A Practical Recuperated Split Cycle Engine for Low Emissions and High Efficiency

Nicholas Owen, Fabrizio Treccarichi, Andrew Atkins, Anoop Selvaraj, David Barnes, Tanzi Besant, Robert Morgan

Research output: Chapter in Book/Conference proceeding with ISSN or ISBNConference contribution with ISSN or ISBN


The Recuperated Split Cycle Engine is a new type of ICE, offering a step change in efficiency and tailpipe emissions. It targets the heavy duty, long-haul sector (trucks, off-highway, rail, shipping), where electrification is most challenging, and distributed generation, where capacity is required to support rising electrification. The engine separates cold (induction, compression) and hot (combustion, expansion) parts of the cycle; waste exhaust heat is recovered between them via a recuperator, as in a recuperated gas turbine. Recent research presented at this conference [1] shows that the sonic airflows seen in the induction event give rise to extraordinary fuel mixing and clean, cool combustion, with potential for after-treated emission levels between SULEV and zero-impact (either unmeasurable or below ambient). Recuperation and thermal insulation of the hot cylinder (both feasible within the capability of common materials) also enable high thermal efficiency, with a flatter efficiency map than a conventional ICE. Combining the two attributes, and introducing sustainable fuels, places this readily manufactured, affordable technology on a par with battery-electric and fuel cell propulsion. Results from simulation to optimise the concept are described. A Ricardo WAVE model was built, with validation of key inputs such as valve breathing, heat transfer and burn-rates from relevant experimental research data. The model was used to develop the cycle around three concepts - a basic layout, “ThermoPower”, was shown to be capable of over 10% fuel saving; “Wet ThermoPower” uses water injection as a compression coolant for greater efficiency, while the ultimate “CryoPower” injects Liquid Nitrogen for quasi-isothermal compression and charge dilution. The optimisation process and practical details are described, especially the development of the critical recuperator, which is subjected to high pressure and temperature; management of its thermal expansion and manufacturing process have been optimised to minimise add-cost over a current ICE bill of materials.
Original languageEnglish
Title of host publication14th International Conference on Engines & Vehicles
Place of PublicationUnited States
PublisherSAE International
Number of pages14
Publication statusPublished - 9 Sep 2019
Event14th International Conference on Engines & Vehicles - Capri, Italy
Duration: 15 Sep 201919 Sep 2019

Publication series

NameSAE Technical Papers
PublisherSAE International
ISSN (Print)0148-7191
ISSN (Electronic)2688-3627


Conference14th International Conference on Engines & Vehicles
Internet address

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    Owen, N., Treccarichi, F., Atkins, A., Selvaraj, A., Barnes, D., Besant, T., & Morgan, R. (2019). A Practical Recuperated Split Cycle Engine for Low Emissions and High Efficiency. In 14th International Conference on Engines & Vehicles (September ed., Vol. 2019-September, pp. 1-14). [2019-24-0190] (SAE Technical Papers ). SAE International. https://doi.org/10.4271/2019-24-0190