The Experts below are selected from a list of 5532 Experts worldwide ranked by ideXlab platform

E Galloni - One of the best experts on this subject based on the ideXlab platform.

  • variable valve timing for fuel economy improvement in a small spark ignition engine
    Applied Energy, 2009
    Co-Authors: G Fontana, E Galloni
    Abstract:

    The potential of a simple variable valve timing (VVT) system has been investigated. This system has been designed to update a small displacement engine pursuing the objective of optimizing both engine performance and, particularly, fuel consumption at part load operation. A continuously variable cam phaser (CVCP), able to produce a reverse Miller cycle effect during the intake phase and a significant internal EGR generation at the end of the Exhaust Stroke, has been introduced. A numerical approach, based on both 1-D and 3-D computational models, has been adopted in order to evaluate the engine performance when load is controlled by the VVT system and to deeply investigate the influence, on in-cylinder phenomena, of the valve timing variation. In this way, the VVT system here analyzed revealed as an effective tool in reducing the pumping losses, hence the specific fuel consumption, at partial load.

  • variable valve timing for fuel economy improvement in a small spark ignition engine
    Applied Energy, 2009
    Co-Authors: G Fontana, E Galloni
    Abstract:

    Abstract The potential of a simple variable valve timing (VVT) system has been investigated. This system has been designed to update a small displacement engine pursuing the objective of optimizing both engine performance and, particularly, fuel consumption at part load operation. A continuously variable cam phaser (CVCP), able to produce a reverse Miller cycle effect during the intake phase and a significant internal EGR generation at the end of the Exhaust Stroke, has been introduced. A numerical approach, based on both 1-D and 3-D computational models, has been adopted in order to evaluate the engine performance when load is controlled by the VVT system and to deeply investigate the influence, on in-cylinder phenomena, of the valve timing variation. In this way, the VVT system here analyzed revealed as an effective tool in reducing the pumping losses, hence the specific fuel consumption, at partial load.

Phil Jenner - One of the best experts on this subject based on the ideXlab platform.

  • Lean-burn characteristics of a turbocharged opposed rotary piston engine fuelled with hydrogen at low engine speed conditions
    International Journal of Hydrogen Energy, 2021
    Co-Authors: Jianbing Gao, Guohong Tian, Yuanjian Zhang, Shikai Xing, Phil Jenner
    Abstract:

    Abstract Opposed rotary piston (ORP) engines have high power density and compact designs which meet the requirements of power sources of hybrid vehicles. Hydrogen applications to ORP engines can effectively decrease greenhouse gas emissions; however, hydrogen combustion in ORP engines around stoichiometric ratio generated large quantities of nitrogen oxides (NOx), especially for low engine speed conditions. Lean-burn as an effective method to decrease NOx emissions was adopted in this research. A 3D numerical simulation method was used to explore the effect of equivalence ratio (≤1) on combustion and NOx emission characteristics of this ORP engine fuelled with hydrogen. The results indicated that peak in-cylinder pressure increased with equivalence ratio for 1000 revolutions per minute (RPM); however, the value over the equivalence ratio of 0.9 was the maximum among 2000 RPM scenarios. The effect of equivalence ratio on heat release rates was greatly dependent on the engine speeds. Start of combustion over 1000 RPM engine speed was advanced with the increase of equivalence ratio; and it was the earliest over the equivalence ratio of 0.9 at 2000 RPM conditions. During the Exhaust Stroke, in-cylinder pressure of free discharge was much higher than atmosphere pressure, which significantly increased the pumping losses of Exhaust Stroke. Accumulated NOx emissions over the equivalence ratio of 0.9 reached the maximum value for given engine speeds; and the NOx emissions were almost zero for severe lean-burn (

G Fontana - One of the best experts on this subject based on the ideXlab platform.

  • variable valve timing for fuel economy improvement in a small spark ignition engine
    Applied Energy, 2009
    Co-Authors: G Fontana, E Galloni
    Abstract:

    The potential of a simple variable valve timing (VVT) system has been investigated. This system has been designed to update a small displacement engine pursuing the objective of optimizing both engine performance and, particularly, fuel consumption at part load operation. A continuously variable cam phaser (CVCP), able to produce a reverse Miller cycle effect during the intake phase and a significant internal EGR generation at the end of the Exhaust Stroke, has been introduced. A numerical approach, based on both 1-D and 3-D computational models, has been adopted in order to evaluate the engine performance when load is controlled by the VVT system and to deeply investigate the influence, on in-cylinder phenomena, of the valve timing variation. In this way, the VVT system here analyzed revealed as an effective tool in reducing the pumping losses, hence the specific fuel consumption, at partial load.

  • variable valve timing for fuel economy improvement in a small spark ignition engine
    Applied Energy, 2009
    Co-Authors: G Fontana, E Galloni
    Abstract:

    Abstract The potential of a simple variable valve timing (VVT) system has been investigated. This system has been designed to update a small displacement engine pursuing the objective of optimizing both engine performance and, particularly, fuel consumption at part load operation. A continuously variable cam phaser (CVCP), able to produce a reverse Miller cycle effect during the intake phase and a significant internal EGR generation at the end of the Exhaust Stroke, has been introduced. A numerical approach, based on both 1-D and 3-D computational models, has been adopted in order to evaluate the engine performance when load is controlled by the VVT system and to deeply investigate the influence, on in-cylinder phenomena, of the valve timing variation. In this way, the VVT system here analyzed revealed as an effective tool in reducing the pumping losses, hence the specific fuel consumption, at partial load.

Thompson Lanzanova - One of the best experts on this subject based on the ideXlab platform.

  • potential of internal egr and throttled operation for low load extension of ethanol diesel dual fuel reactivity controlled compression ignition combustion on a heavy duty engine
    Fuel, 2016
    Co-Authors: Vinicius B Pedrozo, Thompson Lanzanova
    Abstract:

    Abstract High levels of carbon monoxide (CO) and unburnt hydrocarbon (HC) emissions are some of the main limitations of ethanol–diesel dual-fuel reactivity controlled compression ignition (RCCI) combustion at light engine loads. In addition, low Exhaust gas temperatures reduce the effectiveness of the oxidation catalyst, necessary to meet stringent emissions standards. Elevation of in-cylinder gas temperature and increased fuel/air equivalence ratio are desirable to reduce the CO and HC emissions and hence improve combustion efficiency and fuel conversion efficiency. In this work, experimental studies and engine modelling have been carried out to investigate the potential of internal Exhaust gas recirculation (iEGR) and throttled operation for low load extension of ethanol–diesel dual-fuel RCCI combustion. The experiments were performed on a single cylinder heavy-duty (HD) diesel engine equipped with a variable valve actuation system capable of intake valve re-opening during the Exhaust Stroke. The engine model was built in a one-dimensional computational fluid dynamics software. The utilisation of higher residual gas fractions and higher global equivalence ratios increased the mean in-cylinder gas temperatures during combustion. The hotter combustion processes resulted in lower CO and unburnt HC emissions, and higher Exhaust gas temperatures. The lower oxygen concentration and higher heat capacity of the in-cylinder charge using iEGR curbed nitrogen oxides (NOx) formation. Net indicated efficiency was improved with the use of iEGR and remained nearly constant while throttling the engine when compared to the dual-fuel combustion baseline at 0.32 MPa net indicated mean effective pressure (IMEP net ). Compared with conventional diesel combustion, ethanol–diesel dual-fuel RCCI combustion minimised NOx and soot emissions from 0.3 to 0.6 MPa IMEP net and increased efficiency at loads above 0.5 MPa IMEP net .

Jianbing Gao - One of the best experts on this subject based on the ideXlab platform.

  • Lean-burn characteristics of a turbocharged opposed rotary piston engine fuelled with hydrogen at low engine speed conditions
    International Journal of Hydrogen Energy, 2021
    Co-Authors: Jianbing Gao, Guohong Tian, Yuanjian Zhang, Shikai Xing, Phil Jenner
    Abstract:

    Abstract Opposed rotary piston (ORP) engines have high power density and compact designs which meet the requirements of power sources of hybrid vehicles. Hydrogen applications to ORP engines can effectively decrease greenhouse gas emissions; however, hydrogen combustion in ORP engines around stoichiometric ratio generated large quantities of nitrogen oxides (NOx), especially for low engine speed conditions. Lean-burn as an effective method to decrease NOx emissions was adopted in this research. A 3D numerical simulation method was used to explore the effect of equivalence ratio (≤1) on combustion and NOx emission characteristics of this ORP engine fuelled with hydrogen. The results indicated that peak in-cylinder pressure increased with equivalence ratio for 1000 revolutions per minute (RPM); however, the value over the equivalence ratio of 0.9 was the maximum among 2000 RPM scenarios. The effect of equivalence ratio on heat release rates was greatly dependent on the engine speeds. Start of combustion over 1000 RPM engine speed was advanced with the increase of equivalence ratio; and it was the earliest over the equivalence ratio of 0.9 at 2000 RPM conditions. During the Exhaust Stroke, in-cylinder pressure of free discharge was much higher than atmosphere pressure, which significantly increased the pumping losses of Exhaust Stroke. Accumulated NOx emissions over the equivalence ratio of 0.9 reached the maximum value for given engine speeds; and the NOx emissions were almost zero for severe lean-burn (