Study on adsorption refrigeration performance of MIL-101-isobutane working pair

High Propane and Isobutane Adsorption Cooling Capacities in Zirconium-Based Metal–Organic Frameworks Predicted by Molecular Simulations

“…The adsorption and desorption temperatures (not to be confused with the evaporator and condenser temperatures) are 298 and 363 K, respectively. Although having lower adsorption temperature or higher desorption temperature could further increase the working capacity, 20,29,38 making the adsorption at room temperature and keeping the desorption temperature below 373 K (where hot water can be used instead of other more expensive heat sources) will be helpful for practical uses. We first simulated the adsorption isotherms of propane and isobutane in NU-1000 and NU-1003 using grand canonical Monte Carlo (GCMC) simulations.…”

“…This is likely because of the higher saturation loadings in NU-1000 (1 g/g) and NU-1003 (1.4 g/ g) than in MIL-101 (0.5 g/g). 29 The difference is particularly high for refrigeration and heat pump applications (Figure 4), as the type I adsorption isotherm of isobutane in MIL-101 29 leads to a relatively fast pore filling at low pressure, but the loading cannot be further increased at higher pressures due to the lack of a second step. Nevertheless, imperfections in the experimental MOF crystals can hurt the performance of the system from the ideal predicted from simulations.…”

“…For practical uses, the working pairs with water, methanol, or ethanol as refrigerants will require extra care to maintain the high vacuum and avoid leakages, as those refrigerants have much lower vapor pressures than the atmospheric pressure. 29 Halogenated hydrocarbons do not have such a problem but are far from environmental friendly. Pure hydrocarbons, on the other hand, can be a practical and green choice as the refrigerant despite having slightly smaller latent heat than their halogenated counterparts.…”

“…9 Ma and co-workers have demonstrated that the MOF MIL-101 can be paired with isobutane to achieve higher cooling capacities than microporous activated carbon. 29 The enhancement was attributed to the fact that MIL-101 contains not only micropores but also mesopores which lead to higher surface area and larger pore volume than activated carbon. Zirconium-based MOFs (Zr- MOFs) are promising on account of their tunability, stability, and designability.…”

Toward Optimal Metal–Organic Frameworks for Adsorption Chillers: Insights from the Scale‐Up of MIL‐101(Cr) and NH2‐MIL‐125

“…[10,13] To our knowledge, diffusion coefficients for MIL-101(Cr) with water have not been reported. Yet, the diffusion process has been discussed for MIL-101(Cr) with other adsorptives than water: Ma et al [65] found that at early stages of the adsorption process, the diffusion rate of the working pair MIL-101/isobutane is considerably lower than for activated carbon/isobutane. For the working pair MIL-101(Cr)/ethanol, Saha et al [66] determined a higher activation energy, leading to slower adsorption rates, compared with activated carbon/ethanol.…”