Activated carbon and graphene nanoplatelets based novel composite for performance enhancement of adsorption cooling cycle

Adsorption cooling systems powered by low-grade thermal or renewable energy are considered as a potential alternative to the vapor compression systems. To improve the performance and compactness of the system, this study focuses on the synthesis and characterization of activated carbon (AC) composite employing graphene nanoplatelets (GNPs) namely H-grade and C-grade, and polyvinyl alcohol. The influence of GNPs on the porous properties, thermal conductivity, and ethanol adsorption characteristics of composites have been experimentally investigated. Porous properties results show that the studied composites possess high surface area and pore volume with microporous nature. The C-grade contained composite shows the higher porous properties compared to H-grade, however, thermal conductivity for the later one is the highest. The highest thermal conductivity is found to be 1.55 W m(-1) K-1 for H-grade (40 wt%) contained composite which is 23.5 times higher than that of powder AC. Ethanol adsorption characteristics on studied composites are conducted gravimetrically at adsorption temperatures 30-70 degrees C. Experimental data are also fitted with Toth and Dubinin-Astakhov (D-A) isotherm models within +/- 5% RMSD and found 23% improvement of effective volumetric uptake for H25 (20 wt%) composite compared to parent AC. The instantaneous ethanol adsorption uptake onto composites has also been presented for adsorption temperature 30 degrees C and evaporator pressure at 1.8 kPa.