The heat flux in the nucleate boiling regimes is proportional to (where, ΔT = excess temperature)
Heat transfer rate per unit area is called
Log mean temperature difference (LMTD) cannot be used, if
For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are
Grashoff number, which is defined as g . β(Ts - T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to __________ force.
The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is __________ compared to the same size pipes without fins.
Pick out the wrong statement.
In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is
Pick out the wrong statement.
While the total emissivity of a perfect black body is unity, the same for a real body is
Pick out the wrong statement.
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased.
Finned tube heat exchangers
Which of the following accessories is provided in the vapor line of an evaporator for removing the entrained liquid ?
Rate of heat transfer by vaporisation from pools of water is affected by the
Dropwise condensation occurs on __________ surfaces.
A hot liquid is kept in a big room. The logorithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an
Double pipe heat exchangers are used
Trap is used to remove __________ from steam pipe lines.
In a 1-1 cocurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is
During crystallisation, formation of crystal can occur in __________ solution only.
Pick out the wrong statement.
Natural convection is characterised by
When warm and cold liquids are mixed, the heat transfer is mainly by
If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law.
For what value of Prandtl number, the Col-burn analogy is valid ?
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid.
Electromagnetic radiations propagate in vacuum with a velocity of __________ metre/second.
Multiple effect evaporators are commonly used in the manufacture of
P. Paper Q. Superphosphate
R. Sugar S. Fats
Radiation heat transfer rates does not depend upon the
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 areand 1200°K, then the temperature drop (in °K) across the layer of material 'A' is
Viscous & heat sensitive liquids are concentrated in __________ evaporators.
A body is called grey if the monochromatic emissivity of the body is
In an extended surface heat exchanger, fluid having lower co-efficient
An evaporator while concentrating an aqueous solution fromtosolids evaporateskg of water. The amount of solids handled by the system in kg is
Nusselt number for full developed, laminar, constant property flow in a pipe at uniform heat flux is
A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?
Vent pipes are provided in a condenser to
In regenerative air preheater (as practised in heating of coke ovens), the heat is transferred
__________ equation relates the thermal conductivity of a solid to its temperature.
In a forward feed multiple effect, the pressure build up will be
A body cools down from 75°C to 70°C inminutes. It will cool down fromC toC in __________ minutes.
In forced convection, the Nusselt number is a function of
Heat flux is the time rate of heat transfer per unit
Which of the following has the highest thermal conductivity ?
Tube pitch is the __________ of tube diameters and the clearances.
1 BTU/hr.ft.°F is equal to __________ kcal/hr. m.°C.
Radiation heat transfer rates does not depend upon the
In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is
An insulator should have