殼管螺旋式熱交換器參數設計之研究

熱泵熱水器的環保以及節能的優點在近幾年來逐漸受到重視，其中殼管螺旋式熱交換器廣泛地被運用於熱泵熱水器，殼管螺旋式熱交換器利用螺旋管幾何形狀，可以增加離心力作用產生二次流效應，因而增強熱傳效果。其效能與螺旋圈徑、螺旋管節距、管圈數、曲率比等參數有關，本研究中使用CFD軟體ANSYS FLUENT預測殼管螺旋式熱交換器的熱傳性能與壓損，熱側流體與冷側流體是使用水為工作流體，使用不同尺寸的螺旋管，水槽模型固定不變，固定熱側流體及冷側流體速度，並將計算結果與文獻實驗結果比對，結果顯示兩者相當接近，證明CFD模擬的準確性。為達到熱交換器優化設計，本文以實驗設計法中的田口法結合灰關聯分析，尋找能滿足多種品質特性的最佳參數組合，品質特性採用總熱傳係數與摩擦因子，最後數值結果顯示，殼管螺旋式熱交換器最佳參數配置為：逆向流、水槽進出口位置在兩對側、螺旋管節距19.52mm、螺旋管外徑15.875 mm、螺旋管圈徑211.5 mm。

關鍵字

殼管螺旋式熱交換器；摩擦因子；紐賽數；田口法；灰關聯分析；計算流體力學

並列摘要

In recent years, the heat pump water heater becomes a very popular apparatus with the advantage of environmental protection and saving energy. The helical coil heat exchanger is one of the most popular heat transfer devices adopted in the heat pump water heater. Owing to its higher heat transfer performance, caused by the second-flow effect through curvature motion. Parameters, such as the coil diameter, the coil pitch, the coil number, the curvature ratio, and Reynolds number are known as the key to the heat transfer In this study, the CFD software ANSYS FLUENT was employed to predict the heat transfer performance of a helical coil heat exchanger. Water was used as the working fluid on both sides of the hot and cold fluids. Using different size of the helical coil heat exchanger and the same size of the water tank, the velocities of the hot water and the cold water were fixed. According to the comparison of numerical and experimental results, it is found that both results agreed well, revealing the accuracy of the CFD simulation. To reach the goal of optimizing the design of the heat exchanger, the Taguchi method and grey relational analysis were adopted. Overall heat transfer coefficient and Fanning fricition factor were used to evaluate the quality characteristics of the heat exchanger. According to the Numerical results, it is found that the optimal combination of design parameters is the counter flow, the inlet and outlet of the water tank located on the opposite side, the coil pitch of 19.52 mm, the tube outside diameter of 15.875 mm, and the coil diameter of 211.5 mm.

並列關鍵字

Helical coil heat exchanger ； Famming friction factor ； Nusselt Number ； Taguchi method ； Grey relational analysis ； Computational Fluid Dynamics (CFD)

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