The subject invention relates to heat exchangers of the fin-and-tube type with an improved louver configuration.
Fin-and-tube type heat exchangers are well known in the art. These heat exchangers include a number of fins with heat transfer tubes passing therethrough. The fins typically incorporate a number of louvers to redirect and mix the air flow across the fins to increase the heat transfer between the surfaces of the heat exchanger, which include the surfaces of the fins and the outside surfaces of the tubes, and the air flow. One issue that arises when disrupting the air flow is a pressure drop across the fins. A significant increase in the pressure drop across the fins is the penalty paid for the increased heat transfer.
Therefore, there is a need for improved louvered fin designs for fin and tube heat exchangers that improve heat dissipation characteristics while reducing pressure drop in fluid flowing across the fin. Those skilled in the art will better understand the present invention from a review of the preferred embodiment and drawings that appear below and the claims that determine the full scope of the invention.
In accordance with certain embodiments, a cooler for multiple tube banks features a series of parallel and planar fins that have upstream louvers to direct incoming air through a fin near a first row of tubes and a downstream set of louvers near an adjacent tube row to direct air back through the same fin before the air exits. The upstream louvers can have the negative slopes of the downstream louvers, and a constant angle from louver to louver within a bank can be provided. Moreover, a constant length in a section view is also contemplated.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Air coolers are generally known to those skilled in the art. They comprise cooling tubes disposed parallel to each other in rows and the rows being parallel to each other. A collection of fins are generally stacked parallel to each other with a typical, exemplary fin 10 shown in
The upstream louvers are generally 36 and the downstream louvers are generally 38. These two louver banks 36, 38 align generally with and extend adjacent to a respective row of openings 11, 19 for tubes, and the louver banks 36, 38 generally define curved perimeters 39 tracking contours 41 of the openings 11, 19. This forces air that comes in between openings 24 and 26 to work its way around opening 16 since the tubes (not shown) that go in their respective holes are offset from one row to the next. The louvers can be punched out of the fin 10. As illustrated, they all extend above and below a fin but variations can be used where some or all louvers in the upstream bank 36 extend only from the top and some up to all louvers in bank 38 extend only from the bottom.
Now looking at
The desired effect at a single fin 10 is in part illustrated in
Those skilled in the art will appreciate that changes can be made in the optimization process. What is optimized is a collection of variables that relate to cost, pressure drop, overall size and thermal performance. Commonality of patterns such as louver dimensions and angles saves cost; hence the preferred embodiment emphasizes such patterns. In the present invention the mixing of the air stream in an over, under and back to over pattern helps the thermal performance. Using planar fins saves cost. Spreading out the over, under and over pattern through two or more rows of tubes also promotes thermal performance and saves cost. The
Again, the above description is illustrative of exemplary embodiments, and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.
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JP 55118596 Translation. |
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Singapore Written Opinion for Singapore Application No. 200900583-6 dated Nov. 2, 2009. |
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