RHOSS TCHEY 105 Mode D'emploi page 23

2. High precision: "Precision" option
In this operating mode, the unit wor ks at a fi xed set-point and, thanks
to the deli ver y water temperature c ontrol and the evol ved regulation
logic, at a c apacity of between 50% and 100% it is possible to
guarantee an average fluctuati on fr om the water suppl y temperature
of approxi matel y ± 1.5°C from the s et-point value compared to an
average fl uctuation over time of approxi matel y ± 3°C, which is
normally obtained with standard return c ontr ol.
The "Precision" option thus guarantees precision and reliability for all
thos e applicati ons that require a regulator that guarantees a more
accurate constant water s upply temperature, and where there are
particular damp c ontr ol requirements . However, in process
applications it is al ways advisable to use a water buffer tank or a
greater s ystem water content to guarantee higher s ystem thermal
inertia.
s
fluctuation
s
capacity
FC
Unit with water buffer tank, 4 litres/kW i n the s ys tem and
return c ontrol.
Unit with water buffer tank, 2 litres/kW i n the s ys tem and
deliver y control with "Precision" AdaptiveFunction Plu s
functi on
The chart illustrates the fluctuations of the w ater temperature from the
set val ue for the v arious c apacities, demonstrating how a unit with
delivery control and the AdaptiveFunction Plu s "Precision" function
guarantees greater water supply temperature precision
ACM Autotuning compressor management
AdaptiveFunction Plu s enables the C omby-Flow units to adapt to the s ystem they ar e ser ving, so as to always identify the best c ompressor operating
parameters in the different worki ng conditions .
During the initi al operating phases, the special "Autotuning" functi on enables the Comby-Flow unit with Ad aptiveFunction Plus to esti mate the
thermal inertia characteristics that regulate the s ys tem dynamics. The functi on, which is automaticall y acti vated when the unit is s witched on for the first
time, exec utes a number of set operati ng cycles , during which it process es the information relative to the water temperatures. It is thus possible to
estimate the physical characteristics of the s ystem and to identify the optimal value of the parameters to be us ed for the c ontrol.
At the end of this initi al auto-es timate phase, the "Autotuning" func tion r emains acti ve, making it possible to adapt the control parameters quickl y to
ever y change in the water circuit and thus in the s ystem water contents.
Virtual Tank: guaranteed reliability, even with water only in
the pipes
A low water content in the s ystem c an caus e the c hiller units /heat
pumps to be unreliable and can generate s ystem ins tability and poor
perfor manc e. T hanks to the Virtual T ank functi on, this is no l onger a
problem. T he unit c an operate in s ys tems with j ust 2 litres/kW in the
pipes gi ven that the control is able to c ompensate for the lac k of inertia
specific to a water buffer tank, " muffling" the control signal, preventing
the c ompressor from switc hing on and off in an unti mel y fashion and
reducing the average fluctuation of the s et-point value.
T
14
12
10
8
6
4
2
0
2000 3000
Water temperature (°C)
T
Time (s)
t
FC
Set-point temper ature
T1
Deliver y temperature with Virtual Tank
Deliver y temperature without Virtual Tank
The gr aph illustrates diverse temperature trends of output water from a
chiller taking into consideration us e capacity of 80%. It is possibl e to
observe the temperature trends for the unit in w hich in addition to
AdaptiveFunction Plu s the func tion Virtual Tank is also active,
making the trends much less isterico and stabl e ov er ti me with average
temperature v alues closer to the operational s et-point in respect to a
unit without the functi on Virtual T ank. In addition, it c an be obs erved
that in the unit with AdaptiveFunction Plu s and Virtual Tank the
compressor turns on less ti mes in the same ti me interval with obvious
advantages from a s tandpoint of electrical c ons umption and sys tem
reliability.
23
4000 5000 6000 7000
SECTION I: USER
T1
t
8000 9000