Advanced Engineering Capabilities
Computational Fluid Dynamics and Laboratories
Computational Fluid Dynamics (CFD) uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Elm Engineering actively employs the latest advanced CFD software to accurately and comprehensively model airflow, heat transfer, particle transport, and indoor air quality levels in its projects.
Important design questions can be addressed early and accurately in the design process such as how the ventilation system design can affect laboratory hoods. It is desirable to avoid supply air interference with hood capture efficiency and with CFD, clear and concise results can be quickly evaluated. Airflow modeling can also determine the local mean age of air, which represents the freshness of air, or the expected turnover, as well as to identify poorly ventilated areas.
Mean Age of Air at a Laboratory Hood
Other important design considerations that can be addressed with CFD include the determination of thermal comfort levels and modeling of laboratory response in the event of a spill. For example, in the event of a chemical spill, the evaporation rate can be calculated and used in within a CFD model to determine if the laboratory space complies with OSHA STEL levels for occupant safety.
Velocity Distribution at a Laboratory Hood
Velocity Distribution at a Laboratory Hood
Representative CFD Projects
Elm Engineering has successfully and accurately applied CFD models to a wide variety of situations including a fire in a school atrium, airflows in an off-grid naturally ventilated building, under-floor air distribution in a large data center, and the plenum air return in a large university building.
In each case valuable insight was gained about the situation that helped the design team and the owners make critical design decisions with the confidence gained from knowing a space's response rather than having to take stock in rule of thumb design methods that, in many cases, requires additional actions to correct poor performance.
Elm's CFD capabilities are more than just airflow and temperature, it’s also species transport. A project that Elm was involved in required a smoke ventilation system to be designed for a school atrium to meet code requirements. The code's prescriptive design path called for a 40 hp fan, which the designers knew was extremely over sized. Elm utilized a CFD model for this project to design a smoke ventilation system that effectively ensured occupant safety while minimizing over design and cost.
Smoke Distribution in an Atrium
Many buildings are pushing design limits to use as little energy as possible while not sacrificing occupant comfort; naturally ventilated buildings are one of these building types. Elm modeled an off-grid naturally ventilated building with 10 inch high density clay walls to ensure that the design would have adequate thermal comfort.
Knowing how and where a space responds to internal loads and cooling is extremely valuable, and nowhere is this more evident than in data centers. Data centers are not only valuable in their own right, but the services that they represent are arguably more valuable. Elm Engineering used CFD modeling to determine the exact placement of underfloor air distribution diffusers and to ensure the ideal operating environment for computer equipment.
Air temperatures and airflow patterns are extremely useful in determining an underfloor air distribution system in a data center. Knowing precisely how the system responds enables a much more sound engineering design than a rule of thumb process and results in better, more reliable, performance.
In summary, Elm Engineering CFD solutions include:
- Modeling particle paths for laboratory ventilation with velocity magnitude gradients
- Analysis of Carbon Monoxide levels for parking decks
- Air intake and exhaust plumes for high rise buildings
- Cleanroom ventilation design
- Displacement ventilation design and verification
- Temperature, humidity and airflow distribution in naturally ventilated buildings
- HVAC diffuser size and location optimization
- Detailed smoke exhaust design verification and optimization
- Determination of building IAQ and standard ASHRAE comfort levels
- Industrial paint spray booth ventilation design
- Effect of photocopier VOC emissions on IAQ
- Thermal cooling of a high density computer data center
Fast and accurate CFD modeling enables Elm Engineering to deliver designs with minimal oversizing that take into account occupant comfort with a minimized environmental impact. Knowledge of the projects predicted behavior early in the design process ensures the best life cycle cost and equipment selection.