超临界HCs及HCs/阻燃剂混合物在螺旋管内的换热机理和吸热匹配特性

Transcritical Organic Rankine Cycle (SORC) is a kind of advanced mid-low grade heat/power conversion technology. The improvement of SORC performance depends on further in-depth investigation on the heat transfer characteristics of supercritical fluid in tube. The mixtures of hydrocarbon and retardant are potential substitute refrigerants for mid-low grade heat recovery. This study focuses on the heat transfer mechanisms and match characteristics of supercritical R290 and mixtures of R290 and retardant in helically coiled tube. The heat transfer coefficient correlations and the heat transfer deterioration criteria for supercritical R290 or R290/retardant in the helically coiled tube are obtained experimentally. The effects of the geometrical dimensions of helically coiled tube on the heat transfer deterioration suppression are analyzed emphatically by the modified model. Taking the two factors of suppressing heat transfer deterioration and reducing pressure drop into account, the optimum structure parameters of helically coiled tube are obtained by the optimum exergy destruction method. On this basis, an available energy match model is established by the variation of heat capacity in heat-absorbing process．The relationship of the available energy match between the mixtures and waste heat with the irreversible exergy destruction is established, and the energy-saving mechanism of the mixtures is revealed. This project would provide valuable basic data and physical model to promote the practical application process of SORC system.

跨临界有机Rankine循环（SORC）是一种先进的中低品位热功转换技术。SORC系统效率的有效提高依赖于更深入研究超临界流体在管内的换热特性。HCs/阻燃剂混合物是具有研发潜质的中低温余热热源作功工质。本研究着眼于超临界R290及R290/阻燃剂混合物在螺旋管内的换热机理和吸热匹配特性研究。通过实验研究获取超临界R290及R290/阻燃剂混合物在螺旋管内的换热关联式和传热恶化判据。基于超临界R290在螺旋管内传热修正模型，重点分析螺旋管的几何尺寸对传热恶化抑制的影响，同时考虑抑制传热恶化和减小阻力两方面因素，应用最小㶲损优化方法得到螺旋管的最佳结构参数。在此基础上，建立利用混合工质比热变化改善吸热过程可用能匹配的模型，揭示混合工质与余热热源的“可用能”匹配性能与其不可逆损失之间的内在联系和混合工质的节能机理。本项目的研究为推进SORC系统的实用化进程提供有价值的基础数据与物理模型。

跨临界有机Rankine循环（SORC）是一种先进的中低品位热功转换技术。SORC系统效率的有效提高依赖于更深入研究超临界流体在管内的换热特性。HCs/阻燃剂混合物是具有研发潜质的中低温余热热源作功工质。本研究着眼于超临界R290及R290/CO2在螺旋管内的换热机理和吸热匹配特性研究。通过实验研究获取超临界R290及R290/CO2在螺旋管内的换热关联式。以边界层微分方程的对流项考虑边界层热加速作用建立了新的换热恶化模型。该模型能更准确预测换热恶化的发生。考虑螺旋管几何结构对流体流场分布的影响，结合能量守恒，建立了适用于螺旋管的浮升力准则。基于超临界R290在螺旋管内传热修正模型，重点分析螺旋管的几何尺寸对传热恶化抑制的影响，同时考虑抑制传热恶化和减小阻力两方面因素，应用最小损优化方法得到螺旋管的最佳结构参数。开展了超临界烷烃/CO2二元混合体系在拟临界区域的相互作用系数的理论研究，获得预测烷烃/CO2混合体系在拟临界区域的相互作用系数的关联式。本项目的研究为推进SORC系统的实用化进程提供有价值的基础数据与物理模型。申请人以通讯作者/第一作者在国内外学术刊物和国际学术会议发表了学术论文25篇，其中境外国际期刊17篇，国内核心刊物5篇，目前被SCI 收录17篇（SCI 1区14篇、SCI 2区3篇），EI收录5篇。

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