The ratio of thermal conductivity of water to that of ice is nearly
A.4
B.2
Category: Heat Transfer Mcqs
If the amount of radiant energy received per unit area per second from the sun is measured at the Earth, Mars and Jupiter it will be
A.identical on all the three planets
B.in the decreasing order – Jupiter, Mars, Earth
C.in the increasing order – Earth, Mars, Jupiter
D.in the increasing order – Jupiter, Mars, Earth
Unsteady state of heat flow occurs in
A.Flow of heat through furnace walls
B.Flow of heat through insulated pipe with constant surface temperature
C.Annealing of castings
D.Flow of heat through refrigerator walls
E.None of the above
Ablation heat transfer method is used on
A.submarines
B.rockets
C.satellites
D.nuclear war heads
A block of wood and a block of metal feel equally cold or equally hot when touched. Then their common temperature is
A.0?K
B.0?F
C.0?C
D.the same as that of the human body
A dimensionless number which is the ratio of kinematic viscosity to thermal diffusivity is known as
A.Prandtl number
B.Reynolds number
C.Nusselt number
D.Pacelet number
E.Grashoff number
The value of the wavelength for maximum emissive power is given by
A.Planck’s law
B.D’Alembert’s rule
C.Kirchhoff’s law
D.Stefan law
E.Wein’s law
Heat sensitive liquids are connected
A.By using insulated vessels
B.By using small quantities
C.By using deoxidisers
D.By using vacuum
E.By using low intensity heating
In heat exchanger design, one transfer unit means
A.One fluid exchanging with another fluid of the same chemical composition
B.The section of heat exchanger which will cause temperature drop of one degree centigrade
C.The section of heat exchanger where heat transfer surface area is one square metre
D.The equivalent length of tubes in case the heat exchange was for a temperature difference of 1?C
E.Condition when the change in temperature of 1?C numerically equals the average driving force.
A grey body has emissivity
A.more than 1
B.1
C.less than 1
D.0.5
