Active Chilled Beams

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Active chilled beams rely on the induction principle to move large quantities of room air through the coil.

The unique design of the chilled beam creates a low pressure system above the coil, which induces the warmer room air into the beam. Active chilled beams are suited for heating and cooling applications and can use a 2‐pipe with changeover valve system or a 4‐pipe system.

Active chilled beams fulfill the minimum fresh air requirements and space conditioning in one unit. They are available in a variety of sizes and configurations which allow them to be used in a multitude of applications.

Beam Components

  • 2 or 4 pipe cooling and/or heating coil
  • Chilled beam casing (may be specified by engineer or architect)
  • Mixing chamber
  • Pressure chamber with nozzles, where the fresh air is supplied
  • Induction grille (may be specified by engineer or architect)

How does it work?

Fresh air from the air handler via duct work is supplied into the pressure chamber, typically at 0.2‐ 0.6 inches of W.C. and between 55‐60 degrees F. The pressure in the chamber causes the air to rush out through the nozzles at a high velocity into the mixing chamber. Due to the nature of the nozzles, a low pressure system is created above the coil, inducing more air through the coil into the mixing chamber. Conditioned air from the space mixes with the fresh air and is supplied back into the room through linear slots located along the casing of the beam.

Nozzle Pressure gradient





 
The air gets supplied back to the space through the linear slots at a higher velocity and at its coldest state. Due to the air density, the design of the beam, and the phenomenon known as the Coanda Effect, the air naturally travels along the ceiling. This type of air distribution is optimally designed to create a homogeneous fresh air and temperature distribution, low vertical temperature gradient, and no drafts in occupied zone, meaning the velocity of the air in the occupied zone is less than 40fpm (as prescribed by ASHRAE Standard 55P).

Applications:

The design of the beam is flexible allowing the beams to fit in any standard grid system: either recessed or suspended below the ceiling.

Standard beams offer 1‐way, 2‐way, or 4‐way air distribution to accommodate for space design and loads. The beams come with either fixed or adjustable nozzles.

Chilled beams are suited for:
  1. Hospitals
  2. Schools / Universities
  3. Laboratories
  4. Commercial buildings
  5. Airports
  6. Hotels

For the Engineer – Design Example:


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