Multi-stage indirect-direct evaporative cooling process and apparatus

The process of cooling a first air stream, comprising the steps of:

• passing the air stream through a first heat exchanger in heat exchange relationship with but out of contact with a recirculating first body of water that is evaporatively cooled by a second air stream, passing said first air stream through a second heat exchanger in heat exchange relationship with but out of contact with a recirculating second body of water that is evaporatively cooled downstream by said first air stream, and passing said first air stream in direct contact heat exchange relationship with a third heat exchanger which includes said second body of evaporatively cooled water.

An air conditioning apparatus comprising, a first body of evaporatively cooled water, a first heat exchanger, a first air stream passing through said first heat exchanger, a second air stream cooled by said water and passing through said first heat exchanger but out of contact with said first air stream, a second heat exchanger having conduit means through which a second body of water flows, means for flowing said second body of water over an extended surface area and recirculating it through said conduit means, means for passing said first air stream through said second heat exchanger in heat exchange relationship with said conduit means, and then passing said first air stream through a third heat exchanger which includes the extended surface area of said second body of water.

An air conditioning apparatus comprising a first heat exchanger having first conduit means through which a first body of water flows, means for flowing said first body of water over a first extended surface area and recirculating it through said first conduit means in said first heat exchanger, means for passing a first air stream through said first heat exchanger in heat exchange relationship with said first conduit means, means for passing a second air stream over the extended surface area of the first body of water, a second heat exchanger having second conduit means through which a second body of water flows, means for flowing said second body of water over a second extended surface area and recirculating it through said second conduit means, means for passing said first air stream through said second heat exchanger in heat exchange relationship with said second conduit means, and then passing said first air stream over a third heat exchanger which includes the extended surface area of said second body of water.