Assessment and Ranking of Difluoromethane (R32) and Pentafluoroethane (R125) Interatomic Potentials Using Several Thermophysical and Transport Properties Across Multiple State Points
Assessment and Ranking of Difluoromethane (R32) and Pentafluoroethane (R125) Interatomic Potentials Using Several Thermophysical and Transport Properties Across Multiple State Points
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DOI：
10.1021/acs.jced.3c00379
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发表时间：
2023-09
期刊：
影响因子：
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通讯作者：
Barnabas Agbodekhe;Eliseo Marin-Rimoldi;Yong Zhang;A. Dowling;E. Maginn
中科院分区：
文献类型：
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作者：
Barnabas Agbodekhe;Eliseo Marin-Rimoldi;Yong Zhang;A. Dowling;E. Maginn
二氟甲烷(R32)和五氟乙烷(R125)是两种常见的氢氟烃制冷剂，通常用于一种名为R410a的混合物中。许多制冷剂，包括R32，特别是R125，具有很高的全球变暖潜力，因此正在被逐步淘汰。人们希望开发能够分离和回收这些材料的工艺，这意味着需要确定这些流体的热力学和传输性质。在这项工作中，我们评估了分子动力学模拟确定这两种流体的关键热力学和输运性质的能力。我们测试了使用机器学习指导(MLD)方法针对汽液平衡(VLE)数据进行参数化的经典原子间力场(FE)是否也可以产生对其他关键性质的准确估计。根据VLE结果，根据VLE数据调整的最高性能MLD FF几乎无法区分。这项工作试图调查这些MLD调谐的FF是否可以转移到其他不用于调谐它们的属性，以及它们是否可以被排序以识别“最好的”FF。研究中包括了R32和R125各一个的文献Ff。总共测试了10个FF。用分子动力学计算了体系的导热系数(λ)、粘度(η)、自扩散系数(D)、液体密度(ρ)、等压热容量(CP)、等容热容量(CV)、热膨胀系数(αP)、热压力系数(γρ)、等温压缩系数(βT)、声速(CSound)、焦耳-汤姆逊系数(μJT)和质心径向分布函数(GR)，并与实验进行了比较。有些令人惊讶的是，MLD调谐的FF被发现可以转移到许多不用于调谐它们的性质上。对MLD调谐的FF进行了排名。在广泛的性质范围内，标记为R32a和R125b的Ff分别是R32和R125的最佳Ff。MLD调谐的FF被发现优于以前开发的文献中的FF。
Difluoromethane (R32) and pentafluoroethane (R125) are two common hydrofluorocarbon refrigerants, often used in a mixture termed R410A. Many refrigerants, including R32 and especially R125, have high global warming potentials and so are being phased out. There is a desire to develop processes that can separate and recover these materials, which means that there is a need to determine the thermodynamic and transport properties of these fluids. In this work, we evaluate the ability of molecular dynamics simulations to determine the key thermodynamic and transport properties of these two fluids. We test whether classical interatomic force fields (FFs) parametrized against vapor–liquid equilibrium (VLE) data using a machine learning directed (MLD) approach can also yield accurate estimates of other key properties. The top-performing MLD FFs tuned against VLE data were nearly indistinguishable based on VLE results. This work seeks to investigate if these MLD-tuned FFs are transferable to other properties not used in tuning them and if they can be ranked to identify the “best” FFs. Literature FFs, one each for R32 and R125, are included in the study. A total of ten FFs were tested. Thermal conductivity (λ), viscosity (η), self-diffusivity (D), liquid density (ρ), isobaric heat capacity (CP), isochoric heat capacity (CV), thermal expansivity (αP), thermal pressure coefficient (γρ), isothermal compressibility (βT), speed of sound (csound), Joule-Thomson coefficient (μJT), and center of mass radial distribution functions (gr) were computed using molecular dynamics and compared with experiments when possible. Somewhat surprisingly, the MLD-tuned FFs are found to be transferable to a wide range of properties not used in tuning them. The MLD-tuned FFs were ranked. The FFs labeled R32aand R125bwere found to be the “best” FFs for R32 and R125, respectively, across a broad range of properties. The MLD-tuned FFs were found to be superior to previously developed literature FFs.