Reconsider Prob. 18–61. Using an appropriate software, investigate the effect of the initial temperature of the apples on the final center and surface temperatures and the amount of heat transfer. Let the initial temperature vary from 2°C to 30°C. Plot the center temperature, the surface temperature, and the amount of heat transfer as a function of the initial temperature and discuss the results.

Reconsider Prob.

A person puts a few apples into the freezer at - 15°C to cool them quickly for guests who are about to arrive. Initially, the apples are at a uniform temperature of 20°C, and the heat transfer coefficient on the surfaces is 8 W/m²·K. Treating the apples as 9-cm-diameter spheres and taking their properties to be ρ = 840 kg/m³, c_p = 3.81 kJ/kg·K, k = 0.418 W/m·K, and α = 1.3 3 10^-7 m²/s, determine the center and surface temperatures of the apples in 1 h. Also, determine the amount of heat transfer from each apple. Solve this problem using analytical one-term approximation method (not the Heisler charts).