太阳能聚光集热与多蒸发器环路热管传输方法

Solar heating is an environment-friendly and effective approach to reduce the increasingly building energy consumption, to possess the equal chance enjoying heating comfort for people in both urban and rural areas. The problems for present solar heating are low heat transfer coefficient and large area for solar collector, which decrease the integration flexibility with buildings. This research puts forward an innovative idea to combine the non-imaging solar concentration and capillary-driven phase change heat transmission methods in solar building heating.Firstly,using extending method for marginal rays principle, taking loop heat pipe (LHP)evaporators as the solar absorbers, create and solve the partial equaitons for the compound parabolic concentrator (CPC), to achieve the static CPC surface shape and realize the high-efficienty solar heat collection. Secondly, the interaction mechanism between ramified LHP heat transfer characteristics and inside vapor-liquid interface movements are researched by the Front Tracking Method,which first computing the phase interface velocity and then the displacement, by the interworking between finite element analysis and MATLAB scripting programing. Thirdly, optimization analysis for the capillary porous wick structure with maximum capillary pressure as the optimation function at the high heat rate.With the guideline of optimizaiton of analysis, seek the controllable method of capillary wick fabrication at characterized specification. Finially, the system experiments are carried out to test the solar concentration characteristics, the solar thermal transmission characteristics, and form the passive building solar heating design method.

太阳能采暖是降低日益增加的建筑能耗、使城村享有同等采暖舒适度的既环保又有效的手段，但现有集热方式集热面积大、传热效率低、与建筑集成的灵活度低。本项目提出聚光集热与毛细驱动相变传热的太阳能集输新思路。采用边缘光线原理的延伸方法，以环路热管的蒸发器为太阳能吸收器，通过建立并求解非平面吸收体的复合抛物面聚光器的面形微分方程，获得静态大角度接收太阳光的聚光器面形，实现时空分布不均的低热流密度太阳能的高效收集。采用界面跟踪法，借助有限元分析和MATLAB编程交互工作，通过计算相界面移动速度获得相界面位移，获得多蒸发器环路热管气液界面运移与传热性能的相互作用机理。基于多孔介质理论，以最大毛细力为目标函数，优化分析并实验获得高热流密度下具有高换热性能和高毛细驱动力的多孔芯结构。最后通过系统整体实验测试，形成无机械驱动的太阳能建筑采暖设计方法。

高效吸收并传输低热流密度太阳能是太阳能采暖等光热利用的关键问题，本项目提出采用非平面吸收体的复合抛物面聚光集热与多蒸发器环路热管相变传输相结合的方法来解决这一问题。采用边缘光线原理，以环路热管圆柱形蒸发器为吸收器，采用凹面抛物面和圆柱形渐开面的组合，分析了不同型线下非平面吸收体的太阳能复合抛物面聚光集热性能。采用有限元软件COMOSOL和Level Set 界面跟踪法，进行了双蒸发器环路热管传热性能以及不同孔径分布下双孔径分布毛细芯中气液界面运移特性分析。采用熔盐造孔的Bi-porous wick方法进行了双孔径分布镍芯的正交烧结实验，通过5个关键烧结参数对双孔径分布镍芯4个主要性能参数的影响分析，确定了高效多孔毛细芯的最优烧结工艺。