Q. The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is

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Q. Sensible heat of hot industrial flue gases can not be recovered by a/an

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Q. The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h₀ = heat transfer coefficient at the outer surface)

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Q. Radiator of an automobile engine is a __________ type of heat exchanger.

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Q. In pipe flow, heat is transferred from hot wall to the liquid by

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Q. Which of the following has the minimum absorptivity ?

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Q. A black body when hot, emits heat radiation of __________ wavelengths.

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Q. A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when

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Q. Vibrations in the tubes of a shell and tube heat exchanger is induced due to the

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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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