Effect of variable ambient temperature on fin efficiency in a two-dimensional flow passage

Jorma Heikkinen

Research output: Contribution to journalArticleScientificpeer-review


The fin efficiency in a heat exchanger element that is a simplification of one row in a tube-and-fin heat exchanger was theoretically examined within wide ranges of the affecting variables: the conventional fin efficiency and the isothermal effectiveness of the heat exchanger. These variables are suggested for use also in the further studies. An analytical solution can be found for the case of a constant heat transfer coefficient. The ambient temperature variation alone decreases the fin efficiency less than 4%. The local heat transfer coefficient obtained from the numerical fluid flow simulations is strongly affected by the fin properties because the thermal boundary conditions for the fluid flow changes. On a poorly conducting fin surface the heat transfer coefficient in front of the fin base is much larger than on an isothermal fin because the heat flux is increasing in the flow direction. At low fin efficiencies this compensates for the decrease in fin efficiency due to ambient temperature variation. (14 refs.)
Original languageEnglish
Pages (from-to)341-350
JournalHeat and Mass Transfer
Issue number4
Publication statusPublished - 2007
MoE publication typeA1 Journal article-refereed


  • fin efficiency
  • heat exchangers
  • heat flows
  • heat transfer


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