hw4-010

# hw4-010 - D e p a r t m e n t o f C h e m ic a l E n g in e...

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Department of Chemical Engineering University of California, Santa Barbara ChE120B Heat Transfer Winter 2010 Homework 4 Out: Wednesday, February 3, 2010 In: Wednesday, February 10, 2010 Read: up to section 6 of class notes a) in last week’s assignment, take the fluid viscosity to be 10 cp in the problem regarding falling through a fluid, if you haven’t already assumed a value. 1. Estimate the thermal penetration depth in water, brick, and steel after 1 second and after 1 hour. Assume no convection in water. Material k(W/m-K) C p (J/kg-K) ρ (kg/m 3 Steel 61 460 7870 Water 0.6 4100 1000 Brick 0.45 840 1800 2. Estimate the contact temperature between a human foot and three beds of 400 C rocks, one of porous lava rocks of solid volume fraction 0.25, a second of porous lava rocks with a solid volume fraction of 0.75 and a third of solid lava rock. Assume that the rock part of the lava rocks has a thermal conductivity, k o = 3 W/m-K, a heat capacity of 800 J/kg-K and a density, ρ o of 2200 kg/m 3 , and the rest is air. The effective thermal conductivity of a porous rock is in which k o is the thermal conductivity of the continuous medium (rock), k 1 is the thermal

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## This note was uploaded on 03/22/2011 for the course CHE 120B taught by Professor Zasadinski during the Winter '10 term at UCSB.

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hw4-010 - D e p a r t m e n t o f C h e m ic a l E n g in e...

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