Q. A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time

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Q. LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.

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Q. Thermal diffusivity of a material

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Q. h.D/K is called the __________ number.

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Q. Prandtl number is the ratio of

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Q. Conductance is given by(where, x = thickness, A = heat flow area, K = thermal conductivity.)

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Q. Heat flux, as defined in heat flow is analogous to __________ in electricity flow.

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Q. The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)

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Q. Which is the most suitable for cold viscous feed?

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Q. Dropwise condensation is promoted on a/an __________ surface.

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Q. At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the

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Q. In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.

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Q. A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?

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Q. The separation of liquid droplets from the vapor is done by a/an __________ , in the evaporators.

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Q. If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will

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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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