| Features
and
Benefits |
System Options —
Ice Storage |
Trane centrifugal chillers are well
suited for ice production. The unique multi- stage compressor design allows the lower suction temperatures required to produce
ice and the higher chiller efficiencies attributed to
centrifugal chillers. Trane three stage and two stage centrifugal chillers produce ice by supplying ice storage vessels with a constant
supply of 22 to 24 F glycol. Centrifugal 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.
A glycol solution is used to transfer
heat from the ice storage tanks to the centrifugal chiller and from the cooling coils to either the chiller or ice storage tanks.
The use of a freeze protected solution eliminates the
design time, field construction cost, large refrigerant
charges, and leaks associated with ice plants. Ice is produced by circulating 22-24 F glycol through modular insulated ice
storage tanks. Each tank contains a heat exchanger
constructed of polyethylene tubing. Water in each
tank is completely frozen with no need for agitation. The problems of ice bridging and air pumps are eliminated.
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 centrifugal
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® controls 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 centrifugal
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 centrifugal chiller leaving fluid setpoint and start the chiller, chiller and ice pumps, and other accessories. Any incidental loads that persists 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. |
