Dinitrogen tetroxide
Power generation using N<sub>2</sub>O<sub>4</sub>
Power generation using N2O4
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The tendency of N2O4 to reversibly break into NO2 has led to research into its use in advanced power generation systems as a so\-called dissociating gas. "Cool" dinitrogen tetroxide is compressed and heated, causing it to dissociate into [nitrogen dioxide](/wiki/Nitrogen_dioxide "Nitrogen dioxide") at half the molecular weight. This hot nitrogen dioxide is expanded through a turbine, cooling it and lowering the pressure, and then cooled further in a heat sink, causing it to recombine into nitrogen tetroxide at the original molecular weight. It is then much easier to compress to start the entire cycle again. Such dissociative gas [Brayton cycles](/wiki/Brayton_cycle "Brayton cycle") have the potential to considerably increase efficiencies of power conversion equipment.

The high molecular weight and smaller volumetric expansion ratio of nitrogen dioxide compared to steam allows the turbines to be more compact.

N2O4 was the main component of the "nitrin" working fluid in the decommissioned [Pamir\-630D](/wiki/Pamir-630D "Pamir-630D") portable nuclear reactor which operated from 1985 to 1987\.


Why are turbines for NO2 more compact compared to steam?