The Ultra Low Emissions Potential of the Recuperated Split Cycle Combustion System

Morgan, Rod; Lenartowicz, Christopher; Vogiatzaki, Konstantina; Harvey, Simon; Kennaird, David; Owen, Nicholas; Pickett, Rhys; Atkins, Andrew

doi:10.4271/2019-24-0189

Cited by 11 publications

(17 citation statements)

References 15 publications

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“…It is "injected" into the expander cylinder at around TDC, where it meets injected fuel, giving rise to a very energetic mixing event. It is this mixing, plus the controllability of intake conditions at the point of ignition, which are believed to be responsible for a cool, homogeneous combustion phenomenon (similar to HCCI, but much more controllable and stable), and very low levels of engine-out soot and NOx [1,12,13]. Research has already demonstrated that SULEV NOx levels are possible; with development, tailpipe NOx can be reduced below observed city ambient levels.…”

Section: Recuperationmentioning

confidence: 99%

“…A single cylinder research engine, representing the expander half of the cycle, has been used to demonstrate the potential of the technology for low emissions, especially NOx [1,12,13]. However, this approach is of limited use for optimising the wider system, as the compressor hardware is absent, and losses to friction and heat are not representative of a better integrated multi-cylinder unit.…”

Section: Wave Modelsmentioning

confidence: 99%

“…In practical terms, this necessitates very low engine-out emissions, so that an after-treated system can approach the point of zero impact; and high thermal efficiency, so that carbon emissions can be reduced and future, more costly sustainable fuels can be used sparingly. This paper, together with that of Morgan et al [1], presents the development of recuperated split-cycle engines that meet those needs.…”

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

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

Owen¹,

Treccarichi²,

Atkins³

et al. 2019

SAE Technical Paper Series

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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 conceptsa 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.

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Section: Recuperationmentioning

confidence: 99%

Section: Wave Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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

Owen¹,

Treccarichi²,

Atkins³

et al. 2019

SAE Technical Paper Series

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“…Follow up injection of these liquids to a higher temperature environment causes rapid re-gasification and large expansion in volume. This can either drive a turbine or piston engine even without combustion (see for example the Dearman engine [1]) or be used in novel ultra-low emission combustion systems in order to optimise the compression stroke and reduce emissions as in the case of the Cryopower split-cycle engine [2][3][4]. Most importantly, because of the low boiling point of cryogenic liquids, low-grade or ambient heat can be used as a heat source, which otherwise is wasted.…”

Section: Introductionmentioning

confidence: 99%

“…Until now, limited studies have been performed for the potential use of these fluids in transportation and novel combustion systems. Experimental work has been focused on system level [4,11], while the specifics of injection have not yet been fully investigated, mostly because of the complexity of optical access and diagnostics. In internal combustion (IC) engines the injection process of cryogenics has different characteristics from those found in propulsion systems for space applications examined in the past.…”

Section: Introductionmentioning

confidence: 99%

Understanding Sub and Supercritical Cryogenic Fluid Dynamics in Conditions Relevant to Novel Ultra Low Emission Engines

et al. 2020

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In this paper we provide insight into the thermophysical properties and the dynamics of cryogenic jets. The motivation of the work is to optimise the use of cryogenic fluids in novel ultra low emission engines. For demonstration, we use conditions relevant to an internal combustion engine currently being developed by Dolphin N2 and the University of Brighton, the CryoPower recuperated split cycle engine (RSCE). The principle of this engine is a split-cycle combustion concept which can use cryogenic injection in the compression cylinder to achieve isothermal compression and thus help maximise the efficiency of the engine. Combined experimental and numerical findings are presented and the effects of atomisation dynamics of the LN 2 are explored at both sub- and supercritical conditions in order to cover different pressure and temperature conditions representative of the engine compression cycle. For subcritical regimes, we observe that the appearance of the jet coincides with the predicted atomisation regimes based on the Weber, Ohnesorge and Reynolds numbers for other common fluids. For the modelling of supercritical jets, a new methodology within OpenFoam which accounts for Real Fluid Thermodynamics has been developed and the jet behaviour under various pressure and temperature conditions has been investigated. To our knowledge this is the first study where a cryogenic spray process evolution is examined for conditions relevant to the ones prevailing in a compression chamber accounting for both sub and supercritical conditions.

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The recuperated split-cycle engine as a sustainable heavy-duty solution

Owen¹,

Morgan

Atkins

2020

Proceedings

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The Ultra Low Emissions Potential of the Recuperated Split Cycle Combustion System

Cited by 11 publications

References 15 publications

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

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

Understanding Sub and Supercritical Cryogenic Fluid Dynamics in Conditions Relevant to Novel Ultra Low Emission Engines

The recuperated split-cycle engine as a sustainable heavy-duty solution

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