单列水平管束外膜状凝结管束效应问题试验研究

Efficient use of energy is an important means contributes to saving energy consumption, reducing pollution and sustaining development. Surface condensers with vapor condense on a horizontal tube bundle, such as shell and tube condenser, are widely used in refrigeration and air conditioning field, petrochemical industry, energy power field, desalination field, etc. To meet the high efficient shell and tube condenser requirements of these energy-intensive industries, this project aims to solve the critical issue facing us by build an accurate normalization model which can not only reflects the mechanism of inundation effect but also work out the inundation effect coefficient high-precisely for the classical Nusselt's film condensation problem on an array of horizontal tubes through well-designed experimental researches and theoretical analysis, for the design and development of this type of condenser. .Firstly, this project proposes new test methods to obtain the condensation heat transfer coefficient on single horizontal tube and inundation effect coefficient on horizontal tube bundle high-precisely, new test methods for experimental researches on four kinds of sub-problems of inundation effect that hindered the development Nusselt's film condensation theory for horizontal tube bundle for a long time, and new method to build an accurate normalization model for the Nusselt's film condensation inundation effect problem..Secondly, this project plan to put all the new test methods into practice by a series of activities, including design, implementation, commissioning and testing, then built a systematically testing platform. Then all task relates to the modeling process of Nusselt's film condensation inundation effect problem, including the four kinds of sub-problems of inundation effect, the condensation heat transfer coefficient of single horizontal test tube and the inundation effect coefficient of the test horizontal tube array, was studied experimentally. This provides the required data support for further theoretical analysis..Thirdly, this project plan to model the inundation effect of film condensation on an array of horizontal test tube based on the theoretical analysis of the former experimental results of the four kinds of sub-problems of inundation effect and the proposed model method which can be used to build an accurate normalization model for the Nusselt's film condensation inundation effect problem..Finally, this project plan to check the normalization inundation effect model with accurate inundation effect coefficient result gain by the proposed new test methods which can gain the inundation effect coefficient on a horizontal tube bundle high-precisely..The achievements of this project have significant scientific value to revealing the mechanism of inundation effect of film condensation and improving the theory of inundation effect for film condensation on horizontal tube bundle, and have significant society and economic values to the improvement of the energy efficiency of shell and tube condenser in many fields.

能源高效利用是我国实现节能减排，保证可持续发展面临的有效手段。本项目以制冷空调等领域对高效卧式壳管式冷凝器的需求为研究背景，以建立准确求解Nusselt膜状凝结管束效应问题的数学模型、阐明制冷工质气液相变条件下水平列管换热面在竖直方向的离散对列管中凝液与管壁和饱和蒸气之间热交换方式的影响为目标，通过试验深入研究制约该类冷凝器发展的关键基础问题——Nusselt膜状凝结管束效应问题；提出管束效应系数的高精度测试方法、管束效应四类子问题的试验方法、管束效应问题的建模方法；试验求解各子问题基础上，结合理论分析建立分项模型，最终基于提出建模方法融合各分项模型完成Nusselt膜状凝结管束效应问题的建模，并结合高精度管束效应参数测试结果完成模型检验，解决目前研究工作在试验方法、理论建模方法等方面的不足；为正确认识管束效应作用机理，完善膜状凝结管束效应理论，实现我国大型高效冷凝器的自主研发奠定基础。

本项目以制冷空调等领域对高效卧式壳管式冷凝器的需求为研究背景，以建立准确求解Nusselt膜状凝结管束效应问题的数学模型、阐明制冷工质气液相变条件下水平列管换热面在竖直方向的离散对列管中凝液与管壁和饱和蒸气之间热交换方式的影响为目标，通过试验深入研究了制约该类冷凝器发展的关键基础问题——Nusselt膜状凝结管束效应问题。.首先，提出了管束效应系数的高精度测试方法、建立了高精度求解单列光管与三维肋管膜状凝结传热系数与管束效应问题实验系统，高精度实验求解了15排深光管与6排深三维肋管的膜状凝结传热系数与管束效应因子；.其次，建立了单列管外降膜流型观测实验系统，在试验观测不同肋结构二维肋管与三维肋管列管外降膜流型基础上，结合理论分析分别建立了考虑肋结构与管间距的二维肋管降膜流型判定准则与三维肋管降膜流型判定准则；.第三，基于降膜流型的归一化处理方法，结合理论分析，建立了光管与三维实验肋管的Nusselt膜状凝结管束效应问题求解模型，并结合精密实验结果回归求解了模型中的待定因子，建立了高精度求解光管与实验三维肋管膜状凝结管束效应问题的求解模型，模型预测结果与精密管束效应因子结果的偏差均在±4.0%以内，满足本研究领域对标模实验及其检验标准的要求。.第四，本项目研究过程中，还取得两项意外突破：一是在发现了光管降膜流型实验中经典的均匀布液假设的错误，并通过通过实验量化了非均匀布液条件对凝液流型影响，为进一步完善膜状凝结管束效应理论突破瓶颈；二是在分离三维肋管膜状凝结传热系数的基础研究中，提出了该类管内湍流临界点的预测模型，为进一步建立该类换热管对应流动与换热问题奠定基础。.最终，本项目的试验方法成功推广应用于沸腾换热管束效应问题的高精度求解，建立的多头内螺纹管流动换热模型成功用于指导厂家开展高效换热器热工设计计算。.综上，本项目为正确认识管束效应作用机理，完善膜状凝结管束效应理论，实现我国大型高效冷凝器的自主研发奠定基础。