在台灣潮濕的氣候條件下，除濕機成為了維持室內環境舒適和人體健康的重要家電。本論文針對應用於家用型的空氣源熱泵除濕機(air source heat pump dehumidifiers, ASHPDs)進行研究，討論提升除濕機效率的方法，以及建構一熱交換器之熱傳率保持固定的除濕機熱流場模型，以期望解析出除濕機內部濕度分布及冷凝出液態水的能力。為了達成上述目標，本研究以計算流體力學進行數值分析與優化，以及利用實驗量測驗證計算結果。在實驗量測方面，一共進行了葉輪轉速、出口風量、出口溫度、以及蒸氣冷凍循環各狀態節點的溫度與壓力之量測；在數值計算方面，根據理論基礎及實際情形建立統御方程式與邊界條件，以及建構出具有可信度的流場與熱流場數值模型，以前述之實驗量測數據驗證之，並對於計算結果進行工程分析與討論。
在目前的結果中，已透過針對葉輪相位、出口柵欄表面與葉輪切環上進行定量分析，了解流場之分布特性，並且計算結果與實驗之出口流量誤差皆小於5 %，即完成流場驗證，因此以此模型進行流場優化。研究中透過NACA四位數翼型之定義方法優化分析，並歸納出較佳出口風量的扇葉應為刀片型形狀，透過對於定義的參數進行敏感度分析，最終已成功找出最佳的扇葉參數組合以得出其幾何形狀，其結果與原型扇葉相比，提升了33.4 %的出口風量，也就是提高了除濕機之效率。另外也透過紊流強度分析最佳扇葉之潛在聲噪，因最佳扇葉的紊流強度大小與位置分布皆近乎與原型扇葉相同，表示其聲噪在可接受範圍內。而針對熱流場模型，研究中將熱交換器結構簡化，並將內部銅管來自冷媒的熱量，利用熱力學性質計算而簡化為固定的吸、放熱傳率，並在銅管之間給定固定的空氣間隙，目的在於找到與實際熱交換器相同的等效流阻，最終在空氣間隙為2.22 mm、蒸氣冷凍循環狀態1之乾度為0.88時，找到熱交換器之熱傳率保持固定的除濕機熱流場模型。

In this work we aim to enhance the performance of air source heat pump dehumidifiers (ASHPDs) for household use in Taiwan's humid climate. To that end, a thermofluid model of dehumidifier with prescribed heat exchange rate is constructed. Based upon the model, numerical computations are carried out to calculate the distributions of significant thermofluid variables—such as the velocity, pressure, temperature and humidity of air—in a dehumidifier. And the numerically calculated air flow rate through the dehumidifier agrees with experimental measurement within a 5% discrepancy for the prescribed impeller speeds of 500, 600, and 700 rpm. The calculated thermofluid fields also are examined and physically interpreted. Then we attempt to optimize the blade geometry.
Initially, to facilitate the optimization of blade geometry, the NACA four-digit airfoil definition method is utilized to describe the blade geometry, thereby reducing the task to finding the optimal combination of just three parameters, namely the camber, location of maximum camber, and thickness of the blade/airfoil. It then transpires that a knife-type blade tends to maximize the air flow rate under the impeller speeds prescribed above. Sensitivity analysis of the knife-type blade parameters, namely its base width, base-circle radius, angle of attack, and total number, then is carried out systematically, which yields a particular knife-type blade geometry that would increase the air flow rate by as much as 33.4% compared with the existing prototype. Meanwhile, the calculated turbulence intensity of the air flow in the dehumidifier confirms that the noise level produced by the optimized knife-type blade geometry would not exceeds that of the existing prototype, and thus should also be acceptable.
As mentioned above, in the present model, the heat exchanger module is greatly simplified, and the heat transfer to and from the air is prescribed based upon the thermodynamic states of the refrigerant measured at the inlet and outlet of the heat exchanger. Moreover, an equivalent flow resistance is determined by setting a fixed air gap between copper tubes. Specifically, with an air gap of 2.22 mm and a vapor quality of 0.88 at the beginning of the vapor compression cycle, satisfactory agreement between the numerical and experimental results is obtained.

[1]“氣候月平均 | 交通部中央氣象署.” Accessed: Jun. 03, 2024. [Online]. Available: https://www.cwa.gov.tw/V8/C/C/Statistics/monthlymean.html
[2]“Dehumidifier Market Size to Hit USD 5.17 Billion by 2033.” Accessed: Jun. 03, 2024. [Online]. Available: https://www.precedenceresearch.com/dehumidifier-market
[3]M. I. Fadhel, K. Sopian, and W. R. W. Daud, “Performance analysis of solar-assisted chemical heat-pump dryer,” Solar Energy, vol. 84, no. 11, 2010.
[4]H. Ogura, T. Yamamoto, Y. Otsubo, H. Ishida, H. Kage, and A. S. Mujumdar, “A control strategy for a chemical heat pump dryer,” Drying Technology, vol. 23, no. 6, 2005.
[5]C. G. Carrington and Q. Liu, “Calorimeter measurements of a heat pump dehumidifier: Influence of evaporator air flow,” Int J Energy Res, vol. 19, no. 8, 1995.
[6]X. Q. Duong and J. D. Chung, “Numerical Analysis of a Compressor Type of Dehumidifier: (I) Fluid Flow,” International Journal of Air-Conditioning and Refrigeration, vol. 25, no. 2, 2017.
[7]S. Choudhary, R. R. Patil, and P. S. Jadhav, “Comparative Analysis between Backward Inclined and Backward Curved Blades of Centrifugal Fan,” International Journal of Innovative Research in Science, Engineering and Technology (An ISO, vol. 3297, 2007.
[8]A. K. Latt, S. Y. Htwe, T. S. Tin, and M. Zaw, “Design comparison of forward and backward curved radial tip blades for centrifugal blower,” Iconic Research And Engineering Journals, vol. 2, no. 5, 2018.
[9]O. P. Singh, R. Khilwani, O. P. Singh, T. Sreenivasulu, and M. Kannan, “Parametric Study of Centrifugal Fan Performance: Experiments and Numerical Simulation,” 2011.
[10]G. Shankaran and M. B. Dogruoz, “Advances in fan modeling - Using Multiple Reference Frame (MRF) approach on blowers,” in ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems, InterPACK 2011, 2011.
[11]C. K. Huang and M. E. Hsieh, “Performance analysis and optimized design of Backward-Curved airfoil centrifugal blowers,” HVAC and R Research, vol. 15, no. 3, 2009.
[12]S. C. Lin and C. L. Huang, “An integrated experimental and numerical study of forward-curved centrifugal fan,” Exp Therm Fluid Sci, vol. 26, no. 5, 2002.
[13]D. Banks, An introduction to thermogeology: Ground source heating and cooling: Second edition. 2012.
[14]L. J. Goh, M. Y. Othman, S. Mat, H. Ruslan, and K. Sopian, “Review of heat pump systems for drying application,” 2011.
[15]M. Fatouh, M. N. Metwally, A. B. Helali, and M. H. Shedid, “Herbs drying using a heat pump dryer,” Energy Convers Manag, vol. 47, no. 15–16, 2006.
[16]F. Salehi, “Recent Applications of Heat Pump Dryer for Drying of Fruit Crops: A Review,” 2021.
[17]K. Chapchaimoh, N. Poomsa-Ad, L. Wiset, and J. Morris, “Thermal characteristics of heat pump dryer for ginger drying,” Appl Therm Eng, vol. 95, 2016.
[18]S. Prasertsan and P. Saen-saby, “Heat pump drying of agricultural materials,” Drying Technology, vol. 16, no. 1–2, 1998.
[19]W. Su, W. Li, B. Sun, and X. Zhang, “Experimental study and correlations for heat and mass transfer coefficients in the dehumidifier of a frost-free heat pump system,” Int J Heat Mass Transf, vol. 131, 2019.
[20]V. R. Pendyala, D. S., and P. V. S., “Heat‐pump‐assisted dryer part 1: Mathematical model,” Int J Energy Res, vol. 14, no. 5, 1990.
[21]X. Jia, P. Jolly, and S. Clements, “Heat pump assisted continuous drying part 2: Simulation results,” Int J Energy Res, vol. 14, no. 7, 1990.
[22]S. Clements, X. Jia, and P. Jolly, “Experimental verification of a heat pump assisted continuous dryer simulation model,” Int J Energy Res, vol. 17, no. 1, 1993.
[23]K. J. Chua, S. K. Chou, J. C. Ho, and M. N. A. Hawlader, “Heat pump drying: Recent developments and future trends,” Drying Technology, vol. 20, no. 8, 2002.
[24]A. Y. Cengel and A. B. Michael, Thermodynamics An Engineering Approach Eighth Edition, vol. 53, no. 9. 2014.
[25]W. X. Chu, C. H. Chiu, and C. C. Wang, “Improvement on dehumidifier performance using a plastic assisted condenser,” Appl Therm Eng, vol. 167, 2020.
[26]“如何利用閃頻儀測試轉速?” Accessed: Jun. 13, 2024. [Online]. Available: https://www.sugawara-labs.co.jp/cn/guide/strobe/measuring_rotation_speed
[27]“Thermocouple (2024) Wikipedia.” Accessed: Jun. 13, 2024. [Online]. Available: https://en.wikipedia.org/wiki/Thermocouple
[28]F. Szlivka, C. Hetyei, G. Fekete, and I. Molnár, “Comparison of Mixing Plane, Frozen Rotor, and Sliding Mesh Methods on a Counter-Rotating Dual-Rotor Wind Turbine,” Applied Sciences (Switzerland), vol. 13, no. 15, 2023.
[29]D. L. Sondak and R. H. Pletcher, “Application of wall functions to generalized nonorthogonal curvilinear coordinate systems,” AIAA Journal, vol. 33, no. 1, 1995.
[30]W. Y. Kim, S. Senguttuvan, and S. M. Kim, “Effect of rotor spacing and duct diffusion angle on the aerodynamic performances of a counter-rotating ducted fan in hover mode,” Processes, vol. 8, no. 11, 2020.
[31]“K-epsilon turbulence model.” Accessed: Jun. 15, 2024. [Online]. Available: https://en.wikipedia.org/wiki/K-epsilon_turbulence_model
[32]P. A. Durbin and S. H. Bader, “TURBULENCE MODELING FOR HEAT TRANSFER,” in Annual Review of Heat Transfer, vol. 24, no. 1, 2022.
[33]C. H. Huang and M. H. Hung, “An optimal design algorithm for centrifugal fans: Theoretical and experimental studies,” Journal of Mechanical Science and Technology, vol. 27, no. 3, 2013.
[34]N. Buckney, S. Green, A. Pirrera, and P. M. Weaver, “On the structural topology of wind turbine blades,” Wind Energy, vol. 16, no. 4, 2013.
[35]M. W. Heo, J. H. Kim, T. W. Seo, and K. Y. Kim, “Aerodynamic and aeroacoustic optimization for design of a forward-curved blades centrifugal fan,” Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, vol. 230, no. 2, 2016.
[36]E. Jacobs, K. Ward, and R. Pinkerton, “The characteristics of 78 related airfoil sections from tests in the variable-density wind tunnel,” National Advisory Committee for Aeronautics, 1933.
[37]J. D. Anderson, “Fundamentals of aerodynamics.,” 1984.
[38]G. Leishman, Introduction to Aerospace Flight Vehicles. 2022.
[39]M. Morgenroth and D. S. Weaver, “Sound generation by a centrifugal pump at blade passing frequency,” J Turbomach, vol. 120, no. 4, 1998.
[40]“On sound generated aerodynamically I. General theory,” Proc R Soc Lond A Math Phys Sci, vol. 211, no. 1107, 1952.