A review of mass transfer measurements using naphthalene sublimation

The naphthalene sublimation method can be used to study mass and heat transfer with confidence for a variety of applications, but with certain restrictions. This method is particularly useful in complex flows and geometries and for flows with large gradients in wall transport rate. Mass transfer boundary conditions analogous to isothermal and adiabatic walls in convective heat transfer can be easily imposed. Furthermore, the nature of mass transfer allows one to impose these boundary conditions such that errors analogous to conductive losses in a wall are not present. The test specimen can be easily prepared by several methods, including dipping, machining spraying, and casting. The local transfer coefficients can be determined with high accuracy and in detail by automated measurement systems that eliminate most human errors and reduce extraneous sublimation losses during the measurement process. The heat transfer coefficient, which is often desired, can be readily determined from the measured mass transfer results with good confidence via a heat/mass transfer analogy. However this method cannot generally be used in certain flow situations such as high-velocity flows because of recovery temperature effects and natural convection due to the thermal buoyancy effects of sublimation latent heat.