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 °C. The measured data are fitted with modified D-A and Tóth 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 °C with a fixed adsorption/condenser temperature of 30 °C. AC-GNPs based composites are found suitable for developing compact adsorption cooling systems.