Q. What is the value of surface fluid constant for water-brass combination?

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Q. Spherical bubbles of 3 mm diameter are observed in the bulk fluid boiling of water at standard atmospheric pressure. Assuming pure water vapor in the bubble and vapor pressure equal to 101.325 k N/m², calculate the temperature of the vapor

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Q. An electric wire of 1.25 mm diameter and 250 mm long is laid horizontally and submerged in water at 7 bar. The wire has an applied voltage of 2.2 V and carries a current of 130 amperes. If the surface of the wire is maintained at 200 degree Celsius, make calculations for the heat flux

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Q. Which of the following parameters affect burnout heat flux in the nucleate boiling region

(i) Heat of evaporation
(ii) Temperature difference
(iii) Density of vapor
(iv) Density of liquid
(v) Surface tension at the vapor-liquid interface

Mark the correct answer from the codes indicated below

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Q. All the following statements are correct, except

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Q. Milk spills over when it is boiled in an open vessel. The boiling of milk at this instant is referred to as

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Q. For laminar film condensation on a vertical plate, the velocity distribution at a distance δ from the top edge is given by

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Q. For laminar film condensation on a vertical plate, the mass flow rate of the condensate per unit depth of the film at any position x is given by

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Q. For laminar film condensation on a vertical plate, the gravitational acceleration g is replaced by

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Q. Mark the wrong statement with respect to laminar flow condensation on a vertical plate

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Q. A plate condenser of dimensions l * b has been designed to be kept with side l in the vertical position. However due to oversight during erection and installation, it was fixed with side b vertical. How would this affect the heat transfer? Assume laminar conditions and same thermos-physical properties and take b = l/2

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Q. Determine the length of a 25 cm outer diameter tube if the condensate formed on the surface of the tube is to be same whether it is kept vertical or horizontal

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Q. The critical Reynolds number for transition from laminar to turbulent film condensation is

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Q. Which of the following is a wrong statement in the context of a convective heat transfer coefficient in laminar film condensation?

The heat transfer coefficient varies as

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Q. Which parameter is responsible for commencement of the turbulent flow?

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Q. The transition from laminar to turbulent flow occurs at a critical Reynolds number of

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Q. A condenser is to be designed to condense 225.0 kg of steam per hour at a pressure of 0.15 bar. A square array of 400 tubes, each of 6 mm in diameter, is available for the task. If the tube surface temperature is to be maintained at 26 degree Celsius, make calculations for the length of the tube

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Q. The outer surface of a vertical tube is 1.25 m long and outer diameter is 50 mm is exposed to saturated steam at atmospheric pressure. If the tube surface is maintained at 80 degree Celsius by the flow of cooling water through it, determine the rate of heat transfer to the coolant

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Q. What is the value of characteristics length in turbulent film condensation?
(Where, δ is length of the plate)

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Q. What is the value of Reynolds number in terms of mass flow rate?
(Where, δ is length of the plate and b is width of the plate)

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