Q.1
A diathermaneous substance __________ the thermal radiation completely.
Q.2
For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in
Q.3
To reduce the tube side pressure drop for the same flow rate, the heat exchanger recomended is
Q.4
In the free convection regime of pool boiling, the heat flux is proportional to
Q.5
In natural convection heat transfer, the correlating parameter is the
Q.6
Stefen's block body radiation law can also be derived from __________ law.
Q.7
jH factor for heat transfer depends upon the __________ number.
Q.8
Maximum heat transfer rate is achieved in __________ flow.
Q.9
The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is
Q.10
Dropwise condensation is promoted on a/an __________ surface.
Q.11
Pick out the wrong statement.
Q.12
A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.
Q.13
The average heat transfer co-efficient over the entire length of the plate (ha) and the local heat transfer co-efficient (hL), in case of heat transfer over a flat plate in lminar zone is related as
Q.14
For what value of Prandtl number, St = f/2?
Q.15
What is the emissivity of a black body?
Q.16
Pick out the wrong statement.
Q.17
The non-dimensional temperature gradient in a liquid at the wall of a pipe is the
Q.18
The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is
Q.19
With increase in porosity, the thermal conductivity of a solid substance
Q.20
It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is
Q.21
In a forward feed multiple effect, the pressure build up will be
Q.22
Prandtl and Reynolds analogy are same, when Prandtl number is
Q.23
Unsteady state heat conduction occurs, when
Q.24
Economy of a multiple effect evaporator depends upon the
Q.25
In a forward feed multiple effect evaporator, the pressure is
Q.26
Correction is applied to LMTD for __________ flow.
Q.27
The range of electromagnetic spectrum important in heat transfer by radiation is __________ microns.
Q.28
A black body does not __________ radiation.
Q.29
A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides
Q.30
'Duhring's plot' is of use in
Q.31
Heat exchangers operating, when the asymptotic range is reached,
Q.32
Pick out the wrong statement.
Q.33
A body is called grey if the monochromatic emissivity of the body is
Q.34
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid.
Q.35
The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium. This is __________ law.
Q.36
__________ paint has the maximum absorption coefficient.
Q.37
Which of the following is not concerned with the heat transfer?
Q.38
1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m² and the overall heat transfer co-efficient to the liquid is 1500 W/m².°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be
Q.39
Heat produced when a steady state current, I passes through an electrical conductor having resistance, 'R' is
Q.40
In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.
Q.41
Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling?
Q.42
Pick out the wrong statement.
Q.43
Film boiling is usually not desired in commercial equipments, because
Q.44
A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to
Q.45
Rate of crystallisation does not depend upon the
Q.46
Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.
Q.47
Solid angle subtended by the finite surface at the radiating element is
Q.48
Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called
Q.49
A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun?
Q.50
The interchange factor for radiation heat transfer from surface 'x' to surface 'y' in case of an infinite parallel planes with emis-sivities εx & εy is given by
0 h : 0 m : 1 s