York Ylca 12, Installation Manual

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1.4.1 Selection guide with glycol (cool only units)
Necessary information
The following information is needed to select a YLCA cooling unit:
1 Cooling capacity needed
2 Design cold water/glycol inlet and outlet temperatures.
3 Design water/glycol flow rate.
4 Design inlet temperature of air to the condenser. 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 fouling factor of the evaporator.
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 rate (litres/sec.)
Glycol factor
Temp. differential (°C) = Liquid Inlet Temp. ‑ Liquid Outlet Temp.
To determine the glycol factor, please see
Glycol concentration and correcting tables , see on page
10 (Recommended ethylene glycol concentrations) for ethylene glycol or (Recommended propylene
glycol concentrations) for propylene glycol. For design outlet temperature, please see the recommended
glycol concentration and the glycol factor in this concentration. This is the minimum concentration to be
used for design outlet temperature. If a greater concentration is required, the glycol factor can be deter‐
mined by means of
Glycol concentration and correcting tables , see on page 10 (Ethylene glycol in other
concentrations) or (Propylene glycol in other concentrations).
Selection method
1 Determine the correct cooling unit 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 cooler, set the design temperature range, or the flow rate, to
balance the formulae appearing in
Selection guide (YLCA/YLHA) , see on page 4.
4 Always recheck to make sure these selections are within the specified design limits.
Selection example
A cooler is required to chill ethylene glycol from 1 a to ‑4 °C, with an output of 3,5 kW.
The following design conditions are applicable:
• Fouling factor: 0,088m °C/kW
• Altitude: 1 200m
• Ambient air: 30 °C
• Glycol concentration: 30% w/w
For a ‑4 °C ethylene glycol outlet, the concentration recommended in Figure 1 is 30%. Therefore, the
specified concentration is appropriate.
From Table
Cooling capacities YLCA 5 ÷ 27 (35% ethylene glycol) , see on page 29, we infer that a
YLCA 5 unit, at the established design conditions, gives a capacity of 3,4 kW and a consumption of 1,35
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 9).
On design altitude, apply the capacity correcting factors x 10,973 and power x 1,020 (see
Altitude fac‐
tors , see on page 12).
Installation manual 1
Selection guide (YLCA/YLHA) 1.4
7