Dual fuel reactivity controlled compression ignition (RCCI) combustion is a promising method to achieve high efficiency with near zero NOx and soot emissions; however, the requirement to carry two fuels on-board has limited practical applications. Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. The reformed fuel mixture can then be used as a low reactivity fuel stream to enable RCCI out of a single parent fuel. Beyond enabling dual-fuel combustion strategies out of a single parent fuel, fuel reforming can be endothermic and allow recovery of exhaust heat to drive the reforming reactions, potentially improving overall efficiency of the system. Previous works have focused on using reformed fuel to extend the lean limit of spark ignited engines, and enhancing the control of HCCI type combustion. The strategy pairs naturally with advanced dual-fuel combustion strategies, and the use of dual-fuel strategies in the context of on-board reforming and energy recovery has not been explored. Accordingly, the work presented in this dissertation attempts to fill in the gaps in the current literature and provide a pathway to "single" fuel RCCI combustion through a combination of experiments and computational fluid dynamics modeling. Initially, a system level analysis focusing on three common reforming techniques (i.e., partial oxidation, steam reforming and auto-thermal reforming) was conducted to evaluate the potential of reformed fuel. A system layout was proposed for each reforming technique and a detailed thermodynamic analysis using first- and second-law approaches were used to identify the sources of efficiency improvements. The results showed that reformed fuel combustion with a near TDC injection of diesel fuel can increase engine-only efficiency by 4% absolute when compared to a conventional diesel baseline. The efficiency improvements were a result of reduced heat transfer and shorter, more thermodynamically efficient, combustion process. For exothermic reforming processes, losses in the reformer outweigh the improvements to engine efficiency, while for endothermic processes the recovery of exhaust energy was able to allow the system efficiency to retain a large portion of the benefits to the engine combustion. Energy flow analysis showed that the reformer temperature and availability of high grade exhaust heat were the main limiting factors preventing higher efficiencies. RCCI combustion was explored experimentally for its potential to expand on the optimization results and achieve low soot and NOx emissions. The results showed that reformed fuel can be used with diesel to enable RCCI combustion and resulted in low NOx and soot emissions while achieving efficiencies similar to conventional diesel combustion. Experiments showed that the ratio H2/(H2+CO) is an important parameter for optimal engine operation. Under part-load conditions, fractions of H2/(H2+CO) higher than 60% led to pressure oscillations inside the cylinder that substantially increased heat transfer and negated any efficiency benefits. The system analysis approach was applied to the experimental results and showed that chemical equilibrium limited operation of the engine to sub-optimal operating conditions. RCCI combustion was able to achieve "diesel like" system level efficiencies without optimization of either the engine operating conditions or the combustion system. Reformed fuel RCCI was able to provide a pathway to meeting current and future emission targets with a reduction or complete elimination of aftertreatment costs. Particle size distribution experiments showed that addition of reformed fuel had a significant impact on the shape of the particle size distribution. Addition of reformed fuel reduced accumulation-mode particle concentration while increasing nucleation-mode particles. When considering the full range of particle sizes there was a significant increase in total particle concentration. However, when considering currently regulated (Dm>23nm) particles, total concentration was comparable. To address limitations identified in the system analysis of the RCCI experiments a solid oxide fuel cell was combined with the engine into a hybrid electrochemical combustion system. The addition of the fuel cell addresses the limitations by providing sufficient high grade heat to fully drive the reforming reactions. From a system level perspective, the impact of the high frequency oscillations observed in the experiments are reduced, as the system efficiency is less dependent on the engine efficiency. From an engine perspective, the high operating pressures and low reactivity of the anode gas allow reduction of the likelihood of such events. A 0-D system level code was developed and used to find representative conditions for experimental engine validation. The results showed that the system can achieve system electrical efficiencies higher than 70% at 1 MWe power level. Experimental validation showed that the engine was able to operate under both RCCI and HCCI combustion modes and resulted in low emissions and stable combustion. The potential of a hybrid electrochemical combustion system was demonstrated for high efficiency power generation

The thermochemical recuperation process uses endothermic reformation reactions to upgrade a portion of an engine's primary fuel into a hydrogen-rich gas, thereby converting part of the exhaust heat from an internal combustion engine into chemical potential energy. Enriching the primary fuel air mixture of the internal combustion engine with this hydrogen-rich gas potentially enables combustion with very lean or dilute mixtures, resulting in higher efficiency and lower emissions as compared to standard combustion regimes. It may be possible to simplify thermochemical recuperation system architecture by directly mixing exhaust gases with the fuel in the reformation process to supply a significant portion of the heat and water required. To evaluate the effect of direct exhaust gas mixing on ethanol autothermal reformation, this work experimentally and theoretically investigated dilution with a mixture of nitrogen and carbon dioxide to simulate an exhaust composition, in combination with a range of inlet temperatures, to simulate exhaust gas temperatures, at a constant steam to carbon ratio. Parameters such as the chemical coefficient of performance, chemical energy output divided by chemical energy input, are introduced to better enable quantification of thermochemical recuperation. Trends in yield and performance metrics for ethanol autothermal reformation were observed under operating conditions across a range of oxygen to carbon ratio, a range of dilution amount, and a range of inlet temperature. For high inlet temperature cases, dilution increases hydrogen yield and chemical coefficient of performance suggesting that direct exhaust mixing would be beneficial. However, for low inlet temperatures, dilution decreased hydrogen yield and other performance metrics suggesting that direct exhaust mixing would not be beneficial. Dilution decreased methane production for many conditions. High inlet temperature conditions were found to cause homogeneous oxidation and homogenous conversion of ethanol upstream of the catalyst leading to high conversions of ethanol and high methane yields before reaching the catalyst. Coke formation rates varied over two orders of magnitude, with high coke formation rates for the high inlet temperature cases and low coke formation rates for the low inlet temperature cases. Dilution decreased the rate of coke formation. Models of intrinsic rate phenomenon were constructed in this study. The models predict that mass transport rates will be faster than the rate of chemical reaction kinetics over the range of ethanol concentrations and temperatures measured in the catalyst monolith both with and without dilution. Bounding cases for heat generation and transfer rates indicate that these phenomena could be the rate limiting mechanism or could be faster than both chemical kinetics and mass transport rates depending upon the distribution of oxidation heat between the catalyst and gas stream. Based on these results direct exhaust gas mixing is expected to be a practical method for supplying heat and water vapor for ethanol autothermal reformation in thermochemical recuperation systems when exhaust temperatures are above a certain threshold. For low exhaust temperatures direct exhaust gas mixing can supply water vapor but reduces other performance metrics.

Natural gas internal combustion engines release over half of the fuel's energy as waste heat and emit pollution that harms human health and accelerates climate change. Enriching natural gas with hydrogen has been shown to mitigate these impacts by reducing emissions and increasing engine efficiency. Thermal energy in the exhaust gas from natural gas engines can be used to drive chemical reactions to reform a biomass-derived feedstock into a hydrogen-rich gas. This gas can be blended with the primary fuel to enhance combustion and displace some of the natural gas demand. Two types of chemical reformation processes, aqueous-phase reformation (APR) and vapor-phase reformation (VPR), have been identified which can convert a biomass-derived sugar feedstock solution into a hydrogen-rich gas by recovering waste heat from engine exhaust gas. VPR operates at higher temperatures than APR, which limits the amount of heat that can be transferred from the exhaust gas to the reaction temperature. This study used a thermodynamic pinch analysis to compare the performance of these two processes based on their respective process heat demands and the thermal energy available from engine exhaust gas to determine how many moles of feedstock can be reformed. The calculations were performed using specifications for eight natural gas engines with reactor conditions from fourteen APR and ten VPR experiments, using glycerol as a model compound.

This monograph covers different aspects of internal combustion engines including engine performance and emissions and presents various solutions to resolve these issues. The contents provide examples of utilization of methanol as a fuel for CI engines in different modes of transportation, such as railroad, personal vehicles or heavy duty road transportation. The volume provides information about the current methanol utilization and its potential, its effect on the engine in terms of efficiency, combustion, performance, pollutants formation and prediction. The contents are also based on review of technologies present, the status of different combustion and emission control technologies and their suitability for different types of IC engines. Few novel technologies for spark ignition (SI) engines have been also included in this book, which makes this book a complete solution for both kind of engines. This book will be useful for engine researchers, energy experts and students involved in fuels, IC engines, engine instrumentation and environmental research.

It's crucial to use advanced combustion strategies to increase efficiency and decrease engine-out pollutants because of the compelling need to reduce the global carbon footprint. This dissertation proposes dual fuel low-temperature combustion as a viable strategy to decrease engine-out emissions and increase the thermal efficiency of future heavy-duty internal combustion (IC) engines. In dual fuel combustion, a low reactivity fuel (e.g. methane, propane) is ignited by a high reactivity fuel (diesel) in a compression-ignited engine. Generally, the energy fraction of low reactivity fuel is maintained at much higher levels than the energy fraction of the high reactivity fuel. For a properly calibrated engine, combustion occurs at lean and low-temperature conditions (LTC). This decreases the chances of the formation of soot and oxides of nitrogen within the engine. However, at low load conditions, this type of combustion results in high hydrocarbon and carbon monoxide emissions. The first part of this research experimentally examines the effect of methane (a natural gas surrogate) substitution on early injection dual fuel combustion at representative low loads of 3.3 and 5.0 bar BMEPs in a single-cylinder compression ignition engine (SCRE). Gaseous methane fumigated into the intake manifold at various methane energy fractions was ignited using a high-pressure diesel pilot injection at 310 CAD. Cyclic combustion variations at both loads were also analyzed to obtain further insights into the combustion process and identify opportunities to further improve fuel conversion efficiencies at low load operation. In the second part, the cyclic variations in dual fuel combustion of three different low reactivity fuels (methane, propane, and gasoline) ignited using a high-pressure diesel pilot injection was examined and the challenges and opportunities in utilizing methane, propane, and gasoline in diesel ignited dual fuel combustion, as well as strategies for mitigating cyclic variations, were explored. Finally, in the third part a CFD model was created for diesel methane dual fuel LTC. The validated model was used to investigate the effect of methane on diesel autoignition and various spray targeting strategies were explored to mitigate high hydrocarbon and carbon monoxide emissions at low load conditions.

Advances in Oxygenated Fuels for Sustainable Development: Feedstocks and Precursors for Catalysts Synthesis provides a roadmap to the sustainable implementation of oxygenated fuels in internal combustion engines through sustainable production, smart distribution and effective utilization. Focusing on the sustainability of feedstocks, the book assesses availability, emissions impact and reduction potential, and biodiversity and land utilization impact. Existing technologies and supply chains are reviewed, and recommendations are provided on how to sustainably implement or update these technologies, including for rural communities. Furthermore, effective supply and distribution network designs are provided alongside methods for monitoring and assessing their sustainability, accounting for social, economic, environmental and ecological factors. This book guides readers through every aspect of the production and commercialization of sustainable oxygenated fuels for internal combustion engines and their implementation across the global transport industry. Provides multilevel perspectives on how to facilitate the sustainable production of oxygenated fuel and develop new indices for measuring the effectiveness and sustainability of implementation Recommends a framework and criteria for assessing the suitability, sustainability, and environmental benefits of oxygenated biofuels Describes the fuel properties of all oxygenated fuels and their performance in unmodified and enhanced CI and SI engines