Q.1
Heat sensitive materials can be concentrated in an evaporator employing
Q.2
In case of evaporators, liquid entrainment results primarily due to
Q.3
In a shell and tube heat exchanger, the shell side fluid velocity can not be changed by changing the
Q.4
The unit of conductance in SI unit is
Q.5
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer
Q.6
In which mode of heat transfer, the Biot number is important?
Q.7
When warm and cold liquids are mixed, the heat transfer is mainly by
Q.8
Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is
Q.9
Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is
Q.10
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally
Q.11
Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is
Q.12
The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)
Q.13
In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.
Q.14
Indirect contact heat exchangers are preferred over direct contact heat exchangers, because
Q.15
Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the
Q.16
For a multipass shell and tube heat exchanger, the LMTD correction factor is always
Q.17
The energy radiated from a surface Q at absolute temperature T is related as
Q.18
For evaporation of viscous solution in a multiple effect evaporator, the prefered feeding scheme is
Q.19
Pick out the wrong statement:
Q.20
In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.
Q.21
Open pan evaporators are preferred to be used, when the solution to be concentrated is
Q.22
For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number)
Q.23
Intermittant tube cleaning is possible to be done in case of a __________ evaporator.
Q.24
Steam is routed through the tube in case of a __________ evaporator.
Q.25
A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when
Q.26
Planck's distribution law is valid for __________ bodies.
Q.27
Corrosiveness of steam condensate is due to the presence of
Q.28
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
Q.29
LMTD correction factor which is to be applied for a cross-flow heat exchanger increases with increase in the number of shell passes. Its value for a single pass cross flow heat exchanger is
Q.30
Maximum heat transfer rate is obtained in __________ flow.
Q.31
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)
Q.32
Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be
Q.33
For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area
Q.34
The critical radius 'r' of insulation on a pipe is given by
Q.35
Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by
Q.36
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface?
Q.37
In a shell and tube heat exchanger,
Q.38
Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger?
Q.39
An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a
Q.40
Small scale evaporation is done in a
Q.41
1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is
Q.42
Thermal diffusivity of a material
Q.43
Leidenfrost point is a term concerned with the
Q.44
Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)
Q.45
Pick out the wrong statement.
Q.46
The thickness of condensate layer in filmwise condensation depends on the
Q.47
A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is
Q.48
(NRe.NPr)(D/L) is called the __________ number
Q.49
In a boiling curve, the peak heat flux is called the __________ point.
Q.50
Sensible heat of hot industrial flue gases can not be recovered by a/an
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