Optimized MIL-101(Cr)/graphene oxide/calcium chloride composites for efficient adsorption refrigeration.

Improving water vapor adsorption performance at low humidity and enhancing thermal conductivity are beneficial for the performances of adsorption refrigeration materials. In this study, MIL-101(Cr) was integrated with graphene oxide (GO) and calcium chloride (CaCl₂) to develop high-performance composite adsorbents. The materials were characterized by XRD, Raman spectroscopy, nitrogen adsorption-desorption, and thermal conductivity measurements. Adsorption and desorption tests revealed that the MIL-101(Cr)/2 % GO + 20 % CaCl₂ composite exhibited the best performance, achieving a dynamic adsorption capacity of 0.368 g/g and a 36 % increase in thermal conductivity compared to pure MIL-101(Cr). Meanwhile, the heat and mass transfer performance of the materials and the COP and SCP of the system were analyzed by modeling the adsorbent and the system under the corresponding operating conditions, and MIL-101(Cr)/2 % GO + 20 % CaCl₂ showed the best performance among all the samples of the present study in all these models. Furthermore, the composite demonstrated excellent stability after 50 adsorption-desorption cycles, retaining a desorption efficiency above 93 %. The synergistic effects of GO and CaCl₂ significantly improved both water vapor adsorption and thermal conductivity, making this composite a promising candidate for energy-efficient adsorption refrigeration systems.