TCB-RB - TROX

Nomenclature · Example
Nomenclature
V WK in l/hr: Water volume flow rate, cooling
Q WK in W: Water cooling capacity
q WK in W/m: Specific cooling capacity per m
W/m²: or per m²
t WV in °C: Chilled water flow temperature
t WR in °C: Chilled water return temperature
t WM in °C: Chilled water mean temperature
t R in °C: Maximum room air temperature
t W in K: Temperature difference between water
flow and return temperature
t RW in K: Temperature difference between max.
room air temperature and mean chilled
water temperature
V in m/s: Maximum time averaged air velocity
measured
approx. 1 m below passive chilled beam
B in mm: Width of cooling coil
H in mm: Passive beam stack height
fo in %: Ceiling free area underneath the TCB-RB
Z in mm: Return air gap above beam
K Z/W
Correction factor for Z /W ratio
K fo
Correction factor for airflow % free area
p W in kPa: Water pressure drop
Reference Values
t WV = 16 °C Chilled water flow temperature
t WR = 18 °C Chilled water return temperature
t R = 27 °C Room air temperature
t RW = 10 K Temperature difference between room
air temperature and mean chilled water
temperature
Z/W = 0.5 Ratio of clear height against coil width
Example
Room size: 3 m x 6 m
Room height: 2.8 m
Suspended ceiling: 45% free area
Ceiling void: 400 mm
t R 24 °C
t WV 14 °C
t WR 17 °C
t RW 8.5 K
q WK 60 W/m²
60 x 3 x 6 = 1080 W
Q WK
The architect has specified a row of units maximum 6 m
along the centre line of the room (2 x 3 m)
Room sketch
Diagrams I…III (see page 8)
Coil width (B): 410 mm
Unit height (H): 250 mm
Unit length (L 1 ): 3000 mm Q = 550 W
For installation behind a perforated ceiling 45%,
correction factor K fo must be applied.
K fo : 0.99 Q = 550 W x 0.99 = 544 W
Diagrams IV and V
At a differential between water flow and return temperature
of 3 K, the water flow rate V W = 156 l/hr. Since the water flow
rate is greater then the nominal water flow rate of 110 l/hr,
a correction factor K W = 1.07 is applied to the calculated
capacity
Q = 544 W x 1.07 = 582 W
Diagram VII
For installation within a ceiling void, correction factor K Z/W
must be applied.
Z
B
= (400-250) = 0.36
410
K Z/W : 0.97 Q = 582 W x 0.97 = 565 W
For the room as planned with 2 chilled beams units
3000 mm long, the available overall cooling capacity is:
Q WK = 2 x 565 W = 1130 W
Diagram VII
Waterside pressure drop.
p w = 0.7 x 3 m = 2.1 kPa
Diagram VIII
The air velocity 1 m below the chilled beam will be between
0.17 and 0.23 m/s.
NOTE: If required cooling output cannot be achieved with
a 1 row coil, repeat above steps with diagrams on page 9.
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