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Unformatted text preview: of the concrete at r = 0.0 (center) and 0.3 m (surface) after 24 hours? The properties of the concrete are as follows: α = 7 × 10 7 − m 2 /s and k = 1 W/mºC. (ANSWER: 23.2ºC, 21.7ºC) NOTE: For a cylinder with a convection boundary, the oneterm approximation is given as follows: ) ( ) exp( 1 2 1 1 o o o i r r J F C T T T T ζ − = − − ∞ ∞ The values for Bessel function are given in Table B.4. 3. On a hot summer day a concrete driveway may reach a temperature of 50ºC. Suppose that a stream of water is directed on the driveway so that the surface temperature is suddenly lowered to 20ºC. How long will it take to cool the concrete to 30ºC at a depth of 5 cm from the surface? (ANSWER: 9620 s)...
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This note was uploaded on 07/30/2011 for the course ME 324 taught by Professor Nezihtopaloglu during the Spring '11 term at Yeditepe Üniversitesi.
 Spring '11
 nezihtopaloglu
 Heat Transfer

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