(57) Apparatus and a process of heat transfer employ a fluid flow passage in which the
flow consists of non-turbulent boundary-layers adjacent the surfaces and a non-turbulent
core-layer between the boundary-layers and interfacing therewith. An interrupter-structure
is disposed within the flow passage and interrupts the full development of the boundary-layers
at a multitude of spaced spots, leaving the heat transfer surfaces unaltered, unmodified
and uninterrupted, so that the boundary-layers cannot increase in thickness but will
partially separate from the surfaces and mix non-turbulently with the core-layer to
effect the required heat transfer between the walls and the fluid. The interrupter-structure
preferably consists of a plurality of spheres, or a sheet in which spherical, elliptical,
drop-shaped or egg-shaped protrusions have been formed, all of which can be obtained
readily on the market place at very low cost. This is to be contrasted with prior
art apparatus which increase the heat exchange by rendering the fluid turbulent e.g.
by turbulence promoters or roughening, ridging or interrupting the heat transfer walls.
The increased turbulence increases heat transfer but produces a proportionally much
greater increase in pumping power that makes these proposals uneconomic for many applications.
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