Daikin EUWA/Y5-30HB/C(Z) - Page 140

Pre-Test Run Checks ESIE98–06A
4–6 Part 4 – Commissioning and Test Run
3
1
4
5
Calculation of the
minimum water
volume
The following calculation method is based on the fact that the water volume in a chiller should be large
enough to prevent the compressor from excessive cycling. Sufficient water volume will give a certain
inertia to the system so that water (or glycol) temperature does not drop too fast when the unit turns
on and that the temperature does not rise too fast when the unit turns off.
with:
V: Required system volume [m³]
Q: Cooling capacity at the lowest capacity step of each chiller in the system [W]
t: Minimum cycling time allowed by the compressor [s] (default = 600 s)
ρ: Specific mass of the fluid [kg/m³] (default ρ
water
= 1000 kg/m³)
d: Thermostat step difference [K] (default = 0.2 K for outlet water control and 0.5 K for inlet water
control)
C
w
: Specific heat capacity of the fluid [J/kgK] (default C
w, water
= 4186 J/kgK).
Water quality In the table below you will find the required water quality specifications:
0,5 x Q x t
V = [m³]
2 x
ρ
x d x C
w
Evaporator water Heated water (low temperature)
Tendency if out of
criteria
Circulating
water (< 20 °C)
supply water Circulating water
(20 °C-60 °C)
supply water
Items to be controlled
pH at 25 °C 6.8~8.0 6.8~8.0 7.0~8.0 7.0~8.0 corrosion + scale
Electrical conductivity mS/m
(at 25 °C)
< 40 < 30 < 30 < 30 corrosion + scale
Chloride ion
mg Cl
-
/l
< 50 < 50 < 50 < 50 corrosion
Sulphate ion
mg SO
4
2-
/l
< 50 < 50 < 50 < 50 corrosion
M-alkalinity (pH 4.8) mg CaCO
3
/l < 50 < 50 < 50 < 50 scale
Total hardness mg CaCO
3
/l < 70 < 70 < 70 < 70 scale
Calcium hardness mg CaCO
3
/l < 50 < 50 < 50 < 50 scale
Silica ion mg SiO
2
/l < 30 < 30 < 30 < 30 scale
Items to be referred to
Iron mg Fe/l < 1.0 < 0.3 < 1.0 < 0.3 corrosion + scale
Copper mg Cu/l < 1.0 < 0.1 < 1.0 < 0.1 corrosion
Sulphide ion
mg S
2-
/l
not detectable not detectable not detectable not detectable corrosion
Ammonium ion
mg NH
4
+
/l
< 1.0 < 0.1 < 0.3 < 0.1 corrosion
Remaining chloride mg Cl/l < 0.3 < 0.3 < 0.25 < 0.3 corrosion
Free carbide mg CO
2
/l < 4.0 < 4.0 < 0.4 < 4.0 corrosion
Stability index – – – – corrosion + scale