ENERGY STORAGE UNIT WITH INTEGRATED TWO-PHASE COOLING

Embodiments are disclosed of an energy storage unit. The unit includes a battery housing and a battery stack positioned in the battery housing. The battery stack includes N vertically stacked battery packs, N ≥ 2, and the N battery packs include at least a bottom battery pack and a top battery pack. N fluid channels formed in the battery housing, with each fluid channel fluidly coupled to a corresponding battery pack and extending vertically from its corresponding battery pack to the top of the battery housing. A condenser is positioned at the top of the battery housing and is fluidly coupled to the N fluid channels, so that vapor from each battery pack flows through the battery pack’s corresponding fluid channel to the condenser and liquid condensed by the condenser return to the channels of corresponding battery pack.