Cross-Contamination in a Laboratory Cleanroom
Duncan Phillips, Vincent
Tang, and Ray Sinclair Rowan Williams
Davies & Irwin, Inc.
The use of computational fluid dynamic (CFD) modeling techniques
has become more common for the design of specialized laboratories.
CFD is a computer modeling technique in which the standard equations
describing fluid flow (conservation of mass, momentum, energy, contaminants,
etc.) are solved at many locations within a space using a computer.
In addition, a mathematical representation of the effects of turbulence
within the flow are typically included within the simulation. There
are a number of methods to represent turbulence in CFD simulations.
Traditional CFD modeling (RANS based) approximates the effects of
turbulence by "smearing" the influence across space. LES
is an alternate approach gaining acceptance whereby the large turbulent
eddies are modeled more explicitly. This permits one to assess turbulent
mixing in a room more faithfully. This paper briefly reviews CFD
modeling theory and demonstrates the different levels of solution
that one achieves with the two modeling techniques.
The main focus of the presentation is the design of a cleanroom
in which the production of blood products occurs. The individual
workstations at which the processing occurred were designed to have
cleanroom flows within them and were connected to one another along
a central corridor. While the ventilation flows within a cleanroom
are designed to provide protection to the product or process contained
within the room, the occupants within the space, or both. In some
cases, it is necessary, or at least desirable, to provide cleanroom-type
conditions in adjacent spaces without having a full partition between
the spaces. The comparison of modeling tools presented here provides
an opportunity to learn how the interaction of flows from within
the individual cleanrooms can contribute to cross-contamination
of product and what steps can be implemented to mitigate the problem.
The audience members will also have an opportunity to assess which
tools are able to predict cross-contamination.
Labs21 Connection:
CFD modeling is an effective way to assess HVAC designs in advance
of constructing the laboratory. RANS has been a traditional approach
and is used by many design teams, LES modeling provides additional
advantages in that it provides more fidelity in the simulation results
and provides better estimates of mixing within a space. The contents
of this presentation highlight how this form of modeling can:
- Minimize overall environmental impacts - the impact
of design changes which minimize energy use can be assessed in
advance of construction.
- Protect occupant safety - by reducing the likelihood
or severity of cross-contamination within an open environment.
- Establish goals, track performance, and share results for
continuous improvement - minimizing the risk of cross-contamination
in product production is an important aspect of quality control.
Biographies:
Duncan A. Phillips, Ph.D., P.Eng. has a Ph.D.
in Mechanical Engineering from the University of Waterloo in Ontario.
During his graduate work he investigated the measurement and quantification
of room air and contaminant mixing within occupied spaces. This
work involved both the development of instrumentation for, and measurements
of, contaminant transport. Duncan is a registered Professional Engineer
in the Province of Ontario.
Duncan joined Rowan Williams Davies & Irwin Consulting Engineers
in 2000. He is a Senior Specialist for CFD and Ventilation. He is
an Associate of the firm. His role at RWDI as the Senior member
of the CFD and ventilation team is to technically oversee the execution
of client based projects. In addition he is responsible as coordinating
the technical advancement of RWDI's ventilation and modeling services.
Vincent Tang,
MA.Sc. joined RWDI in 2001 after completing his MA.Sc. in Mechanical
Engineering at the University of Toronto. He is responsible for
executing client based projects including flows within laboratories,
atria, and pollution control equipment. As a member of RWDI's R&D
department, he is actively involved in the development of RWDI's
ventilation and CFD capabilities.
Ray Sinclair, Ph.D.
is a Principal of RWDI. In this position, Dr. Sinclair provides
technical direction and leadership on a wide range of projects involving
building and tunnel ventilation, fire safety, air pollution, sustainable
design, wind engineering and industrial processes. He joined RWDI
in 1991 after completing a Ph.D. in Mechanical Engineering. He is
a leader of the CFD modeling group and the Marketing Division Leader
for RWDI's Environmental Modeling Division.
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