Heat rejection apparatus, plume abatement system, and method

A heat rejection apparatus comprising:

• an air inlet;
• an air outlet;
• an evaporative heat exchanger;
• a primary fan operable to direct first ambient air into the air inlet, cause the first ambient air to interact with the evaporative heat exchanger to produce heated air, and discharge the heated air from the air outlet;
• a base;
• an adjustable damper of the base, the adjustable damper having:
• an open configuration wherein the adjustable damper permits second ambient air from beneath the heat rejection apparatus to enter the heat rejection apparatus and contact the heated air upstream of the air outlet;
• and
• a closed configuration wherein the adjustable damper permits less of the second ambient air to enter the heat rejection apparatus from below the heat rejection apparatus than in the open configuration;
• a controller operatively connected to the primary fan and the adjustable damper, the controller configured to shift the adjustable damper from the closed configuration to the open configuration to abate plume.