Experimental Investigation and Thermodynamic Analysis of Coconut-Shell-Derived Activated Carbon for CO <sub>2</sub> -Based Advanced Adsorption Cooling Systems
Gautam Gautam, Anupam Chaudhary, Aditya Singh, Pawan Kumar Singh, Satyabrata Sahoo
Abstract
The current investigation explores the CO 2 adsorption capacity of an indigenous coconut-shell-derived activated carbon, namely AC CARB 6X12 55, at an adsorption temperature and pressure of 5–70 °C and 0–42 bar, respectively, suitable for CO 2 -based adsorption cooling applications using an in-house developed high-pressure test facility. Additionally, experiments are conducted to measure thermal diffusivity, thermal conductivity, and specific heat of activated carbon using the hot-disk method on a TPS 2500 S analyzer. The activated carbon possesses the maximum CO 2 adsorption capacity of 0.70 kg/kg at 5 °C and 32 bar. Isotherm modeling is carried out based on experimental data employing Toth, D–A, and modified D–A isotherm models, followed by detailed thermodynamic investigation to estimate the heat of adsorption, adsorbed phase-specific heat, enthalpy, and entropy. Based on the adsorption isotherm data and thermophysical properties, study is extended to explore the performance of different advanced CO 2 -based adsorption cooling systems employing internal heat and mass recovery schemes, an ejector expansion, and a thermoelectric subcooler. The results confirm that the suggested cycle modifications are crucial for cooling applications, as a maximum COP and SCE of 0.341 and 44.88 kJ/kg, respectively, with an increment of 163% in system COP compared to the basic cycle, are achieved.