基于流体拓扑优化方法的新型换热器强化传热和流动减阻机理研究

This study aims to broaden the research idea and method of heat exchanger, and to solve several key theoretical problems in the area of the heat transfer enhancement and the fluid drag reduction. Taking the indirect-contact heat exchanger (usually applied in petro-chemical industry) as research object, the mathematical model of the heat exchanger flow channel unit will be built based on the turbulent coherent structure and multi-objective optimization method to investigate the mechanism of fluid flow and heat exchange enhancement inside the heat exchanger. The novel heat transfer enhancement and flow fluid drag reduction mechanism will be proposed via this research. The detailed research contents are as follows: a three-dimensional topology optimization mathematical model of the flow channel inside the heat exchanger will be built to investigate the status (functional and non-functional) of the solid partition domain and fluid domain inside the heat exchanger, and also to investigate the efficient of the topology optimization of fluid. Through the flow channel topology optimization, the best solid partition domain and fluid domain are determined to seek the best flow channel and structure of the heat exchanger. Based on the numerical simulation and experimental measuring technology, the heat exchanger experimental platform will be built in order to analyze and validate the heat transfer property and fluid flow pattern of different heat exchanger structure and compare to the best structure. Through the above-mentioned research, the theories of heat transfer enhancement and flow fluid drag reduction of heat exchanger will be enriched and improved, it is useful to the development of the new type heat exchanger, which has both the energy saving and emission reduction meaning in the industry process in our country.

本研究旨在拓宽换热器的研究思路和方法，解决束缚换热器强化传热和流动减阻的若干关键机理问题。以石油和化学工业领域应用的间壁换热器为研究对象，应用场协同等理论和多目标优化方法，建立换热器流体流动与传热问题的数学模型，进行换热器多目标优化研究，探求换热器强化传热和流体流动的规律；研究换热器流道固体间壁域和流体域的单元死活描述方法，建立换热器流道空间三维拓扑优化数学模型；研究流体拓扑优化的高效算法；通过流体流道拓扑优化确定换热器最佳的固体间壁域和流体域，实现换热器拓扑优化，获得换热器最佳流道形式和结构，揭示换热器强化传热和流动减阻的关键机理；利用数值模拟和现代实验测量技术相结合，搭建换热器实验模型，分析比较验证换热器不同结构与最佳流道结构的传热与流动特性规律。通过以上研究，丰富和完善换热器的强化传热和流动减阻的理论规律，有助于研发全新的换热器型式，对我国的节能降耗减排事业有重要意义。

换热器在热量回收和能源综合利用中发挥着越来越大的作用。换热器强化传热和流动减阻不仅可提高传热速率和降低热量输运过程中的能耗，而且可降低传热设备尺寸和初投资，对我国的节能降耗减排意义重大。. 目前，换热器的强化传热和流动减阻研究，大都基于管式、板式、翅片式等型式换热器基础上，来进行进一步的结构优化和参数优化。如何打破换热器型式结构的束缚，以传热及流动阻力等性能指标作为目标函数，对换热器进行目标优化和拓扑优化研究，获得换热器最佳流道形式和结构，揭示换热器强化传热和流动减阻的关键机理。. 本课题建立了螺旋内肋扭曲管换热器、螺旋缠绕管换热器、凹坑凸胞板式换热器、螺旋扭曲缠绕管换热器、双向扭曲管换热器等多种型式换热器的流体流动与传热问题的数学模型，并对其进行了数值模拟与仿真研究，获得换热器内流动场、温度场、压力场的细观描述，分析了换热器各种结构参数变化对流动与传热的影响规律；应用场协同理论，并根据火积理论推导出火积减综合方程，对换热器进行多目标优化研究，通过参数灵敏度分析和响应面分析，获得换热器强化传热和流动减阻的影响要素，得到最优结果的换热器；将换热器作为一个空间区域，通过非线性过滤方程和投影方程改进变密度法，建立换热器流动与传热问题的拓扑优化数学模型，通过大量换热器拓扑优化算例分析表明，通过换热器拓扑优化研究，获得了换热器最佳流道形式和结构，揭示出换热器强化传热和流动减阻的机理；搭建了换热器实验模型，分析比较了换热器不同结构的传热与流动特性规律，验证了数值模拟与优化的准确性。. 换热器拓扑优化方法打破了传统换热器的研究思路，减少了人为干预和盲目性，可根据换热器实际使用场合与目的，通过确定优化目标函数，利用拓扑优化方法寻求得到最优换热器结构。本课题研究成果丰富和拓宽了换热器强化传热和流动减阻的理论与实践，为获得最优换热器结构的研究提供了技术指导和理论依据。