預測空氣乾燥用吸附塔內空氣－吸附劑間熱傳與質傳過程之數學模型

A mathematical model for prediction of the heat and mass transfer process between the air and desiccant in a desiccant tower for air drying

盧勁宏(Jing-Hung Lu)；洪偉倫(Wei-Lun Hung)；陳鈞振(Jiun-Jen Chen)

吸附塔 ； 空氣乾燥 ； 數學模型 ； desiccant tower ； air drying ； mathematical model

冷凍空調&能源科技

136期（2022 / 11 / 10）

93 - 99

繁體中文

為協助設計空氣乾燥用之吸附塔，本文建立一數學模型描述塔內空氣與吸附劑間熱傳與質傳現象，透過數值方法求解可計算運轉時塔內各位置空氣溫濕度、吸附劑含水量等狀態參數隨時間變化。該模型可用於評估吸附塔性能或是找出最佳化設計條件，並且在採用新型吸附劑之設計上預期比傳統設計方式更具優勢。已知吸附塔運轉普遍包含再生與吸附乾燥階段，本文將兩種階段之計算結果與實際案例比較。結果顯示計算之塔出口氣溫於再生時出現與實際案例相同之破出現象，而算出之塔出口空氣露點於吸附乾燥時亦可見此情形。雖然計算之準確度尚需更進階研究後方可評估，但此結果已顯示本文模型可正確預測空氣通過吸附塔後之溫濕度變化趨勢。

To aid the design of desiccant towers for air drying, a mathematical model is developed in this study that describes the heat and mass transfer between the air and desiccant in a tower. Solving the model's governing equations numerically yields the temperatures and water contents of air and desiccant at different locations in the tower, at different time during its working process. This model can be used to evaluate the performance of a tower or to optimize its design parameters. Also, the model is expected to have an edge over traditional design methods when it comes to designing a tower containing novel desiccant materials. Since the working of a desiccant tower generally includes a regeneration and an adsorptive-drying process, in this study the model predictions of both processes are compared to the data of commercial desiccant towers. The results show that the predicted air temperature at the tower outlet undergoes a ＂breakthrough＂ during regeneration, and so do the commercial towers. The resemblance in behavior with commercial towers can also be found for the predicted dew point temperature of the air at tower outlet during adsorptive-drying. Although evaluating the accuracy of the model still requires further research, the results of this study indicate that the model can correctly predict the temperature and water content of the air going through the tower in terms of behavior.

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