氣冷式冰水機能源效率提昇之研究

A Study on Improving Energy Performance of Air-Cooled Water Chillers

吳武杰(Wu-Chieh Wu)

指導教授 ： 蔡尤溪 ； 李宗興

國立臺北科技大學/機電學院/機電科技研究所/博士(2013年)

摘要

本研究針對現有大型氣冷式冰水機的VV型冷凝盤管配置，在氣流分佈所面臨上下不均且內外不一致的現象，在不增加總熱傳面積、銅管總數量及風機數量的前提下，設計五種不同角度、三種不同鰭片間距與四種不同管列數等十二種冷凝盤管配置。利用CFD數值模擬與熱傳分析方法找出最佳盤管角度與最佳創新冷凝盤管配置。並藉由建立氣冷式冰水機系統及其各元件的數學模型，模擬機組實際運轉的整體性能，發展系統各元件的不可逆性與可用能方程式，用以找出不同冷凝盤管配置對氣冷式冰水機性能和系統各元件能源轉換效率的影響程度與改善方向。最後開發與製造實際的氣冷式冰水機進行全尺度實驗，探討最佳冷凝盤管配置，對於實際氣冷式冰水機整體性能與系統各元件效率的影響程度，並驗證冷凝盤管的CFD數值與機組模擬分析結果。本研究獲致成果可歸結有: 採用創新不對稱管列數配置(Case C4)具有最佳的改善效果，可較最佳角度配置(Case A5) 的平均風速與總熱傳量分別提升約10.3%與5.3%；當氣冷式冰水機分別搭配直膨式與滿液式蒸發器進行全尺度實驗，創新冷凝盤管配置相較於最佳角度冷凝盤管配置，在整體性能(COP)可提升7.3%與6.7%，在系統總不可逆性可改善4.4%與2.6%；創新不對稱管列數配置冷凝盤管，經實驗驗證確能提升冷凝器熱傳性能而使氣冷式冰水機的性能係數(COP)達3.26。本研究找出最佳VV冷凝盤管角度配置，可直接作為氣冷式冰水機製造廠重要參考依據；而創新變管列數冷凝盤管配置未來將可導入製造廠進行商品化設計，進而提升氣冷式冰水機能源效率標準。所以，本研究最後所獲得的研究成果，將可作為製造廠開發高效率氣冷式冰水機的相關設計與研發工作的重要參考。

關鍵字

氣冷式冷凝器 ； 冰水機 ； 數值模擬分析 ； 可用能分析 ； 能源效率

並列摘要

The objective of this study is to design condensers for large air-cooled chillers, and configurations for VV-shaped finned-tube condenser coils to deal with unevenly distributed flow and varying air-flow speed without increasing material costs nor the number of tubes and fans. This study designed 12 types of condensing coil configurations of five different angles, three types of different fin spacing and four types of different number of rows. First, the CFD numerical simulation and heat transfer analysis methods were used to determine the optimum condensing coil angle and the optimum innovative condensing coil configuration. Secondly, by using the mathematical model of the air-cooled chiller system and its components, this study simulated the overall performance of the actual operation of the air-cooled chiller to develop the individual component’s irreversibility and exergy equations to identify the level of influence of different condensing coil configurations on air-cooled chiller performance, the energy conversion efficiency of the individual components of the system, and the directions for improvement. Finally, this study developed an air-cooled chiller for full-scale experiment to explore the level of influence of the optimum condensing coil configuration on the overall performance of the air-cooled chiller and the efficiency of individual components. It also verified the CFD numerical simulation of the condensing coil and the air-cooled chiller simulation analysis results. The findings of this study can be summarized as follows: the configuration of the innovative asymmetrical number of rows (Case C4) has the optimum improvement effects as the average air-flow speed and total heat transfer can be improved by about 10.3% and 5.3% respectively, as compared with the configuration of optimum angle (Case A5). According to the full-scale experiments of using the air-cooled chiller coupled with direct-expansion type and flooded type evaporators respectively, the overall performance (COP) can be improved by 7.3% and 6.7%. The total system irreversibility can be improved by 4.4% and 2.6% for the configuration of the condensing coil, as compared with the condensing coil configuration of the optimum angle. The condensing coil configuration of innovative asymmetric number of rows can improve the heat transfer performance of the condenser to realize the performance coefficient of the air-cooled chiller (COP) to 3.26 as the experimental results have suggested. The optimum angle configuration of VV condensing coil identified in this study can be directly used as a main reference to air-cooled chiller manufacturers. The innovative condensing coil configuration of different number of rows can be used for commercialized design by manufacturers to further raise the energy efficiency of the air-cooled chillers. Therefore, the findings and achievements of this study can provide an important reference to manufacturers in the development of high efficiency air-cooled chiller design, research and development.

並列關鍵字

air-cooled condenser ； water chiller ； Computational fluid dynamics (CFD) ； exergy analysis ； Coefficient of performance (COP)

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