CB503VENTILATION & AIR CONDITIONING 3

TOPIC 4 : CHILLED BEAM SYSTEM

NAZRIZAM BINTI AB. WAHABpnnazz@gmail.com

017-612 5556

1. A chilled beam is a type of convection HVAC system designed to heat or cool large buildings such as commercial buildings, schools, universities, dry labs, and hospitals.

2. A chilled beam primarily gives off its cooling effect through convection by using water to remove heat from a room.

INTRODUCTION OF CHILLED BEAM SYSTEM

3. Pipes of water are passed through a "beam" (a heat exchanger) suspended a short distance from the ceiling of a room.

4. As the beam chills the air around it, the air becomes denser and falls to the floor.

5. It is replaced by warmer air moving up from below, causing a constant flow of convection and cooling the room.

WARM AIR

WARM AIR

WARM AIRWARM AIR

COOL AIR

COOL AIR

COOL AIR

PRINCIPLE OF CHILLED BEAM SYSTEM

HISTORY OF CHILLED BEAMS

1. Chilled beams were developed in Norway in 1975.2. They have been used successfully in Europe for 20

years, where they have become standard practice.3. Chilled beam technology is emerging in the U.S. as an

alternative to conventional systems such as VAV.4. US Installations:

Astra Zeneca – Boston, MA Penn State University – Philedelphia, PA Harvard University – Boston, MA Portland Center Stage – Portland, OR Tahoe Center for Environmental Sciences – Tahoe,

NV Clemson University – Clemson, SC University of Wisconsin – Madison, WI

TYPES OF CHILLED BEAM SYSTEM

1. There are two types of chilled beam system: i. Passive chilled beam system

ii. Active chilled beam system

2. Common to each of the system, is a cooling coil which provides radiant cooling via circulated cool water.

3. Chilled beams can be either recessed in the ceiling or exposed below the ceiling.

4. Multi-Service Chilled Beams are also available.

Multi service chilled beam system

PASSIVE CHILLED BEAM SYSTEM

1. Heat transfer of passive beams occurs mainly by natural convection with a minor part by radiation.

2. Warm room air in contact with the cooled surface of the heat exchanger flows downwards through the beam into the room.

3. Passive chilled beams are not connected to the ventilation system and can be positioned fully exposed, recessed within a suspended ceiling or above a perforated ceiling.

4. Supply air can be introduced either from high or low level.

5. Primary air supply arrangements need to be designed carefully in order not to interfere with the operation of passive chilled beam.

6. When the primary air is supplied using ceiling diffusers, the air jet should not obstruct the convective flow of chilled beam.

7. In some cases where this could be exploited is to prevent downdraught from a beam, the capacity reduction of chilled beam should be taken into account (e.g. in full scale mock-up

PASSIVE CHILLED BEAM

PASSIVE CHILLED BEAMS WITH FLOOR GRILLES

PASSIVE CHILLED BEAMS ABOVE PERFORATED CEILING

PASSIVE CHILLED BEAM – DESIGN VALUES

ACTIVE CHILLED BEAM SYSTEM

1. Active beams contain a supply air plenum making heat transfer more effective due to forced convection.

2. Primary air is supplied directly into the plenum where it exits via nozzles along its length.

3. Air leaving the nozzles induces room air through the heat exchanger.

4. The mixture of supply air and induced air is introduced into the room through the longitudinal slots along both sides of the beam.

5. With greater heat transfer between the secondary room air and the heat exchanger active beams are better suited to spaces with higher loads than static beams.

6. Depending on requirements, available space and beam positioning, it is possible to supply air in one or two directions.

7. The active chilled beam operation is based on induction. 8. The induction rate varies between 1:3 and 1:5

depending on the model

ACTIVE CHILLED BEAMS

ACTIVE CHILLED BEAMS FLUSH MOUNTED

ACTIVE CHILLED BEAM – DESIGN VALUES

COMPONENTS OF CHILLED BEAM SYSTEM

1. Passive chilled beam system:• Coil• Fin-tube-heat exchanger

2. Active chilled beam system:• Coil• Fin-tube-heat exchanger• Nozzle• Air plenum

Find out the function of each component

ADVANTAGES OF USING THE CHILLED BEAM SYSTEM

1. Simple to design and control.• Constant volume supply air system• Easy ASHRAE 62 ventilation calculation• Less complicated AHU controls• Less complicated terminal unit controls• No cooling coil condensate

2. Less supply air.• 50% - 65% less supply air required• Smaller ductwork • Smaller AHU

3. Smaller ductwork.• Reduces ceiling space

4. Less mechanical space.• Reduced mechanical room size• Reduced mechanical shaft size

5. Lower construction cost.• Reduced floor to floor height lowers exterior wall

cost • Size of chilled beams installed in ceilings lowers

ceiling system cost • Reduced mechanical and shaft floor area lowers

floor, roof and wall cost

6. Less maintenance; almost no maintenance required.• No moving parts • No filters to maintain • Most manufacturers units are easily serviced

through the removable room air inlet grille • Requires minimal cleaning. Typically remains dust

and dirt free.

7. Increased comfort.• Individual room temperature control is achieved at

minimal additional cost • System noise is lower due to lower velocity and

pressure drop of the constant volume system and no VAV boxes

• Better control of space humidity levels • More uniform space temperature is achieved • Occupants are less likely to feel cold drafts

8. Improve IAQ.• Better than ASHRAE 62 ventilation rates• No contaminant mixing

9. Higher efficiency.• Up to 30% reduction in energy use • Reduced fan energy• Ideal application for energy recovery• Higher design chilled water temperature

10. LEED points.• An additional 8 – 10 LEED points can be achieved.

DISADVANTAGES OF USING THE CHILLED BEAM SYSTEM

1. Not well known in our industry.

2. Higher construction cost compared to VAV. • Chilled beams may cost up to 15% more than

conventional VAV systems and are manufactured primarily overseas; they can be hard to obtain, contributing to high costs.

3. Many engineers aren't very familiar with this technology.

4. Dew point concerns, building must have good control of humidity to prevent condensation on chilled beam surface.

5. Affects traditional ceiling appearance.• Chilled beams are larger than

traditional ceiling diffusers. Can present challenges for lighting coordination.

6. Positioning chilled beams isn't easy. • There needs to be adequate space between the top

of the passive beam and the bottom of the structure to make sure warm air can rise, turn, and go past the heat exchanger's cooling fins. Passive beams shouldn't be located above work areas due to drafts. They should also be kept away from copy machines, printers, etc.—the warm air from these machines offsets the cool air from the beam.

CHILLED BEAM SYSTEM

VSCONVENTIONAL SYSTEM

CHILLED BEAM IN MALAYSIA

Chilled Beams Installed At TROX Malaysia

TROX Malaysia Sdn. Bhd. Headquarter of South East Asia/Pacific Operations

Main Office and Factory20 Persiaran Bunga Tanjung 1, Senawang Land Industrial Park,70400 Seremban, Negeri Sembilan,Malaysia.

Tel : (+6) 06 - 6788 188Fax : (+6) 06 - 6788 288 / 388

How could chilled beam system increased comfort level?

• Chilled beams should not be used in low ceiling height applications where the distance between the ceiling and the top of the occupied zone is less than 3 ft (0.9 m).

• When applied in lobbies, atriums or other areas with high and/or uncontrollable infiltration rates, provide adequate condensation prevention strategies.

• To maintain high levels of thermal comfort (velocities within the occupied zone no greater than 50 fpm or [0.25 m/s]), active chilled beams were mounted at least 3.5 ft (1.1 m) above the designated occupied zone should be sized and located such that their throw to a terminal velocity of 100 fpm (0.5 m/s) does not exceed half the distance between them and another beam with an opposing blow. Active beams mounted 6 ft (2 m)or more above the designated occupied zone may be located such that their throw to a terminal velocity of 150 fpm (0.75 m/s) is as much as half the distance between the beam and an adjacent beam with an opposing discharge.

• Smaller nozzles result in higher induction ratios and higher sensible cooling capacities per cfm (m3 /h) of primary air. However, the use of smaller nozzles generally results in higher noise levels and inlet pressure requirements for a given primary airflow rate that increases the number of beams required.

• Designing for space humidity levels lower than that actually required may result in significantly higher primary airflow rates.

TASBIH KIFARAH

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(Maha Suci Engkau Ya Allah dan Segala Puji BagiMu, aku bersaksi bahawa tiada Tuhan

melainkan Engkau, aku memohon keampunan dan taubat daripada Engkau)