Homogeneous Charge Compression Ignition (HCCI) combustion: Implementation and effects on pollutants in direct injection diesel engines

The Internal Combustion Engine (ICE) is the technological innovation that has changed the world. It is considered both as one of the greater sources of benefits and one of the main reasons of the atmospheric pollution. Therefore, in order to satisfy polluting emission legislations with particular attention for CO2 production, the engine design has been continuously improved and new components have been introduced, such as sensors and complete subsystems. The generation of polluting substances produced by the combustion depends not only on the engine structure, but also on the engine management system that is mainly responsible for the engine behavior, and so for the emission levels. Because of the introduction of new electronic components, which determines a strong increase of the degrees of freedom available during the engine operations, the optimization of engine behavior becomes more complex and less intuitive thus not obtaining the best performances of the system. Nowadays, the engine control system is an enormous collection of tuning tables, obtained adding the new tables related to new electronic components to the previous ones. This control structure is usually defined using trial-and-error approaches: engineers dedicated to the calibration process transform the goals, such as fuel consumption, engine emission, performances of the vehicle, and so on, in control references to be followed by some engine and vehicle variables that can be measured on-line. These goals are obtained through proper closed-loop control strategies receiving measurements by sensors and acting on actuators. In this chapter after a short description of the operating principles of reciprocating ICEs and their classification, an overview of a functional architecture of an Engine Management System (EMS) is given.

Introduction to Internal Combustion Engines

Increasing demand for fossil fuels due to the luxurious lifestyle, significant growth of population, transportation and the basic industry sectors has caused serious environmental problems. Moreover, a rapid decline in the fossil fuels has led scientists and researchers to look for new alternatives. In this regard, alternative fuels such as biofuels are becoming important increasingly due to environmental and energy concerns. Biofuels are commonly referred to as first generations, which are produced primarily from food crops. However, the use of edible oil to produce biodiesel in many countries is not feasible in view of a big gap in the demand and supply of such oils for dietary consumption. This paper critically reviews the facts and prospects of biofuel utilization especially, three edible biodiesels namely soybean, rapeseed, palm and two non-edible viz. jatropha and cottonseed to reduce engine exhaust gas, noise emission and petro dependency. Based on various biofuel feedstocks, this paper generally found that biodiesel fuels are considered as offering many benefits, including sustainability, reduction of greenhouse gas emissions and many harmful pollutants along with noise emission, regional development, social structure and agriculture, and security of supply.

Impact of various biodiesel fuels obtained from edible and non-edible oils on engine exhaust gas and noise emissions

Hydrogen is viewed as a sustainable strategic alternative to fossil fuels, especially in the field of road and air transport. Currently, hydrogen production is derived from fossil fuels or is manufactured by splitting water. A novel option, H2-generation from lignocellulosic biomass, based on renewable resources is currently in a pilot-scale demonstration or at a commercial stage. The present study reviews the thermochemical, biological, and electrochemical approaches used for biomass-to-hydrogen. The advantages, limitations, and major improvements of each process are presented. A techno-economic assessment is also established based on the production cost, technology readiness level, and industrial scalability. The objective is to allow industrial producers to visualise the degree of technological maturity of each option, clarify the necessary development efforts before reaching the commercial stage, determine the most relevant and competitive routes, and assess the suitability of biomass as a feedstock for renewable hydrogen production. In the reviewed results, the thermochemical process, particularly gasification, partial oxidation, and steam reforming, presented the best yield for H2 production. Steam gasification is the best compromise because it is suitable for wet and dry biomass, and it does not require an oxidising agent. As for biological conversion, dark fermentation is more worthwhile than photo-fermentation due to its lower energy consumption. Additionally, the electrochemical process is feasible for biomass. The findings of this study indicate that biomass-hydrogen-based processes are promising options that contribute to the H2 production capacity but require improvements to produce larger competitive volumes.

Willard W. Pulkrabek

Papers

Engineering Fundamentals of the Internal Combustion Engine, 2nd Ed.