Traditional Passive Chilled Beams are water driven cooling units that usually rely on the natural 'Convection' process for heat transfer. The circulation of chilled water through the aluminium finned block coil makes the aluminium fins cold (note: Chilled Beams operate above dew point, hence typically 14°C chilled water flow, thus no condensation tray or condensation pumps and/or drains are required, unlike other HVAC equipment) and when the air in the room becomes in contact with the cold aluminium fins, the density of the air increases (cold air is heavier than warm air) and as such this heavier denser air falls to the floor directly below the fin coil block, thus displacing warmer room air which easily rises as lighter (less dense) upto to sides and rear of the cold fin coil block, thus repeating the process of the surrounding air becoming more dense as a continuous cycle whilst ever chilled water is circulated through the fin coil block.
It is usual to conceal the aluminium fin coil block (fin coil battery) either behind a perforated metal ceiling or in a perforated metal casing - this type of old technology (Frengers 'Convect' product) can achieve high levels of cooling in terms of Watts/linear meter, however care should be taken to limit the cooling to a maximum of 225 Watts/linear meter to avoid excessive air velocities in the occupied zone if good Thermal Comfort is a requirement (ie less than 0.25m/s air speeds). Frenger would only offer this old technology for transient areas if requested and in excess of 225 W/m required - see 'What are Radiant Passive Chilled Beams' for second generation passive beam solutions that can achieve 325 W/m with less than 0.25m/s air velocities.
Frequently Asked Questions
Passive Chilled Beams