Question

Question 5

a) Derive equations to describe the heat flux in the steel and the insulating layer. 10 b) What is the temperature at the outside surface of the steel? c) What is the heat flux from the steel to the insulator? 17] 13] 5. a) On a plant floor, ethanol has spilt and forms a layer with 1 mm thickness. If we assume that the rate of evaporation of the ethanol is controlled by the rate of diffusion of ethanol through a stagnant film ofair with 5 mm thickness, calculate the time needed for the evaporation of al the ethanol. Derive any equations you use The temperature is 20 °C and the pressure is 760 mmHg 115] b) State all the assumptions you use in the above problem. 151 Ethanol properties: , Density 795 kg m Molecular weight 46 kg kmol Vapour pressure (at 20 °C) 45 mmHg Diffusion coefficient of ethanol in ai 1.337 x 10 m s END OF PAPER CENG102P

Answer 1

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