Filter
Top Products
7RLC-PRC006-EN
Figure 3 — Ice Storage Demand Cost Savings
Superior Control with Tracer
™
Chiller Controllers
The Adaptive Control
™
microprocessor
system enhances the air-cooled Series R
chiller by providing the very latest chiller
control technology. With the Adaptive
Control microprocessor, unnecessary
service calls and unhappy tenants are
avoided. The unit is designed not to trip
or unnecessarily shut down. Only when
the Tracer
™
chiller controllers have
exhausted all possible corrective actions
and the unit is still violating an operating
limit will the chiller shut down. Controls
on other equipment typically shut down
the chiller, usually just when it is needed
the most.
For example:
A typical five-year-old chiller with dirty
coils might trip-out on high pressure
cutout on a 100°F (38°C) day in August. A
hot day is just when comfort cooling is
needed the most. In contrast, the air-
cooled Series R chiller with an Adaptive
Control microprocessor will stage fans
on, modulate electronic expansion valve,
and modulate slide valve position as it
approaches a high pressure cutout,
thereby keeping the chiller on-line when
you need it the most.
System Options — Ice Storage
Trane air-cooled Series R Chillers are
well suited for ice production. An air-
cooled machine typically switches to ice
production at night. Two things happen
under this assumption. First, the leaving
brine temperature from the evaporator is
lowered to around 22 to 24°F
(-5.5 to –4.4°C). Second, the ambient
temperature has typically dropped about
15 to 20°F (8.3 to 11°C) from the peak
daytime ambient. This effectively places
a lift on the compressors that is similar
to daytime running conditions. The
chiller can operate in lower ambient at
night and successfully produce ice to
supplement the next day’s cooling
demands.
The Model RTAC produces ice by
supplying ice storage tanks with a
constant supply of glycol solution. Air-
cooled chillers selected for these lower
leaving fluid temperatures are also
selected for efficient production of
chilled fluid at nominal comfort cooling
conditions. The ability of Trane chillers to
serve “double duty” in ice production
and comfort cooling greatly reduces the
capital cost of ice storage systems.
When cooling is required, ice chilled
glycol is pumped from the ice storage
tanks directly to the cooling coils. No
expensive heat exchanger is required.
The glycol loop is a sealed system,
eliminating expensive annual chemical
treatment costs. The air-cooled chiller is
also available for comfort cooling duty at
nominal cooling conditions and
efficiencies. The modular concept of
glycol ice storage systems and the
proven simplicity of Trane Tracer
controllers allow the successful blend of
reliability and energy saving
performance in any ice storage
application.
The ice storage system is operated in six
different modes: each optimized for the
utility cost of the hour.
1. Provide comfort cooling with chiller
2. Provide comfort cooling with ice
3. Provide comfort cooling with ice and
chiller
4. Freeze ice storage
5. Freeze ice storage when comfort
cooling is required
6. Off
Tracer optimization software controls
operation of the required equipment and
accessories to easily transition from one
mode of operation to another. For
example:
Even with ice storage systems there are
numerous hours when ice is neither
produced or consumed, but saved. In
this mode the chiller is the sole source of
cooling. For example, to cool the
building after all ice is produced but
before high electrical demand charges
take effect, Tracer sets the air-cooled
chiller leaving fluid setpoint to its most
efficient setting and starts the chiller,
chiller pump, and load pump.
When electrical demand is high, the ice
pump is started and the chiller is either
demand limited or shut down
completely. Tracer controls have the
intelligence to optimally balance the
contribution of ice and chiller in meeting
the cooling load.
The capacity of the chiller plant is
extended by operating the chiller and ice
in tandem. Tracer rations the ice,
augmenting chiller capacity while
reducing cooling costs. When ice is
produced, Tracer will lower the air-
cooled chiller leaving fluid setpoint and
start the chiller, ice and chiller pumps,
and other accessories. Any incidental
loads that persist while producing ice
can be addressed by starting the load
pump and drawing spent cooling fluid
from the ice storage tanks.
For specific information on ice storage
applications, contact your local Trane
sales office.
Features and
Benefits