Q. 1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m² and the overall heat transfer co-efficient to the liquid is 1500 W/m².°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be

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Q. Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the

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Q. Double pipe heat exchangers are preferably useful, when

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Q. Removal of __________ heat is involved in the condensation of a vapor under saturated conditions.

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Q. In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.

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Q. When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is

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Q. The purpose of providing bleed points in the evaporator is to

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Q. Water always boils when its

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Q. A multiple effect evaporator as compared to a single effect evaporator of the same capacity has

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Q. When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids ?

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Q. The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re^0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as

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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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