AERMEC URX CF, Selection And Installation Manual

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Heat recovery units with refrigeration circuit -
URX_CF
-
11
Selection and installation manual
GB
Performance variations cooling and heating
The URX_CF series heat recovery unit with
refrigerating circuit allow the renewal of
the internal air giving the necessary hourly
change in order to obtain the ideal comfort
conditions.
The use of a high efficiency cross-flow heat
recovery unit and a heat pump refrigerating
circuit allows, in most applications and in
the most common external air temperature
conditions, in addition to the neutralisation
of the heating load of the external air, to
supply an adequate heating and cooling
capacity to compensate the internal heating
loads. Fig. 4 illustrates the graph from which
it is possible to take the coefficients to be
multiplied by the nominal values which are
present in the technical data table so as to be
able to determine the total refrigerating and
heating performance based on the outside
conditions.
fig.04
fig.05
The variations of the static pressure used
by the fans to change the air flow (which
can be set by means of the electronic
regulators during the setting phase) in
relation to the nominal values present in
the technical data table, are represented in
the graph of fig. 5.
The curve is valid for all sizes of the URX_
CF series. Keep the feed to the fans at the
maximum value
.
As an example, a unit of the URX_CF 15
series is considered.
The following performances are taken
from the technical data table:
nominal delivery flow rate 1500 m 3 /h;
nominal recovery flow rate 1500 m 3 /h;
available delivery static head = 223 Pa;
available recovery
static head = 206 Pa.
It is supposed that the pressure drops
of the air distribution system on the
supply side are equal to 210 Pa, while
the pressure drops of the air distribution
system on the exhaust side are equal to
180 Pa.
Fans available static pressure
The "Effective useful pressure/Nominal
useful pressure" reports are 210/223
= 0.94 and 180/206 = 0.87
respectively. The coefficients that can
be taken from the graph are 1.08 and
1.18.
Therefore the effective flow rate on
the supply side is 1500 x 1.08 = 1620
mc/h; the effective flow rate on the
exhaust side is 1500 x 1.18 = 1770
mc/h.
Outdoor air temperature [°C]
Key
Internal air temperature
Summer operation: 26 °C 50% RH
Multiplicational coefficient
Internal air temperature
Winter functioning: 20 °C 50% RH
Effective useful head/Nominal useful head
Corrective coefficient for the cooling capacity according to the variation of the room temperature in summer and winter mode:
SUMMER MODE:
Room air temperature 22°C, 50% RH --> corrective coefficient = 1,109
Room air temperature 24°C, 50% RH --> corrective coefficient = 1,033
Room air temperature 26°C, 50% RH --> corrective coefficient = 1
Room air temperature 28°C, 50% RH --> corrective coefficient = 0,963
WINTER MODE:
Room air temperature 18°C, 50% RH --> corrective coefficient = 0,945
Room air temperature 20°C, 50% RH --> corrective coefficient = 1
Room air temperature 22°C, 50% RH --> corrective coefficient = 1,056
Room air temperature 24°C, 50% RH --> corrective coefficient = 1,133
0,60
0,70
0,80
0,90
1,00
1,10
1,20
1,30
-10 -5 0 5 10 15 20 25 30 35 40
Variazione della resa frigorifera
resa termica resa frigorifera
Heating capacity
Refrigerating capacity
0,70
0,75
0,80
0,85
0,90
0,95
1,00
1,05
1,10
1,15
1,20
0,80 0,85 0,90 0,95 1,00 1,05 1,10 1,15 1,20 1,25
P.statica utile ventil.
Effective flow rate/nominal flow rate
Variation of cooling capacity