The Influence of Brazing on Very Compact Heat Exchanger Surfaces
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چکیده
Three geometrically similar offset rectangular platefin surfaces with area densities in the range from goo to 2000 ft 2/ft3 were tested to establish the heat transfer., j-NR~ and flow friction, f-NR, characteristics. The Reynolds number range was from 60 to 3000. One surface was unbrazed while the other two, because of a two-to-one difference in plate, fin and offset spacing dimensions~ were characterized by different degrees of brazing 11 roughness 11 • The test results reveal a relatively small effect of brazing on j-NR but a significant influence on f-NR with ~ , a 35 to 50 percent higher friction for the brazed surface. There is an 11 area penalty'' of 14 percent due to brazing associated with the complete coverage of the interface area at the brazed joints. The magnitude of this penalty depends on the geometry of the surface .
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