非稳态对流传热过程的优化理论和方法

Investigation on heat transfer process is of great importance to the implementation of energy saving and emission reduction as well as the promotion of modern science and technology development. Among various heat transfer processes, convective heat transfer process is the most studied and the most widely used one. However, the existing studies mainly focus on steady convection heat transfer process, and there is lack of research on the optimization theory and method for the unsteady convective heat transfer one. Therefore, it is difficult to maximize the performance of heat exchange system under unsteady process. This project studies the optimization theory and method for unsteady convective heat transfer process. The functional objectives are proposed to describe various optimization targets of the heat exchange system, respectively, including the average temperature, the maximum temperature and the temperature uniformity of the system. The functional variation method is introduced to construct the unsteady Euler’s equation of the optimal flow field of the heat exchange system for various optimization targets. Based on the configuration of the optimal flow field and its evolution rule over time, the relationship among various optimization targets are analyzed. Meanwhile, the mechanism of the heat transfer optimization of the unsteady convective heat transfer process is revealed. The influence of the operating parameters and the structural parameters on heat transfer performance of the system is studied and effective method is proposed to improve the performance of the system. Finally, the effectiveness of the proposed optimization theory and method are validate through numerical simulation and experimental investigation on air-cooled battery thermal management system. This project will develop the optimization theory and method for unsteady heat transfer process and provide theoretical guidance for the optimization of heat exchange system.

热量传递过程的研究对于实现节能减排和促进现代科技发展具有重要的意义。其中对流传热过程是研究最多、应用最广的热量传递过程。然而，已有研究主要针对稳态对流传热过程，而缺乏对非稳态对流传热过程优化理论和方法的探讨，因而难以最大限度地提高非稳态情况下换热系统的性能。本项目研究非稳态对流传热过程的优化理论和方法：分别提出表征系统平均温度、最高温度和温度均匀性的泛函目标函数，针对不同目标采用变分原理建立换热优化时最优速度场的非稳态欧拉方程；基于最优速度场的构型及其随时间的演化规律，从机理上分析不同优化目标之间的区别与联系，揭示非稳态对流传热优化的内在机制；研究运行参数和结构参数对系统换热性能的影响规律，提出改善系统换热性能的有效方法。最后以风冷式电池热管理系统为例，通过数值模拟和实验测试验证提出的优化理论和方法的有效性。本项目将建立非稳态对流传热过程的优化理论和方法，为换热系统的性能优化提供理论指导。

本项目针对非稳态对流传热过程，开展了优化理论和方法研究。通过变分原理建立了非稳态对流传热优化对应的最佳速度场方程，可用于指导非稳态对流传热过程的优化；以并行风冷式动力电池热管理系统的非稳态对流传热过程为例，采用无量纲分析和数值方法探究了运行参数对系统换热性能的影响规律，明确了系统参数的优化方向；建立了用于速度计算和温度计算的简化模型，能在短时间内得到风冷系统冷却流道速度和电池平均温度，为系统的性能评估和快速优化奠定了基础；针对系统导流板角度、电池间距、进出口位置等关键结构参数，分别开发了高效的优化方法，并将各方法进行综合，实现了系统的多参数优化；将开发的方法用于风冷系统的结构优化，实现了系统换热性能的提高和功耗的降低；最后，通过实验测试验证了研究结果的有效性。本项目的研究成果有助于揭示非稳态对流传热过程中参数的影响规律，为换热系统的性能优化提供了理论指导。基于项目研究成果，项目组已经发表了论文15篇，包括SCI论文11篇、EI论文2篇和国际会议论文2篇，授权发明专利1项、实用新型专利4项和软件著作权2项。