Q. A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions ? Assume that the conductive heat transfer co-efficient is infinitely large.

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Q. Nucleate boiling is promoted

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Q. In forced circulation, the heating element is injected

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Q. If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is

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Q. The equation, Nst = f/2, is the __________ analogy.

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Q. 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.

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Q. Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the

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Q. Evaporator tubes are generally

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Q. In a boiling curve, the peak heat flux is called the __________ point.

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Q. Pick out the wrong statement.

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Q. The type of liquor circulation system to be employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid.

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Q. Thermal diffusivity is the most important in heat transfer by

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Q. (NGr x NPr) is called the __________ number.

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Q. A dephlegmator is a

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Q. Rate of crystallisation does not depend upon the

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Q. Stefen's block body radiation law can also be derived from __________ law.

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Q. Multipass heat exchangers are used

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Q. A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case,

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Q. Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m² .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the

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Q. Viscosity of gases __________ with increase in temperature.

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