Comparison of the Airside Performance of Fin-and-Tube Heat Exchangers Under Wet Condition – Effects of Fin Pattern and Tube Geometry

In this study, wet surface j and f factors were obtained for spiral fin-and-tube heat exchangers. Nine samples having different fin pitches (2.12, 2.54 and 3.18 mm) and different tube rows (1, 2 and 3 row) were tested. Data are compared with those of the dry surface. For the wet surface, the effect of fin pitch on j factor is not significant. However, f factor decreases as the number of tube row increases. The j factor increases as the number of tube row increases. Different from the j factor, f factor decreases as the number of tube row increases. At one row configuration, the dry surface j factor is larger than that of the wet surface one. As the number of tube row increases, the trend is gradually reversed. Possible reasoning is provided considering the condensate behavior under wet condition. A new j and f factor correlation is developed, which predicts j and f factors within ± 20% and ± 30%, respectively.

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The New Mathematical Models for Plain Fin-and-Tube Heat Exchangers With Dehumidification

Journal of Heat Transfer ◽

10.1115/1.4029037 ◽

2015 ◽

Vol 137 (3) ◽

Cited By ~ 1

Author(s):

Worachest Pirompugd ◽

Chi-Chuan Wang ◽

Somchai Wongwises

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Heat Exchangers ◽

Heat Transfer Performance ◽

Transfer Performance ◽

Fin Efficiency ◽

Tube Heat Exchanger ◽

Model Based ◽

Transfer Characteristics ◽

Wet Condition

For evaluating performance of fin-and-tube heat exchangers under dehumidifying conditions, the recent lumped approach models are based on the enthalpy potential or equivalent dry bulb temperature. This study proposes a new lumped approach model based on the dry bulb temperature difference. The concept of dry bulb temperature was first presented by McQuiston for derivation of fin efficiency under dehumidifying conditions in 1975. This concept is simpler than the concepts of enthalpy potential and equivalent dry bulb temperature. Nevertheless, it cannot be found that this concept is applied to the fin-and-tube heat exchangers. Moreover, this study also presents the finite circular fin method (FCFM) based on the dry bulb temperature and equivalent dry bulb temperature. The FCFM was first presented in our published literature but it was based on the enthalpy potential. The FCFM is done by dividing the fin-and-tube heat exchanger into many small segments. Then, the segments are divided into three cases: fully dry condition, fully wet condition, and partially wet condition. From the results, the new lumped approach model based on dry bulb temperature gives a good result. It is the simplest method for evaluating heat transfer performance of fin-and-tube heat exchangers under fully wet conditions. For the FCFM, the heat and mass transfer characteristics obtained by dry bulb temperature and equivalent dry bulb temperature are nearly the same as those obtained by the enthalpy potential. However, the heat and mass transfer characteristics by the FCFM based on equivalent dry bulb temperature are higher than those obtained by the FCFM based on dry bulb temperature. This is because of the effect of the nonconstant term in the two methods. The correlations applicable for both fully wet and partially wet conditions for the FCFMs based on equivalent dry bulb temperature and dry bulb temperature are proposed to describe the heat and mass transfer characteristics for the present plain fin configuration.

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Air-side heat transfer and pressure drop of the fin-and-tube heat exchangers having oval tubes under wet condition

Heat and Mass Transfer ◽

10.1007/s00231-021-03058-1 ◽

2021 ◽

Author(s):

Nae-Hyun Kim

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Heat Exchangers ◽

Wet Condition

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Airside performance of fin-and-tube heat exchangers having sine wave fins under wet condition

Journal of Mechanical Science and Technology ◽

10.1007/s12206-015-0852-0 ◽

2015 ◽

Vol 29 (9) ◽

pp. 4061-4070 ◽

Cited By ~ 2

Author(s):

Nae-Hyun Kim

Keyword(s):

Heat Exchangers ◽

Sine Wave ◽

Wet Condition

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Airside Performance of Fin-and-Tube Heat Exchangers Having Nonrepeating Nonsymmetrical Slit Fins under Wet Condition

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132519500330 ◽

2019 ◽

Vol 27 (04) ◽

pp. 1950033 ◽

Cited By ~ 2

Author(s):

Nae-Hyun Kim

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Water Film ◽

Finned Tube ◽

Heat Transfer Characteristics ◽

Wet Condition ◽

Study Heat Transfer ◽

The Many ◽

The One ◽

Thin Water Film

In this study, heat-transfer and friction characteristics of newly developed nonsymmetric slit-finned-tube heat exchangers are experimentally investigated. The newly developed slit fin had more slits in the second row than the first row. As a result, different row effect on [Formula: see text] factor than that of conventional enhanced finned-tube heat exchangers was observed. In other words, two-row configuration yielded larger [Formula: see text] factor than the one-row configuration. Comparison with conventional louver fin or slit fin heat exchangers revealed that the present slit fin heat exchangers show superior heat-transfer characteristics, especially at the second row. The reason was attributed to the many narrow slits that formed at the second row, which maintain thin water film along the slits and smooth the condensate flow.

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