Systems and methods for evaporative heat rejection equipment fan speed control

A method for evaporative heat rejection equipment fan speed control, comprising:

• receiving, by a processing circuit from a humidity sensor, humidity data indicative of a relative humidity of an entering airflow being moved across an evaporative heat rejection device by a fan;
• receiving, by the processing circuit, capacity data indicative of a percentage of capacity at least one component of a refrigeration system is operating at, wherein the refrigeration system is fluidly coupled with the heat rejection device;
• and
• controlling, by the processing circuit, a speed of the fan based on the relative humidity of the entering airflow and the percentage of capacity the at least one component of the refrigeration system is operating at.

A thermal management system, comprising:

• a refrigeration system having a compressor, an evaporator, a condenser, and an expansion valve;
• a cooling tower fluidly coupled to the condenser;
• a fan positioned to provide an airflow across the cooling tower to cool a flow of water within the cooling tower;
• and
• a controller configured to control a speed of the fan based on a relative humidity of the airflow and a capacity ratio of the condenser.