chemical engineering heat transfer chemical engineering MCQs – Page 3

Practise multiple-choice questions from chemical engineering heat transfer chemical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering heat transfer chemical engineering Mcqs
41. Which of the following situations can be approximated to a steady state heat transfer system ?
comments icon0

A. ntained constant at 180C

B. Boiling brine kept in open vessel when the bottom surface temperature of the vessel is

C. osed to atmospheric air at 35C</strong>

D. e exposed to atmospheric air at 35C

E. A red hot steel slab (having outside surface temperature as 1300C) exposed to the

F. 10 kg of dry saturated steam at 8 kgf/cm2 flowing through a short length of stainless steel pipe
42. In case of a super-cooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is ________________?
comments icon0

A. Same

B. More or less; depends on the nature of solution

C. Less

D. More
43. The inner wall of a furnace is at a temperature of 700C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.C- 1 respectively. The ambient air is at 30C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.C-1. The rate of heat loss from the outer surface in W.m-2is__________________?
comments icon0

A. 172.5

B. 165.4

C. 167.5

D. 175

44. Peclet number (Pe) is given by____________________?
comments icon0

A. Pe = Nu.Re

B. Pe = Re.Pr

C. Pe = Re/Pr

D. Pe = Pr/Re

45. The purpose of providing expansion bellows in the shell of tubular exchanger is to _____________________?
comments icon0

A. Facilitate increase of shell length, if needed

B. Account for the uneven expansion of shell and tube bundles

C. Increase the heating load

D. Impart structural strength

46. The advantage of using a 1 2 shell and tube heat exchanger over a 1 1 shell and tube heat exchanger is_________________?
comments icon0

A. Higher shell side heat transfer co-efficient

B. Higher tube side heat transfer co-efficient

C. Lower tube side pressure drop

D. Lower shell side pressure drop

47. Prandtl number is the ratio of________________?
comments icon0

A. Thermal diffusivity to momentum diffusivity

B. Momentum diffusivity to thermal diffusivity

C. Thermal diffusivity to mass diffusivity

D. Momentum diffusivity to mass diffusivity

48. A graph between _____________ is called Wilson plot?
comments icon0

A. (1/U) Vs. (1/V)

B. v0.8 Vs . U

C. (1/U) Vs. (1/v0.8)

D. (1/v0.8) Vs. U

49. The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m2.K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m2.K. The overall heat transfer co-efficient at this time is _____________________?
comments icon0

A. 287 W/m2.K

B. 333 W/m2.K

C. 894 W/m2.K

D. 1200 W/m2.K

50. Evaporator tubes are generally_____________________?
comments icon0

A. Horizontal

B. Vertical

C. Inclined

D. Random

51. Corrosiveness of steam condensate is due to the presence of________________?
comments icon0

A. CO2

B. Dissolved O2

C. Both A. & B.

D. Neither A. nor B.

52. Heat transfer by ____________ may not necessarily require the presence of a medium?
comments icon0

A. Forced convection

B. Natural convection

C. Conduction

D. Radiation
53. View factor is important in heat transfer by_____________________?
comments icon0

A. Natural convection

B. Steady state conduction

C. Radiation

D. Forced convection

54. The thermal boundary layer at NPr > 1 ?
comments icon0
A. Is thinner than hydrodynamic boundary layer

B. Is thicker than hydrodynamic boundary layer

C. Disappears

D. And the hydrodynamic boundary layers are identical

55. Radiation heat losses from satisfactorily insulated high pressure boiler may be about _____________ percent?
comments icon0

A. 1

B. 26

C. 18

D. 7
56. Vent pipes are provided in a condenser to ________________?
comments icon0

A. Facilitate easy cleaning of tubes

B. Remove non-condensable gases

C. Purge the condenser

D. None of these

57. Multipass heat exchangers are used______________________?
comments icon0
A. To obtain higher heat transfer co-efficient and shorter tube

B. For low heat load

C. Because of simplicity of fabrication

D. To reduce the pressure drop

58. Extremely large or small volumes of fluids are generally best routed through the shell side of a shell and tube heat exchanger, because of the________________?
comments icon0

A. High heat transfer co-efficient

B. Less corrosion problems

C. Low pressure drop

D. Flexibility possible in the baffle arrangement
59. In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used________________?
comments icon0

A. In low range of temperature differences

B. To prevent corrosion of the tube bundles

C. Because of its low cost

D. In high range of temperature differences
60. Heat transfer rate described by Fouriers law will decrease, if the _____________ increases?
comments icon0

A. Heat transfer area

B. Temperature difference

C. Thickness

D. Thermal conductivity