Flooded type water cooled screw chiller (PCB Control)
23
System minimum water volume
Water volume is necessary for stable operation. It is often necessary to add a buffer water tank to the
circuit in order to achieve the required volume. The tank must itself be internally baffled in order to
ensure proper mixing of the liquid (water or brine). Water tank volume is large than 1 / 10 whole system
water volume at least.
Refer to the examples below.
How to calculate minimum volume in pipeline system:
W=QgT/CP
▽
t
W
— Minimum water volume
（
kg
）；
Qg
— Total cooling/heating capacity of the terminal
（
kW
）；
T
— Thermal stability time requirement
，
Take
（
8
～
10
）
×60s
；
CP
— Water specific heat at constant pressure
，
4.187kj/
（
kg·
℃
）；
▽
t
— Water temperature fluctuation required value
，
take 5
℃
.
For system, Qg is calculated according to the lowest load so that it operates steadily.
It can also calculated according to 0.5Q(50%). T takes 8 minutes, the shortest time that the unit running.
That is 480s. Cp=4.18kj/kg,
▽
t =5
℃
According to the above formula, the result is as following:
W=0.5Q*480/
（
4.18*5
）
=11.48Q kg
Note:
The above formula is only for reference, different factor should be adopted to suit for different condition.
