A Review of the External and Internal Residual Exhaust Gas in the Internal Combustion Engine

Nguyen Xuan Khoa,Ocktaeck Lim

doi:10.3390/en15031208

Nguyen Xuan Khoa, Ocktaeck Lim

Open Access

https://doi.org/10.3390/en15031208

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Journal: Energies	Publication Date: Feb 7, 2022
Citations: 6	License type: CC BY 4.0

Affiliation: Hanoi University of Industry, University of Ulsan

Abstract

Efficiency and emission reduction are the primary targets of internal combustion engine research due the large number of vehicles in operation and the impact of emissions-related pollution on human and ecosystem health. Harmful components of engine exhaust gases include nitrous oxides (NOx), carbon dioxide, hydrocarbons, and particulate matter. NOx emissions in particular are associated with significant health threats. The recirculation of exhaust gases can reduce NOx emissions and improve engine efficiency when combined with other advanced techniques. On the other hand, the residual exhaust gas also effects on the quality of lubricating engine oil and therefore causes an increase in engine piston ring wear. In this review paper, the effects of external and internal exhaust gas recirculation on the performance and emission characteristics of diesel, gasoline, and alternative fuel engines are summarized and discussed in detail. Because it is difficult to estimate the internal residual exhaust gas in the combustion engine by doing experiments. This review paper introduces control strategies and prediction methods for internal and external exhaust gas recirculation.

Highlights

Several effective methods are available to improve internal combustion engine efficiency and reduce harmful emissions, including optimal ignition timing [1,2,3], optimal injection timing [4,5,6], alternative fuels [7,8], and turbocharger use [9,10].The formation of nitrous oxides (NOx) in the combustion chamber is strongly dependent on the peak firing temperature and oxygen concentration area [11,12]
A significant effect from the increased external exhaust gas recirculation (eEGR) rate was observed in the form of reduced NOx emissions but increased hydrocarbon and carbon dioxide (CO) emissions, as in a diesel engine
Using internal exhaust gas recirculation (iEGR) with the same exhaust gas recirculation rate and full load conditions resulted in lower NOx emissions, lower engine torque, and higher brake-specific fuel consumption (BSFC) compared with eEGR

Summary

Introduction

Several effective methods are available to improve internal combustion engine efficiency and reduce harmful emissions, including optimal ignition timing [1,2,3], optimal injection timing [4,5,6], alternative fuels [7,8], and turbocharger use [9,10]. In eEGR, the gas from the exhaust pipe is routed back to the cylinder through the intake pipe This is a useful and more effective method of reducing NOx emissions in diesel engines [32,33,34] because up to 50% of the exhaust gases can be recirculated without affecting combustion stability. At high loads, eEGR rates of up to 20% result in little change in engine thermal efficiency because higher CO2 levels reduce the peak firing temperature and oxygen concentration, and the unburned hydrocarbons from the previous cycle are less significant. AAA lllaaaggggggiiinnnggg pppeeeaaakkk hhheeeaaattt rrreeellleeeaaassseee rrraaattteee aaannnddd pppeeeaaakkk ppprrreeessssssuuurrreee rrriiissseee wwwiiittthhh aaannn iiinnncccrrreeaasseeiinntthheeeeEEGGRRrrraaattetee In these results, a significant effect from the increased eEGR rate was observed in the form of reduced NOx emissions but increased hydrocarbon and CO emissions, as in a diesel engine.

Control System and Prediction of eEGR Methods

The Effect of iEGR on Engine Performance and Emission Characteristics

Findings

Conclusions