| 摘要: |
| 大型制冷系统中的换热管通常采用管内、管外表面双侧强化结构，因不便于在壁面布置温度传感元件，双侧强化管需要特别的实验方法来测定其性能，包括Wilson图解法(WPM)、修正Gnielinski公式法(MGF)、Wilson-Gnielinski公式法(W-GF)。不同的方法有各自的应用场合和使用局限性。本文针对双侧强化管提出一种便于应用的新方法，称为待定指数法(UEM)，通过线性拟合和优化得到关联式中的待定参数，可有效分离管内、管外对流换热表面传热系数。在双侧强化管上进行了R134a管外蒸发、水管内流动的两组实验，以此对包含新方法的4种实验方法进行应用对比。结果表明，4种实验方法得到的强化管管内对流换热表面传热系数的强化倍率在2.88~3.23之间，管外对流换热表面传热系数的强化倍率在3.15~3.54之间，不同方法得到的管内对流换热表面传热系数数差异在15%以内，管外对流换热表面传热系数差异在11%以内。4种实验方法可根据不同的应用条件选择使用，UEM限制条件少、应用方便，是一种更加高效、准确的实验方法。 |
| 关键词: 传热系数 实验方法 制冷换热器 双侧强化管 |
| DOI： |
| 投稿时间：2022-11-08 修订日期：2023-02-12
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| 基金项目: |
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| Comparison of Experimental Methods for Double-Sided Enhanced Tubes in Refrigeration Heat Exchangers |
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Su Bowen, Ouyang Xinping
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| (School of Energy and Power Engineering, University of Shanghai for Science and Technology) |
| Abstract: |
| Heat exchanger tubes used in large refrigeration systems are generally enhanced, both inside and outside. Because it is difficult to attach temperature sensors for wall temperature measurements, specific test methods are required for the performance evaluation of such double-sided enhanced tubes. These include the Wilson plot method (WPM), modified Gnielinski formula (MGF), and Wilson–Gnielinski formula (W-GF), which have their own applications and limitations. In this study, a new and user-friendly test method––the undetermined exponent method (UEM)––was developed for double-sided enhanced tubes. The internal and external heat transfer coefficients can be separated effectively and efficiently by obtaining the undetermined parameters in the correlation through linear fitting and optimization. Experiments under two different conditions on a double-sided enhanced tube with R134a evaporating outside and water flowing inside were conducted, and a comparative study of the WPM, MGF, W-GF, and UEM test methods was performed. The internal and external enhanced factors obtained by the four methods were 2.88–3.23 and 3.15–3.54, respectively, and the difference in the internal and external heat transfer coefficients was within 15% and 11%, respectively. These four methods can be applied under different conditions, yet the proposed UEM is a more efficient and accurate test method with fewer restrictions and more convenience. |
| Key words: coefficient of heat transfer experimental methods refrigeration heat exchanger double-side enhanced tube |
