Sturnfoam Insulation. R-value =9.0 Vacuum Insulation (Yeti), R-value =22 Thermal Resistance or R-value. The R-value is a combination of thermal conductivity and thickness. R= thickness/thermal conductivity, Metric units are m2K/W The heat flow, through a layer of material, by conduction is given by: tQ=AR(THTC) Where ' Q ' is the heat, ' t ' is time, ' A ' is area and TH and TC are the temperatures in Kelvin on either side of the layer. As an example, consider the window of a house with an R-value of 1.02 . If the window is 0.75m wide 1.5m tall calculate the heat flow in Watts (Q/t) for the temperatures shown. TH=35CTC=25CtQ=(0.751.5)1.02(306296)=11Watts Note how the temperatures were converted to Kelvin. If needed we could convert 11watts=11sJ1J0.239Cal=2.6Cal/s Finally calculate the amount of ice meited using: Q=mLr Where the latent heat of fusion for ice is: L=79.5cal/g Convection Convection is heat transfer by the movement of a fluid. As the fluid mass moves it carries heat energy with it. Thermal Resistance or R-value. The R-value is a combination of thermal conductivity and thickness. R= thickness/thermal conductivity. Metric units are m2K/W The heat flow, through a layer of material, by conduction is given by: tQ=AR(THTC) Where ' Q ' is the heat, ' t ' is time, ' A ' is area and TH and TC are the temperatures in Kelvin on either side of the layer. As an example, consider the window of a house with an R-value of 1.02 . If the window is 0.75m wide 1.5m tall calculate the heat flow in Watts (Q/t) for the temperatures shown. TH=35CTC=25CtQ=(0.751.5)1.02(306296)=11Watts Note how the temperatures were converted to Kelvin. If needed we could convert 11watts=115J1J0.239Cal=2.6Cal/s Stvrofoam Insulation. R-value =9.0 Vacium Ineulatinn (Vati) D-ualue - o? Finally calculate the amount of ice melted using: Q=mLf Where the latent heat of fusion for ice is: L=79.5cal/g Styrofoam Insulation. R-value =9.0 Vacuum Insulatinn (Yoti) D-ualua - 23 Finally calculate the amount of ice melted using: Q=mLf