RG-CPA方程计算固体在超临界流体中的溶解度

Modeling Solubility of Solids in Supercritical Fluids Using the RG-CPA EOS

超临界流体广泛地应用于能源动力、制冷空调等多个领域,而固体在超临界流体中的溶解度对于工业过程有较大的影响。工程上常用状态方程计算溶解度,本文将结合了重整化群理论的RG-CPA方程推广到了溶解度的计算中,RG-CPA方程能够准确地描述流体在近临界和远临界区域的热力学性质,有效地克服了经典立方型状态方程无法准确描述近临界区域热力学性质的缺点。采用该方法对7种有机固体在超临界CO_2中的溶解度进行了计算,并与经典方程进行了比较。结果表明,与经典方程相比,RG-CPA方程能更好地再现极接近临界点处溶解度的陡峭变化规律。

Supercritical fluids have been extensively used in energy, power, refrigeration and air conditioning fields in recent years. The solubility of solids in supercritical fluids greatly influences industrial processes, which makes accurate predictions of the solubility rather important. Cubic equations of state （EOS） are commonly used to predict solubilities in industry. However, the cubic EOSs fail to predict the thermodynamic properties near the critical point, because of density fluctuations asymptotically close to the critical point. The RG-CPA EOS which combines the original cubic-plus-association （CPA） EOS with renormMization group theory （RG） can give accurate predictions of the thermodynamic properties both near the critical point and far from the critical point. Therefore, the RG-CPA EOS was used to model solid solubility using solubility data of 7 solid organic compounds in supercritical CO2. The results show significant improvement in the repre- sentation of the sharp change of solubility near the critical point compared with the original CPA EOS.