Experimental and Numerical Investigation of Ethanol/Diethyl Ether Mixtures in a CI Engine

Vedharaj, S.; Vallinayagam, R.; Ali, Mohammed Jaasim Mubarak; Alfazazi, Adamu; Lu, Tianfeng; Im, Hong G.; Sarathy, S. Mani; Dibble, Robert W.

doi:10.4271/2016-01-2180

Cited by 24 publications

(17 citation statements)

References 49 publications

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“…The resulting minimum cell size in each direction becomes 2/2 3 = 0.125 mm. The mesh strategy is in general based on previous CFD studies in a CI engine [14].…”

Section: Spray Model Setupmentioning

confidence: 99%

CFD Study of Heat Transfer Reduction Using Multiple Injectors in a DCEE Concept

Nyrenstedt

Alturkestani

2019

SAE Technical Paper Series

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Earlier studies on efficiency improvement in CI engines have suggested that heat transfer losses contribute largely to the total energy losses. Fuel impingement on the cylinder walls is typically associated with high heat transfer. This study proposes a two-injector concept to reduce heat losses and thereby improve efficiency. The two injectors are placed at the rim of the bowl to change the spray pattern. Computational simulations based on the Reynolds-Averaged Navier-Stokes approach have been performed for four different fuel injection timings in order to quantify the reduction in heat losses for the proposed concept. Two-injector concepts were compared to reference cases using only one centrally mounted injector. All simulations were performed in a double compression expansion engine (DCEE) concept using the Volvo D13 single-cylinder engine. In the DCEE, a large portion of the exhaust energy is re-used in the second expansion, thus increasing the thermodynamic efficiency. To isolate the heat losses associated with the changed spray pattern of the two-injector concept, effects of the heat release are excluded during the analysis. Results showed that the optimal injection strategy allows a decrease in the temperature close to the walls, leading to heat loss reduction up to 13 % or 2 % of the fuel energy. The residual exhaust energy was increased by 1.5 %-points with the twoinjector concept when compared to the reference case. This proved the advantage of the two-injector concept compared to conventional single injector case for the DCEE application.

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“…The resulting minimum cell size in each direction becomes 2/2 3 = 0.125 mm. The mesh strategy is in general based on previous CFD studies in a CI engine [14].…”

Section: Spray Model Setupmentioning

confidence: 99%

CFD Study of Heat Transfer Reduction Using Multiple Injectors in a DCEE Concept

Nyrenstedt

Alturkestani

2019

SAE Technical Paper Series

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“…where n is the level of refinement provided. The meshing strategy is further described in a previous CFD study [16].…”

Section: Cfd Models and Validationmentioning

confidence: 99%

Novel Geometry Reaching High Efficiency for Multiple Injector Concepts

Nyrenstedt

Andersson

2019

SAE Technical Paper Series

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Heat losses are known to decrease the efficiency of CI engines largely. Here, multiple injectors have been suggested to shrink these losses through reduction of spray wall impingement. Studies on multiple injectors have proven the concept's heat transfer reduction but also highlighted the difficulty of using a standard piston bowl. This study proposes a two-injector concept combined with a flat bowl to reduce heat losses further. To change the spray pattern, the two injectors are injecting in a swirling motion while placed at the rim of the bowl. Four injection timings have been investigated using Reynolds-Averaged Navier-Stokes simulations. This computational method quantified the amount of heat loss reduction possible. A conventional single injector concept is compared to two injector concepts with a standard and flat bowl. A Double Compression Expansion Engine (DCEE) concept, based on a modified Volvo D13 single-cylinder engine, was the base for all simulations. The DCEE can re-use the residual exhaust energy for a second expansion meaning increased importance of reduced heat losses. Heat release effects were discarded in the evaluation as an explanation for the reduced heat losses in order to isolate the effects of the changed spray pattern. Results showed a decrease in heat losses by 25.1 % or 4.2 % of the fuel energy as well as an increased IMEP of 4.5 % or 1.9 % of the fuel energy. Together with the increased exhaust energy, results showed a possible total engine efficiency increase of 2.6 % using the DCEE concept. This work successfully proves the benefits of using two injectors with a flat bowl over a standard bowl and the conventional one-injector strategy.

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“…Low-temperature cool flames and associated heat release during the first stage affects the heat release, the timing of the second stage ignition, and even knocking [3][4][5]. Engine studies [3][4][5][6][7] have shown that stratified combustion concepts display ignition phenomenon that is governed by both molecular transport and chemical kinetic processes.…”

Section: Introductionmentioning

confidence: 99%

Cool diffusion flames of butane isomers activated by ozone in the counterflow

Alfazazi

AlOmier

Secco

et al. 2018

Combustion and Flame

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Ignition in low temperature combustion engines is governed by a coupling between lowtemperature oxidation kinetics and diffusive transport. Therefore, a detailed understanding of the coupled effects of heat release, low-temperature oxidation chemistry, and molecular transport in cool flames is imperative to the advancement of new combustion concepts. This study provides an understanding of the low temperature cool flame behavior of butane isomers in the counterflow configuration through the addition of ozone. The initiation and extinction limits of butane isomers' cool flames have been investigated under a variety of strain rates. Results revealed that, with ozone addition, establishment of butane cool diffusion flames was successful at low and moderate strain rates. Iso-butane has lower reactivity than n-butane, as shown by higher fuel mole fractions needed for cool flame initiation and lower extinction strain rate limits. Ozone addition showed a significant influence on the initiation and sustenance of cool diffusion flames; as ozone-less cool diffusion flame of butane isomers could not be established even at high fuel mole fractions. The structure of a stable n-butane cool diffusion flame was qualitatively examined using a time of flight mass spectrometer. Numerical simulations were performed using a detailed chemical kinetic model and molecular transport to simulate the extinction limits of the cool diffusion flames of the tested fuels. The model qualitatively captured experimental trends for both fuels and ozone levels, but over-predicted extinction limits of the flames. Reactions involving low-temperature species predominantly govern extinction limits of cool flames. The simulations were used to understand the effects of methyl branching on the behavior of n-butane and iso-butane cool diffusion flames.

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Experimental and Numerical Investigation of Ethanol/Diethyl Ether Mixtures in a CI Engine

Cited by 24 publications

References 49 publications

CFD Study of Heat Transfer Reduction Using Multiple Injectors in a DCEE Concept

CFD Study of Heat Transfer Reduction Using Multiple Injectors in a DCEE Concept

Novel Geometry Reaching High Efficiency for Multiple Injector Concepts

Cool diffusion flames of butane isomers activated by ozone in the counterflow

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