HW8 solution

# HW8 solution - ME/CHE 109 Homework#8 Name Problem I Natural...

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ME/CHE 109 Homework #8 Name______________________ Problem I. Natural Convection in cylindrical enclosure A simple solar collector is built by placing a 5-cm-diameter clear plastic tube around a garden hose whose outer diameter is 1.4 cm. The hose is painted black to maximize solar absorption, and some plastic rings are used to keep the spacing between thehose and the clear plastic cover constant. During a clear day, the temperature of the hose is measured to be 65 0 C, while the ambient air temperature is 26 0 C. a. Determine the rate of heat loss from the water in the hose per meter of its length by natural convection and the surface temperature of plastic tube. T-hose(degC)= 65 T-hose(degC)= 65 T-inf (degC) = 26 T-inf (degC) = 26 (guess) T-surf (C) = 37.535 (guess) T-surf (C) = 37.535 T-film (deg C) = 51.2675 T-film (deg C) = 31.7675 T-film (K) = 324.268 T-film (K) = 304.768 Di= 0.014 D0= 0.05 del (m)= 0.05 L= 1 L= 1 k - air (@Tfilm)W/mC= 0.02745 k - air (@Tfilm)W/mC= 0.02601 nu (m2/s)= 1.810E- 05 nu (m2/s)= 1.625E-05 Pr= 0.7225 Pr= 0.7276 Fcyl(eqn 9-58)= 0.183 keff(eqn 9-57)= 0.058 A-HT(eqn7-21)m2= 0.08885 A-HT(m2)= 0.15708 Ra= 1.07E+04 Ra= 1.28E+05 Nu(eqn 9-25)= 8.32E+00 h= 4.33E+00 Qdot(eqn 9.56)= 7.84193 Qdot-convection 7.84382 Problem II. Natural convection in a rectangular enclosure

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## This note was uploaded on 11/08/2010 for the course ME 109 taught by Professor Staff during the Spring '08 term at San Jose State.

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HW8 solution - ME/CHE 109 Homework#8 Name Problem I Natural...

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