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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Q. 'Duhring's plot' is of use in

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Q. Which has the lowest Prandtl number ?

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Q. Pick out the wrong statement.

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Q. Prandtl number for most of dry gases is about

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Q. Prandtl number is the reciprocal of

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Q. The purpose of providing expansion bellows in the shell of tubular exchanger is to

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Q. Grashhoff number is given by

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Q. The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m².K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m².K. The overall heat transfer co-efficient at this time is

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Q. 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

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