Technical information

26
116.3 x 860
Hot water temp. differential = = 6.10°C
16 340
Thus, hot water return
temperature is = 38.9°C
All values are within operating limits.
- Available pressure in hydraulic circuit of a unit with pack.
- From Table 6 we infer that the YLHA 120, with a 16 340 l/h
flow, has an available pressure of 289 kPa.
- Pressure drop in hydraulic circuit of a unit without pack.
- From Table 7 we infer that the YLHA 120, with a 16 340 l/h
flow, has a pressure drop of 21 kPa.
- Pressure drop in filter.
- From Table 8, 2 1/2" filter, we infer that with a 16 340 l/h
flow, said filter has a pressure drop of 2.2 kPa.
Selection guide with glycol (cool only units)
Necessary information
The following information is needed to select a YLCA water
chiller:
1. Cooling capacity needed.
2. Design cold water/glycol input and output temperatures
to and from the condensing unit.
3. Design water/glycol flow.
4. Design input temperature of air to condensing unit.
Normally, this will be the design ambient temperature of
summer air, unless influenced by the situation or other
factors.
5. Altitude above sea level.
6. Design gumming coefficient of the evaporating unit.
Note: Points 1, 2 and 3 should be related by means of the
following formulae:
   Dt (°C) x Flow (litres/second)
Capacity (kW) =
Glycol factor
In which Dt = liquid intake temp. - liquid output temp.
To determine the glycol factor, please see Figure 1 for eth-
ylene glycol, or Figure 3 for propylene glycol. For design
output temperature, please see the recommended glycol
concentration and the glycol factor in this concentration. This
is the minimum concentration to be used for design output
temperature. If a greater concentration is required, the glycol
factor can be determined by means of Figure 2 on ethylene
glycol or Figure 4 on propylene glycol.
Selection method
1. Determine the correct chiller model by selecting the one
that is closest to the capacities required by the design con-
ditions of the glycol outlet and air intake temperatures.
2. Apply the gumming correcting factors that correspond to
the gumming coefficient, altitude and glycol concentration,
to the capacity and power values in the capacity tables.
Make sure the corrected capacity is still sufficient for your
needs.
3. Using the corrected capacities of the chiller, set the design
temperature range, or the flow, to balance the formulae
appearing in the "Necessary information" section.
4. Always recheck to make sure these selections are within
the specified design limits.
Selection example
A chiller is required to chill ethylene glycol from 1 to -4°C,
with a capacity of 75 kW.
The following design conditions are applicable:
Gumming coefficient: 0.088m² °C/kW
Altitude: 1 200 m
Ambient air: 25°C
Concentration of glycol: 30% w/w
For a -4°C ethylene glycol output, the concentration recom-
mended in Figure 1 is 30%. Therefore, the specified concen-
tration is appropriate.
From Table 2 (capacities with 35% glycol) we infer that a
YLCA-120 unit, at the established design conditions, gives
a capacity of 80.2 kW and a consumption of 26.6 kW.
With the design gumming coefficient, use the capacity cor-
recting factors x 0.987 and power x 0.995 (Table 11).
On design altitude, apply the capacity correcting factors x
9.973 and power x 1.020 (Table 12).
On design glycol concentration, apply the capacity correcting
factors x 1.015 and power x 1.005 (Table 9).
Applying these factors to the selection: YLCA-120
Capacity = 80.2 x 0.987 x 0.973 x 1.015 = 78.1 kW
Comp. power = 26.6 x 0.995 x 1.020 x 1.005 = 27 kW
For the specified glycol concentration and a -4°C output
temperature, Figure 3 shows a 0.248 glycol factor. Thus, the
flow can be determined with the formula appearing in the
"Necessary information" section.
(1 - (-4)) x Flow (l/s)
78.1 kW =
0.248
78.1 x 0.248
Flow = = 3.87 (l/s) or 13 945 (l/h)
5
This covers the limits of use.
The evaporating unit pressure drop can be determined by