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• An in-house adsorption test rig is designed and developed for CH 4 -AC pair. • Isotherm and kinetic constants are determined for subzero and high temperatures. • Physiochemical and thermophysical properties are experimentally estimated. • Heat of adsorption, adsorbed phase-specific heat, enthalpy, entropy are estimated. • 3D transient analysis of the ANG reactor is conducted. The current study investigates the equilibrium methane (CH 4) adsorption capacity and the adsorption kinetics of a locally produced coconut shell-derived activated carbon (AC CARB 6X12 60) for pressure and temperatures ranging from 0 to 55 bar and -20 to 70 °C, respectively. The adsorption isotherms and kinetics are determined using an in-house developed adsorption test rig. A maximum methane adsorption uptake of 0.140 kg/kg is obtained at -20 °C and 40 bar pressure. The adsorption equilibrium isotherm data are fitted using Toth, Dubinin-Astakhov (DA), and Modified-DA isotherm models. Afterwards, the kinetics study is done considering pseudo first order, second order, Elovich, and intra-particle diffusion models. In continuation, based on the DA isotherm model, Clausius Clapeyron relation, and Maxwell's relations, the expressions for the crucial thermodynamic parameter of adsorbed phase, i.e., isosteric heat of adsorption, specific heat capacity, enthalpy, and entropy is derived, and same is estimated using DA isotherm parameters. Additionally, the activated carbon's thermophysical properties (i.e., thermal conductivity, thermal diffusivity, and specific heat) are determined using the TPS 2500 S analyzer, which works on the hot-disk principle. Using the most suitable isotherm (DA) and kinetic model (pseudo second order), heat and mass transfer analysis is carried out on novel reactor configuration with an external cooling jacket, double row of cooling pipes with external longitudinal fins for methane storage using a 3D transient model in Comsol Multiphysics. The charge characteristics are studied for gas charging pressure varying from 1 to 50 bar and cooling fluid temperature of -20 to 70 °C. Iso-concentration contours are plotted to identify the pressure-temperature combination resulting in identical storage capacity (i.e., including both gaseous and adsorbed phases). Further simulations are carried out for constant pressure charging and constant flow discharge conditions to expound upon the effects of the dormancy period, gas charging pressure, and cooling/heating fluid temperature. 14% improvement in total discharge amount is obtained with a dormancy period between charging and discharging compared to no dormancy case. [ABSTRACT FROM AUTHOR]

• 12 adsorbent composites are synthesized with enhanced thermophysical properties. • Composites are employed in post-combustion CO 2 capture applications. • 6–606% increment in thermal conductivity is achieved. • 5 isotherm models have been used to correlate the measured isotherm data. • Thermodynamic performance is investigated under different operation conditions. The present investigation aims at developing consolidated adsorbent composites with enhanced thermophysical and transport properties at the cost of a minimum sacrifice in equilibrium CO 2 uptake. Twelve samples are synthesized using a coconut shell-derived activated carbon (CSAC) as the parent material, graphite, graphene nanoplatelets, and CuO as the additives and PVA as the binder. All the synthesized had undergone a proper characterization using N 2 adsorption/ desorption and FE-SEM to highlight the changes in the BET surface area, pore volume, pore size distribution, and pore networking compared to the parent activated carbon and surface morphology. The thermophysical (specific heat capacity) and transport properties (thermal conductivity and thermal diffusivity) of all the composites of various mass fractions of the additives (10–40%) are measured using a TPS-2500 S transient hot disk method. The experimental results show that maximum thermal conductivity of 1.72 W/m K is achieved with graphite as the additive with a ratio of CSAC: graphite: PVA (Composite 4) of 50:40:10 wt%, corresponding to an increment of 606% compared to parent CSAC. The increment is comparable and better than the other consolidated adsorbent composites reported in the literature. All the constants of various isotherm models are obtained based on the experimentally obtained pressure-temperature and concentration data using the non-linear regression analysis. Based on the R2 values, the Toth model is identified as the best model for all the composites. A detailed thermodynamic analysis is further carried out, and important thermodynamic parameters, i.e., Enthalpy, Entropy, Gibbs free energy change associated with the adsorption process and the Isosteric heat of adsorption are obtained. The estimated thermodynamic parameters, isotherm and thermophysical data are crucial for the actual design and development of compact systems suitable for adsorption-based CO 2 capture applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Expressions for the efficiency and effectiveness of a porous fin with prescribed tip temperature are developed. • Analytical expressions for fin temperature profile and performance parameters are obtained using Galerkin's method of weighted residual. • The critical value of fin parameter S H is identified and different behaviour of the fin in the two different zone S H < S H * & S H > S H * are expounded. • The non-operating zone for a porous fin with prescribed tip temperature is identified. • Four different fin profile are explored. The present investigation aims at estimating the efficiency and effectiveness of porous fins of various profiles in a natural convection environment with both the ends imposed at certain temperatures. Unlike the other boundary conditions (insulated tip, convective tip) the maximum heat transfer rate for the present case cannot be determined considering the whole fin being at the base temperature. The maximum heat transfer rate is calculated by first finding the temperature profile of the fin corresponds to a very high value of thermal conductivity (i.e. k eff → ∞). Using the local maximum temperature values the maximum heat transfer rate is calculated. The variation of the temperature as well as the performance parameters for the longitudinal porous fin as a function of fin parameter (S H), is presented for four different profiles (rectangular, trapezoidal, parabolic concave and cubic concave). The variation of the fin efficiency with S H for different values of fin tip to base temperature ratio (θ L / θ b), depicts that for certain value of θ L / θ b the fin behaves differently in the two different zones S H < S H * and S H > S H *. The results indicate that for θ L / θ b ≥ 0.45 there exists a range of S H for which the fin efficiency is reduced and there exist local maxima and minima. This range of S H is undesirable to operate and it should be avoided for the proper design of the fin. The nonlinear governing differential equations are solved using the finite difference method followed by an iterative solver. To get approximate analytical expressions for the temperature as well as the fin efficiency and effectiveness semi- analytical solutions are also presented using Galerkin's method of weighted residual. [ABSTRACT FROM AUTHOR]