Cooling tower with indirect heat exchanger
A heat exchange apparatus is provided with an indirect evaporative heat exchange section. The indirect evaporative heat exchange section includes a series of serpentine tubes, and an evaporative liquid is passed downwardly onto the indirect heat exchange section. The evaporative liquid is collected in a sump and then pumped upwardly to be distributed again across the indirect heat exchange section. An improved heat exchange apparatus is provided with an indirect evaporative heat exchange section including a series of serpentine tubes with run sections and return bend sections of both normal and increased height. A secondary spray system or a direct heat exchange section may be provided in the vertical spacing between run section formed by the increased height return bends.
1. A method of exchanging heat comprising the steps of:
providing an indirect evaporative heat exchange section,
the indirect heat exchange section conducting a fluid stream within a plurality of pathways,
the indirect heat exchange section comprising a top and a bottom,
distributing an evaporative liquid generally downward onto and through the indirect heat exchange section such that indirect heat exchange occurs between the fluid stream within the plurality of pathways and the evaporative liquid,
moving air through the indirect section,
the air moving through the indirect heat exchange section exchanging heat with the evaporative liquid moving through the indirect heat exchange section and hence indirectly exchanging heat with the fluid stream within the plurality of pathways in the indirect section,
wherein the indirect heat exchange section is comprised of a series of serpentine tubes comprising run sections and normal and increased height return bend sections,
the series of serpentine tubes including at least one area having an increased vertical spacing between vertically adjacent run sections of the serpentine tubes, such increased vertical spacing formed by the increased height return bend sections which have a height greater that the normal return bend sections, wherein a secondary system is provided to distribute the evaporative liquid downwardly and through the indirect heat exchange section from a position below the top of the indirect heat exchange section.
2. The method of exchanging heat of claim 1 , further comprising:
collecting substantially all of the evaporative liquid that exits the
indirect heat exchange section, and
pumping the collected evaporative liquid upwardly such that it can be distributed generally downward onto and through the indirect heat exchange section.
3. The method of exchanging heat of claim 1 wherein the air moving through the indirect heat exchange section moves generally counter-current to the direction of flow of the evaporative liquid through the indirect heat exchange section.
4. The method of exchanging heat of claim 1 wherein the air moving through the indirect heat exchange section moves generally cross-current to the direction of flow of the evaporative liquid through the indirect heat exchange section.
5. The method of exchanging heat of claim 1 wherein a direct heat exchange section is provided in one or more of the areas in the indirect heat exchange sections having increased vertical spacing between vertically adjacent run sections of the series of serpentine tubes.
6. The method of exchanging heat of claim 1 wherein a direct heat exchange section is provided, such direct heat exchange section comprising a fill assembly located in one of the areas in the indirect heat exchange section having increased vertical spacing between vertically adjacent run sections of the series of serpentine tubes.
7. The method of exchanging heat of claim 6 wherein a direct heat exchange section is provided in one or more of the areas in the indirect heat exchange sections having increased vertical spacing between vertically adjacent run sections of the series of serpentine tubes.