Indirect heat exchanger

A method of operating an indirect heat exchanger comprising:

• providing an indirect heat exchanger comprising:
• a plurality of coils having length sections and bend sections,
• a fan to draw air across the plurality of coils,
• a water distribution system located above the plurality of coils and comprising
• a series of discharge sections, an inlet header connected to the series of discharge sections,
• a plurality of openings in each discharge section that allow water to be distributed downwardly over the plurality of coils and a sump to collect the water after passing over the plurality of coils,
• wherein the water distribution system also comprises an exit opening in the sump, and a pump connected to the exit opening, and a return line to supply the water from the sump to the inlet header of the water distribution system, with the pump having a capacity at any given time results in water being discharged from the water distribution system onto the plurality of coils to provide a density zone profile (DZP) according to:
• DZP=Cf*NROWS*[(NCKTS*DP)/CW]^2 Equation 1
• Where:
• DZP=Density Zone Profile Number
• Cf=correction factor for fins described in table 1 below
• NROWS=number of tubes fed from top to bottom
• NCKTS=number of circuits in a casing width
• DP=projected tube diameter, inches
• CW=casing width, inches
• Wherein DZP is the density zone profile of the plurality of coils,
• TABLE 1
• % of Rows that
• Cf (Finned
• are finned
• Description
• Correction factor)
• 0%
• None of the tubes
• 1.0
• are finned
• 5% < finned rows < 33%
• 1.3
• 33% < finned rows < 66%
• 1.6
• >66% finned rows
• Most or all rows
• 2.0
• are finned
• wherein a water distribution spray water flow rate is set to:
• greater than 4 gpm/ft2 when DZP is less than 10, and
• between 2 to 4 gpm/ft2 when DZP is greater than or equal to 10.