CFD-Driven Design of a Low Airflow, Rapid Recovery Containment Control System

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

Abstract:

In this paper we address performance characteristics of a new variable air volume (VAV) low airflow containment control system. VAV laboratory systems are designed to maintain constant face velocity at the hood sash, hence aiming to improve operator safety and maximize energy efficiency. Towards this goal computerized and programmed controls are employed to continuously adjust air volume supply in order to compensate for face velocity fluctuations resulting from operator activities, room air current perturbations and sash height variations. The dynamic nature of VAV systems carries the potential for intermittent face velocity instabilities and places additional demands on containment control system optimization. The patented closed-loop control system presented in the paper maintains constant velocity at the face of the enclosure by monitoring instantaneous flow pressure perturbations. Accurate pressure measurement allows to directly access physical characteristics of the flow, as opposed to indirect measurements such as sash height variation, and is the key in improving control system recovery time.

Current design uniquely combines the new rapid recovery air volume control mechanism with CFD-optimized laminar airflow patterns inside the work area to provide the needed operational balance resulting in a stable, safe and predictable containment system. As documented in a previous paper presented in January, the detailed velocity and pressure distributions determined by numerical computer simulations provide a realistic airflow model necessary to evaluate system performance for a specific set of operational parameters, thus allowing for a comprehensive design optimization. Present results extend this approach for a specific VAV system with numerical modeling used to investigate airflow distribution for a variety of sash height and face velocity combinations aiming to achieve a turbulence-free work-area airflow distribution. The final design is shown to provide stable containment at face velocities significantly lower than those generally accepted as operating values, hence resulting in significant energy cost reduction. Energy management gains achieved through the use of the low airflow containment control system are therefore attained without compromising operator safety.

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, PhD., 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.