Q.1
Reynold's analogy states that (where, St = Stanton number f = friction factor)
Q.2
Which is the most suitable for the concentration of foamy & frothy liquors?
Q.3
In Fourier's law, the proportionality constant is called the
Q.4
Which area is used in case of heat flow by conduction through a cylinder?
Q.5
A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m³ and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m².K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is
Q.6
A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires
Q.7
Which of the following is unimportant in forced convection?
Q.8
Duhring rule is important in solving problems on
Q.9
Fourier's law of heat conduction applies to __________ surfaces.
Q.10
Peclet number (Pe) is given by
Q.11
Pick out the correct equation.
Q.12
Pick out the wrong statement.
Q.13
Boiling point of a solution according to Duhring's rule is a linear function of the __________ of water.
Q.14
__________ heat exchanger is used for chilling oil to be dewaxed.
Q.15
For concentrating an aqueous solution of a material like anhydrous Na₂SO₄, whose solubility decreases with rise in temperature, the most suitable evaporator is a __________ evaporator.
Q.16
The number of kg vaporised per kg of steam fed to the evaporator is defined as
Q.17
Circulation pump is located below the evaporater to
Q.18
A measure of the extent to which viscous heating is important relative to the heat flow resulting from the impressed temperature difference is represented by the __________ number.
Q.19
Nucleate boiling is promoted
Q.20
Removal of __________ heat is involved in the condensation of a vapor under saturated conditions.
Q.21
A hot body will radiate heat most rapidly, if its surface is
Q.22
Fourier's law applies to the heat transfer by
Q.23
Kirchoff s law applies to __________ radiation.
Q.24
Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is
Q.25
The purpose of providing a 'catchall' in the vapor line of an evaporator is to
Q.26
Dropwise condensation occurs on __________ surfaces.
Q.27
The absorptivity of a body is equal to its emissivity
Q.28
In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is
Q.29
Thermal conductivity of a conducting solid material depends upon its
Q.30
With increase in temperature, the total emissivity of conductors
Q.31
For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are
Q.32
Black liquor generated during paper manufacture is concentrated in a
Q.33
If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid
Q.34
One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to
Q.35
jH factor for heat transfer is not a function of the __________ number.
Q.36
__________ equation relates the thermal conductivity of a solid to its temperature.
Q.37
A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m².°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be
Q.38
Dropwise condensation of steam on cooling surface is promoted
Q.39
Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid
Q.40
The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid
Q.41
For __________ Prandtl number values, the heat conduction will be negligible in the buffer zone.
Q.42
__________ paint has the minimum absorption co-efficient.
Q.43
The steam ejector is used to
Q.44
A body cools down from 75°C to 70°C in 10 minutes. It will cool down from 70° C to 65° C in __________ minutes.
Q.45
Nusselt number (for forced convection heat transfer) is a function of the __________ number.
Q.46
Prandtl number is the reciprocal of
Q.47
Crystallisation of solids from a homogeneous solution is a/an __________ process.
Q.48
For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
Q.49
The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K₀ + at. where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be
Q.50
Viscous & heat sensitive liquids are concentrated in __________ evaporators.
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