Dinitrogen Tetroxide

"Steady, keep those ion exchange cells lined up and stable lads, or we will have quite the fire on our hands!" Spoke Mariwolfe Tannenbaum, OR-09 Tiger-Striped Javelin Bundle, 6THFLEETMED 6THFLEETCHAP. Which for those following along at home, means she's the personnel officer for the Kagomine Sixth Fleet. "Come on lads, we want to finish this installation, it's delaying our departure, Southie can't go anywhere without those!"
"Zim-Zim."
"Nice work, now we lined up the ships' propulsion, all 24 cells for this side, and your fellows report doing the same on the other side. We can break for refreshments."
"Shouldn't we put some safeties on? Aren't those gases madly hypergolic together?"
"Not through a palladium membrane they aren't thankfully. If an enemy warhead passes all the bulkheads in this compartment, it could get very exciting in here though."
"Zim?"
"Aye decorated haft Hongbin?"
"How much armor in those bulkheads? Some of us plan to serve on this ship!"
"I'll be with you, decorated half, I'm chief of staff of this fine vessel, I'll be sailing with you, and sending cheques home so you get paid!"
"Zim-Zim!"
Later, around a lounge table in a dingy dock dive bar.
"What was that you said, hypergolic? What's that?"
"Means it takes a miracle or a powerful priestess to extinguish. It burns without oxygen. Like a low explosive would, for instance."
"And we carry that aboard ship?"
"We do, that fuel cell is the most efficient power generation system we've been able to devise, it's close to 90 per cent effective. It's pricey, but the fact that it burns the rocket fuel the orbital craft burn means we only carry one fuel, and it's carried in multiple modular components, all armored. It's not easy to lit, which is good, makes it safe, because once it's lit, it's hard to stop. No Navy uses any different fuel now, but Kagomei is a leader in having solar panels under transparent polymers all across decks, helps to recharge some of the fuel tanks by recombining the nitrogen and oxygen in air into dinitetro. We also have secret trailing panels drifting behind the ship, don't spread that around."
"How big?"
"Two deck sizes worth, only unfurled when at anchor and on calm seas though. But refuels the cells nicely."

Properties

Physical & Chemical Properties

Hypergolic with Hydrazines When heated, decomposes to 2xNO₂ which drives a turbine, which cools it and lowers its pressure, then pushes it into a heat sink which makes it go back to N₂O₄

N2O4

Type

Elemental / Molecular

Odor

Smells like smog

Taste

Tastes slightly of Ammonia

Color

Colorless liquid, orange gas

Boiling / Condensation Point

22C

Melting / Freezing Point

-12C, decomposes to NO2

Density

1.44246 g/cm3 (liquid, 21 °C)

Common State

Liquid at room temp