Appeal No. 1999-0404 Page 8
Application No. 08/580,256
optimized for use in one application frequently does not
perform as well when used in the other application. To
obtain maximum performance in a given system under these
circumstances, it would be necessary to use two types of
tubing, one for each functional application. But there is
at least one type of AC&R system where a given heat
exchanger must perform both functions, i.e. a reversible
vapor compression or heat pump type air conditioning
system. It is not possible to optimize a given heat
exchanger for a single function in such a system and the
heat transfer tube selected must be able to perform both
functions well.
Chiang discloses that the configuration of the enhancement
gives improved heat transfer performance both in a condensing
and an evaporating application.
Figure 1 of Chiang shows, in an overall isometric view, a
heat transfer tube 50 including a tube wall 51 having an
internal surface enhancement 52. Figure 2 depicts heat
transfer tube 50 in a cross sectioned elevation view wherein
only a single rib 53 and a single notch 54 of surface
enhancement 52 is shown for clarity, but in the tube of
Chiang's invention, a plurality of ribs 53 (all parallel to
each other) extend out from wall 51 of tube 50. Rib 53 is
inclined at helix angle " from tube longitudinal axis a .
T
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