Ethylene Glycol Solution - AERMEC ANR Serie Manual Tecnico

- The cooling capacity and input
power correction factors take into
account the presence of glycol and
the different evaporation tempera-
ture.
- 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 fac-
tor 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
following factors:
On the basis of the fluid considered
32

ETHYLENE GLYCOL SOLUTION

9
(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 coef-
ficients will have to pass.
9. 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 percenta-
ge of glycol on the basis of the out-
side air temperature, it is necessary
to enter from the left-hand axis and
once the curve is intersected, draw
a vertical line which will intercept
all the other curves in its turn; the
points obtained from the upper cur-
ves, 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 percentage 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
which will intercept all the other cur-
ves in its turn; the points obtained
from the upper curves, represent the
coefficients for the cooling capacity
and input power, for the flow rates
and the pressure drops (remember
that these coefficients must anyway
be multiplied by the
KEY::
FcGPf Correction factor of the cooling
capacity
FcGPa Input power correction factor
FcGDpF (a) Pressure drop correction
factor (evaporator) (avera-
ge temp. = -3.5 °C)
FcGDpF (b) Pressure drop correction
factor (average temperatu-
re = 0.5 °C)
FcGDpF (c) Pressure drop correction
factor (average temperatu-
re = 5.5 °C)
FcGDpF (d) Pressure drop correction
factor (average temperatu-
re = 9.5 °C)
FcGDpF (e) Pressure drop correction
factor (average temperatu-
re = 47.5 °C)
FcGQF Flow rate correction factor
(evap.) (average tempera-
ture = 9.5 °C)
FcGQC Flow rate correction factor (con-
denser) (average tempera-
ture = 47.5 °C)
NOTE
Although it reaches outside air
temperatures to -40 °C, it is
necessary for the graph to main-
tain the machine's operating limits
as reference.