CO2 adsorption onto activated carbon-graphene composite for cooling applications

Adsorption cooling system using composite adsorbent and high energy density adsorbate (CO2) provides a significant advantage to reduce the system geometry. This study presents the adsorption characteristics of CO2 onto synthesized composites employing graphene nanoplatelets (GNPs) and activated carbon (AC). The influence of GNPs in the composite is investigated in terms of porous properties, thermal conductivity, and CO2 adsorption capacity. The composite 3 (50 wt% AC and 40 wt% H-25) achieves the highest thermal conductivity enhancement which is 23.5 times higher than parent AC powder. The CO2 adsorption uptakes onto different composites are measured gravimetrically at adsorption temperatures 20-70 degrees C. The measured data are fitted with modified D-A and Toth models. The specific cooling effect (SCE) and coefficient of performance (COP) are estimated for various driving heat source temperatures and two evaporation temperatures of 5 and 10 degrees C with a fixed adsorption/condenser temperature of 30 degrees C. AC-GNPs based composites are found suitable for developing compact adsorption cooling systems. (C) 2019 Elsevier Ltd and IIR. All rights reserved.