Ethylene Glycol Solution; Cooling Capacity And Input Power - AERMEC WSA Serie Manual Técnico De Instalación Y Mantenimiento

- The cooling capacity and input power
correction factors take into account
the presence of glycol and the diffe-
rent evaporation temperature.
- The pressure drop correction factor
already takes into account the dif-
ferent flow rate deriving from the
application of the water flow rate
correction factor.
- The water flow rate correction factor
is calculated in such a way as to
keep the same ¨t that there would
be without glycol.
NOTE
To make it easier to read the graph, an
example is given on the next page.
By using the diagram below it possible
to establish the percentage of glycol
necessary; this percentage can be cal-
culated taking into account one of the
2.20
2. 1 0
2.00
1.90
1.80
1.70
1.60
1.50
1.40
1.30
1.20
1. 1 0
1.00
0.99
098
0.97
0.96
0.95
0.94
5
0
-5
-10
-15
-20
-25
-30
-35
-40
0 5 10 15

ETHYLENE GLYCOL SOLUTION

10
following factors:
On the basis of the fluid considered
(water or air), it will be necessary to
enter the graph from the right or left
side, from the intersection of the out-
side air temperature or processed
water temperature straight lines and
the relative curves, a point is obtained
through which the vertical line that will
identify both the percentage of glycol
and the relative corrective coefficients
will have to pass.
10. 1 HOW TO READ
GLYCOL CURVES
The curves shown in the figure sum
up a considerable quantity of data, all
of which is represented by a specific
curve. To be able to use these curves in
the proper way, it is necessary to make
some initial considerations:
- If you wish to calculate the percen-
20 25 30 35 40 45
tage of glycol on the basis of the
outside air temperature, it is neces-
sary to enter from the left-hand axis
and once the curve is intersected,
draw a vertical line which will inter-
cept all the other curves in its turn;
the points obtained from the upper
curves, represent the coefficients
for the correction of the cooling
capacity and input power , for the
flow rates and the pressure drops
(remember that these coefficients
must anyway be multiplied by the
nominal value of the sizes examined);
while the lower axis advises the per-
centage of glycol necessary on the
basis of the outside air temperature
considered.
- If you wish to calculate the percen-
tage of glycol on the basis of the
processed water temperature,
it is necessary to enter from the
right-hand axis and once the curve
is intersected, draw a vertical line
KEY:
FcGPf
FcGDpF (a)
FcGDpF (b)
FcGPa
FcGDpF (c)
FcGDpF (a) Correction factors for
FcGDpF (d)
FcGDpF (b) Correction factors for
FcGDpF (e)
FcGDpF (c) Correction factors for
FcGQF
FcGQ (PdC)
FcGDpF (d) Correction factors for
FcGPf (PdC)
FcGDpF (e) Correction factors for
FcGPa
FcGQF
FcGPf
5
FcGQC
0
-6
NOTE
Although graph shows up to exter-
nal air temperature of -40°C, unit
operational limits must be consi-
dered.
50 55
Corrective factors for coo-
ling capacity
Corrective factors of the
input power
pressure drop (evapora-
tor) (av. temp. = -3.5 °C)
pressure drops (av. temp.
= 0.5 °C)
pressure drops (av. temp.
= 5.5 °C)
pressure drops (av. temp.
= 9.5 °C)
pressure drops (av. temp.
= 47.5 °C)
Correction factor of flow
rates (evap.) (av. temp. =
9.5 °C)
Correction factors of flow
rates (condenser) (av.
temp. = 47.5 °C)
17