Digital holography interferometry for measuring the mass diffusion coefficients of N₂ in RP-3 and RP-5 jet fuels

Abstract

Purpose The purpose of this study is to measure the mass diffusion coefficient of nitrogen in jet fuel using digital holography interferometry for cost-effective designing and modeling of the aircraft tank inerting system. Design/methodology/approach The mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels were measured by digital holography interferometry at temperatures ranging from 278.15 to 343.15 K. The Arrhenius equation is used to adequately describe the relationship between mass diffusion coefficients and temperature. The viscosities of RP-3 and RP-5 jet fuels were also measured to examine the accuracy of the Stokes–Einstein model in calculating mass diffusion coefficients. Findings As temperature increases from 278.15 to 343.15 K, the mass diffusion coefficients increase 4.23-fold for N2 in RP-3 jet fuel and 5.13-fold for N2 in RP-5 jet fuel. The value of Dµ/T is not constant as the Stokes–Einstein equation expressed, but is a weak linear function of temperature. Practical implications A more accurate diffusion model is proposed by fitting the measured Dµ/T with the temperature and calculating the mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels within 10 per cent relative deviation. Originality/value A measurement system for mass diffusion coefficients of N2 in RP-3 and RP-5 jet fuels was constructed based on the digital holography interferometry. The mass diffusion coefficient can be expressed by a uniform polynomial function of temperature and viscosity.

Experimental determination of gas diffusivity in liquids—A review

“…[ 57 ] In a similar manner, the phase difference of a laser beam transmitted through a gas‐liquid mixture between two different times is related to gas concentration, and utilized for diffusivity determination in digital holography interferometry method. [ 58 ]…”

Interferometric Probing of Physical and Chemical Properties of Solutions: Noncontact Investigation of Liquids

“…This asymmetry is not caused by diffusion but by mixing during liquid filling. Feng et al (118) investigated the diffusion of N 2 in jet fuels. They used a similar method to calculate the diffusion constant but determined only the position of the maximum of the phase-difference profile in the liquid phase and assumed symmetry.…”