The influence of different fuels and injection methods of RCCI and DCI in hybrid ICE-Battery vehicle performance

The incorporation of two recent technologies of using the dual-fuel reactivity controlled compression ignition (RCCI) combustion engine within the hybrid electric vehicle (HEV) is practiced to show how this combination can reduce the emission and enhance the thermal efficiency of the system. In particular, the heat transfers from the engine wall and the exhaust heat flow from the engine under different injection modes and fuels are of interest. The study in terms of thermal performance, fuel consumption, and battery state of charge (SOC) focuses mainly on the comparison between three cases of D100 (pure diesel) as the reference (baseline conventional direct pure diesel injection) case, D80H20 (80% diesel, 20% hydrogen) direct co-injection (DCI), and D80H20 RCCI (port + direct dual fuel injection). The NOx emission and engine power in the simulated drive cycle are investigated where the battery capacity and D50M50 (direct co-injection of 50% diesel with 50% methanol) are the additional cases. The findings indicate that the Battery SOC is preserved in better condition when the RCCI mode engine is coupled in the hybrid vehicle. The piston wall heat flux for D80H20 in DCI increases by 45.2% and for the RCCI increases by 60.5% compared to baseline diesel injection mode. It is also proved that the HEV releases considerably lower NOx compared to DCI and more NOx compared to D100 and D50M50

New insight into air/spray boundary interaction for diesel and biodiesel fuels under different fuel temperatures

The liquid fuel breakup mechanism in spray injection with ambient air for diesel and biodiesel at different fuel temperatures is studied numerically. We find that biodiesel fuel type injection with low fuel temperature induces more air entrainment volume to the boundary of the spray than diesel fuel injection and higher fuel temperature. Meanwhile, the normalized parcel density for biodiesel is 12% larger than that of diesel and peaks at a shorter distance along the spray line from the injection point (42 vs. 46 mm). Biodiesel fuel demonstrates a maximum 0.395 mg/s of air mass flow while diesel max mass flow is 0.279 mg/s. As a result, the air entrainment volume of biodiesel to the moving spray area at 1.4 ms reaches 3723.98 mm3 while for diesel the amount is 3151.27 mm3. However, the absorbed y-direction air velocity into the spray core for diesel fuel is dominant. The results give new insights into air exchange to spray boundary in the near nozzle and spray tip area: towards the tip of spray the air pushout is remarkable. Higher fuel temperature leads to slightly lower air exchange flow and entrainment (5.2%), cone angle reduction from 300 to 325 K fuel temperature, and increased surface area:volume ratio for diesel

Data-driven modeling of energy-exergy in marine engines by supervised ANNs based on fuel type and injection angle classification

The application of artificial neural networks with the involvement of a modified homogeneity factor to predict exergetic terms from combustive and/or mixing dynamics in a marine engine is considered in this study. This is a significant step since the mathematical formulation of exergy in combustion is complicated and even unconvincing due to the turbulent and highly nonlinear nature of the combustion process. The computational simulations are carried out on a marine CI (compression ignition) engine and the respective data per different fuel types that are used for thermodynamic exergetic computations as well as energetic simulations. A new parameter namely the modified homogeneity factor derived by an artificial neural network (ANN) is considered for the mixing dynamics, i.e. as an input parameter for the availability and irreversibility predictions. This parameter is based on the standard deviation from an ideal air-fuel mixture formed within the combustion chamber of the marine engine. Furthermore, spray and injection quantities along with the combustion process and its heat transfer parameters are served to predict the exergetic terms for two study cases: (a) fuel type and (b) injection orientation. It is shown that using data analytics that consists of neural networks can provide an adequate approach in diesel engines for improving energy efficiency and reducing emissions

Life cycle emission and cost assessment for LNG-retrofitted vessels: the risk and sensitivity analyses under fuel property and load variations

There are various energy efficiency and emission reduction regulations enforced by the national and international maritime authorities for the shipping industry to adopt greener technologies. In this light, LNG-fueled vessels can be a promising alternative for ocean going diesel operated ships. It will be more beneficial if the price of LNG is lower than diesel to make that an economically viable fuel. Otherwise, there are concerns over the emission/economic considerations under the cost-benefit analyses of such fuels during their lifetimes with the initial investment risk for the technology, related infrastructure including fueling facilities and technology retrofitting processes. This study is an attempt to address the respective emission, energy, and cost concerns of LNG as a possible greener fuel with innovative dual-fuel engines within the SeaTech H2020 project (seatech2020. eu) initiative. The fuel life cycle of LNG in two scenarios of fuel property modification and load management for the cost analysis is considered. The life cycle assessment (LCA) section is designed to compare typical diesel and LNG fuels with selected short and deep-sea ship routes. Moreover, it is found that the effect of the ship travel distance on the amount of emissions is not significant when compared with the respective ratio. The life cycle cost assessment (LCCA) indicated that the fuel quality is more influential than the load variations in ship navigation. A 39% GHG emission reduction and up to a 22% fuel efficiency can be achieved under more optimal operational conditions by replacing LNG with diesel. The results also showed that the feasibility of using good quality LNG (higher Wobbe Index) instead of poor diesel characteristics in a selected ship is guaranteed within 30% of the sensitivity range. The fuel consumption variations under different engine loads (50% max to 85% min) can decrease the payback period from 6-years to 4-years as per the LCCA

Scaling spray penetration at supersonic conditions through shockwave analysis

[EN] In the current paper, an investigation of the supersonic flow effect on shockwave generation and diesel spray penetration scaling has been performed. For this purpose, spray visualization tests have been carried out in a constant-pressure chamber at room temperature using shadowgraphy technique. Two working gases have been used: nitrogen, with similar thermodynamic characteristics to the engine environment, and sulfur hexafluoride, aimed at producing supersonic conditions at moderate injection pressure values. A total of 60 operating points, including different nozzle geometries, injection pressures and chamber densities have been studied. From the visualization study, two different kinds of shockwaves have been detected: normal or frontal, for moderate spray tip Mach (between 1 and 1.5); and oblique, when the Mach is higher than 1.5. The penetration results show that, for the same injection conditions in terms of injection pressure and chamber density, the spray propagation is equal for SF6 and N-2 when the spray is on subsonic conditions, while penetration is higher for SF6 when supersonic velocity is reached. This behavior has been related to the density gradient appearing across the shockwave. A new methodology to extrapolate supersonic penetration from the well-known subsonic penetration law has been proposed, showing good agreement with the experimental results.This work was partly sponsored by "Ministerio de Ciencia, Innovacion y Universidades", of the Spanish Government, in the frame of the Project "Estudio de la atomizacion primaria mediante simulaciones DNS y tecnicas opticas de muy alta resolucion", Reference RTI2018-099706-B-I00.Salvador, FJ.; De La Morena, J.; Taghavifar, H.; Nemati, A. (2020). Scaling spray penetration at supersonic conditions through shockwave analysis. 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Application of divergent split injection in a CIDI diesel engine to reduce emissions and boost the efficiency

The application of single injection in diesel engines has been becoming outdated given the advent of High-Pressure Common Rail (HPCR) system. Multiple injection or split injection presents more controllability over the economic use of fuel during the injection process. In this sense, a thorough investigation of a new concept with the use of divergent injection and split injection is proposed, based on which the whole chamber area was covered with two nozzles of different angles. Moreover, the system allows the optimal use of time span for injection in by assigning different dwell-time periods between injection pulses. The results indicate that increasing the divergence of nozzle angles could possibly bring about arise of Uniformity Index (UI) and Indicated Power (IP) of engine. In contrast, increase of dwell time leads to deterioration of Indicated Mean Effective Pressure (IMEP) and Indicated Specific Fuel Consumption (ISFC). The data points of several injection schemes are presented in IMEP-NOx and ISFC-soot plots in comparison with single injection that shows adoption of a proper injection policy can establish an ideal trade-off between emissions and engine performance

The Effect of LNG and Diesel Fuel Emissions of Marine Engines on GHG-Reduction Revenue Policies Under Life-Cycle Costing Analysis in Shipping

The fuel life cycle involves different phases of extraction/refinery (well to tank: WtT), transport (tank to propeller: TtP), and storage where each of these processes can add a specific amount of emissions to the overall LCCA inventory. During the extraction or operation of machinery on the raw material, the released amount of GHG components is undergoing a change in the generated emissions per functional unit of the consumed fuel. As a result, the machinery efficiency, electricity share, and resources mix during the extraction or refinery would impact the emission factor and subsequent carbon credit plans. Additionally, the transportation characteristics such as the traveled distance, multi-model transportation share, and ship engine fuel efficiency can make difference in the emitted GHGs into the atmosphere. The GHG credit rate and duration under different carbon allowance scenarios in the LNG-powered vessel are considered for the current life-cycle carbon emission cost analysis. For the lifecycle costing, the inflation rate, and the discount rate along with the emission reduction incentives are going to be emphasized in the project’s feasibility indicators and its profitability. The results have shown to what extent the LNG use in marine transportation can favor green shipping and how the legislated carbon incentives encourage the shipping industry for the LNG infrastructure development. The methane slip (evaporation) during the liquefaction of LNG will also be addressed, i.e., during the LNG production phase, and its effect on the emission factor of GHGs to have a better understanding of the challenges and outlook on the LNG production industry and its utilization in shipping

Experimental and numerical engine cycle setup for a dual fuel hydrogen, methane, and hythane with diesel to assess the effect of water injection and nozzle geometry

In this study, the potential of gaseous fuels such as hydrogen, methane, and hythane in combination with diesel fuel is assessed in a closed loop thermodynamic framework. An experimental test is conducted with basic diesel fuel and then the model is configured based on the realistic one-cylinder diesel engine to evaluate the robustness and reliability of the simulation. The model is accurate in terms of in-cylinder pressure, temperature, and heat release rate within the 3% error band. In principle, three blend cases of diesel50%—methane50%, diesel50%—hydrogen50%, and diesel50%—hythane50% are compared with baseline neat diesel from engine performance to emissions characteristics. For hythane and hydrogen-involved fuels, the 10% water injection effect is analyzed as well to damp the high flammability and ignition intensity of hydrogen. The findings indicate that the entropy generation in hythane and hydrogen is markedly higher than in diesel case, while water injection can slightly decrease the entropy amount. It is shown that D50H50 has more fuel consumption in higher nozzle diameter (28% at 1 mm hole diameter), while in lower nozzle size range pure diesel fuel consumption dominates. The results revealed that D50Hy40W10 is particularly effective for elevated torque at lower nozzle hole values since the steam contributes toward maximized pressure and the exerted force. The increase of the nozzle number resulted in the CO content increase in the exhaust with the burning temperature reduction