Combustion Mode Design with High Efficiency and Low Emissions Controlled by Mixtures Stratification and Fuel Reactivity

Mingfa Yao,Hu Wang,Zunqing Zheng,Haifeng Liu

doi:10.3389/fmech.2015.00008

Abstract

This paper presents a review on the combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixture stratification that have been conducted in the authors’ group, including the charge reactivity controlled homogeneous charge compression ignition (HCCI) combustion, stratification controlled premixed charge compression ignition (PCCI) combustion, and dual-fuel combustion concepts controlled by both fuel reactivity and mixture stratification. The review starts with the charge reactivity controlled HCCI combustion, and the works on HCCI fuelled with both high cetane number fuels, such as DME and n-heptane, and high octane number fuels, such as methanol, natural gas, gasoline and mixtures of gasoline/alcohols, are reviewed and discussed. Since single fuel cannot meet the reactivity requirements under different loads to control the combustion process, the studies related to concentration stratification and dual-fuel charge reactivity controlled HCCI combustion are then presented, which have been shown to have the potential to achieve effective combustion control. The efforts of using both mixture and thermal stratifications to achieve the auto-ignition and combustion control are also discussed. Thereafter, both charge reactivity and mixture stratification are then applied to control the combustion process. The potential and capability of thermal-atmosphere controlled compound combustion mode and dual-fuel reactivity controlled compression ignition (RCCI)/highly premixed charge combustion (HPCC) mode to achieve clean and high efficiency combustion are then presented and discussed. Based on these results and discussions, combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixtures stratification in the whole operating range is proposed.

Highlights

Clean and high efficiency combustion technology is the key to meet the even stringent emission legislations for internal combustion (IC) engines
The review starts with the homogeneous charge compression ignition (HCCI) combustion control through charge reactivity control, followed by the effects of charge stratification on HCCI combustion, and the dual-fuel compound combustion concept involves both charge reactivity and stratification to achieve effective combustion control, and the combustion mode design with dual-fuel strategy is discussed and proposed
Flexible combustion control and load extension can be achieved by changing the charge reactivity according to the operating conditions in dual-fuel HCCI combustion

Summary

Introduction

Clean and high efficiency combustion technology is the key to meet the even stringent emission legislations for internal combustion (IC) engines. Ultra-low NOx and soot emissions can be obtained simultaneously with this combustion concept, together with high thermal efficiency due to the reduced heat transfer loss This compound dual-fuel combustion concept has the potential to achieve clean and high efficiency combustion within much wider operation ranges. How to achieve and optimize the combustion in the full load range still remains as the challenge for the development of this novel combustion concept This objective of this paper is to present a review on the combustion mode design with high efficiency and low emissions controlled by mixture stratification and charge reactivity that have been conducted in the authors’ group. The paper will start with HCCI combustion control through the charge reactivity and mixture stratification, both the reactivity and stratification are applied to optimize the combustion process using dual-fuel compound combustion concepts (thermo-atmosphere combustion and RCCI/HPCC), and the combustion mode design fueled with dual-fuel strategy will be discussed

Experimental Setup and Instruments

Findings

Conclusion