Entropy Based Design and Convective Heat Transfer in Multiphase Flows

在提高热/流体系统能源效率和减少温室气体排放的需求日益增长的推动下，研究人员正在利用基于熵的设计作为一种新兴工具来识别和最大限度地减少系统流量损失。热力学第二定律的使用已经很好地建立了系统分析，但在空间上跟踪整个流场的局部熵产生率的程度要小得多。特别是，多相流中的熵输运具有突出提高能量转换和效率的新方法的巨大潜力。本研究计画探讨液滴与颗粒在多相流中的对流热与熵输运过程。数值和实验研究提出了更好地理解的传输现象。两个特定的多相系统的应用程序进行检查：热化学制氢与铜-氯（Cu-Cl）循环，和液滴的影响结冰表面。 该研究计划旨在开发基于熵的液滴和颗粒多相系统设计的新方法，特别是在以下方面提供新的见解和改进：1）传输过程; 2）解决方案的准确性;和3）实验测量。这些应用集中在Cu-Cl循环中的多相流和表面结冰（即，船舶;架空电力线）。在前一种情况下（Cu-Cl循环），液滴的固化发生在熔融CuCl的热回收和氯化铜（II）液滴的干燥过程中。在后一种情况下（结冰），液滴撞击和表面积冰期间的热流包括通过未冻结的表面膜和冰的传导、对流冷却、冻结液滴释放的潜热以及进入液滴的动能和过冷。 该研究的目标是开发新的设计工具，积极结合熵和第二定律，以更准确，更强大的预测和测量液滴和颗粒的多相流。具体应用包括Cu-Cl循环和表面结冰（船舶;架空电力线）。其目标是扩展基于熵的设计方法，以提高多相流的能量效率，通过最大限度地减少熵的产生，也提供了新的洞察多相过程的测量和表征的流动不可逆性。本研究计划的另一个目标是使用基于熵的设计来提高Cu-Cl循环的热效率，从而在大工业规模的操作中证明商业可行性。

Driven by the increasing need to improve energy efficiency of thermal / fluid systems and reduce greenhouse gas emissions, researchers are utilizing entropy based design as an emerging tool to identify and minimize system flow losses. The use of the Second Law of Thermodynamics has been well established for system analysis, however to a much lesser extent for spatially tracking the local rates of entropy production throughout a flow field. In particular, entropy transport in multiphase flows has a significant potential to highlight new ways to improve energy conversion and efficiency. This research proposal examines convective heat and entropy transport processes in multiphase flows with droplets and particles. Both numerical and experimental studies are proposed to better understand the transport phenomena. Applications to two specific multiphase systems are examined: thermochemical hydrogen production with a copper-chlorine (Cu-Cl) cycle, and droplet impact on icing surfaces. The research program aims to develop new methods of entropy based design of multiphase systems with droplets and particles, specifically to provide new insight and improvements in: 1) transport processes; 2) solution accuracy; and 3) experimental measurements. The applications focus on multiphase flows in the Cu-Cl cycle and icing of surfaces (i.e., ships; overhead power lines). In the former case (Cu-Cl cycle), solidification of droplets occurs during processes of heat recovery of molten CuCl and drying of copper(II) chloride droplets. In the latter case (icing), the heat flows during droplet impact and ice accretion on a surface include conduction through the unfrozen surface film and ice, convective cooling, release of latent heat by the freezing droplets, and kinetic energy and supercooling of the incoming droplets.  The objectives of the research are to develop new design tools that actively incorporate entropy and the Second Law for more accurate and robust prediction and measurement of multiphase flows with droplets and particles. Specific applications involve the Cu-Cl cycle and icing of surfaces (ships; overhead power lines). The objectives are to extend the methodology of entropy based design so as to improve the energy efficiency of multiphase flows by minimizing the entropy generation and also provide new insight into the multiphase processes by measuring and characterizing the flow irreversibilities. Another goal of this research program is to use entropy based design to improve the thermal efficiency of the Cu-Cl cycle so as to demonstrate commercial viability at a large industrial scale of operation.