Most industrial manufacturing processes require heat consumption and rely on fossil fuels. For renewable energy to replace fossil fuels as the primary 24/7 heat source of industrial processes requiring heat (i.e., cement, steel, glass manufacturing), a high-temperature thermal energy storage system must take intermittent renewable energy and convert it to constant heat output. This paper focuses on the thermal performance of Joule Hive^TM Thermal Battery (JHTB), an electrically heated thermal storage system that can store and provide high process heat up to 1800°C. The JHTB consists of 48 rows of electrically conductive bricks (E-brick) stacked in a snaking path and surrounded by insulating bricks (I-brick). E-bricks are heating elements whereas all bricks store heat and act as heat exchangers. The channels between I-Brick columns allow fluid flow, take in cold gas, and provide hot gas output. There is a need to understand the capabilities of brickwork as a heat exchanger. Therefore, for the first time, high-fidelity conjugate heat transfer modeling of JHTB is conducted. With appropriate symmetrical boundary conditions, the core of JHTB is reduced to a 2-dimensional array of 48 brick stacks and a half of one air channel. The transient model solves energy, mass, and momentum conservation equations using SST k-ω turbulence and surface-to-surface radiation models. Output heat rate and temperature variation across the system and temperature gradients across the whole system are tracked. Two different air channel widths are compared. Both designs show that JHTB can provide 5MW of heat for at least five hours.