| Title |
An Experimental Study on the Effect of the Air Temperature on the Air-Side Heat-Transfer Coefficient and the Friction Factor of a Fin-and-Tube Heat Exchanger |
| Authors |
Nae-Hyun Kim ; Honggi Cho |
| DOI |
https://dx.doi.org/10.6110/KJACR.2017.29.4.149 |
| Keywords |
공기측 성능 ; 핀-관 열교환기 ; 열전달계수 ; 마찰계수 Air-side performance ; Fin-and-tube heat exchanger ; Heat transfer coefficient ; Friction factor |
| Abstract |
In general, the air-side j and f factors of evaporators or condensers are obtained through single-design tests performed under air-dry and wet-bulb temperatures. Considering that the indoor or outdoor air temperatures vary significantly during the operation of an air conditioner, it is necessary to confirm that the experimentally-obtained j and f factors are widely applicable under variable air conditions. In this study, a series of tests were conducted on a two-row slit-finned heat exchanger to confirm the applicability. The results showed that, for the dry-surface condition, the changes of the tube-side water temperature, water-flow rate, and air temperature had virtually no effect on the air-side j and f factors. For the wet condition, however, the f factor was significantly affected by these changes; contrarily, the j factor is relatively independent regarding this change. The formulation of the possible reasoning is in consideration of the condensation behavior underneath the tube. The wet-surface j and f factors are larger than those of the dry surface, with a larger amount for the f factor. |