濕空氣流經熱交換器表面時，倘若其表面溫度低於濕空氣露點，濕空氣內的水蒸氣將冷凝成水滴，附著於鰭片上形成水膜。此時熱交換器同時具有溫差造成的顯熱熱傳及濃度差產生的潛熱熱傳。
本文主要目的即是分別以理論分析與數值模擬討論熱交換器於除濕過程中熱、質傳效益。數值模擬方面則是使用商業套裝軟體ANSYS CFX搭配Wall Condensation Model進行計算，分別對矩形管、矩形鰭片與板鰭管式熱交換器三種模型進行三維數值模擬，再將模擬結果與理論得出之一維近似解進行比對。
從矩形管模擬結果可以發現，當加快進口流速時，熱、質傳係數及總熱傳係數皆有顯著提升。將模擬結果與一維近似解進行比對後，發現近似解會以0.6 ~ 16.2(%)之誤差稍微高估顯熱熱傳係數，並以2.1~ 18.1(%)之誤差低估質傳係數，且質傳係數之誤差會隨進口流速增加而增加，最終近似解會以7.2 ~ 19.1(%)之誤差低估總熱傳係數。
從矩形鰭片模擬結果可以發現，鰭片狀況可以依濕空氣凝結水產生多寡分為全乾、半乾濕及全濕狀態。當鰭片處於全乾或全濕狀態時，增加空氣相對濕度僅令鰭片效率略微下降，但於半乾濕狀態時則隨空氣相對濕度增加迅速下降，而全乾狀態之鰭片效率均較全濕狀態高出15 ~ 20(%)左右。比較一維近似解與模擬結果，發現進口流速越高，近似解會越低估鰭片效率。而乾、濕鰭片效率最大誤差皆出現在進口流速5 (m/s)之情況，誤差分別為14.56(%) 與38.45(%)。
從板鰭管熱交換器模擬結果可發現，濕空氣自進口流入熱交換器後，受到管群干擾導致其背風側出現渦流，而管群亦會阻礙空氣通行，使流道縮減區的流速加快，進而提升該處顯熱熱傳係數與質傳係數。鰭片效率表現則與矩形鰭片模擬結果趨勢相同。比較一維近似解與模擬結果，熱交換器處於乾盤管狀態時，近似解會稍微高估顯熱熱傳係數及低估鰭片效率，兩者平均誤差皆在10(%)左右；而熱交換器若處於濕盤管狀態，近似解則會大幅高估顯熱熱傳係數與質傳係數，並大幅低估鰭片效率。

The purpose of the study was to investigate the heat and mass transfer performance of the fin-tube heat exchanger by using theoretical and CFD analysis. The study used Threlkeld method to calculate 1-D approximate solution for wet coil heat exchanger. In order to verify the accuracy of the approximate solution, the study also used ANSYS CFX with Wall Condensation Model to compute the 3-D flow fluid analysis with rectangular tube, rectangular fin, plate fin-tube heat exchanger models and to calculate their heat, mass transfer coefficient and overall heat transfer coefficient. Finally, compare the results of numerical simulation with those of 1-D approximate solution.
According to the results of the rectangular tube model, it can be found that the heat, mass transfer coefficient and overall heat transfer coefficient were significantly improved when increasing the inlet flow rate. After comparing the simulation results with the 1-D approximate solution, approximate solution overestimated heat transfer coefficient with the errors of 0.6~16.2% and underestimated mass transfer coefficient with the errors of 2.1~18.1%. Finally, approximate solution overestimated overall heat transfer coefficient with the errors of 7.2~19.1% .
Based on the results of the rectangular fin model, it can be found that fin efficiency will change along with inlet relative humidity. The situation of the fin was divided into three parts: dry-coil, half-dry-half-wet, wet-coil. Dry fin efficiency was 15~20% higher than wet fin efficiency. After comparing the simulation results with the 1-D approximate solution, the errors of the fin efficiency were increased when increasing the inlet flow rate. The max errors of dry and wet fin efficiency were 14.56% and 38.45% respectively.
At last, according to the results of the plate fin-tube heat exchanger model, when moist air went through the heat exchanger, the vortex appeared on the leeward side because of disturbance from the tube bank. Simultaneously, obstruction from the tube bank also led to enhancement of air flow rate. Therefore, its heat and mass transfer coefficient were improved. Furthermore, Fin efficiency performance was the same as the trend of rectangular fin model results. After comparing the simulation results with the 1-D approximate solution, approximate solution overestimated heat transfer coefficient and underestimated fin efficiency at dry coil condition, both errors were around 10%. In contrast, approximate solution overestimated heat, mass transfer coefficient and underestimated fin efficiency at wet coil condition substantially.

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