Improved semi-empirical correlations for the evaporation and condensation of zeotropic mixtures

该项目的目的是开发改进的模型方法，用于预测流体混合物蒸发和冷凝过程中的传热。为此，在一个正在进行的项目中设计并建立了快速测试装置，可以为建议的计算方程提供特定的混合物参数。在应用的后续项目中，该程序将通过快速测试装置中的进一步流体混合物来深化，从而进一步开发模型方法。两个地点的快速测试设备基于相同的实验概念。非共沸混合物的沸腾行为的研究是在拜罗伊特大学技术热力学和传输过程主席（Brüggemann工作组）进行的，冷凝行为的研究是在汉诺威莱布尼茨大学热力学研究所（Kabelac工作组）进行的。扩展的模型方法，从目前的二元流体混合物的三元混合物的计划，以及建设性的优化实验装置。将研究乙醇与硅氧烷六甲基二硅氧烷（MM）和八甲基三硅氧烷（MDM）的二元和三元组合。后者作为ORC工艺以及高温热泵中的工作流体表现出有利的性能。乙醇的添加由于显著更大的蒸发焓而可能实现更高的传递热通量。

The aim of this project is to develop improved model approaches for the prediction of heat transfer during the evaporation and condensation of fluid mixtures. To this end, rapid test apparatuses were designed and set up in an ongoing project, with which mixture-specific parameters can be provided for the proposed calculation equations. In the applied follow-up project, the procedure is to be deepened by means of further fluid mixtures in the rapid test apparatuses and the model approaches are thus to be further developed. The rapid test apparatuses at both locations are based on the same experimental concept. The investigations on the boiling behavior of zeotropic mixtures are carried out at the Chair of Technical Thermodynamics and Transport Processes of the University of Bayreuth (Brüggemann working group), the investigations on the condensation behavior at the Institute of Thermodynamics of the Leibniz University of Hannover (Kabelac working group). Extensions of the model approaches from currently binary fluid mixtures to ternary mixtures are planned as well as constructive optimizations of the experimental apparatuses. Binary and ternary combinations of ethanol and the siloxanes hexamethyldisiloxane (MM) and octamethytrisiloxane (MDM) will be investigated. The latter exhibit advantageous properties as working fluids in ORC processes as well as in high temperature heat pumps. The addition of ethanol can potentially enable higher transferred heat fluxes due to the significantly larger enthalpy of vaporization.