Injection Strategy and EGR Optimization on a Viscosity-Improved Vegetable Oil Blend Suitable for Modern Compression Ignition Engines

Abstract

To comply with the ambitious CO2 targets of the European Union, greenhouse gas emissions from the transport sector should be eliminated by 2050. Incremental powertrain improvement and electrification are only a part of the solution and need to be supplemented by carbon-neutral fuels. Due to the high technology readiness level, biofuels offer a short-term decarbonization measure. The high process energy demand for transesterification or hydrotreating however, hinders the well-to-wheel CO2 reduction potential of current market biodiesels. An often-raised, economically and energetically feasible alternative is to use unprocessed oils with viscosity and cold-properties improvers instead. The present work investigates the suitability of one such biofuel (Plantanol TM ) for advanced common rail engines operating in a partially premixed compression ignition mode. Preliminary investigations are carried out on a Euro VIb light-duty car engine. The main focus is on the influence of the fuel blend on the soot/NOX emission trade-off without changing the engine control maps. Single-cylinder engine tests are then focused on the optimization potential of injection parameters and external EGR to reach optimum performanceemissions trade-off on the new fuel. The results highlight that at the factory map setting, without EGR, biofuel offers slightly reduced thermal efficiency with respect to diesel, as a joint effect of retarded combustion and elevated THC and CO emissions. NOX emissions are reduced by 20% at both non-EGR and to 25% EGR operation. With injection parameters optimization, the combustion phasing can be adjusted to diesel-like values while keeping the NOX reduction benefits. The tested bio-oil blend is however sensitive to EGR, where increasing the recirculation rate retards the combustion while the soot emissions increase almost five-fold over the non-EGR baseline.

Evaluating the Influence of Cetane Improver Additives on the Outcomes of a Diesel Engine Characteristics Fueled with Peppermint Oil Diesel Blend

“…However, direct vegetable oil usage in diesel engines is not gaining importance due to its unfavourable properties such as high viscosity and low boiling point. Despite the use of viscosity-improvers having been advocated for [5], and hydro-treating gaining considerable attention [6], transesterification continues to be the main-frame process to reduce the high viscosity vegetable oil into low viscosity biodiesel [7]. This pertains to considerably lower infrastructural investments required to produce fatty acid methyl esters (FAME), yet tradeoffs with insufficient chemical properties to meet most automotive fuel quality standards as a stand-alone fuel.…”

Excess Air Ratio Management in a Diesel Engine with Exhaust Backpressure Compensation

“…The potential application ranges from incremental improvement of conventional diesel combustion (to improve cold-start strategies with smokeless combustion) to advanced low-temperature combustion concepts such as HCCI or RCCI. In the latter case, the λ management issue is of prime importance for achieving controllable combustion with superior efficiency and emission trade-off [ 27 , 28 ].…”

Strategic Model for Yellow Hydrogen Production Using the Metalog Family of Probability Distributions

“…Despite the development of electromobility, alternative fuels for internal combustion engines are being developed simultaneously. In this area, there is a particular development of gas fuels, e.g., LPG, CNG, LNG, [18][19][20][21][22], biofuels [23,24], biodiesel [25][26][27][28], hydrogenated vegetable oil (HVO) [29][30][31], and various fuel mixtures for combustion in piston engines [32][33][34][35], alongside the research on fuel cells [36]. Very intensive work is also underway in the area of using hydrogen as an energy carrier in vehicles [37][38][39][40].…”