Fuel reactivity controlled compression ignition engine and potential strategies to extend the engine operating range: A comprehensive review

Abstract

The objective of this study is to explore various strategies i.e. reactivity stratification, thermal stratification, injection timing, and exhaust gas recirculation as key factors for prolonging the PCCI/RCCI/DDFS engine operational spectrum and suppressing the ringing intensity. Since most of the current motivating strategies can be lumped into the category of premixed Low-Temperature-Combustion (LTC), the potential of this paper is to demonstrate the robustness of LTC in addressing several challenges related to premixed charge compression ignition engine, viz., lack of phasing regulation of combustion at heavy engine loads and excessive pressure rises. With a premixed preparation strategy, however, emission species are seen to decrease, yet the challenges of pre-combustion charge preparation are present. This can deduct a noticeable extent of fuel energy. To avoid the steep trend of pressure rise problem that restricts LTC engines with their operating range, higher levels of fuel blending and regulating the timing of auto-ignition are used. This review demonstrates the ongoing progress in premixed LTC techniques aim to control of nitrogen oxides (NOx), reduction of particulate matter (PM), and hydrocarbon (HC). In comparison to normal LTC operation, the duel fuel charge stratification might increase indicated thermal efficiency (ITE) by 5% to 7% across the survey. For various charge compositions, tests were made in homogeneous charge compression ignition (HCCI) and reactivity controlled compression ignition (RCCI). These results are provided and analyzed in comprehensive detail, with extensive correlations to model predictions and a thorough kinetic analysis. Furthermore, injection strategies were reviewed to accomplish highly efficient preparation of the combustion charge, reduce the combustion environment temperature, and enhance premixing. By highlighting relevant components of this rich and quickly growing field of knowledge, this study aims to give an insight to and summary of current studies on LTC combustion. As a result, this document serves as a fundamental collection of information and recommendations on the current state of combustion research on various fuels.

Keywords

• Reactivity stratification
• N-heptane/ethanol mechanism
• Direct dual fuel stratification
• Extending operation limits
• Engine emissions
• HCCI engine