Heat exchange – With first fluid holder or collector open to second fluid – Trickler
Reexamination Certificate
2002-04-12
2004-03-09
McKinnon, Terrell (Department: 3743)
Heat exchange
With first fluid holder or collector open to second fluid
Trickler
C165S170000, C165S177000, C165S117000, C261S153000
Reexamination Certificate
active
06702004
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for the disposal of heat utilizing a heat exchange liquid in combination with a heat exchange gas. More particularly, the present invention relates to an apparatus for providing an evaporative heat exchanger wherein the heat exchanger is employed, for example, to dispose of large quantities of heat generated by various industrial processes.
BACKGROUND OF THE INVENTION
Evaporative heat exchangers are widely used in many applications where it is necessary to cool or condense fluid and/or gas that must be maintained out of contact with the heat exchange medium to which the heat is transferred. For example, air conditioning systems for large buildings employ evaporative heat exchangers for carrying out a portion of the heat exchange that is essential to the cooling process. In these systems, air inside the building is forced passed coils containing a cooled refrigerant gas thereby transferring heat from inside the building into the refrigerant gas. The warmed refrigerant is then piped outside the building where the excess heat must be removed from the refrigerant so that the refrigerant gas can be re-cooled and the cooling process continued. In addition, industrial processes such as chemical production, metals production, plastics production, food processing, electricity generation, etc., generate heat that must be dissipated and/or disposed of, often by the use evaporative heat exchangers. In all of the foregoing processes and numerous other processes that require the step of dissipating or disposing of heat, evaporative heat exchangers have been employed.
The general principle of the evaporative heat exchange process involves the fluid or gas from which heat is to be extracted flowing through tubes or conduits having an exterior surface that is continuously wetted with an evaporative liquid, usually water. Air is circulated over the wet tubes to promote evaporation of the water and the heat of vaporization necessary for evaporation of the water is supplied from the fluid or gas within the tubes resulting in heat extraction. The portion of the cooling water which is not evaporated is recirculated and losses of fluid due to evaporation are replenished.
Conventional evaporative heat exchangers are presently in widespread use in such areas as factory complexes, chemical processing plants, hospitals, apartment and/or condominium complexes, warehouses and electric generating stations. These heat exchangers usually include an upwardly extending frame structure supporting an array of tubes which form a coil assembly. An air passage is formed by the support structure within which the coil assembly is disposed. A spray section is provided usually above the coil assembly to spray water down over the individual tubes of the coil assembly. A fan is arranged to blow air into the air passage near the bottom thereof and up between the tubes in a counter flow relationship to the downwardly flowing spray water. Heat from the fluid or gas passing through the coil assembly tubes is transferred through the tube walls to the water sprayed over the tubes. As the flowing air contacts the spray water on the tubes, partial evaporation of some of the spray water occurs along with a transfer of heat from the spray water to the air. The air then proceeds to flow out of the heat exchanger system. The remaining unevaporated spray water collects at the bottom of the conduit and is pumped back up and out through the spray section in a recirculatory fashion.
Current practice for improving the above described heat transfer process includes increasing the surface area of the heat exchange tubes. This can be accomplished by increasing the number of coil assembly tubes employed in the evaporative heat exchanger by “packing” the tubes into a tight an array as possible, maximizing the tubular surface available for heat transfer. The tightly packed coils also increase the velocity of the air flowing between adjacent tube segments. The resulting high relative velocity between the air and water promotes evaporation and thereby enhances heat transfer.
Another practice currently employed to increase heat transfer surface area is the use of closely spaced fins which extend outwardly, in a vertical direction from the surface of the tubes. The fins are usually constructed from a heat conductive material, where they function to conduct heat from the tube surface and offer additional surface area for heat exchange.
In addition, another method currently used to increase heat exchange is the use of splash type fill structures placed between individual tubes in a coil assembly that can function to provide additional water surface area for heat transfer.
These current practices can have drawbacks. For example, the use of additional tubes requires additional coil plan area along with increased fan horsepower needed to move the air through the tightly packed coil assembly, increasing unit cost as well as operating cost. In addition, placement of fins between the individual tubes may make the heat exchanger more susceptible to fouling and particle build up. Further, indiscriminate placement of fill sheets within coils assemblies can cause performance degradation by hindering air flow, and the fill sheets can act as an insulator where they abut the tubes, and/or can cause heat already transferred to the air to be transferred back to the cooling water.
Accordingly, it is desirable to provide a method and apparatus for effectuating desirable, evaporative heat exchange that can offer a substantial reduction in parts, improved efficiency and or reduction of complex and costly assembly of components. It is also desirable to provide increased evaporative heat exchange without undesirably increasing the size of the unit, the manufacturing cost of the unit, and/or operating cost of the unit.
SUMMARY OF THE INVENTION
The foregoing needs are met, at least in part, by the present invention where, in one embodiment, an evaporative apparatus for use in a counter flow heat exchange assembly is provided having a plurality of generally vertical arrays adjacently spaced laterally to each other. Each of the individual arrays includes a plurality of generally horizontal conduits extending across the heat exchange assembly in spaced relation to each other at different vertical levels of the counter flow heat exchange assembly. The arrays additionally have connector portions that connect the vertically adjacent conduits to each other. The evaporative apparatus also includes a plurality of generally vertical partitions each extending between at least some of the conduits in each of the arrays and at least some of the partitions extending between less than all conduits of each of the arrays.
In accordance with another embodiment of the present invention, an evaporative apparatus for use in a counter flow heat exchange is provided having a means for exchanging heat from a substance to be cooled having a first height, and a means for spraying a cooling fluid onto the heat exchanging means. The evaporative apparatus additionally has a means for passing air over the heat exchanging means along with a means for partitioning the cooling fluid and the air. The partitioning means includes a plurality of generally vertical partitions each having a second height less than the first height of the heat exchanging means.
In accordance with yet another embodiment of the invention, an evaporative apparatus for use in a counter flow heat exchange assembly is provided having a plurality of generally vertical arrays adjacently spaced laterally to each other. The arrays are each arranged along respective generally vertical centerlines and include a plurality of generally horizontal conduits. The arrays each have a diameter and extend across the heat exchange assembly in spaced relation to each other at different vertical levels of the counter flow heat exchange assembly. The arrays have connector portions for connecting vertically adjacent conduits to each other, and the adjacent vertical arrays ha
Stratman Jason
Yang Jidong
Baker & Hostetler LLP
Marley Cooling Technologies, Inc.
McKinnon Terrell
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