Abstract
Strict emission regulations and demand for better fuel economy are driving forces for finding advanced engines that will be able to replace the conventional internal combustion engines in the near future. Homogeneous charge compression ignition (HCCI) engines use a different combustion technique; there are no spark plugs or injectors to assist the combustion. Instead, when the mixtures reach chemical activation energy, combustion auto-ignites in multiple spots. The main objective of this review paper is to study the engine performance and emission characteristics of HCCI engines operating in various conditions. Additionally, the impact of different fuels and additives on HCCI engine performance is also evaluated. The study also introduces a potential guideline to improve engine performance and emission characteristics. Compared to conventional compression ignition and spark ignition combustion methods, the HCCI combustion mode is noticeably faster and also provides better thermal efficiency. Although a wide range of fuels including alternative and renewable fuels can be used in the HCCI mode, there are some limitation/challenges, such as combustion limited operating range, phase control, high level of noise, cold start, preparation of homogeneous charge, etc. In conclusion, the HCCI combustion mode can be achieved in existing spark ignition (SI) engines with minor adjustments, and it results in lower oxides of nitrogen (NOx) and soot emissions, with practically a similar performance as that of SI combustion. Further improvements are required to permit extensive use of the HCCI mode in future.
Highlights
The negative environmental impact due to greenhouse gas emission as the impact of excessive use of fossil fuels has encouraged scientists to discover a new resource of energy [1]
This review focuses on the role of the Homogeneous charge compression ignition (HCCI) mode on the performance and emission parameters along with the effects of various fuels, additives on those parameters of the HCCI engine
Due to strict emission regulations imposed to cut-down harmful emissions generated by conventional internal combustion engines, it is essential to search for alternative and advanced combustion methods
Summary
The negative environmental impact due to greenhouse gas emission as the impact of excessive use of fossil fuels has encouraged scientists to discover a new resource of energy [1]. Researchers worldwide are looking for better combustion techniques to increase engine efficiency, lower the fuel consumption and reduce emission levels. NOx, PM and HC Direct injection - The benefits of using HCCI are: (i) It operates at fuel-lean condition and compression ratios (>15) comparable to those of diesel engines, it is possible to achieve higher efficiencies compared to SI engines [14–16]; (ii) a wide range of fuels can be used [15,17–19] and (iii) it is able to produce lower PM and NOx [20] emissions, which have negative health and environmental effects. Energies 2019, 12, x FOR PEER REVIEW engines [14–16]; ii) a wide range of fuels can be used [15,17–19] and iii) it is able to produce lower PM aEnnedrgiNesO20x19[2, 102], e35m57issions, which have negative health and environmental effects. This article can be used as a good reference to understand the role of HCCI mode and develop the HCCI technology in order to lower emissions
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