Downsized-Boosted Gasoline Engine with Exhaust Compound and Dilute Advanced Combustion

Abstract

<div class="section abstract"><div class="htmlview paragraph">This article presents experimental results obtained with a disruptive engine platform, designed to maximize the engine efficiency through a synergetic implementation of downsizing, high compression-ratio, and importantly exhaust-heat energy recovery in conjunction with advanced lean/dilute low-temperature type combustion. The engine architecture is a supercharged high-power output, 1.1-liter engine with two-firing cylinders and a high compression ratio of 13.5: 1. The integrated exhaust heat recovery system is an additional, larger displacement, non-fueled cylinder into which the exhaust gas from the two firing cylinders is alternately transferred to be further expanded.</div><div class="htmlview paragraph">The main goal of this work is to implement in this engine, advanced lean/dilute low-temperature combustion for low-NOx and high efficiency operation, and to address the transition between the different operating modes. Those include well-mixed charge compression-ignition at low-load, and a mixed-mode combustion at higher loads, before transitioning to boosted homogenous and stochiometric spark-ignited combustion. Here, the mixed-mode combustion strategy is composed of a deflagration of a stratified mixture created by a late direct injection, then triggering a controlled autoignition of the surrounding gas, improving the robustness of lean/dilute combustion. The paper describes the key features of the engine and details regarding the combustion and multi-mode valve strategies.</div><div class="htmlview paragraph">The experiments were performed under steady-state operation at 2000 rpm, from 1 to 11 bar IMEPn and naturally aspirated conditions. The engine demonstrated great efficiency gains compared to a conventional naturally-aspirated and downsized-boosted spark-ignited engines. The piston-compounding exhaust-heat recovery system contributes to up to 10% of the total efficiency improvement, while lean/dilute advanced combustion increases the fuel economy by up to 38% compared to a naturally aspirated engine, and up to 22%, compared to a downsized-boosted engine. NOx emissions target was met using high-levels of internal and external dilution in mixed-mode combustion operation, as well as by optimizing the injection and ignition strategy. Finally, the analysis shows that a seamless transition between the different valving strategies is achievable in support of robust transient operation.</div></div>

Analysis of Hydrogen Combustion in a Spark Ignition Research Engine with a Barrier Discharge Igniter

“…Traditional spark ignition (SI) engines face challenges in ensuring high performance together with low emissions [3]. In the context of modern spark ignition (SI) engines, the approach to reducing fuel consumption involves implementing high boost levels in conjunction with downsizing [4], along with the adoption of water injection [5], lean and/or exhaust gas recirculation (EGR) diluted mixtures [6]. It is crucial to explore contemporary combustion strategies like lowtemperature combustions (LTCs) [7], increase the hybridization level of vehicles to meet the requirements of sustainable mobility [8], and promote the use of renewable and alternative fuels [9].…”

Theoretical and experimental evaluation of electric coolant pump benefits in real driving cycles

“…These can be summarized but are not limited to combustion improvement [3,4], use of biofuels [5], Waste Heat Recovery (WHR) systems [6][7][8], and engine downsizing [9]. This latter is particularly relevant regarding mechanical efficiency improvement, the reduction of parasitic loss [10] and the decrease of propulsion power. Furthermore, downsizing can be successfully integrated with Internal combustion Engine hybridization leading to even more significant fuel economy benefits [11].…”