The naphthalene sublimation technique involves use of a mass transfer experiment coupled with an analysis based on the heat and mass transfer analogy to obtain local or average convection heat transfer coefficients for complex surface geometries. A coating of naphthalene, which is a volatile solid at room temperature, is applied to the surface and is then subjected to airflow in a wind tunnel. Alternatively solid objects may be cast from liquid naphthalene. Over a designated time interval, ∆t, there is a discernible loss of naphthalene due to sublimation, and by measuring the surface recession at locations of interest or the mass loss of the sample local or average mass transfer coefficients may be determined. Consider a rectangular rod of naphthalene exposed to air in cross flow at V = 10 m/s, T∞ = 300 K, as in Problem 6.10 except now c = 10 mm and d = 30 mm. Determine the change in mass of the L = 500 mm long rod over a time period of ∆t = 30 min. Naphthalene has a molecular weight of MA = 128.16 kg/kmol, and its solid-vapor saturation pressure at 27°C and I atm is PA,sat = 1.33 X 10-4 bar.