Towards optimal mixtures of working fluids: Integrated design of processes and mixtures for Organic Rankine Cycles
Towards optimal mixtures of working fluids: Integrated design of processes and mixtures for Organic Rankine Cycles
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DOI：
10.1016/j.rser.2020.110179
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发表时间：
2021
影响因子：
15.9
通讯作者：
J. Schilling;Marten Entrup;Madlen Hopp;J. Gross;A. Bardow
中科院分区：
文献类型：
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作者：
J. Schilling;Marten Entrup;Madlen Hopp;J. Gross;A. Bardow
摘要 有机朗肯循环将可持续来源的低温热量转化为电能。充分发挥低温热源的潜力需要有机朗肯循环和工作流体的最佳组合。如今，工作流体通常是纯组分。然而，由于混合物在蒸发和冷凝过程中具有有利的温度滑移，因此可以显着提高工艺效率。在这项工作中，我们提出了一种有机朗肯循环和工作流体混合物的集成设计方法，即所谓的一级连续分子靶向计算机辅助混合物和混合设计（CoMT-CAM b D）。在 1 级 CoMT-CAM b D 中，使用基于物理的扰动链统计关联流体理论 (PC-SAFT) 状态方程对混合物的平衡和传输特性进行建模。 CAM b D 公式使我们能够在工艺优化过程中将混合物组分的分子结构及其组成视为自由度。设备的详细尺寸使我们不仅可以优化热力学，还可以优化经济目标。 1 级 CoMT-CAM b D 被证明可用于废热回收的有机朗肯循环的设计。该方法从数百万种可能的混合物中识别出最佳的工作流体混合物，并结合相应的最佳工艺和设备，例如，使净功率输出最大化的丙烷/乙醚混合物（P net= 295 kW）或使特定投资成本最小化的丙烯/丙醛混合物（SIC= 3479€/kW）。所提出的方法使我们能够严格分析与纯组分相比，针对不同的工艺热源和冷却介质的最佳混合物的潜力，并系统地开发有机朗肯循环工作流体混合物的潜力。
Abstract Organic Rankine Cycles transform low-temperature heat from sustainable sources into electrical power. Exploiting the full potential of a low-temperature heat source requires the optimal combination of Organic Rankine Cycles and working fluid. Today, working fluids are commonly pure components. However, mixtures can significantly improve the process efficiency due to their favorable temperature-glide during evaporation and condensation. In this work, we present a method for the integrated design of Organic Rankine Cycles and working fluid mixtures, so-called 1-stage Continuous-Molecular Targeting Computer-aided mixture and blend design (CoMT-CAM b D). In 1-stage CoMT-CAM b D, the physically-based perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state is used to model both, the equilibrium and the transport properties of the mixture. A CAM b D formulation enables us to consider the molecular structure of the mixture components as well as its composition as degrees of freedom during process optimization. A detailed sizing of the equipment allows us to optimize not only thermodynamic but also economic objectives. 1-stage CoMT-CAM b D is demonstrated for the design of an Organic Rankine Cycle for waste heat recovery. The method identifies the optimal working fluid mixture from several million possible mixtures jointly with the corresponding optimal process and equipment, eg, the mixture propane/diethyl ether maximizing the net power output (P net= 295 kW) or propene/propionaldehyde minimizing the specific investment cost (SIC= 3479€/kW). The presented method allows us to rigorously analyze the potential of optimal mixtures compared to pure components for varying heat source and cooling medium of the process and systematically exploit the potential of working fluid mixtures for Organic Rankine Cycles.