“5.93 kWh/L: Displacing Gasoline via the NaH-Relay Reactor.”

Thermal Safety: The Passive Steam-Buffer Governor

The Problem: Traditional hydride reactors suffer from “thermal runaway,” where exothermic hydrolysis accelerates uncontrollably.
The Unambiguous Solution: Our reactor utilizes a stoichiometric water-feed system that acts as a self-regulating thermal fuse.

• Energy Balance: The High-T Relay reaction releases approximately 25 kJ/mol H₂. We maintain a deliberate excess water ratio where the Latent Heat of Vaporization (approximately 41 kJ/mol) significantly exceeds the enthalpy of the reaction.
• The “Vapor Lock”: If the reactor temperature spikes, the water feed instantaneously flashes to steam. This phase change absorbs the excess heat and creates a localized pressure increase that physically displaces the liquid reactants from the fuel core. The reaction is thermally incapable of runaway as long as the water feed is governed.

Mechanical Integrity: Optimized Volumetric Shrinkage

The Problem: Many solid-state hydrogen storage systems fail because the “spent” product expands, jamming the reactor and causing mechanical fatigue.
The Unambiguous Solution: By anchoring our process in the $Y_{Na^{+}} =0.33$eutectic, we exploit a favorable density gradient.

• Zero-Jamming Dynamics: The byproduct (Na₄B₂O₅-NaBO₂) is significantly denser than the hydride fuel mixture. As the reaction proceeds, the “fuel chunks” physically shrink rather than swell.
• Gravity-Fed Simplicity: This volumetric contraction ensures that the spent fuel sloughs off the surface easily, preventing the formation of a “diffusion-blocking” crust. This allows for a simple, gravity-fed vertical reactor design that maintains a constant hydrogen flux without complex mechanical agitation.