Applications of Computational Fluid Dynamics (CFD) for HVAC Design Optimization

Kishor Khankari, AnSight LLC

Air is the primary carrier of heat, moisture, and contaminants in laboratory spaces. Therefore proper airflow management is the key for effective ventilation of labs. The design risk due to poor airflow management in lab spaces is often realized after commissioning and occupancy. The science of Computational Fluid Dynamics (CFD) can help in identifying such risks at early stages in the design and in optimizing the lab HVAC designs for effective and energy efficient performance. However, beyond the colorful pictures, there is a lack of understanding about the basics, benefits, limitations, and pitfalls of CFD technology. This educational presentation will provide a brief overview of nuts and bolts of CFD and what to watch in the CFD simulations beyond colorful pictures. A step-by-step procedure of CFD analysis and the importance of converged solutions will be explained. Several case studies will be presented to demonstrate how CFD analyses helped in identifying the risks and optimizing the HVAC designs. The application examples will include laboratories, clean rooms, data centers, patient rooms, operating rooms, and office spaces. In addition to the three dimensional airflow visualizations this presentation will also show analysis of temperature and contaminant distribution, and importantly, thermal comfort of the occupants. These case studies will demonstrate the importance of understanding and optimization of flow path of contaminants for effective ventilation of laboratory spaces and why high Air Change Rates (ACR) alone are not enough for effective ventilation. Similarly it will demonstrate the importance of three dimensional airflow analysis for predicting thermal comfort of occupants and in identifying cold and hot zones in occupied spaces. The HVAC systems will include stratified air ventilation, active and passive chilled beams, radiant heating and cooling. A few examples will show the applications of CFD for external wind engineering including the atmospheric plume dispersion from laboratory exhaust stacks, air cooled chillers, and cooling towers.

Learning Objectives

  • Understand what to look into CFD simulations beyond colorful pictures. Learn the step-by-step procedure of CFD analysis and the importance of converged solutions.
  • Learn basic principles of airflow management for occupied spaces and how it affects the performance of HVAC systems.
  • Understand the importance of flow path of and understanding of three dimensional distribution of contaminants is important for effective ventilation, Learn why high Air Change Rates (ACR) alone are not enough for effective ventilation.
  • Learn about thermal comfort of occupants criteria and understand why three dimensional airflow distribution plays an important role in determining thermal comfort of occupants. Learn how hot and cold zones cannot be identified with a 'simple' analysis.

Biography:

Dr. Kishor Khankari, Ph.D. is noted expert in Computational Fluid Dynamics (CFD) with several years of experience in providing engineering insights and optimized HVAC design solutions using analytical techniques. He has developed patented technology of exhaust fan assembly. He has published several technical papers and trade magazine articles. Dr. Khankari is ASHRAE Fellow member, Distinguished Lecturer, and recipient of the ASHRAE Exceptional and Distinguished Service Awards.

 

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