Heat Transfer Vacuum is generally maintained in the vapour space of an evaporator mainly to Facilitate forward feeding in multiple effect evaporation Get economical temperature difference by using moderate pressure steam Achieve very high concentration of the final product Concentrate heat sensitive materials Facilitate forward feeding in multiple effect evaporation Get economical temperature difference by using moderate pressure steam Achieve very high concentration of the final product Concentrate heat sensitive materials ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer Graetz number is given by kμ/mCp mCp/kμ mCp/kL kL/mCp kμ/mCp mCp/kμ mCp/kL kL/mCp ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid Excessive corrosion Decrease in heat exchanger efficiency Uneconomic LMTD Its evaporation loss Excessive corrosion Decrease in heat exchanger efficiency Uneconomic LMTD Its evaporation loss ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer 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 CPA > CPB CPA < CPB KA>2 kB KA < 0.5kB CPA > CPB CPA < CPB KA>2 kB KA < 0.5kB ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is In the central core of the fluid Uniformly distributed throughout the fluid None of these Mainly confined to a thin film of fluid near the surface In the central core of the fluid Uniformly distributed throughout the fluid None of these Mainly confined to a thin film of fluid near the surface ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer 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. 10 minutes 5 minutes 40 minutes 20 minutes 10 minutes 5 minutes 40 minutes 20 minutes ANSWER DOWNLOAD EXAMIANS APP
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