Tri-generation of sensible heat, hydrogen, and electricity in an aluminum-air flow battery (AAB) system

The performance of an aluminum-air flow battery (AAB) unit cell is experimentally studied for application to a tri-generation system as a district heating resource of sensible heat storage, hydrogen production, and electric power generation. A layer-type unit cell is designed to protect against leakage of hydrogen gas during operation and to ensure electrolyte circulation in the AAB system. The electrolyte is made with NaOH pellets dissolved in purified water. A direct current (DC) loader is used to measure the electric power of the AAB unit cell, while a resistance temperature detector (RTD) is used to measure the electrolyte temperature at the unit cell inlet and outlet. The objective of the present work is to study the effect of operation parameters [i.e., electrolyte temperature (T_in), mass flow rate (ṁ_NaOH), and molar concentration (X_NaOH)] on the performance of the tri-generation AAB system. The electric power of the AAB unit cell increases in the electrolyte temperature from 20 ℃ to 50 ℃ with increases in the NaOH molar concentration from 1 M to 4 M. The performance measurement of the AAB unit cell shows that the total surface power density of sensible heat, hydrogen, and electric power increased with increases in electrolyte temperature from 35 ℃ to 55 ℃. The tri-generation system operates for 140 min under the condition of T_in = 40 ℃, ṁ_NaOH=14.48 g/s, and X_NaOH=4 M.