High efficiency dual-fuel combustion through thermochemical recovery and diesel reforming

Chuahy, Flavio Dal Forno; Kokjohn, Sage

doi:10.1016/j.apenergy.2017.03.078

Cited by 78 publications

(38 citation statements)

References 53 publications

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“…The reduction in CHM from 1 to 0.5 with a 48 W/m-K PTC results in the reduction of cylinder heat transfer losses by 12 kW (≈7.5 % of fuel energy). The reduction is in line with the observations of Turner et al [11], and Chuahy and Kokjohn [12] in low-temperature combustion concepts of Partially Premixed Combustion (PPC) and Reactivity Controlled Compression Ignition (RCCI), respectively. The CHM value of 0.5 is more conservative than 0.38 used by Turner et al [11].…”

Section: High-pressure Unit Piston Insulation and Convection Heat Mulsupporting

confidence: 90%

Double Compression Expansion Engine: A Parametric Study on a High-Efficiency Engine Concept

Shankar

Johansson

Andersson

2018

SAE Technical Paper Series

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The Double compression expansion engine (DCEE) concept has exhibited a potential for achieving high brake thermal efficiencies (BTE). The effect of different engine components on system efficiency was evaluated in this work using GT Power simulations. A parametric study on piston insulation, convection heat transfer multiplier, expander head insulation, insulation of connecting pipes, ports and tanks, and the expander intake valve lift profiles was conducted to understand the critical parameters that affected engine efficiency. The simulations were constrained to a constant peak cylinder pressure of 300 bar, and a fixed combustion phasing. The results from this study would be useful in making technology choices that will help realise the potential of this engine concept.

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Section: High-pressure Unit Piston Insulation and Convection Heat Mulsupporting

confidence: 90%

Double Compression Expansion Engine: A Parametric Study on a High-Efficiency Engine Concept

Shankar

Johansson

Andersson

2018

SAE Technical Paper Series

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“…For example, reactivity controlled compression ignition (RCCI) is an advanced combustion mode that uses two fuels with vastly different autoignition properties in order to control the heat release process. 6–11 In RCCI, a high-octane fuel is mixed homogeneously with air in the cylinder. During the compression stroke, a low-octane fuel is direct injected into the cylinder.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the complexity of two separate fuel systems is a commercial limitation of RCCI. In order to address this issue, various research groups have investigated RCCI with one fuel, using either a cetane improver 10 or on-board fuel reformer 11 to modify the octane number of the parent fuel, effectively creating a second fuel.…”

Section: Introductionmentioning

confidence: 99%

A split injection of wet ethanol to enable thermally stratified compression ignition

Gainey

Hariharan

Yan

et al. 2018

International Journal of Engine Research

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Thermally stratified compression ignition is a new advanced, low-temperature combustion mode that aims to control the heat release process in a lean, premixed, compression ignition combustion mode by controlling the level of thermal stratification in the cylinder. Specifically, this work uses a mixture of 80% ethanol and 20% water by mass, referred to as “wet ethanol” herein, to increase thermal stratification via evaporative cooling of areas targeted by an injection event during the compression stroke. The experiments conducted aim to both fundamentally understand the effect that a late cycle injection of wet ethanol has on the heat release process, and to use that effect to explore the high-load limit of thermally stratified compression ignition with wet ethanol. At an equivalence ratio of 0.5, injecting just 8% of the fuel during the compression stroke was shown to reduce the peak heat release rate by a factor of 2, subsequently avoiding excessive pressure rise rates. Under pure homogeneous charge compression ignition using wet ethanol as the fuel, the load range was found to be 2.5–3.9 bar gross indicated mean effective pressure. Using a split injection of wet ethanol, the high-load limit was extended to 7.0 bar gross indicated mean effective pressure under naturally aspirated conditions. Finally, intake boost was used to achieve high-load operation with low NOx (oxides of nitrogen (NO or NO2)) emissions and was shown to further increase the high-load limit to 7.6 bar gross indicated mean effective pressure at an intake pressure of 1.43 bar. These results show the ability of a split injection of wet ethanol to successfully control the heat release process and expand the operable load range in low-temperature combustion.

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“…This process can not only enable RCCI combustion from a single fuel stream but can also be endothermic and enable the recovery of exhaust energy. Previous work by the Chuahy and Kokjohn 25,26 has explored this strategy and shown great potential for efficiency improvements. The results showed an increase of 8% in the global system efficiencies with an over 90% reduction in in-cylinder peak soot production.…”

Section: Introductionmentioning

confidence: 99%

An engine size–scaling method for kinetically controlled combustion strategies

Chuahy

Olk

DelVescovo

et al. 2018

International Journal of Engine Research

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A substantial amount of research has recently focused on kinetically controlled combustion strategies such as reactivity-controlled compression ignition combustion. These strategies are promising methods to achieve high efficiency with near-zero NOx and soot emissions; however, despite promising results, very few attempts have been made to develop size-scaling relationships that would allow these results to be generalized to any engine design. Engine design is a long and arduous process that requires a substantial amount of experimental work. Consequently, it is of interest to develop scaling laws that allow results from one engine to be extrapolated to new designs. Several scaling laws have been proposed for diffusion combustion (i.e. mixing limited) that scale parameters such as liquid length and lift-off length. Such parameters have been deemed unimportant for highly premixed low-temperature combustion strategies; thus, a new methodology is needed. The present effort uses a combination of detailed computational fluid dynamics simulations and engine experiments in two engines with different bore sizes to develop a new engine size–scaling methodology for low-temperature kinetically controlled combustion strategies. The effects of pressure, temperature, and turbulence timescales are explored in order to replicate the large-bore engine performance in a small-bore engine. A size-scaling relationship based on the ignition timescale is proposed and used to generalize the results to an arbitrary bore size and fuel combination.

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High efficiency dual-fuel combustion through thermochemical recovery and diesel reforming

Cited by 78 publications

References 53 publications

Double Compression Expansion Engine: A Parametric Study on a High-Efficiency Engine Concept

Double Compression Expansion Engine: A Parametric Study on a High-Efficiency Engine Concept

A split injection of wet ethanol to enable thermally stratified compression ignition

An engine size–scaling method for kinetically controlled combustion strategies

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