Design of Adsorbed Natural Gas Tanks with Metal Inclusions by Topology Optimisation

Adsorbed Natural Gas (ANG) tanks are constituted by porous materials able to store gas at high density and low pressure through adsorption. This phenomenon causes gas molecules to accumulate on the surface of micro-pores in a density near the one from liquid phase. Adsorption is exothermic and highly dependent on the temperature. Also, adsorbent materials present poor thermal conductivity. Thus, the efficiency of the thermal management determines the feasibility of an ANG tank. This work presents the implementation of the Topology Optimisation Method (TOM) for designing ANG tanks aiming to improve the heat exchange for more efficient adsorption and desorption cycles. This is achieved by the optimal placement of aluminium throughout the activated carbon adsorbent bed aiming the maximisation of the total mass of gas adsorbed by the end of the filling cycle and the minimisation of mass after the emptying cycle. The TOM is performed adopting the Solid Isotropic Material Model with Penalisation (SIMP) and a term for the regularisation of the design variables in the objective functions. Resulting topologies for different design domains are presented and compared to the respective homogeneous cases.