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The overall resistance for heat transfer through a series of flat resistance, is the _____________ of the resistances?
Related MCQs
Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8. Pr n, is not valid, if the value of __________?
An ejector is used to__________?
In a laboratory test run, the rate of drying was found to be 0.5 x 10-3 kg/m2.s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry basis. A tray dryer is used to dry 100 kg (dry basis) of the same material under identical conditions. The surface area of the material is 0.04 m2/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is__________?
Peclet number (Pe) is given by__________?
In Fourier’s law, the proportionality constant is called the__________?
When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is __________?
The units of resistance to heat transfer is __________?
For hot feed, forward feeding as compared to backward feeding results in __________ economy?
In sub-cooled boiling ?
Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place__________?
The thickness of condensate layer in filmwise condensation depends on the__________?
The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation?
Steam economy in case of a triple effect evaporator will be __________?
In a forward feed multiple effect evaporator unit__________?
Dropwise condensation is promoted on a/an __________ surface?
Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger ?
It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is__________?
Fqra cold viscous feed, backward feed gives __________ than forward feed?
The Graetz number is concerned with the__________
The unit of conductance in SI unit is__________?
Which of the following has the lowest Prandtl number ?
In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid __________?
The capacity of double-effect evaporator is less than half of the capacity of two single effects, each of which is operating over same terminal temperature difference, when the__________ ?
Nusselt number is a function of Prandtl number and __________ number of fluid in natural convection heat transfer?
Radiation energy is emitted by all the substances, which are above__________?
The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is__________?
Loss of heat from untagged steam pipe to the ambient air is by __________?
In Biot number, the characteristic length used is the ratio of the __________ of the solid?
Boiling point elevation for a strong and concentrated solution is found by Duhring’s rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water?
Stefan-Boltzmann law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K) ?
The equation, (NSt × N2/3 Pr) = f/2, is the __________ analogy ?
The range of electromagnetic spectrum important in heat transfer by radiation is __________ microns?
Boiling point of a solution according to Duhring’s rule is a linear function of the __________ of water?
Prandtl number for most of dry gases is about__________?
Extremely large or small volumes of fluids are generally best routed through the shell side of a shell and tube heat exchanger, because of the__________?
The purpose of providing expansion bellows in the shell of tubular exchanger is to __________?
Multipass heat exchangers are used__________?
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__________?
Finned tube heat exchangers__________?
Fruit juice (a heat sensitive material) can be concentrated in a __________ evaporator?
The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter D. as __________?
For heat flow through very thick walled cylinder, use __________mean radius?
In a shell and tube heat exchanger, the shell side fluid velocity can‟t be changed by changing the__________?
LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow?
The maximum heat transfer co-efficient from steam heating will be attained when the steam is__________?
The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is__________?
Which of the following has maximum thermal conductivity ?
Thermal diffusivity of a material __________?
Nusselt number is the ratio of the temperature gradient at the wall to__________?
What is the unit of thermal conductivity ?
Tubes are held between top and bottom tube sheets in Calandria type evaporator by keeping__________?
The overall resistance for heat transfer through a series of flat resistance, is the _____________ of the resistances?
A. Average
B. Geometric mean
C. Product
D. Sum
Correct Answer:
Sum
✔
Last Updated:
March 03, 2019