The analogy between heat and mass transfer has been discussed in class. If a thermal energy flux q, analogous to molar flux NA, is given by q=h(ThTc) The heat transfer coefficient h and the difference in temperatures across a boundary layer can be compared to NA=km(CbulkCR) The infinite boundary layer results in a Sherwood number of 2 for diffusion from a sphere, and the same process can be followed for thermal conduction to show that the Nusselt number is 2, Nu=kcondhD=2=Sh=DAkmD The thermal conductivity is kcond. Last weekend, the windchill at Mt. Washington in NH was 108F, or 78C. At R, the flux is q=kconddrdT. Windchill means that the thermal energy flux for a Nusselt number of 2 and a temperature difference between an object's surface temperature and 78C, is the same as for the true temperature difference across a finite boundary layer at a higher value of h. If the outside temperature was 28C, and the surface temperature is Th=20C, calculate the Nusselt number and the thickness of the boundary layer, /R