Q. Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is

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Q. For __________ Prandtl number values, the heat conduction will be negligible in the buffer zone.

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Q. The radiation heat flux from a heating element at a temperature of 800°C, in a furnace maintained at 300°C is 8 kW/m². The flux, when the element temperature is increased to 1000°C for the same furnace temperature is

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Q. Heat exchangers operating, when the asymptotic range is reached,

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Q. In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)

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Q. In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.

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Q. Multiple effect evaporators are used to

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Q. Small scale evaporation is done in a

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Q. Heat exchanger tubes are never made of

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Q. At constant temperature, the thermal conductivities of gases __________ with rise in pressure.

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Q. A __________ evaporator employs an annular downtake.

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Q. Radiation heat losses from satisfactorily insulated high pressure boilar may be about __________ percent.

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Q. In natural convection heat transfer, the correlating parameter is the

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Q. Boiling of milk in an open vessel is an example of __________ boiling.

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Q. Pick out the wrong statement.

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Q. The value of Stefan-Boltazman constant in SI unit is

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Q. The unit of heat transfer co-efficient is

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Q. For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus-Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of

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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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