10
AGR 070A through 100A
Product Manual AGR-3
Selection Procedure 60 Hertz, SI Units
Table 10, covers a range of leaving evaporator water temperatures and outside ambient temperatures.
The tables are based on a 5°C temperature drop through the evaporator. The minimum leaving chilled
water temperature setpoint without glycol is 5.6°C. For brine selections, see Table 1 for ethylene or
Table 2 for propylene glycol adjustment factors. Ratings are based on a 0.0176 fouling factor in the
evaporator at sea level operation. For other fouling factors, different Delta-Ts, or altitude correction
factors, see Table 3. For applications outside the catalog ratings contact your local McQuay sales
representative.
Selection Example
Given:
235 kW cooling capacity required
35°C ambient air temperature
11 L/s, 12°C - 7°C chilled water temperature
0.0176 evaporator fouling factor
1.
From Table 10, an AGR 070AS at the given conditions will produce 240.0 kW with a compressor
kW input of 77.5 and a COP of 2.84.
2.
Determine the evaporator pressure drop. Using Figure 9, enter at 11 L/s and follow to the AGR
070AS line intersect. Read horizontally to obtain an evaporator pressure drop of 55 kPa of water.
Selection example using ethylene glycol
Given:
225 kW cooling capacity required
35°C ambient air temperature
11 L/s, 12°C - 7°C chilled water temperature
0.0176 evaporator fouling factor
Protect against freezing down to -18°C
1.
From Table 1, select an ethylene glycol concentration of 40% to protect against freezing
at -18°C
2.
At 40% ethylene glycol, the adjustment factors are: Capacity = 0.961, kW = 0.976,
GPM = 1.121, pressure drop = 1.263
3.
Select the AGR 070AS and correct with 40% ethylene glycol factors.
4.
Correct capacity = 0.961 x 240.0 kW = 230.6 kW
5.
Correct compressor kW = 0.976 x 77.5 kW = 75.6 kW
6.
Calculate flow:
Glycol flow (at 40% solution) = 1.121 X 11.0 L/s = 12.3 L/s
7.
Determine the evaporator pressure drop. Using Figure 9, enter at 11.0 L/s (flow rate for water) and
follow to the AGR 070AS line intersect. Read horizontally to obtain an evaporator pressure drop
of 55 kPa of water.
The pressure drop for 40% solution = 1.263 X 55 kPa = 69.5 kPa