Q. The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m⁻¹.°C⁻¹ respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m⁻².°C⁻¹. The rate of heat loss from the outer surface in W.m⁻² is

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Q. Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a droplet or a spherical particle to a surrounding stagnant film is

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Q. Pick out the wrong statement.

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Q. Evaporation by thermocompression results in the

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Q. Forced circulation evaporators are normally used for concentrating liquids having

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Q. Steam economy in case of a triple effect evaporator will be

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Q. In a heat exchanger with steam outside the tubes, a liquid gets heated to 45°C, when its flow velocity in the tubes is 2 m/s. If the flow velocity is reduced to 1 m/s, other things remaining the same, the temperature of the exit liquid will be

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Q. Multiple effect evaporation accounts for

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Q. In case of a supercooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is

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Q. Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ metres/second.

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Q. In Biot number, the characteristic length used is the ratio of the __________ of the solid.

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Q. Which of the following is the most widely used heat insulating material for pipelines carrying steam ?

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Q. Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re^0.8 . Prⁿ, is not valid, if the value of

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Q. Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling ?

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Q. In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid

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Q. Reason for operating an evaporator in multiple effect is to secure

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Q. In a cooling tower, water becomes cool by

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Q. In Fourier's law, the proportionality constant is called the

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Q. The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.

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Q. Pick out the wrong statement.

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