Cooling tower with direct and indirect heat exchanger

A method of exchanging heat using an apparatus comprising a direct evaporative heat exchange section, an indirect heat exchange section, and an evaporative liquid distribution assembly, the indirect heat exchange section having a housing and an indirect heat exchanger in the housing, the housing having an evaporative liquid inlet and an evaporative liquid outlet and being configured to conduct a fluid stream of evaporative fluid from the evaporative liquid inlet through a plurality of external passageways of the indirect heat exchanger to the evaporative liquid outlet, the direct heat exchange section comprising an air inlet and an air outlet, the evaporative liquid distribution assembly including a conduit connected to the evaporative liquid outlet of the housing, the method comprising:

• directing an evaporative liquid into the indirect heat exchange section housing via the evaporative liquid inlet, through the external passageways of the indirect heat exchanger to exit from the evaporative liquid outlet of the indirect heat exchange housing, wherein indirect heat exchange occurs between a fluid stream in a plurality of internal passageways of the indirect heat exchanger and the evaporative liquid in the external passageways of the indirect heat exchanger,
• directing the evaporative liquid from the evaporative liquid outlet of the indirect heat exchange housing to the conduit of the evaporative liquid distribution assembly,
• distributing the evaporative liquid from the evaporative liquid distribution assembly onto and through the direct heat exchange section, the evaporative liquid distribution assembly being downstream from the indirect heat exchange section housing in the direction of flow of the evaporative liquid,
• operating a fan assembly to move air including moving air between the air inlet and the air outlet of the direct heat exchange section, the air moving through the direct heat exchange section directly exchanging heat with the evaporative liquid moving through the direct heat exchange section;
• contacting an outer surface of the indirect heat exchange section housing with air moved by the fan assembly, the evaporative liquid, or a combination thereof to transfer heat relative to the housing;
• wherein directing an evaporative liquid into the indirect heat exchange section housing via the evaporative liquid inlet includes using an evaporative fluid pump to pump the evaporative liquid to the evaporative liquid inlet of the housing;
• and
• wherein air is pumped into the indirect heat exchange housing and through the indirect heat exchange section when the evaporative fluid pump is off to sensibly cool the indirect heat exchange section.

A cooling tower comprising:

• a direct evaporative heat exchange section;
• an evaporative liquid distribution assembly configured to distribute evaporative liquid onto the direct evaporative heat exchange section, the evaporative liquid distribution assembly including a conduit;
• a fan assembly operable to move air including moving air through the direct evaporative heat exchange section to exchange heat between the air and the evaporative liquid moving through the direct evaporative heat exchange section;
• an indirect heat exchange section comprising:
• a housing having an evaporative liquid inlet and an evaporative liquid outlet, the evaporative liquid outlet connected to the evaporative liquid distribution assembly conduit so that the housing is upstream of the evaporative liquid distribution assembly in the direction of flow of the evaporative liquid;
• the housing having an outer surface configured to be contacted by air moved by the fan assembly, the evaporative liquid, or a combination thereof to transfer heat relative to the housing;
• an indirect heat exchanger in the housing, the indirect heat exchanger comprising:
• an inlet to receive an internal fluid stream;
• a plurality of internal passageways for the internal fluid stream;
• an outlet for the internal fluid stream;
• a plurality of external passageways for the evaporative liquid in the housing;
• wherein the indirect heat exchanger is configured to separate the internal fluid stream in the internal passageways of the indirect heat exchanger from evaporative fluid in the external passageways of the indirect heat exchanger;
• a sump configured to collect evaporative liquid from the direct evaporative heat exchange section;
• an evaporative liquid pump operable to pump the collected evaporative liquid to the evaporative fluid inlet of the housing, through the external passageways of the indirect heat exchanger in the housing, out the evaporative fluid outlet of the housing, and into the conduit of the evaporative liquid distribution assembly;
• and
• an air source operable to direct air into the indirect heat exchange section housing.