Numerical modeling of heat and mass transfer in an adsorbed natural gas storage tank with monolithic active carbon during charging and discharging processes

Adsorbed natural gas (ANG) technology is a promising safe and energy saving alternative to traditional compressed natural gas (CNG) and liquefied natural gas (LNG) storage systems. One of the key disadvantages to the use of ANG is the thermal effects of adsorption and desorption, leading to significant temperature changing in the adsorption layer and losses in the storage capacity. In this work, a study of heat and mass transfer processes in an ANG storage tank equipped with adsorbent monoliths, internal and external heat exchangers was carried out using the method of mathematical modeling in the ANSYS Fluent software package. A modeling method is presented using the "enthalpy approach" to describe thermodynamic processes in the adsorption layer. The presented mathematical method adequately describes the processes of heat and mass transfer in the adsorber. Forced thermal management reduced the duration of gas charging (by 2.5 times) and gas discharging (by 1.6 times) with final difference between the average temperature of the adsorbent and the ambient temperature of 15 K and also reduced gas capacity losses due to thermal effects by about 1.4 times in a shortcut charge–discharge cycle.