period four
Chiller-Plant Control
notes
Chiller Rotation
small electric
chiller largeelectric chiller
absorption chiller
Figure 95
When the system consists of chillers with different capacities, efficiencies, or fuel types, the question of which chiller to turn on or off next becomes more complex. Although each system requires a complete analysis, there are some general principles that apply to most systems.
In systems with chillers of different capacities, such as the “swing” chiller concept introduced in Period Three, the goal is to operate the least number of chillers and the smallest chiller possible. This typically minimizes overall system energy consumption by closely matching the capacity of the plant to the system load, thus reducing the energy used by ancillary equipment.
In systems with chillers of different efficiencies, it makes sense to operate the most efficient chillers first and the least efficient chillers last. If different fuel types are involved, the control system may receive data on the costs of natural gas and electricity and calculate the
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