Computational approach to the experimental determination of diffusion coefficients for oxygen and nitrogen in hydraulic fluids using the pressure-decay method

Abstract

In the presented paper, the applicability of pressure-decay methods to determine the diffusivities of gases in hydraulic fluids is analysed.First, the method is described in detail and compared to other measurement methods.Secondly, the thermodynamics and the mass transfer process of the system are studied.This results in four different thermodynamic models of the gaseous phase in combination with two diffusion models.Thirdly, the influence of the models on the pressure-decay method is evaluated computationally by examining the diffusion process of air in water as all system parameters are available from literature.It is shown that ordinary pressure-decay methods are not applicable to gas mixtures like air and therefore a new method for calculating the diffusivities is suggested.

Authors 6

1. Andris Rambaks corresponding Aachen Chair of Technical Thermodynamics Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University

   Chair of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062 Aachen

   Institute for Fluid Power Drives and Systems, RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen

2. Filipp Kratschun Aachen Chair of Technical Thermodynamics Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University

   Chair of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062 Aachen

   Institute for Fluid Power Drives and Systems, RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen

3. Carsten Flake Aachen Chair of Technical Thermodynamics Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University

   Chair of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062 Aachen

   Institute for Fluid Power Drives and Systems, RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen

4. Maren Messirek Aachen Chair of Technical Thermodynamics Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University

   Chair of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062 Aachen

   Institute for Fluid Power Drives and Systems, RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen

5. Katharina Schmitz Aachen Chair of Technical Thermodynamics Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University

   Chair of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062 Aachen

   Institute for Fluid Power Drives and Systems, RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen

6. Hubertus Murrenhoff Aachen Chair of Technical Thermodynamics Institute for Fluid Power Drives and Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University

   Chair of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062 Aachen

   Institute for Fluid Power Drives and Systems, RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen