Appeal No. 2000-1638
Application No. 08/829,699
walls due to coolant vapor flowing inside the pipe. As a
result, the dry-out point is delayed to a higher dryness
region and evaporation performance is improved. Condensation
performance also is improved by increasing the heat transfer
area and turbulence effect by the projections (translation,
pages 7-8).
Asaumi discloses another heat exchanger pipe that can
selectively perform a condensation and an evaporation in the
same pipe at high performance (translation, page 1). Asaumi's
heat exchanger pipe 1 is provided with spiral fins 2 on the
inner surface thereof. The fins are notched (notches 4) at
the intersection with a virtual spiral in the reverse
direction (translation, page 3). As explained by Asaumi
(translation, page 4), the spiral fins 2 increase the
effective heat exchange area; however, when continuous fins 2
are used, a liquid film of condensation liquid can form in the
grooves 6 between the fins. The notches 4 in the fins 2
permit the condensation liquid to quickly flow down. This
improves condensation performance. However, as pointed out on
page 6 of the translation, a pipe with spiral notch fins,
while achieving good condensation performance, is unacceptable
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Last modified: November 3, 2007