Architectural-Scale CFD Applications for Building Airflow and Energy Balance Prediction. Is the Puzzle Solved? Challenges Remain

Alexy Kolesnikov, CPP, Inc.

Computational fluid dynamics (CFD) have been gaining acceptance as a design tool of choice for indoor airflow prediction and heating and cooling balance characterization, as well as occupant safety and comfort optimization. This presentation will benchmark the use of CFD for laboratory ventilation efficiency and fumehood performance evaluation, present an overview of the current CFD capabilities (computer resource requirements, model scale limitations) as well as outlines future challenges facing CFD HVAC applications.

Aided by rapid advances in the areas most pertinent to HVAC CFD applications, turbulence modeling, and parallel computing technology, CFD finds itself uniquely positioned to provide high fidelity airflow distribution data. Several years ago, models consisting of one to two million cells represented a standard for "high-resolution" HVAC CFD. Today's computer resources allow for 20-30 million cell models to be routinely used in parallel simulations providing reliable flow field predictions for several hundred thousand square feet of indoor floor space. LES and RANS turbulence models have been extensively benchmarked for indoor airflow implementation. This trend is likely to continue providing computer resources sufficient for air quality and energy balance predictions geared towards a "whole-building" analysis approach within the next five to ten years. The initial validation benchmark within this presentation establishes the ability of a CFD simulation to accurately reproduce experimental indoor airflow results. A full-scale section of a research laboratory consisting of eight fume hoods and equipment with corresponding supply and exhaust diffuser configurations and heat loads is addressed. The study illustrates the use of CFD in assessing fume hood operation effectiveness accounting for hood cross-talk and airflow cross-drafts within the space during day/night operations. Recommendations aimed at improved containment performance and energy balance are made on the basis of the CFD analysis.

The physics and numerics have matured to a point of making CFD a viable, cost-effective, and most importantly, trusted (via extensive benchmarking) tool for indoor airflow prediction in pursuit of sustainable, high-performance, and low-energy facilities as outlined in the Labs21 Approach. CFD is uniquely positioned to play a role in addressing key Labs21 principles by evaluating occupant safety and building energy efficiency operation through airflow and heat stratification optimization. Future challenges remain. Acoustics and flow-generated noise prediction and truly dynamic airflow characterization provide an exciting avenue for CFD research within the HVAC field and specific examples are presented in the concluding section of the presentation.

Biography:

Alexy Kolesnikov was a research and development manager at Flow Sciences, Inc. from 2000-2004. He led the company's CFD-driven research and development program and was responsible for providing technical direction in new product design, including identification, assessment, and implementation of new design concepts aimed at maximizing product performance, performing computer modeling, and optimization of airflows in ventilated enclosures, interfacing with manufacturing, and delivering client presentations. He holds a patent covering the CFD-optimized laminar low airflow hood design.

He was also a supervisor within the Worldwide CFD Consulting Services group at CD-adapco from 2004-2007 where he managed multiple projects performed for established clients focusing on a variety of automotive applications (underhood modeling, engine cooling, interior airflow, and acoustics).

Kolesnikov joined CPP, Inc. in 2007 as a senior associate with responsibility for CFD business segment development, project management, and execution. He has authored peer reviewed papers in the Journal of Computational Physics and the American Biological Safety Association Journal among others, and presented at numerous conferences including Labs21, Annual ABSA, AIHce and ASME/JSME conferences. He is also an ASHRAE member.

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