Technical information

1.5.1 Selection guide with glycol (cooling 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.
3 Design water/glycol flow.
4 Design input temperature of air to condensing unit. Normally, this will be the design ambient temper‐
ature of summer air, unless influenced by the situation or other factors.
5 Altitude above sea level.
6 Design fouling factor of the evaporating unit.
N O T E
Points 1, 2 and 3 should be related by means of the following formulae:
Capacity (kW) =
Temp. diff. (°C) x Flow (litres/sec.)
Glycol factor
Temp. diff. (°C) = Liquid inlet Temp. ‑ Liquid output Temp.
To determine the glycol factor, please see Glycol concentration and correcting tables, see on page
16 (Recommended ethylene glycol concentrations) for ethylene glycol or (Recommended propylene
glycol concentrations) 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 de‐
termined by means of Glycol concentration and correcting tables, see on page 16 (Ethylene glycol in
other concentrations) or (Propylene glycol in other concentrations).
Selection method
1 Determine the correct chiller model by selecting the one that is closest to the capacities required by
the design conditions of the glycol outlet and air inlet temperatures.
2 Apply the fouling correcting factors that correspond to the fouling, altitude and glycol concentration
factor, 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 Selection guide (YLCA/YLHA), see on page 10 .
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 a to ‑4°, with a capacity of 75 kW.
The following design conditions are applicable:
• Fouling factor: 0.088m °C/kW
• Altitude: 1,200m
• Ambient air: 25°C
• Glycol concentration: 30% w/w
For a ‑4°C ethylene glycol output, the concentration recommended in Figure 1 is 30%. Therefore, the
specified concentration is appropriate.
From Table
Cooling capacities YLCA 40 ÷ 150 (35% ethylene glycol), see on page 37 , we infer that a
YLCA-120 unit, at the established design conditions, gives a capacity of 76.8 kW and a consumption of
28.8 kW.
With the design fouling factor, use the capacity correcting factors x 0.987 and power x 0.995 (see Fouling
factors, see on page 15 ).
On design altitude, apply the capacity correcting factors x 9.973 and power x 1.020 (see Altitude fac‐
tors, see on page 18 ).
Technical Information
1
Selection guide (YLCA/YLHA) 1.5
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