Near-wall thermal regulation for cryogenic storage by adsorbent coating: Modelling and pore-scale investigation

Cryogenic storage of liquefied natural gas is susceptible to environmental heat influx, which possesses detrimental effects on storage safety and efficiency. Although cold insulation systems are equipped to mitigate heat leakage, active thermal management measures like re-liquefaction and re-cooling are still imperative for cold prevention, which requires supplementary power supply and has restricted capability to handle heat ingress incidents. In this paper, a passive and self-adaptive thermal regulation approach for cryogenic storage is proposed by utilizing adsorbent coatings to inhibit near-wall temperature elevation. A mesoscopic model is established by the combined lattice Boltzmann and finite difference method for evaluating cryogenic adsorption/desorption performances and the thermal regulation effect. The pore-scale adsorption kinetics and temperature transients under LNG storage conditions are predicted by introducing sub-models of isothermal adsorption, interfacial mass and heat transfer, and intraparticle diffusion. The analysis reveals that the adsorbent coating significantly mitigates and prolongs the boil-off gas temperature rise under heat influx. A reduction of gas temperature rise by 78% and an elongation of the duration by 16.6 times was observed under an external heat flux of 1000 W/m2. The results indicate that adsorbent coating has a promising capability for thermal regulation of cryogenic LNG tanks over a prolonged period.