1. The function of a condenser in a thermal power plant is.......
Correct : D. All of the above
2. A condenser where circulating water flows through tubes which are surrounded by steam,is known as.........
Correct : A. Surface condenser
3. The vaccum obtainable in a condenser is dependent upon......
Correct : D. Temperature of cooling water
4. The ratio of actual vaccum to the ideal vaccum in a condenser is called.......
Correct : B. Vaccum efficiency
5. A condenser in a steam power plant is .......
Correct : D. All of the above
6. The actual vaccum in a condenser is equal to......
Correct : B. Barometric pressure - actual pressure
7. According to Dalton’s law, the total pressure of the mixture of gases is equal to
Correct : C. sum of the partial pressures of all
8. At ideal condition of vapour power cycle, reversible constant pressure heat rejection is carried out at
Correct : C. condenser
9. A condenser condenses the steam coming out from___________.
Correct : B. Turbine
10. What is use of the air pumps in the condenser?
Correct : B. Air leaking in the condenser and to maintain the vacuum.
11. What is the correct formula for net work done of reciprocating engine?
Correct : C. Wnet = mean effective pressure × displacement volume
12. Minimum work in compressor is possible when the value of adiabatic index n is equal to
Correct : B. 1
13. Compressed air coming out from a punctured football
Correct : B. becomes cooler
14. The capacity of a compressor is 5 m /min. 5 m /min refers to
Correct : B. free air
15. The overall isothermal efficiency of compressor is defined as the ratio of
Correct : A. isothermal h.p. to the BHP of motor
16. The- most efficient method of compressing air is to compress it
Correct : A. isothermally
17. Maximum work is done in compressing air when the compression is
Correct : B. adiabatic
18. The pressure and temperature conditions of air at the suction of compressor are
Correct : A. pressure sightly less than atmospheric and temperature slightly more than atmospheric.
19. Isothermal compression effeicency can be attained by running the compressor
Correct : B. at very slow speed
20. The compressor capacity with decrease in suction temperature
Correct : A. increases
21. Isothermal compression efficiency, even when running at high speed, can be approached by using
Correct : C. both (a) and (b) above
22. Compression efficiency is compared against
Correct : C. isothermal compression
23. Aeroplanes employ following type of compressor
Correct : B. axial flow
24. Inter cooling in compressors
Correct : B. results in saving of power in compressing a given volume to given pressure
25. An ideal air compressor cycle without clearance on p-v diagram can be represented by following processes
Correct : A. one adiabatic, two isobaric, and one constant volume
26. An ideal air compressor cycle with clearance on p-v diagram can be represented by following processes
Correct : B. two adiabatic and two isobaric
27. The work done per unit mass of air in compression will be least when n is equal to
Correct : A. 1
28. Isothermal compression though most efficient, but is not -practicable because
Correct : D. compressor has to run at very slow speed to achieve it
29. Ratio of indicated H.P. and brake H.P. is known as
Correct : A. mechanical efficiency
30. The ratio of work doen per cycle to the swept volume in case of compressor is called
Correct : D. mean effective pressure
31. Cylinder clearance in a compressor should be
Correct : B. as small as possible
32. Ratio of compression is the ratio of
Correct : B. absolute discharge pressure to the absolute intake pressure
33. Clearance volume in actual reciprocating compressors is essential
Correct : D. to provide cushioning effect and also to avoid mechanical bang of piston with cylinder head.
34. The net work input required for compressor with increase in clearance volume
Correct : C. remains same
35. Ratio of indicated h.p. to shaft h.p. is known as
Correct : D. mechanical efficiency
36. Volumetric efficiency is
Correct : B. the ratio of the air actually delivered to the amount of piston displacement
37. Volumetric efficiency of a compressor with clearance volume
Correct : B. decreases with increase in compression ratio
38. Volumetric efficiency of a compressor without clearance volume
Correct : C. is not dependent upon compression ratio
39. The clearance volume of the air compressor is kept minimum because
Correct : B. it greatly affects volumetric efficiency
40. Which is false statement about multistage compression.
Correct : B. Volumetric efficiency is high
41. Reciprocating air compressor is best suited for
Correct : B. small quantity of air at high pressure
42. Rotary compressor is best suited for
Correct : D. large quantity of air at low pressure
43. After-cooler is used to
Correct : C. cause moisture and oil vapour to drop out
44. The compressor performance at higher altitude compared to sea level will be
Correct : C. lower
45. Pick up the wrong statement about advantages of multistage compression
Correct : B. more loss of air due to leakage past the cylinder
46. Losses in a centrifugal compressor are due to
Correct : D. all of the above
47. For supplying intermittent small quantity of air at high pressure, following compressor is best suited
Correct : B. reciprocating
48. For minimum work in multistage compression, assuming same index of compression in all stages
Correct : D. work done in all stages should be equal
49. Diffuser in a compressor is used to
Correct : D. convert kinetic energy into pressure energy
50. Phenomenon of choking in compressor means
Correct : B. fixed mass flow rate regardless of pressure ratio
51. Axial flow compressor has the following advantage over centrifugal compressor
Correct : A. larger air handling ability per unit frontal area
52. Rotary compressors are suitable for
Correct : C. large discharge at low pressure
53. The vloumetric efficiency of compressor with increase in compression ratio will
Correct : B. decrease
54. Unit of thermal conductivity in S.I. units is
Correct : C. W/m °K
55. Thermal conductivity of solid metals with rise in temperature normally
Correct : B. decreases
56. Heat transfer takes place as per -
Correct : C. second law of the thermodynamics
57. When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to
as heat transfer by
Correct : A. conduction
58. When heat is transferred from hot body to cold body, in a straight line, without affecting the intervening medium, it is
referred as heat transfer by
Correct : C. radiation
59. The insulation ability of an insulator with the presence of moisture would
Correct : B. decrease
60. When heat is Transferred by molecular collision, it is referred to as heat transfer by
Correct : B. convection
61. Heat transfer in liquid and gases takes place by
Correct : B. convection
62. Which of the following is the case of heat transfer by radiation
Correct : D. all of the above.
63. Heat is closely related with
Correct : C. temperature
64. Metals are good conductors of heat because
Correct : A. their atoms collide frequently
65. Thermal conductivity of air with rise in temperature
Correct : A. increases
66. Heat flows from one body to other when they have
Correct : D. different temperatures
67. The concept of overall coefficient of heat transfer is used in heat transfer problems of
Correct : D. conduction and convection.
68. In heat transfer, conductance equals conductivity (kcal/hr/sqm/°C/cm) divided by
Correct : D. cm (thickness)
69. The amount of heat flow through a body by conduction is
Correct : D. all of the above.
70. Which of the following has least value of conductivity
Correct : D. air
71. Which of the following is expected to have highest thermal conductivity
Correct : B. solid ice
72. Thermal conductivity of a material may be defined as the
Correct : D. all of the above
73. Which of the following has maximum value of thermal conductivity
Correct : A. aluminium
74. Heat is transferred by all three modes of transfer (conduction, convection and radiation) in,
Correct : D. boiler.
75. Heat transfer by radiation mainly depends upon
Correct : D. all of the above
76. Thermal conductivity of wood depends on
Correct : D. all of the above
77. Heat conducted through unit area and unit thick face per unit time when temperature difference between opposite faces
is unity,is called
Correct : D. thermal conductivity
78. Emissivity of a white polished body in comparison to a black body is
Correct : B. lower
79. A grey body is one whose absorptivity
Correct : C. is equal to its emissivity
80. A non-dimensional number generally associated with natural convection heat transfer is
Correct : A. Grashoff number
81. LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is
Correct : A. higher
82. In counter flow heat exchangers
Correct : B. both the fluids at inlet are in their hottest state
83. Fourier's law of heat conduction is valid for
Correct : A. one dimensional cases only
84. All radiations in a black body are
Correct : D. absorbed
85. According to Kirchoff's law, ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a
Correct : D. black body
86. The unit of overall coefficient of heat transfer is
Correct : C. W/m2 °C
87. According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to
Correct : C. fourth power of absolute temperature
88. The unit of Stefan Boltzmann constant is
Correct : D. watt/cm2 °K4
89. Stefan Boltzmann law is applicable for heat transfer by
Correct : C. radiation
90. The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a
perfectly black body. This statement is known as
Correct : A. Krichoff's law
91. The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit
Correct : D. time
92. The ratio of the energy absorbed by the body to total energy falling on it is called
Correct : A. absorptive power
93. 40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of
the body be 0.15, then the absorptivity of surface is
Correct : A. 0.45
94. The amount of radiation mainly depends on
Correct : D. all of the above
95. The emissive power of a body depends upon its
Correct : D. all of the above
96. Two plates spaced 150 mm apart are maintained at 1000°C and 70°C. The heat transfer will take place mainly by
Correct : D. radiation
97. In regenerative type heat exchanger, heat transfer takes place by
Correct : A. direct mixing of hot and cold fluids
98. A perfect black body is one which
Correct : D. absorbs heat radiations of all wave lengths falling on it
99. If the temperature of a solid surface changes from 27°C to 627°C, then its emissive power changes in the ratio of