Consider the freezing of a large stagnant lake during a winter that lasts for 60 days. The average air temperature for this period is -10°C with an average heat transfer coefficient of 20 W / m2 k...

Consider the freezing of a large stagnant lake during a winter that lasts for 60 days. The average air temperature for this period is -10°C with an average heat transfer coefficient of 20 W / m2 k over the lake surface. Neglect any sensible heat effect by assuming that the lake temperature stays at 0°C during the season. The latent heat for freezing of water is 335 kJ/kg, the density of water is 1000 kg/m3, the thermal conductivity of water is 0.61 W / mK, and the thermal conductivity of ice is 2.3 W /mK. 1) Determine the depth to which this lake will be frozen at the end of the winter. 2) In the springtime, the lake begins to thaw. Assume the entire frozen layer is at 0°C when thawing begins. The air temperature for spring is 10°C and it has the same surface heat transfer coefficient value. Calculate the time it would take for the frozen layer (that you just calculated) to thaw in the springtime. 3) Explain the reasons for the thawing time being longer or shorter.