| Finned tube heat exchangers are applied in industry for a long time, while the heat transfer enhancement of the finned tube heat exchangers has become one of the important research area in academia. Academician Guo zengyuan analyzed the mechanism of heat transfer enhancement from the new view of field and originally advanced the field synergy principle of heat transfer enhancement . Based on the field synergy principle of heat transfer enhancement, the uniformity of temperature difference field of the finned tube heat-exchanger has been deeply researched in this article.In this article, the general situation of development on the finned tube heat exchanger in recent years has been summarized and the field synergy principle of heat transfer enhancement as well as the applications in heat transfer enhancement of the heat exchangers have also been presented . An experiment has been designed to measure the efficiency of the finned tube heat exchangers and the uniformity factor of the TDF. Eleven finned tube heat exchangers with different kinds of changed flow circuitries are compared with the one that is originally used as the condenser of a window—type air-condition.Some results can be indicated in the experiment. The pressure loss in the water side of finned tube heat exchanger are equal at the same flow mass rate of water,velocity of air and the same arrangement of branch flow, the more uniform of the TDF, the higher efficiency of the finned tube heat exchanger. the more uniform of the TDF, the higher efficiency of the finned tube heat exchanger. The validity of the principle of the TDF is confirmed by the result. At the same flow rate of water, the uniformity factor of the TDF in the finned tube heat exchanger will decrease when the air velocity increases, and the efficiency will increase when the air velocity increases. When the air velocity increases, the uniformity of the TDF in the finned tube heat exchanger will become worse,so the increase of the efficiency will become slow. At the same velocity of air, when the flow of water rate increases, the efficiency of the finned tube heat exchanger will minish, the uniformity factor of the TDF will increase firstly and then decrease. At the same velocity of air , there is a optimized flow rate which attains the best uniformity of the TDF. The arrangement of branch flow is an efficient way to minish the pressure loss and improve the uniformity of the TDF in the finned tube heat exchanger. The efficiency of original condenser can be improved,by improving its uniformity of the TDF . |
