Hitecsa EWNLM 115 Manual De Instalación, Funcionamiento Y Mantenimiento página 25

2. High precision: "Precision" Option
In this operating mode, the unit works at a fixed set-point and, thanks
to the delivery water temperature control and the evolved regulation
logic, at a capacity of between 50% and 100% it is possible to
guarantee an average fluctuation from the water supply temperature
of approximately ± 1.5°C from the set-point value compared to an
average fluctuation over time of approximately ± 3°C, which is
normally obtained with standard return control.
The "Precision" option thus guarantees precision and reliability for all
those applications that require a regulator that guarantees a more
accurate constant water supply temperature, and where there are
particular damp control requirements. However, in process
applications it is always advisable to use a water buffer tank or a
greater system water content to guarantee higher system thermal
inertia.
s
s fluctuation
FC capacity
Unit with water buffer tank, 4 litres/kW in the system and
return control.
Unit with water buffer tank, 2 litres/kW in the system and
delivery control with "Precision" AdaptiveFunction Plus
function
The chart illustrates the fluctuations of the water temperature from the
set value for the various capacities, demonstrating how a unit with
delivery control and the AdaptiveFunction Plus"Precision" function
guarantees greater water supply temperature precision.
ACM Autotuning compressor management
AdaptiveFunction Plus enables the Y-Flow units to adapt to the system they are serving, so as to always identify the best compressor operating
parameters in the different working conditions.
During the initial operating phases, the special "Autotuning" function enables the Y-Flow unit with AdaptiveFunction Plus to estimate the thermal
inertia characteristics that regulate the system dynamics. The function, which is automatically activated when the unit is switched on for the first time,
executes a number of set operating cycles, during which it processes the information relative to the water temperatures. It is thus possible to estimate
the physical characteristics of the system and to identify the optimal value of the parameters to be used for the control. In this phase it must be
considered normal that the delivery temperature drops by a few degrees, below the set value set, however remaining above the anti-freeze set.
At the end of this initial auto-estimate phase, the "Autotuning" function remains active, making it possible to adapt the control parameters quickly to
every change in the water circuit and thus in the system water contents.
Virtual Tank: guaranteed reliability, even with water only in
the pipes pipe
Low water content in the system can cause the chiller units/heat pumps
to be unreliable and can generate system instability and poor
performance. Thanks to the Virtual Tank function, this is no longer a
problem. The unit can operate in systems with just 2 litres/kW in the
pipes given that the control is able to compensate for the lack of inertia
specific to a water buffer tank, "muffling" the control signal, preventing
the compressor from switching on and off in an untimely fashion and
reducing the average fluctuation of the set-point value.
T
14
12
10
8
6
4
2
0
3000
2000
T Water temperature (°C)
t Time (s)
FC
T1 Set-point temperature
Delivery temperature with Virtual Tank
Delivery temperature without Virtual Tank
The graphics states the different trends of the temperature of the
water leaving the chiller taking into consideration use capacity
of 80%. It is possible to observe the trend of the temperature for the
unit in which, as well as the AdaptiveFunction Plus logic, the Virtual
Tank function is active. It is less hysterical and stable through
time with average temperature values closer to the work set-point with
respect to a unit without the Virtual Tank function. It is also possible to
observe that in the unit with AdaptiveFunction Plus and Virtual Tank
the compressor turns on less times in the same time interval with
obvious advantages from a standpoint of electrical consumption and
system reliability.
26
4000 5000 6000 7000
SECTION I: USER
T 1
8000 9000 t