scholarly journals On the combination of high-pressure and low-pressure exhaust gas recirculation loops for improved fuel economy and reduced emissions in high-speed direct-injection engines

2012 ◽  
Vol 14 (1) ◽  
pp. 3-11 ◽  
Author(s):  
José M Desantes ◽  
José M Luján ◽  
Benjamín Pla ◽  
José A Soler
Keyword(s):  
High Pressure ◽  
Fuel Economy ◽  
High Speed ◽  
Direct Injection ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Exhaust Gas ◽  
Direct Injection Engines ◽  
Gas Recirculation ◽  
Reduced Emissions

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.

Effect of balance valve on an asymmetric twin-scroll turbine for heavy-duty diesel engine

2020 ◽  
pp. 146808742093016
Author(s):  
Jianjiao Jin ◽  
Jianfeng Pan ◽  
Zhigang Lu ◽  
Qingrui Wu ◽  
Lizhong Xu
Keyword(s):  
Fuel Economy ◽  
High Speed ◽  
Engine Speed ◽  
Flow Parameter ◽  
Engine Performance ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Engine Fuel ◽  
Recirculation Rate ◽  
Gas Recirculation

A conventional asymmetric twin-scroll turbine with wastegate is capable of effectively tackling down the contradiction between fuel economy degradation and low nitrogen oxide emissions. However, as the engine speed has been rising at middle- and high-speed ranges, the pressure of small scroll inlet will be increasingly higher as compared with the intake pressure, thereby worsening fuel economy. In this study, a novel turbocharging technology of asymmetric twin-scroll turbine with a balance valve was first analyzed to more effectively balance the engine fuel economy and emission. The experiments on turbine test rig and engine performance were performed to explore the effects of balance valve on turbine performance, asymmetric ratio, exhaust gas recirculation rate, as well as engine performance. As the balance valve open degree was elevated, the turbine flow parameter was being extended, while the turbine efficiency was enhanced. Moreover, a lower asymmetric ratio could lead to a broader flow parameter range between that of partial admission and equal admission, thereby resulting in a broader regulating range of exhaust gas recirculation rate. In contrast with the asymmetric twin-scroll turbine with wastegate, the turbine running efficiency of asymmetric twin-scroll turbine with balance valve was enhanced by nearly 2%–11% at middle and high engine speed ranges, while the fuel economy was improved by nearly 1.5%–8%.

Characterization of temporal variations and feedback timescales of exhaust gas recirculation gas properties using high-speed diode laser absorption spectroscopy for next-cycle control of cyclic variability

2018 ◽  
Vol 20 (8-9) ◽  
pp. 945-952
Author(s):  
Gurneesh S Jatana ◽  
Brian C Kaul
Keyword(s):  
High Speed ◽  
Control Strategies ◽  
Direct Injection ◽  
Exhaust Gas Recirculation ◽  
Gasoline Direct Injection ◽  
Exhaust Gas ◽  
Recirculation Flow ◽  
Cyclic Variability ◽  
Laser Absorption ◽  
Gas Recirculation

Dilute combustion offers efficiency gains in boosted gasoline direct injection engines both through knock-limit extension and thermodynamic advantages (i.e. the effect of γ on cycle efficiency), but is limited by cyclic variability at high dilution levels. Past studies have shown that the cycle-to-cycle dynamics are a combination of deterministic and stochastic effects. The deterministic causes of cyclic variations, which arise from feedback due to exhaust gas recirculation, imply the possibility of using active control strategies for dilution limit extension. While internal exhaust gas recirculation will largely provide a next-cycle effect (short-timescale feedback), the feedback of external exhaust gas recirculation will have an effect after a delay of several cycles (long timescale). Therefore, control strategies aiming to improve engine stability at dilution limit may have to account for both short- and long-timescale feedback pathways. This study shows the results of a study examining the extent to which variations in exhaust gas recirculation composition are preserved along the exhaust gas recirculation flow path and thus the relative importance and information content of the long-timescale feedback pathway. To characterize the filtering or retention of cycle-resolved feedback information, high-speed (1–5 kHz) CO2 concentration measurements were performed simultaneously at three different locations along the low-pressure external exhaust gas recirculation loop of a four-cylinder General Motors gasoline direct injection engine using a multiplexed two-color diode laser absorption spectroscopy sensor system during steady-state and transient engine operation at various exhaust gas recirculation levels. It was determined that cycle-resolved feedback propagates through internal residual gases but is filtered out by the low-pressure exhaust gas recirculation flow system and do not reach the intake manifold. Intermediate variations driven by flow rate and compositional changes are also distinguished and identified.

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.

Effects of high-pressure and donor-cylinder exhaust gas recirculation on fuel economy and emissions of marine diesel engines

Fuel ◽  
2022 ◽  
Vol 309 ◽  
pp. 122226
Author(s):  
Xuyang Tang ◽  
Peng Wang ◽  
Zhongyuan Zhang ◽  
Fengli Zhang ◽  
Lei Shi ◽  
...  
Keyword(s):  
High Pressure ◽  
Fuel Economy ◽  
Diesel Engines ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Marine Diesel ◽  
Gas Recirculation

scholarly journals Experimental study on diesel engine exhaust gas recirculation performance and optimum exhaust gas recirculation rate determination method

2019 ◽  
Vol 6 (6) ◽  
pp. 181907 ◽  
Author(s):  
Xiang-huan Zu ◽  
Chuan-lei Yang ◽  
He-Chun Wang ◽  
Yin-yan Wang
Keyword(s):  
Decision Making ◽  
High Pressure ◽  
Diesel Engine ◽  
High Speed ◽  
Performance Test ◽  
Exhaust Gas Recirculation ◽  
Venturi Tube ◽  
Pressure Curve ◽  
Exhaust Gas ◽  
Gas Recirculation

In order to study the exhaust gas recirculation (EGR) performance of marine diesel engines, a venturi high-pressure EGR device was established to overcome the exhaust gas reflow problem based on a certain type of turbocharged diesel engine. The EGR performance test is accomplished and an optimal EGR decision-making optimization method based on grey correlation coefficient modified is proposed. The results show that the venturi tube EGR can basically meet the injection requirements of high-pressure exhaust gas and achieve good results. Through the venturi tube EGR, the NO X emissions reduce significantly with the maximum drop of 30.6%. The explosive pressure in cylinder reduces with the EGR rate increases and the cylinder pressure curve shows a single peak at low-speed conditions and double peaks at high-speed condition. However, the fuel consumption rate, NO X and smoke have been negatively affected. Due to small samples, the traditional evaluation method is difficult to determine the optimal EGR rate reasonably, while the proposed method can effectively solve this problem. It can weaken the shortcomings of subjective judgement and greatly improve the rationality of decision-making results.

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