Q. Heat flux increases with temperature excess beyond the Leiden-frost point due to

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Q. The excess temperature range 50 degree Celsius < d t < 200 degree Celsius is indicative of the region of

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Q. With increase in excess temperature, the heat flux in boiling

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Q. In spite of large heat transfer coefficient in boiling liquids, fins are used advantageously when the entire surface is exposed to

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Q. The bubble diameter at the time of detachment from the surface can be worked out from the relation proposed by Fritz and is given by
(Where, β is the angle of contact)

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Q. Consider the following phenomena
(i) Boiling
(ii) Free convection in air
(iii) Forced convection in air
(iv) Conduction in air
Identify the correct sequence (heat transfer coefficient)

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Q. The nucleate pool boiling is influenced by the following factors
(i) Pressure
(ii) Liquid properties
(iii) Material
Identify the correct statements

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Q. The bubble diameter at the time of detachment from the surface can be worked out from the relation proposed by

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Q. For n-tubes in a vertical column of the tube bank pattern, identify the correct statement.
(Where, D is the diameter of a single tube in the bank)

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Q. Kirk bride criterion is given by

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

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

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

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

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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. 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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