Measuring Dynamic Storage and Predicting Flow Dynamics in Adsorbed Natural Gas Systems

Gas adsorption measurements are traditionally made in equilibrium conditions on small amounts of adsorbent material. While these measurements accurately determine a material’s optimal storage capacity, they do not provide much information on the system’s storage evolution. When attempting to implement large scale adsorption systems, such as those proposed to be used as automotive fuel tanks, the temperature rise seen during gas loading decreases the adsorbent's storage capacity. The low permeability of the adsorbent can also cause pressure gradients in the system. Implying the storage capacity may vary throughout the system. Accounting for these pressure and temperature gradients makes experimentally determining adsorption in non-equilibrium systems difficult. In this work, we propose a new technique for experimentally measuring the dynamic storage of adsorbents. Using the temperature change in the system, along with the adsorbent's heat of adsorption, the amount of adsorbed gas can be determined. Once the amount of adsorbed gas is determined, an average system pressure can be calculated and used to predict system flow dynamics. The method has been shown to accurately predict the storage evolution in a 40 L natural gas tank and provide insights on the systems pressure evolution.