The Dearman engine – a novel piston engine driven by the expansion of liquid nitrogen or liquid air, to produce clean cold and power.
Liquid nitrogen expands 710 times between liquid and gas phases and this expansion is used to drive the pistons of an engine. Dearman engines operate like high-pressure steam engines, but the low boiling temperature of liquid nitrogen means that low-grade or ambient heat can be used as a heat source, eliminating the need for a traditional fuel.
A unique feature of Dearman engines is the use of heat exchange fluid (warm water). When it mixes with the extremely cold nitrogen, this fluid enables a quasi-isothermal (near constant) expansion and significantly increases the engine’s efficiency.
Crucially, the only emission from a Dearman engine is air or nitrogen, with no emissions of NOx, CO2 or particulates.
Dearman engine has a number of benefits compared to other low carbon technologies: