A chilled beam is an air distribution device with an integral coil designed to heat or cool large buildings. Chilled beams are made up of convective coils placed in the ceiling’s thermal zone to provide sensible cooling and heating. They can either have two pipes (cooling only) or four pipes (heating and cooling).
The coil consists of a fin and tube heat exchanger which is the basic heat transfer component in a chilled beam. Rows of interconnected copper pipes are attached to aluminum thermal conducting fins. This arrangement is then framed in a sheet metal casing, which can either be suspended freely from the soffit or mounted above a perforated metal ceiling.
This article discusses the history, types, advantages, and disadvantages of chilled beams.
1. History of Chilled Beams
The modern active chilled beams are based on the concept of under-sill induction units, developed by Willis Carrier in the 1920s . During the mid-1970s, Scandinavian engineers adopted this technology (use of the air-water system to transfer heat) and radiant heating/cooling panels for overhead applications to work with new buildings designed to utilize natural ventilation.
As a result of this, passive chilled beams were developed. In the places where natural ventilation was not effective, developers integrated mechanical ventilation into a chilled beam, resulting in the development of an active chilled beam.
2. Types of Chilled Beams
There are mainly two types of chilled beams:
2.1 Passive Chilled Beam
Passive chilled beams work using the phenomenon of natural convection. When the air within the space is heated or warmed, it rises in space where it comes in contact with the chilled beam cooling coil. The air gets cooled after passing through the coil, falls back into the occupied space, picks up heat, and repeats the cycle.
A passive chilled beam does not require any primary air supply; it relies on induction air being drawn across the coil by the natural gravitational forces and buoyancy of air.
Passive chilled beams are suitable to provide sensible cooling in labs or other places where there are high heat loads and no need for additional airflow. For the operation of passive chilled beams, good air circulation is essential, and sufficiently large openings above the passive beam must be provided for proper air circulation. Passive beams should be used only for cooling purposes, and they cannot be used for heating applications due to the stratification of hot air.
2.2 Active Chilled Beam
Active chilled beams consist of a primary air supply connection that provides conditioned/dehumidified air and enhances air induction through the coil. There is some form of plenum or primary air duct running along the length of the beam that allows air to be discharged through the nozzles into the beam, enhancing air induction through the coil. The primary air is then cooled by mixing it with the cooled air and discharged into space using integral slots.
Active chilled beams are used when sensible cooling, heating, and air ventilation are required. They can be used in school buildings, public and private office buildings, health care facilities, meeting facilities, and other environments that may have moderate to high sensible heat ratios.
Multi-service chilled beams are active or passive chilled beams with additional building services such as lighting, fire sprinklers, sound devices, motion detectors, and various other equipment.
3. Advantages of Chilled Beams
- Simple to design and easy to control.
- A chilled beam requires a smaller duct for the supply of air, and it also reduces the supply of air by 50%-65%.
- A chilled beam reduces ceiling space, minimizing it by 18 inches.
- A chilled beam requires less floor area for its installation.
- It lowers the overall construction cost of the building.
- A chilled beam does not require any maintenance as there is no moving part associated with the system.
- A chilled beam provides superior comfort to the occupants.
- They require less energy to operate, offering up to a 30% reduction in energy consumption.
- A chilled beam improves indoor air quality.
- It reduces the operation cost of the building throughout its lifecycle.
- A chilled beam is visually pleasing and helps increase the aesthetic appearance of the space.
- A chilled beam produces less noise due to the absence of moving parts and slower air velocity.
4. Disadvantages of Chilled Beam
- Poor control of temperature can lead to indoor rain.
- Chilled beam requires careful coordination to get the proper cooling.
- Airflow could be more than what is required.
- Higher construction costs.
- Chilled beams affect the appearance of the traditional ceiling.
FAQs
A chilled beam is an air distribution device with an integral coil designed to heat or cool large buildings. Chilled beams are made up of convective coils placed in the ceiling’s thermal zone to provide sensible cooling and heating.
There are mainly two types of chilled beams:
1. Passive chilled beam
2. Active chilled beam
1. Simple to design and easy to control. A chilled beam requires a smaller duct for the supply of air, and it also reduces the supply of air by 50%-65%.
2. A chilled beam reduces ceiling space, minimizing it by 18 inches.
3. A chilled beam requires less floor area for its installation.
4. It lowers the overall construction cost of the building.
5. A chilled beam does not require any maintenance as there is no moving part associated with the system.
1. Poor control of temperature can lead to indoor rain.
2. Chilled beam requires careful coordination to get the proper cooling.
3. Airflow could be more than what is required.
4. Higher construction costs.
5. Chilled beams affect the appearance of the traditional ceiling.
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