EXPERIMENTAL INVESTIGATION OF FLAT TUBE-LOUVER FIN HEAT EXCHANGER PERFORMANCE WORKING AS A COOLER IN DRY AND WET CONDITIONS

摘要

An experimental study has been conducted to evaluate the performance of a flat-tube louver-fin heat exchanger working as a cooler, with frontal area of 0.25 m~2 in both dry and wet conditions. Deluge water cooling at different flow rates was achieved by incorporating perforated tube-type distributor on top of the heat exchanger. Water at 35°C temperature was used as heat transfer fluid at cooler inlet. Ambient air and deluge cooling water were both maintained at 22°C temperature. Heat exchanger capacity and air-side pressure drop were measured with the heat exchanger angle set at 0° and 21° from vertical, with a frontal air velocity of 1.4 m/s and 3.5 m/s without deluge water cooling, and a frontal air velocity of 1.2 m/s, 1.4 m/s with deluge water cooling. Significant capacity enhancement could be obtained both with the use of deluge water cooling and with the heat exchanger angle set at 21° from vertical. Furthermore, it was found that approximately same capacity was obtained at both 0° and 21° angle when wetting water flow rate was reduced from 0.17 kg/s to 0.063 kg/s, without significant reduction in air-side pressure drop. This study highlights the importance of wetting of heat transfer surfaces of compact flat tube heat exchangers and provides motivation for further research in this area.