Reconsider Prob. 7–76. Using EES (or other) software, plot the temperature of the tank as a function of the cooling time as the time varies from 30 min to 5 h, and discuss the results.

Data from problem 76

Consider a 50-cm-diameter and 95-cm-long hot water  tank. The tank is placed on the roof of a house. The water  inside the tank is heated to 80°C by a flat-plate solar collector  during the day. The tank is then exposed to windy air at 18°C with an average velocity of 40 km/h during the night. Estimate the temperature of the tank after a 45-min period. Assume the tank surface to be at the same temperature as the water inside, and the heat transfer coefficient on the top and bottom surfaces to be the same as that on the side surface. Evaluate the air properties at 50°C.