Investigation of Sectional-Stage Loading Strategies on a Two-Stage Turbocharged Heavy-Duty Diesel Engine under Transient Operation with EGR

Zhongchang Liu,Jing Tian,Yongqiang Han,Guanlong Gao,Runzhao Li,Xing Yuan

doi:10.3390/en11010069

Abstract

The influence of loading strategies on combustion and emissions parameters is experimentally and numerically studied under typical 5 s transient conditions of constant speed and increasing torque. The experiment is conducted on a two-stage turbocharged heavy-duty diesel engine with a constant opening valve high-pressure exhaust gas recirculation (EGR) system. The test results show that: compared with the full-stage loading (FSL) strategy (constant loading rate during the entire transient process), the sectional-stage loading (SSL) strategies (holding a certain time at 50% load) can significantly reduce soot emissions (by 41.3%); the greater the first-stage loading rate, the better the torque response performance, which maximally increases by 56.7%. Besides, longer loading holding time can effectively restrain the overshoot of EGR rate and advance the combustion phase (CA10, CA50) at medium and large loads. However, the larger second-stage loading rate slightly deteriorates the combustion and emission performance. This deterioration situation can be markedly suppressed by adopting a suitable loading hold time.

Highlights

The working conditions of the vehicle engine on urban roads are mostly in transient processes such as starting, acceleration and deceleration, and the proportion of constant speed and changing torque conditions is larger [1,2]
The purpose of this paper is to reduce soot emissions as much as possible, while improving the dynamical response performance during typical 5 s transient conditions, with reference to increasing torque from 10% to 100% and constant speed at 1650 rpm over 5 s transient time [19,26]
The larger the δ, the better the dynamical strategy is defined by the torque response rate (δ)

Summary

Introduction

The working conditions of the vehicle engine on urban roads are mostly in transient processes such as starting, acceleration and deceleration, and the proportion of constant speed and changing torque conditions is larger [1,2]. The overshoot of EGR rate occurs in turbocharging diesel engine under transient process conditions [5]. Aiming at addressing the increasingly serious environmental problems and stringent emission regulations, optimization of transient combustion and emission performance has become a focus of vehicle engine research. The two-stage turbocharging system can raise intake air and decrease emissions, and optimize the dynamic response performance and obtain high EGR rates, which is widely utilized in engines [9,10,11]

Objectives

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Results

Conclusion