During a cold autumn in a frigid land (a.k.a. central Illinois), the air temperature occasionally drops so low that ice forms on the surface of ponds and lakes. If the bulk temperature of the lake is held constant at 37°F, find the air temperature at which ice will first form on the surface of the lake assuming steady state heat transfer.
1.Thermal conductivity of ice: k = 1.3 Btu/hr ft°F
2.Heat transfer coefficients: Ice to air (forced convection,wind) h= 7.2 Btu/hr ft2°F
3. Ice to water (natural convection) h = 1.9 Btu/hr ft2