Appeal 2006-1847
Application 10/295,813
FINDINGS OF FACT
We agree with Appellant that Suzuki discloses a heat transfer pipe
with integral outer fins and integral inner fins extending helically at a helix
angle measured against the tube axis with primary grooves on the inside of
the tube and secondary grooves at a second helically angle measured against
the tube axis as illustrated in Figure 1. Apparently, the primary and
secondary grooves have the same depth and result in a uniform structure as
shown in Figure 4. The secondary grooves extend in an opposite direction
compared to the primary grooves. Suzuki does not disclose the exact values
for the parameters claimed in the independent claims.
All of the references cited by the examiner evince a recognition in the
art that the inner structured area of a heat exchanger tube should beneficially
break up the boundary layers near the tube wall and provide greater surface
area for heat exchange contact. On the other hand, the structured area on the
inner wall of the tube must not result in an inordinate increase in the flow
resistance.
It is the examiner’s finding, discussed on pages 6 and 7 of the
Answer that the Chiang reference teaches that the helix angle α of the inner
fin, the angle γ of the secondary grooves with respect to the primary
grooves, and the depth of the secondary grooves are result effective
variables well known in this art for optimization of heat exchange in heat
exchanger tubes.
The examiner further finds that Suzuki discloses that the height of the
ribs or fins, the depth of the secondary grooves relative to the fin height and
the angle of secondary grooves are result effective variables. The examiner
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Last modified: September 9, 2013