Split Cycle Engine

Hiflux has developed recuperators for Dolphin N2’s revolutionary ThermoPower® and CryoPower® recuperated split cycle engines. The engines target sectors such as long-haul trucks, where zero emission technology such as battery power is difficult to apply, distributed power generation, rail and marine. The engines are based on internal combustion piston engines, but separate the cylinders into ‘cold’ and ‘hot’ parts. The cold cylinders draw in air and compress efficiently using injection cooling. The compressed air passes through the recuperator where it is heated by engine exhaust, thus reducing the fuel needed for combustion. The recuperated air finally enters the hot cylinders where combustion and expansion occur. This hot air enters the cylinders at high pressure and speed leading to extremely high levels of mixing with the fuel, resulting in cool combustion. This yields very low levels of emissions such as NOx – close to zero impact. Thermal efficiency will be significantly higher than conventional ICE’s but the costs and changes required to integrate the engine into current production lines and drivetrains will be lower than alternative zero emission technologies such as fuel cells or batteries.

Hiflux has been part of two grant-funded consortium projects which have supported this development. The StepCO2 (Innovate UK) programme helped deliver a multi-cylinder prototype. A full demonstrator integrated into a truck is under development.