Using Data Loggers to Improve Chilled Water Plant Efficiency

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Overview:

The focus of this guide is on using data to evaluate the potential positive impacts of controlling chilled water coil differential temperature (ΔT) on overall chilled water plant efficiency.

Chilled water plant efficiency refers to the total electrical energy it takes to produce and distribute a ton (12,000 BTU) of cooling. System design, water quality, maintenance routines, cooling tower design, and cooling coil load all affect chiller water plant efficiency and the expense of operating the system.

Chilled water pumps circulate chilled water from the chiller to air-handler cooling coils in order to transfer heat from the air stream to water. This water then returns to the evaporator side of the chiller where the heat is passed from the water to a liquid refrigerant. The refrigerant leaves the evaporator as a cold vapor and enters the compressor where it is compressed into a hot vapor. Upon leaving the compressor, the vapor enters the condenser side of the chiller where heat is transferred from the refrigerant to the water side of the condenser where it is circulated to a cooling tower for the last stage of heat rejection via evaporation in the cooling tower.