递级流换热设备复杂结构流动减阻与传热强化机理研究

The problem of energy and environment has become an important issue for the sustainable development of the world. Especially in recent years, most of the country emerging fog and haze, which make people have higher demands for energy saving and emission reduction. In the process industry, improving the heat transfer efficiency of process equipment is an important mean to conserve energy and reduce energy consumption. Using the flow and heat transfer characteristics of varieties of graded flow heat transfer equipment, including chain-hole baffle heat exchanger and inclined grating baffle heat exchanger, are researched by methods of numerical simulation and experimental research in the project. The impact of geometric parameters, shell-side fluid Reynolds, tube arrangement, support structure and other factors on fluid flow and heat transfer characteristics are analyzed in graded flow heat transfer equipment. Combined with theoretical analysis, the mechanisms of flow resistance reduction and heat transfer enhancement in graded flow heat transfer equipment are clarified; the flow and heat transfer correlations are also fitted. Using the theory of Minimum entropy production, field synergy and entransy dissipation to optimize the design of graded flow heat transfer equipment. Based on different working conditions, a new equipment optimization selection method of graded flow heat exchanger equipment is proposed, which could improve the heat transfer efficiency of local system and achieve the purpose of energy saving and emission reduction. The project aims to reveal the mechanisms of flow resistance reduction and heat transfer enhancement in graded flow heat transfer equipment and provide a theoretical basis for the development of new graded flow heat transfer equipment.

能源与环境问题已成为当今世界可持续发展面临的一个重要问题。特别是近年来国内大部分地区不断出现的雾霾天气，使人们对节能减排有了更高的要求。在过程工业中，提高过程装备传热效能是节约能源和降低能耗的重要手段之一。本项目通过数值模拟和实验研究的方法，对包括链孔式支撑板换热器和斜栅式折流片换热器在内的多种递级流换热设备的流动与传热特性进行研究，分析壳体几何参数、壳程流体雷诺数、布管方式和管束支撑结构等因素对递级流换热设备的流体流动及换热特性的影响，并结合理论分析阐明递级流换热设备流动减阻和传热强化的机理，拟合流动与换热关联式。采用熵产最小、场协同和火积耗散等理论，对递级流换热设备进行优化设计。基于不同工况，提出递级流换热设备优化选型新方法，提高区域系统换热性能，以达到节能减排的目的。本项目旨在揭示递级流换热设备流动减阻与传热强化机理，为研发新型递级流换热设备提供理论依据。

在过程工业中，递级流换热器应用广泛，提高其传热效能是节约能源和降低能耗的重要手段之一。本项目在递级流换热器整体模型的基础上，对其进行合理简化得到递级流换热器的周期性模型和周期性单元流道模型。对比分析了递级流换热器周期性模型和周期性单元流道模型的精度和适用范围，并且采用两种模型对四/三叶孔板换热器壳程流体流动和传热特性进行了分析。基于周期性模型，对比了大孔板换热器和四/三叶孔板换热器的流动与换热性能。相比四叶孔板换热器和大孔板换热器，三叶孔板换热器具有较高的综合性能。采用实验方法研究了三叶孔板换热器壳程的流体流动特性，验证了数值模拟结果的准确性。分析了多种递级流换热设备的应用范围。.研究了壳体几何参数、壳程流体雷诺数、布管方式和管束支撑结构间距、布置方式以及支撑结构类型等因素对弓形折流板换热器、螺旋折流板换热器、折流杆换热器、折流片换热器、扇叶形折流板换热器等多种递级流换热器壳程流体流动规律和传热性能的影响。壳程雷诺数在2200~6200范围内时，杆式支撑和片式支撑换热器的壳程传热系数、综合性能均明显小于弓形折流板和螺旋折流板换热器。连续螺旋折流板换热器传热性能、综合性能均优于四分螺旋折流板换热器。分析了壳程流体流动死区，阐明了流体流动减阻与传热强化机理。拟合了传热与阻力的关联式，为递级流换热设备的设计、优化和应用提供参考。.通过对递级流换热器壳程流体流动减阻和传热强化机理的研究，提出了采用新型壳程结构的新型高效节能递级流换热设备。这些设备包括新型四分螺旋折流板换热器、新型四分变角度螺旋折流板换热器、扇叶型折流板换热器、异形片式支撑换热器等。对其壳程流体流动与换热特性进行了相应的研究，优化了壳程传热性能。开发的新型递级流换热器均具有较高的流动与传热性能，能够达到节能减排的目的。