Adsorption and Energy Storage Properties of a Zeotropic Working Fluid in MOF-5

An in-depth understanding of the adsorption and energy storage mechanism of a zeotropic working fluid in metal-organic framework materials is significant for the application of nanomaterials in thermodynamic cycles. In this study, the adsorption behavior and energy storage properties of R32, R1234yf, and their mixtures in MOF-5 were investigated using the grand canonical Monte Carlo (GCMC) method. The adsorption characteristics and adsorption heat were revealed under different pressure, temperature, and composition conditions. In addition, the rationality of the ideal adsorbed solution theory (IAST) used in the present models was also verified. The study showed that the uptake of R32 was sensitive to both temperature and pressure while that of R1234yf was sensitive to pressure below 1000 kPa but insensitive in the range of 1000-6000 kPa and insensitive to temperature. During the adsorption of R32/R1234yf mixtures, the adsorption of R1234yf also exhibits a similar trend. The selective adsorption coefficient of MOF-5 for R32 in comparison to R1234yf decreased with an increase in temperature and increased with an increase in pressure. By adding MOF-5 to the R32/R1234yf zeotropic mixtures, the enthalpy change of the zeotropic/MOF-5 nanofluid could be improved.