Reconsider Prob. 18€“91. Using an appropriate software, investigate the effect of the cooling time on the center temperature of the cylinder, the center temperature of the top surface of the cylinder, and the total heat transfer. Let the time vary from 5 min to 60 min. Plot the center temperature of the cylinder, the center temperature of the top surface, and the total heat transfer as a function of the time and discuss the results.

Data from 18-91

The soil temperature in the upper layers of the earth varies with the variations in the atmospheric conditions. Before a cold front moves in, the earth at a location is initially at a uniform temperature of 10°C. Then the area is subjected to a temperature of €“ 10°C and high winds that resulted in a convection heat transfer coefficient of 40 W/m²·K on the earth€™s surface for a period of 10 h. Taking the properties of the soil at that location to be k = 0.9 W/m · K and α = 1.6 × 10^€“5 m²/s, determine the soil temperature at distances 0, 10, 20, and 50 cm from the earth€™s surface at the end of this 10-h period.

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Ambient air Brass cylinder 20°C 15 cm -8 cm- 150°C