Cycles of Concentration (COC)

The ratio of dissolved solids in the tower water to dissolved solids in the makeup. The single most important variable governing water use, chemical consumption, and scaling risk in an open recirculating system. Leads to the relationship M = B x COC.

$$\text{COC}=\frac{C_{\text{tower}}}{C_{\text{makeup}}}$$

Variables

Symbol	Meaning	Unit
COC	Cycles of concentration	dimensionless
$C_{t}ower$	Dissolved solids concentration in tower water	varies
$C_{m}akeup$	Dissolved solids concentration in makeup water	varies

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Part of The Blueprint of Water