Glycol Solutions - Daikin WGZ030DW Installation And Maintenance Manual

Glycol Solutions

Do not use automotive antifreeze. Industrial glycols must be used.
Automotive antifreeze contains inhibitors that causes plating on
copper tubes. The type and handling of glycol used must be
consistent with local codes.
WGZ units are designed to operate with a leaving chilled fluid
temperature from 15°F (-9.4°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 anti-freeze 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 and temperature. This should be taken into
consideration during initial system design. Glycol in the
condenser will have a negligible effect on performance
because glycol at these higher temperatures will perform with
characteristics similar to water.
Daikin Applied recommends 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 need to be
recalculated and possibly added to the system.
Chiller capacity, flow rate, evaporator pressure drop, and
power input for glycol solutions can be calculated using the
following formulas and reference to
glycol and Table 3 for propylene glycol. Test coolant with a
clean, accurate, glycol solution hydrometer (similar to that
found in service stations) to determine the freezing point.
Note: Ethylene and propylene glycol ratings are outside the
scope of AHRI Standard 550/590 certification program.
Capacity is reduced compared to that with plain water. To find
the reduced value, multiply the chiller's capacity when using
water by the capacity correction factor C to find the chiller's
capacity when using glycol.
Flow -To determine evaporator gpm (or T) knowing T (or
gpm) and capacity:
24 x Glycol Capacity
=
Glycol GPM
Δ
T
For Metric Applications -- Determine evaporator lps (or T)
knowing T (or lps) and kW:
kW
=
Glycol Lps
Δ
. 4 18 x T
Pressure Drop - To determine glycol pressure drop through
the cooler, enter the water pressure drop graph on
the actual glycol flow. Multiply the water pressure drop found
there by P to obtain corrected glycol pressure drop.
Power -To determine glycol system kW, multiply the water
system kW by factor K.
IM 1131-2
CAUTION
Table 2 for ethylene
x Flow Correction G From
x Flow Correction G from
page 14
Table 2: Ethylene Glycol Correction Factors
Freeze Point Capacity
% E.G.
° F ° C
25.0 -3.9
10%
18.0 -7.8
20%
30% 7.0 -14.0
-7.0 -22.0
40%
50% -28.0
P
Table 3: ropylene Glycol Correction Factors
Freeze Point Capacity
% P.G.
° F
25.0
10%
19.0
20%
30% 9.0
40% -5.0
-27.0
50%
Condenser Water Piping
Arrange the condenser water so the water enters the bottom
connection of the condenser. The condenser water will
discharge from the top connection. Failing to arrange the
condenser water as stated above will negatively affect the
capacity and efficiency.
Install pressure gauges in the inlet and outlet water lines to the
condenser. Pressure drop through the condenser should be
measured to determine flow on the pressure drop/flow curves
beginning on page
in both the supply and return water lines. Install a 20-mesh
strainer in the inlet piping to the condenser.
Water-cooled condensers can be piped for use with cooling
towers, well water, or heat recovery applications. Cooling
tower applications must be made with consideration of freeze
protection and scaling problems. Contact the cooling tower
manufacturer for equipment characteristics and limitations for
the specific application. Head pressure control must be
provided if the entering condenser water can fall below 60°F.
The WGZ condenser has two refrigerant circuits with a
common condenser water circuit. This arrangement makes
head pressure control with discharge pressure actuated control
valves difficult.
If the tower water temperature cannot be maintained at a 60°F
Tables
minimum, or when pond, lake, or well water that can fall
below 60°F (15°C) is used as the condensing medium, special
discharge pressure control must be used. A water recirculating
system with recirculating pump as shown in
Tables
recommended. This system also has the advantage of
maintaining tube velocity to help prevent tube fouling. The
pump must cycle with the chiller.
at
Figure 5: Recirculating Discharge Water System
Circuit #1
Inlet
Circuit #1
Outlet
Water Piping
Power Flow
"C" "K" "G"
0.997 0.999 1.030 1.113
0.993 0.997 1.060 1.226
0.987 0.995 1.092 1.369
0.980 0.992 1.132 1.557
0.973 0.991 1.182 1.791
Power Flow
° C "C" "K" "G"
-3.9 0.994 0.998 1.016
-7.2 0.987 0.995 1.032
-13.0 0.978 0.992 1.057
-21.0 0.964 0.987 1.092
-32.8 0.952 0.983 1.140
14. Vibration eliminators are recommended
Circuit #2
Inlet
Condenser
Circuit #2
Outlet
PD
"P"
PD
"P"
1.106
1.211
1.380
1.703
2.250
Figure 6 is
T emperature
Control
Valve
Condenser
W ater
9