scholarly journals Switching strategy between HP (high pressure)- and LPEGR (low pressure exhaust gas recirculation) systems for reduced fuel consumption and emissions

Energy ◽  
2015 ◽  
Vol 90 ◽  
pp. 1790-1798 ◽  
Author(s):  
José Manuel Luján ◽  
Carlos Guardiola ◽  
Benjamín Pla ◽  
Alberto Reig
Keyword(s):  
High Pressure ◽  
Fuel Consumption ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Exhaust Gas ◽  
Switching Strategy ◽  
Gas Recirculation ◽  
Fuel Consumption And Emissions

scholarly journals Experimental study on the effect of high-pressure and low-pressure exhaust gas recirculation on gasoline engine and turbocharger

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880960 ◽  
Author(s):  
Xianqing Shen ◽  
Kai Shen ◽  
Zhendong Zhang
Keyword(s):  
High Pressure ◽  
Fuel Consumption ◽  
Gasoline Engine ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Partial Load ◽  
Recirculation System ◽  
Gas Recirculation

The effects of high-pressure and low-pressure exhaust gas recirculation on engine and turbocharger performance were investigated in a turbocharged gasoline direct injection engine. Some performances, such as engine combustion, fuel consumption, intake and exhaust, and turbocharger operating conditions, were compared at wide open throttle and partial load with the high-pressure and low-pressure exhaust gas recirculation systems. The reasons for these changes are analyzed. The results showed EGR system of gasoline engine could optimize the cylinder combustion, reduce pumping mean effective pressure and lower fuel consumption. Low-pressure exhaust gas recirculation system has higher thermal efficiency than high-pressure exhaust gas recirculation, especially on partial load condition. The main reasons are as follows: more exhaust energy is used by the turbocharger with low-pressure exhaust gas recirculation system, and the lower exhaust gas temperature of engine would optimize the combustion in cylinder.

Emission reduction through internal and low-pressure loop exhaust gas recirculation configuration with negative valve overlap and late intake valve closing strategy in a compression ignition engine

2017 ◽  
Vol 18 (10) ◽  
pp. 973-990 ◽  
Author(s):  
Jaeheun Kim ◽  
Choongsik Bae
Keyword(s):  
High Pressure ◽  
Nitrogen Oxides ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Exhaust Gas ◽  
Effective Pressure ◽  
Intake Valve ◽  
Trade Off ◽  
Indicated Mean Effective Pressure ◽  
Gas Recirculation

An investigation was carried out to examine the feasibility of replacing the conventional high-pressure loop/low-pressure loop exhaust gas recirculation with a combination of internal and low-pressure loop exhaust gas recirculation. The main objective of this alternative exhaust gas recirculation path configuration is to extend the limits of the late intake valve closing strategy, without the concern of backpressure caused by the high-pressure loop exhaust gas recirculation. The late intake valve closing strategy improved the conventional trade-off relation between nitrogen oxides and smoke emissions. The gross indicated mean effective pressure was maintained at a similar level, as long as the intake boosting pressure kept changing with respect to the intake valve closing timing. Applying the high-pressure loop exhaust gas recirculation in the boosted conditions yielded concern of the exhaust backpressure increase. The presence of high-pressure loop exhaust gas recirculation limited further intake valve closing retardation when the negative effect of increased pumping work cancelled out the positive effect of improving the emissions’ trade-off. Replacing high-pressure loop exhaust gas recirculation with internal exhaust gas recirculation reduced the burden of such exhaust backpressure and the pumping loss. However, a simple feasibility analysis indicated that a high-efficiency turbocharger was required to make the pumping work close to zero. The internal exhaust gas recirculation strategy was able to control the nitrogen oxides emissions at a low level with much lower O2 concentration, even though the initial in-cylinder temperature was high due to hot residual gas. Retardation of intake valve closing timing and intake boosting contributed to increasing the charge density; therefore, the smoke emission reduced due to the higher air–fuel ratio value exceeding 25. The combination of internal and low pressure loop loop exhaust gas recirculation with late intake valve closing strategy exhibited an improvement on the trade-off relation between nitrogen oxides and smoke emissions, while maintaining the gross indicated mean effective pressure at a comparable level with that of the high-pressure loop exhaust gas recirculation configuration.

Cylinder-to-cylinder high-pressure exhaust gas recirculation dispersion effect on opacity and NOx emissions in a diesel automotive engine

2020 ◽  
pp. 146808741989540 ◽  
Author(s):  
Vicente Macián ◽  
José Manuel Luján ◽  
Héctor Climent ◽  
Julián Miguel-García ◽  
Stéphane Guilain ◽  
...  
Keyword(s):  
High Pressure ◽  
Fuel Consumption ◽  
Exhaust Gas Recirculation ◽  
Accurate Information ◽  
Exhaust Gas ◽  
Engine Operation ◽  
Automotive Engine ◽  
Brake Mean Effective Pressure ◽  
Recirculation Rate ◽  
Gas Recirculation

The objective of the study is to determine the effect of the high-pressure exhaust gas recirculation dispersion in automotive diesel engines in NO x and smoke emissions in steady engine operation. The investigation quantifies the NO x and smoke emissions as a function of the dispersion of the high-pressure exhaust gas recirculation among cylinders. The experiments are performed on a test bench with a 1.6-L automotive diesel engine. In order to track the high-pressure exhaust gas recirculation dispersion in the intake pipes, a valves system to measure CO2, that is, exhaust gas recirculation rate, was installed pipe to pipe. In addition, a valves device to measure NO x emissions cylinder to cylinder in the exhaust was installed. Moreover, a smoke meter device was installed downstream the turbine, to measure the effect of the high-pressure exhaust gas recirculation dispersion on smoke emissions. Five different engine speeds were studied with different torque levels; thus, the engine map was widely studied, from 1250 to 3000 r/min and between 6 and 20 bar of brake mean effective pressure. The exhaust gas recirculation rate varies between 4% and 25% depending on the operating point. The methodology focused on experimental tools combining traditional measuring devices with a specific valves system, which offers accurate information about species concentration in both the intake and the exhaust manifolds. The study was performed at constant raw NO x emissions to observe the effect of the exhaust gas recirculation dispersion in the opacity and fuel consumption. The study concludes that when the exhaust gas recirculation dispersion is low, the opacity presents reduced values in all operating points. However, above a certain level of exhaust gas recirculation dispersion, the opacity increases dramatically with different slopes depending on the engine running condition. This study allows quantifying the exhaust gas recirculation dispersion threshold. In addition, the exhaust gas recirculation dispersion could contribute to increase the fuel consumption up to 3.5%.

scholarly journals High-pressure versus low-pressure exhaust gas recirculation in a Euro 6 diesel engine with lean-NOx trap: Effectiveness to reduce NOx emissions

2018 ◽  
Vol 20 (1) ◽  
pp. 155-163 ◽  
Author(s):  
Magín Lapuerta ◽  
Ángel Ramos ◽  
David Fernández-Rodríguez ◽  
Inmaculada González-García
Keyword(s):  
High Pressure ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Lean Nox Trap ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Nox Trap ◽  
Aftertreatment System ◽  
Lean Nox ◽  
Gas Recirculation

Exhaust gas recirculation can be achieved by means of two different routes: the high-pressure route (high-pressure exhaust gas recirculation), where exhaust gas is conducted from upstream of the turbine to downstream of the compressor, and the low-pressure one (low-pressure exhaust gas recirculation), where exhaust gas is recirculated from downstream of the turbine and of the aftertreatment system to upstream of the compressor. In this study, the effectiveness of both exhaust gas recirculation systems on the improvement of the NOx-particulate matter emission trade-off has been compared on a Euro 6 turbocharged diesel engine equipped with a diesel oxidation catalyst, a lean-NOx trap, and a diesel particulate filter. Emissions were measured both upstream and downstream of the aftertreatment system, at different combinations of engine speed and torque (corresponding to different vehicle speeds), at transient and steady conditions, and at different coolant temperatures as switch points to change from high-pressure exhaust gas recirculation to low-pressure exhaust gas recirculation. It was shown that low-pressure exhaust gas recirculation was more efficient than high-pressure exhaust gas recirculation to reduce NOx emissions, mainly due to the higher recirculation potential and the lower temperature of the recirculated gas. However, such a differential benefit decreased as the coolant temperature decreased, which suggests the use of high-pressure exhaust gas recirculation during the engine warm-up. It was also shown that the lean-NOx trap storage efficiency decreased more rapidly at high engine load than at medium load and that such reduction in efficiency was much faster when high-pressure exhaust gas recirculation was used than when low-pressure exhaust gas recirculation was used.

scholarly journals Ensuring Requirements for Emissions of Harmful Substances of Diesel Engines

2020 ◽  
Vol 19 (4) ◽  
pp. 305-310
Author(s):  
G. M. Kuharonak ◽  
D. V. Kapskiy ◽  
V. I. Berezun
Keyword(s):  
Diesel Engine ◽  
Nitrogen Oxides ◽  
Fuel Consumption ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Average Temperature ◽  
Dispersed Particles ◽  
Harmful Substances ◽  
Gas Recirculation ◽  
Emissions Of Harmful Substances

The purpose of this work is to consider the requirements for emissions of harmful substances of diesel engines by selecting design and adjustment parameters that determine the organization of the workflow, and the exhaust gas cleaning system, taking into account the reduction of fuel consumption. Design elements and geometric characteristics of structures for a turbocharged diesel engine of Д-245 series produced by JSC HMC Minsk Motor Plant (4ЧН11/12.5) with a capacity of 90 kW equipped with an electronically controlled battery fuel injection have been developed: exhaust gas recirculation along the high pressure circuit, shape and dimensions of the combustion chamber, the number and angular arrangement of the nozzle openings in a nozzle atomizer, and inlet channels of the cylinder head. Methods for organizing a workflow are proposed that take into account the shape of the indicator diagrams and affect the emissions of nitrogen oxides and dispersed particles differently. Their implementation allows us to determine the boundary ranges of changes in the control parameters of the fuel supply and exhaust gas recirculation systems when determining the area of minimizing the specific effective fuel consumption and the range of studies for the environmental performance of a diesel engine. The paper presents results of the study on the ways to meet  the requirements for emissions of harmful substances, obtained by considering options for the organization of working processes, taking into account the reduction in specific effective fuel consumption, changes in the average temperature of the exhaust gases and diesel equipment. To evaluate these methods, the following indicators have been identified: changes in specific fuel consumption and average temperature of the toxicity cycle relative to the base cycle, the necessary degree of conversion of the purification system for dispersed particles and NOx. Recommendations are given on choosing a diesel engine to meet Stage 4 emission standards for nitrogen oxides and dispersed particles.

Design, Fabrication, and Testing of a Semi-Closed Cycle Gas Turbine Engine

2001 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Low Pressure ◽  
Exhaust Gas ◽  
Closed Cycle ◽  
Demonstration Program ◽  
Turbine Engine ◽  
Compressor Inlet ◽  
Gas Recirculation ◽  
Engine Development

A small semi-closed gas turbine was designed, fabricated, and tested to demonstrate the cycle the cycle feasibility with exhaust gas recirculation. The demonstrator unit comprised a low pressure spool compressor and turbine supercharging a high pressure spool compressor and turbine, whose exhaust passed through a recuperator, and was subsequently split, one half being recirculated to the high pressure spool compressor inlet via an intercooler, and the remaining half expanded across the low pressure spool turbine. The design and fabrication phases proceeded on schedule but commencement of engine development testing encountered mechanical difficulties. These were eventually resolved and shakedown testing of the demonstrator accomplished prior to final contractual delivery. The demonstration program was funded under a NASA LeRc contract NAS3-27396.

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