McQuay AGZ 030AM, Product Manual

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10 AGZ 030A through 065A Product Manual AGZ-2
Selection Procedure
Packaged Chiller, Model AS
Selection with Inch-Pound (I-P) units
Table 9 covers the range of leaving evaporator water temperatures and outside ambient temperatures
included under ARI 550/590-98. The tables are based on a 10 degree F (5.5 degree c) temperature
drop through the evaporator. Adjustment factors for applications having other than a 10 degree F (5.5
degree C) drop can be found in Table 3. The minimum leaving chilled water temperature setpoint
without glycol is 40°F (4
°
C) . For brine selections, see Table 1 for ethylene or Table 2 for propylene
glycol adjustment factors. Ratings are based on a 0.0001 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:
50 tons minimum
95°F ambient temperature
120 gpm, 54
°
F to 44°F chilled water
0.0001 evaporator fouling factor
1.
From Performance Table 9, an AGZ 055AS at the given conditions will produce 54.0 tons with a
compressor kW input of 59.0 and a unit EER of 9.9.
2. Use the following formula to calculate any unknown elements.
gpm =
24
F
tons
°
×
3. Determine the evaporator pressure drop. Using Figure 8, enter at 120 gpm and follow up to the
AGZ 055AS line intersect. Read horizontally to obtain an evaporator pressure drop of 14.0 feet
of water.
Selection example using ethylene glycol
Given:
45 tons minimum
95°F ambient air temperature
54°F - 44°F chilled water temperature
0.0001 evaporator fouling factor
Protect from freezing down to 0°F
1.
From Table 1, select an ethylene glycol concentration of 40% to protect against freezing at 0°F.
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 AGZ 050AS and correct with 40% ethylene glycol factors.
4. Correct capacity = 0.961 X 49.0 tons = 47.1 tons
5. Correct compressor kW = 0.976 X 52.6 kW = 51.3 kW
6. Calculate chilled water flow:
gpm 113.0 =
10
24 1 . 47
= capacity) corrected (at flow Water
F
tons
°
×
Glycol flow (at 40% solution) = 1.121 X 113.0 gpm = 126.2 gpm