Q. Solid angle subtended by the finite surface at the radiating element is

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Q. Pick out the wrong statement.

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Q. In forced convection, the heat transfer depends on

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Q. With increase in temperature, the thermal conductivity of most liquids

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Q. What is the unit of thermal conductivity ?

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Q. The thermal radiation emitted by a body is proportional to Tⁿ, where T is its absolute temperature. The value of 'n' is exactly 4 for

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Q. It is not preferable to use superheated steam in evaporators, because of its very

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Q. 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

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Q. LMTD for counterflow and prallel flow heat exchanger will be the same, when the

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Q. For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it

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Q. Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because

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Q. Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow. )

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Q. Temperature profile in steady state heat transfer is

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Q. Which area is used in case of heat flow by conduction through a cylinder ?

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Q. Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer can not take place

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Q. The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is

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Q. Finned tube heat exchangers

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Q. The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation.

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Q. A perfect black body is a perfect __________ of radiation.

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Q. In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.

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