Chapter 1 Basics of Heat Transfer1-84 A styrofoam ice chest is initially filled with 40 kg of ice at 0°C. The time it takes for the ice in the chest to melt completely is to be determined.Assumptions1Steady operating conditions exist.2The inner and outer surface temperatures of the ice chest remain constant at 0°C and 8°C, respectively, at all times. 3Thermal properties of the chest are constant. 4 Heat transfer from the base of the ice chest is negligible.PropertiesThe thermal conductivity of the styrofoam is given to be k = 0.033 W/m⋅°C. The heat of fusion of ice at 0°C is 333.7 kJ/kg. AnalysisDisregarding any heat loss through the bottom of the ice chest and using the average thicknesses, the total heat transfer area becomes A=−−+×−−==()()().403 4034403 303536505365cmm22The rate of heat transfer to the ice chest becomes &(.)..QkATL==°−°=Δ0 03305365003472W/m. C)m(8 0) CmW2The total amount of heat needed to melt the ice completely is Qmhif=(,4013 348kg)(333.7 kJ / kg)kJ
This is the end of the preview. Sign up
access the rest of the document.