CES-07
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164. A condenser of a refrigeration system rejects heat at rate of 170 kW, while its compressor
consumes a power of 80 kW. The coefficient of performance of the system would be
(a) 17/8 (b) 8/17 (c) 9/8 (d) 8/9
165. For the same maximum temperature and pressure and for the same quantity of energy
rejection, Otto cycle
(a) is more efficient than diesel cycle (b) is less efficient than diesel cycle
(c) and diesel cycle are equally efficient (d) and diesel cycle cannot be compared
166. A gas is enclosed in piston-cylinder arrangement as system. The gas is initially at a
pressure of 500 kPa and occupies a volume of 0.2 m 3. The gas is taken to final state where
pressure is 100 kPa through a process in which volume of gas is inversely proportional to
the pressure. The work done by the gas is
(a) 100 In 5 kJ (b) 80 kJ (c) 160 kJ (d) 200 kJ
167. Internal energy of a perfect gas depends on
(a) temperature, specific heats and pressure
(b) temperature, specific heats and enthalpy
(c) temperature, specific heats and entropy
(d) temperature only
168. In air standard diesel cycle, at fixed compression ratio and fixed value of adiabatic index (v),
thermal efficiency
(a) increases with increase in heat addition cut-off ratio
(b) decreases with increase in heat addition cut-off ratio
(c) remains same with increase in heat addition cut-off ratio
(d) none of the above
169. In Rankine cycle the work output from the turbine is given by
(a) change of internal energy between inlet and outlet
(b) change of enthalpy between inlet and outlet
(c) change of entropy between inlet and outlet
(d) change of temperature between inlet and outlet
170. If a finite body at temperature T interacts with a thermal reservoir (sink) at T 0 temperature,
the maximum work obtained will be : (CP is specific heat)
(a) CP (T – T0)
(b) greater than CP (T – T0)
(c) less than CP (T – T0)
(d) can be calculated but some more data is required
171. A storage battery, having a terminal potential of 8.5 volts, draws a current of 8 amperes for
3 hours. If the stored energy of the battery is decreased by 1200 kJ, evaluate the heat
interaction across the boundary enveloping the storage battery in kJ
(a) 465.6 (b) 386 (c) 378 (d) 100
Series-A 34 CES-07
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172. A cycle consisting of two adiabatics and two constant pressure processes is known as
(a) Otto cycle (b) Ericsson cycle (c) Joule cycle (d) Stirling cycle
173. A series of composite wall is made up of fire brick (length l1, thermal conductivity k1),
insulating brick (length l2, thermal conductivity k2) and ordinary brick (length l3, thermal
conductivity k3). The fire brick forms the inner layer and is exposed to thin hot gas film
(heat transfer coefficient hg). Ordinary brick forms outer layer and is exposed to thin air
film (heat transfer coefficient ha). The overall heat transfer coefficient U is :
1 1
(a) U = (b) U =
1 l1 l2 l3 1 1 l1 l2 l3 1
hg k1 k 2 k 3 ha hg k1 k 2 k 3 ha
1 1
(c) U= (d) U=
1 l1 l2 l3 1 1 l1 l2 l3 1
hg k1 k 2 k 3 ha hg k1 k 2 k 3 ha
174. The relation between total emissive power E of a surface and intensity of radiation of
surface I is
E I
(a) = (b) = (c) E = 2I (d) I = 2E
I E
175. The value of shape factor of a surface with respect to itself is zero. Then the surface is
(a) Concave (b) Concave or flat
(c) Concave or convex (d) Convex or flat
176. The value of Nusselt number is
(a) between 0 and 0.2 (b) between 0.3 and 0.5
(c) between 0.6 and 0.8 (d) always greater than 1
177. The performance of parallel flow heat exchanger is studied in terms of effectiveness ,
capacity ratio C and number of transfer units NTU, we see that
(a) 0 < C < 1 and NTU > 0
(b) C > 1 and NTU < 0
(c) is plotted against C with NTU as parameters.
(d) NTU is plotted against heat transfer area.
178. The wavelength of the radiation emitted by a body depends upon
(a) the nature of its surface (b) the area of its surface
(c) the temperature of its surface (d) all the above
179. The ratio of surface convection resistance to internal conduction resistance is known as
(a) Grasshoff number (b) Biot number
(c) Stanton number (d) Prandtl number
180. When a system executes an irreversible cycle
Q Q
(a) <0 (b) ds > 0 (c) ds = 0 (d) T >0
T
Series-A 36 CES-07
Text of page 37
172. () ,
(a) (b) (c) (d)
173. ( l1, k1), ( l2,
k2) ( l3, k3)
( hg)
( ha) U :
1 1
(a) U= (b) U=
1 l1 l2 l3 1 1 l1 l2 l3 1
hg k1 k 2 k 3 ha hg k1 k 2 k 3 ha
1 1
(c) U= (d) U=
1 l1 l2 l3 1 1 l1 l2 l3 1
hg k1 k 2 k 3 ha hg k1 k 2 k 3 ha
174. E I
E I
(a) = (b) = (c) E = 2I (d) I = 2E
I E
175.
(a) (b) (c) (d)
176.
(a) 0 0.2 (b) 0.3 0.5
(c) 0.6 0.8 (d) 1
177. , , C
NTU
(a) 0 < C < 1 NTU > 0
(b) C > 1 NTU < 0
(c) NTU C
(d) NTU
178.
(a) (b)
(c) (d)
179.
(a) (b) (c) (d)
180.
Q Q
(a) <0 (b) ds > 0 (c) ds = 0 (d) T >0
T
CES-07 37 Series-A
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Space For Rough Work / Series-A 38 CES-07
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Space For Rough Work / CES-07 39 Series-A
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Space For Rough Work / Series-A 40 CES-07
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Source: Uttarakhand Public Service Commission. Question paper published by Uttarakhand Public Service Commission.