Enhanced Respiratory Protection Technology

Powered Air-Purifying Respitators (PAPR) are used in hazardous environments to provide a clean air supply to the wearer by forcing air through a filter by means of a blower. Older models of PAPRs provided continuous flow, but this is wasteful with respect to filter and battery life. Some modern designs are breath-responsive, providing air only in response to a detected demand from the user.
It is desired to produce an optimised design of breath-responsive PAPR for use with chemical, biological, radiological and nuclear (CBRN) protection. Optimisation consist of a number of factors, including improving the pressure drop, filter life and ergonomics of the filter.

In this project, computational fluid dynamics (CFD) is used as the primary tool to gain a better understanding of how the flow is distributed throughout the filter. Some simulations are comparatively simple two dimensional models, which allow the effects of key aspects of the filter geometry to be isolated and better understood. The information learned from this is then used to build more complicated three dimensional simulations to give greater insight into the flow field. Additionally, detailed adsorption modelling is considered, which takes into account the chemistry of the contaminant. It is desired to use the more detailed models to relate key parameters to the simpler simulations, in order to develop these quick, simple simulations as a design tool. All of these simulations must consider the complex nature of the filter material and realistically model expected breathing patterns.

This work is carried out in close collaboration with DSTL, who provide support in the form of experimental data.