NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Longitudinal Heat Conduction in Finned-Tube Evaporators.


pdf icon Longitudinal Heat Conduction in Finned-Tube Evaporators. (404 K)
Domanski, P. A.; Choi, J. M.; Payne, W. V.

ARTI-21CR/605-5005-01;

Refrigeration Creates the Future. International Congress of Refirgeration 2007, 22nd IIR. ICR 2007. August 21-26, 2007, Beijing, China, 1-8 pp, 2007.

Sponsor:

Heating Refrigeration Air Conditioning Institute, Canada

Keywords:

refrigeration; evaporators; heat conduction; experiments; tests; heat exchangers

Abstract:

The paper evaluates performance of finned-tube evaporators at different refrigerant exit superheats to assess the impact of longitudinal heat conduction on capacity. A combination of capacity measurements obtained from laboratory testing, the pattern of measured return bend temperatures, and the theoretical analysis suggests the occurrence of tube-to-tube transfer via fins and rejects the tube longitudinal heat transfer as the possible causes of capacity degradation. The impact of tube-to-tube heat transfer was negligible in tests with a uniform 5.6DGC superheat, but it was significant in tests involving 16.7DGC superheat. The measured difference in capacity between two evaporators - in one of which tube-to-tube heat transfer was prevented by cuts in common fins - was as much as 23%. The level of capacity degradation was affected by air volumetric flow rate.