Surface bio-decontamination is an important aspect in many sterile pharmaceutical applications. Frequently, the method of choice is the exposure of the surfaces to hydrogen peroxide (H2O2) vapor [1, 2]. This operation is called decontamination by hydrogen peroxide (DHP). The work's objectives are the simulation of the decontamination processes in a closed volume, known as a DHP chamber. The flow in the DHP chamber may be affected by the condensation of water and H2O2 vapor. Depending on the parameters local condensation occurs or is avoided. Thus, a detailed study of the influence of operating conditions on the flow characteristics and condensation is the basis for the design of the DHP chamber.

In this work we have developed a detailed model to study the condensation of water and H2O2 vapor in the presence of air as a non-condensable species in a DHP chamber. The film model based on the Stefan-Maxwell equations for the multicomponent diffusion is adopted. In this work, the model is extended to compute the condensation in complex geometries like DHP chambers and is solved using exact solution of Taylor and Krishna [3]. Effects of buoyancy are also included. The flow fields in the DHP chamber are solved using Reynolds-averaged Navier-Stokes (RANS) equations. The species transport equations are used to compute the distribution of water, H2O2 vapor and air in the chamber. The binary condensation is accounted for by a new wall boundary condition. The activity coefficient of the liquid phase is calculated using the Redlich-Kister approach with temperature-dependent coefficients [4]. Thus, the dew point of the mixture and the condensation phenomenon in the DHP chamber can be predicted accurately. The model is validated by experimental data available in literature and shows good agreement.

References

[1] C. Hultman, A. Hill and G. McDonell, The physical chemistry of decontamination with gaseous hydrogen peroxide, Pharmaceutical Engineering (2004).

[2] M. Park, D. Walting, The relationship between saturated hydrogen peroxide, water vapour and temperature. Pharmaceutical Technology Europe (2004).

[3] R. Taylor, R. Krishna, Multicomponent mass transfer, John Wiley and Sons, New York (1993).

[4] S. Manatt, M. R. Manatt, On the analyses of mixture vapor pressure data: The hydrogen peroxide/water system and its excess thermodynamic functions, Chemistry-A European Journal (2006).