Product Manual WHR-2 17
3) Graphical solution to Case a) is shown below.
d) The THR for the WHR
110EA is plotted using two
points; TD=10 degrees
(105°F-95°F) and TD=25
degrees (120°F-95°F).
e) The THR for the ACD 210A
is plotted using its capacity
at TD+15 degrees and
TD=18 degrees.
f) The curves intersect at
TD=16.5 degrees or 111.5°F
condensing temperature.
g) Extrapolating the WHR
capacity at 111.5°F gives
101.5 tons which will meet
the job requirements. It will
be the highest cost but
most efficient unit.
EA Remote Condenser, R-134a
Use the same selection procedures as with R-22 except multiply the values in the R-22 Performance
Tables as follows: Capacity x 0.68, Power x 0.65, EER x 1.05.
Selection Adjustment Factors
Ethylene and Propylene Glycol Factors
WHR units are designed to operate with a leaving chilled fluid temperature from 21°F (-6.1°C) to
60°F (16°C). Leaving chilled fluid temperatures below 40°F (4.6°C) result in suction temperatures at
or below the freezing point of water and a glycol solution is required. The use of glycol in the
evaporator will reduce the performance of the unit. The reduction in performance depends upon
the glycol concentration. This should be taken into consideration during initial system design.
McQuay encourages a minimum concentration of 25% be provided on all glycol applications.
Glycol concentrations below 25% are too diluted for long-term corrosion protection of ferrous
metals and corrosion inhibitors may need to be recalculated. Glycol in the condenser will have a
negligible effect on performance because glycol at higher temperatures will perform with
characteristics similar to water.
Table 1, Adjustment Factors for Ethylene Glycol
Freeze PointPercent
E.G
°F °C
Cap. Power Flow PD
10 26 -3 0.991 0.966 1.013 1.070
20 18 -8 0.982 0.992 1.040 1.129
30 7 -14 0.972 0.986 1.074 1.181
40 -7 -22 0.961 0.976 1.121 1.263
50 -28 -33 0.946 0.966 1.178 1.308
Table 2, Adjustment Factors for Propylene Glycol
Freeze PointPercent
P.G
°F °C
Cap. Power GPM PD
10 26 -3 0.987 0.992 1.010 1.068
20 19 -7 0.975 0.985 1.028 1.147
30 9 -13 0.962 0.978 1.050 1.248
To Next Page
Loading...
Need help?
General
