The determination of average mass transfer coefficients for flow over a flat plate using the naphthalene sublimation technique

An expression for mass transfer coefficients from a flat plate with a step change in concentration in parallel turbulent flow was obtained. The Von Karman-Pohlhausen boundary layer integral method was applied.; The 1/n power profile was assumed for both the velocity and concentration profiles. In this study however, the Reynolds analogy was circumvented by keeping the Schmidt number raised to a power {dollar}alpha{dollar} as an integral part of the solution. Expressions for the values of {dollar}alpha{dollar} and the coefficient for the power profile, C, in terms of n were proposed. In addition, an empirical relationship relating n to the Reynolds number was obtained based on turbulent boundary layer flows. Thus mass, transfer coefficients could be obtained directly from the Reynolds number.; An aluminum flat plate with a recess for casting naphthalene was tested in an open loop wind tunnel. The concentration discontinuity was fixed at 5 cm (2 in.) downstream of the leading edge and four naphthalene plate lengths were cast ranging from 21 cm (8.25 in.) up to 65 cm (25.5 in.). The experimental Sherwood numbers agreed with the 1/n power profile solution for Reynolds numbers ranging from 500 000 to 2 000 000. The scatter in the data was due to the nature of the testing facility. Comparisons beyond this range of Reynolds numbers were not feasible due to limitations of the testing facility. A Schmidt number of 2.5 was used and the naphthalene vapor pressure was determined according to a method based on ideal gas theory and the Clapeyron equation (Sogin, 1958).; The proposed 1/n solution was also compared to heat transfer data (Love et al., 1989). Experimental overall values were calculated directly from the data and compared to the proposed equation. Better agreement with the experimental data was obtained using the proposed equation over the 1/7 power law. Also, the heat-mass transfer analogy was used to compare the mass transfer results of this study to the heat transfer data of Love et al.