CFD-driven Optimization of Room Airflow Patterns and Their Effect on Hood Containment for Flexible Labs of the Future

Alexy Kolesnikov and Ray Ryan, Flow Sciences, Inc.
Douglas B. Walters, KCP, Inc.

Objectives:

The function of the standard lab has changed. The past that was rich in synthesis-based R&D has moved into the new millennium and been replaced with advanced analysis/discovery processes utilizing highly sophisticated computer technology and high throughput robotic processes requiring safe, adaptable and energy efficient containment devices functioning in a fast changing open lab environment. Two interlinked aspects of containment performance must be considered to adequately address these demands. First, the conventional fume hood, which controls about 75% of the lab containment technology to date, will have to undergo monumental changes in design aimed at improving containment and energy efficiency at lower face velocities (low airflow design). Second, the airflow patterns in the lab itself create cross-drafts near the sash opening and their effect on hood containment performance must be investigated for specific lab configurations in order to provide a comprehensive containment analysis of the entire lab/hood airflow system.

Findings:

Following the results presented at the October 2002 Labs 21st century conference, that documented performance of a newly designed containment system combining a rapid recovery variable air volume control mechanism with computer-optimized laminar airflow pattern inside the work area, current paper extends the application of this technology to a new low-airflow hood design. The new hood design is shown to provide stable containment in the face velocity range of 40-60 ft/min, resulting in significant operational energy cost reduction. Further, the CFD-driven airflow modeling is used to investigate hood containment performance within a sample laboratory room configuration. In that, the effects of diffuser/hood position, diffuser/hood separation, hood separation, hood position and equipment arrangement within the lab on the airflow distribution near the sash opening are parametrically analyzed for a variety of geometric configurations. Airflow patterns within the laboratory are shown to directly influence hood containment performance, with CFD-driven parametric studies enabling to make specific lab design and hood placement recommendations prior to any construction installation or mock up.

Labs21 Connection:

Two interlinked aspects affect performance of containment devices within the lab environment, namely airflow distribution inside the device itself and airflow patterns inside the laboratory. In that, inadequate hood design causes turbulent, irregular airflow inside the hood work area, while improper ventilation design and/or hood placement within the lab causes significant cross-drafts near the sash opening of the hood, both leading to loss of containment and breach of occupant safety. The problem is compounded by the modern open laboratory flexibility demands. Experimental tests are costly, provide limited data and often identify the problem only after the laboratory has been designed and build and hoods installed. Computational fluid dynamics, i.e. computer modeling of airflows inside the hood and the lab room environment, permits to parametrically study airflow distribution for a variety of geometric configurations, optimizing diffuser, equipment and hood layouts for a particular lab configuration, thus allowing for predicting and optimizing containment performance of the entire laboratory/hood airflow system, making changes to the entire system layout knowing the exact effect of such variations, using only enough air changes per hour to satisfy the requirements, conserving energy via hood face velocity optimization, all prior to construction or mock up. The paper presents results and recommend-ations for a sample lab room configuration, documents and validates performance of a newly designed low airflow VAV hood system, thus addressing the following Labs 21 approaches: use lifecycle cost decision making, by emphasizing safety and long-term energy savings; employ a broad range of sustainable energy strategies, by optimizing supply/exhaust and hood placement strategies and performance and documenting design of a low airflow VAV hood; promote energy efficiency operation and training efforts, by introducing an low airflow VAV containment system as well as computer modeling airflow visualization data absolutely unavailable otherwise.

Biographies:

Dr. Alexy Kolesnikov joined Flow Sciences in May 2000 as a Sr. Design engineer. Dr. Kolesnikov received his PhD in Mechanical Engineering with a focus in fluid dynamics and heat transfer from the University of Tennessee, Knoxville in May 2000 and his BS and MS in mechanics and mathematics from Moscow State University in May 1991. He specializes in advanced computer simulation of complex multi-dimensional fluid/gas flows in industrial processes. His research has been published in peer reviewed scientific journals and presented at numerous CFD-related conferences.

Raymond F. Ryan, is the Founder, President and CEO of Flow Sciences, Inc. Flow Sciences engineers, designs, manufactures and markets solutions for the modern technology company through the engineering of ventilation containment systems that protect workers and the environment from exposure to toxic and "potent" compounds. The products are used to protect workers from exposure during the handling of hazardous powders and vapors. These operations take place in laboratories, pilot plants and manufacturing locations. In 1999 Flow Sciences received an award for being one of the fifty fastest growing high technology companies in North Carolina. Prior to founding Flow Sciences, Mr. Ryan founded two other companies that serviced the pharmaceutical safety industry. Laboratory Safety Services, which Mr. Ryan sold in 1986, provided certification testing for biological safety hoods, chemical fume hoods and laboratory airflow control systems. The customer base was the major medical schools, pharmaceutical and chemical companies in metro NY, NJ and Philadelphia. Mr. Ryan also founded and sold a manufacturers rep company that specialized in capital equipment for the biomedical research and biotechnology markets.

In the late 60's and early 70's Mr. Ryan worked for Mettler Instruments, manufacturer of laboratory automation equipment and balances, Arthur H. Thomas Company, a manufacturer of laboratory equipment and was a research engineer for Fairchild Environmental Systems developing solutions for water and air pollution monitoring equipment. From 1966 through 1968 Mr. Ryan served in the US Army as the Director of Communication Center in Chu Lai, Vietnam for the 3rd BN/82nd Artillery. He received the US Army Commendation Medal. He received his BS in Chemistry at Adelphi University, NY and studied Chemical Engineering at Clarkson University, New York. Mr. Ryan is a member of: American Chemical Society (ACS), American Society of Safety Engineers (ASSE), American Biological Safety Association (ABSA), American Industrial Hygiene Association (AIHA), American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), International Society of Pharmaceutical Engineering (ISPE), Scientific Equipment & Furniture Association (SEFA). He has authored numerous journal articles, lectured internationally, and has several patents pending.

Douglas B. Walters, Ph.D., CSP, CCHO is on the advisory board for Flow Sciences, Inc. Dr. Walters is President of KCP Inc.; a consulting company in Raleigh, NC specializing is laboratory health and safety, laboratory ventilation and hoods, and industrial hygiene. He is the former Head of Laboratory Health and Safety for the National Toxicology Program (NTP at the National Institute of Environmental Health Sciences (NIEHS, NIH) and former adjunct associate professor in the Program of Public Health at Old Dominion University. Dr. Walters has been a reviewer and served on the Editorial Board for several publishers. Dr. Walters is a Certified Safety Professional (CSP) and a Certified Chemical Hygiene Officer (CCHO). He is the American Industrial Hygiene Association (AIHA) Liaison to the American Chemical Society (ACS), a member of ANSI Z 9.5 Laboratory Subcommittee, a member of numerous AIHA and ACS committees, and is past Chair of the ACS Division of Chemical Health and Safety and the ACS Northeast Georgia Section. Dr. Walters has lectured internationally, received two ACS awards for his contributions to chemical health and safety, and received three government awards. He has authored more than 100 publications, books, book chapters, electronic databases, journal articles, one patent and one video.

Dr. Walters received his PhD in Chemistry at the University of Georgia, Athens, received his MS and BS in Chemistry from Long Island University, Brooklyn, NY.