Technology - Fintube Products - Comparison of Absorber Plates

Comparison of Various Absorber Technologies

Ultrasonic Weld:
The ultrasonic welded fin tube is very similar in appearance to Thermafin's, but there the similarity ends. Ultrasonic welding does not create a true fused joint and it actually weakens the copper fin which may cause a heat flow restriction. This is due a reduction in the thickness of the fins at the edge of the weld zone. Another result of this process is fin breakage at the edge of the weld.

Integral Construction -
same tube wall & sheet surface:

The tube and wall must be thick enough to withstand fluid pressure and prevent corrosion. The absorber sheet, in turn, is necessarily twice as thick as the tube wall, resulting in an ultra-thick plate that weighs almost twice as much and cost 50 % more than the tube and fin absorber, yet provides only a small gain in efficiency.

Tube & Fin Construction -
Mechanical Joining:

The mechanical joint is the simplest construction, but it offers comparatively poor thermal conductivity. To overcome this problem, the contact area must be large and the joint must be uniformly tight (requiring wrapping the fin around most or all of the tube). However, when the joint loosens with age and thermal cycling and develops a gap, or when the contacting surfaces corrode, the heat transfer capability will be greatly reduced.

Tube & Fin Construction -
Adhesive or Solder Bonding:

Although solder or adhesive bonding avoids certain of the problems of mechanical joining, low thermal conductivity remains a problem. To provide sufficient heat flow from fin to tube, both a large contact area and a thin, continuous layer of the bonding agent are necessary, and this bonding agent can deteriorate with aging and thermal cycling.

Thermafin Construction - EMF-Weld:
Because the Thermafin forge-welded joint has the same conductivity as the fin material, there is no need to make the joint wider than the thickness of the fin. Since there are really, two ''fins", one on each side of the tube, the Thermafin joint is made at least twice as wide as the thickness of a single fin. This special invention is a development from Thermafin Manufacturing and is patented.

No wrap around is needed. Heat enters the tube through a channel that is the same width as the fin. As heat comes only from the fin, a wider joint would serve no purpose -any more than putting a wide bulge in the middle of a garden house would allow any more water to flow out the end.

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