Nicos Ladommatos

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Verified

Nicos verified their affiliation via an institutional email.

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• Doctor of Philosophy
• Professor Emeritus at University College London

div class="section abstract"> The development of new fuels for internal combustion engines (ICE) requires further technical support by understanding the pollutant formation mechanism in various phases of combustion so that emissions can be minimised. This research will therefore utilize a bespoke in-cylinder sampling system to analyse the precursor...

Expanding the use of sustainable fuels in hard to decarbonise transport vehicles utilising heavy-duty engines is urgently required to reduce greenhouse gas emissions from sectors reliant on these engines. As...

Rapidly decreasing urban air quality and the resultant health impacts are of increasing global concern, with an estimated 7 million premature deaths worldwide attributable to airborne pollutants. Many European and North American cities are increasingly implementing emissions monitoring and control schemes, however, those in the Middle East, Africa,...

Renewable alternatives to fossil diesel (FD) including fatty acid methyl ester (FAME) biodiesel have become more prevalent. However, toxicity of exhaust material from their combustion, relative to the fuels they are displacing has not been fully characterised. This study was carried out to examine particle toxicity within the lung epithelium and th...

Air pollution in many major cities is endangering public health and is causing deterioration of the environment. Particulate emissions (PM) contribute to air pollution as they carry toxic polyaromatic hydrocarbons (PAHs) on their surface. Abatement of PM requires continuous strict emission regulation and, in parallel, the development of fuels with...

Air pollution has reached critical levels in many major industrial cities, endangering public health, deteriorating the environment, and causing harm to property and landscape. The particulate emissions (PM) from propulsion which contribute to air pollution vary greatly in size and composition, conveying carcinogenic polyaromatic hydrocarbons (PAHs...

This paper examines the effect of equalizing ignition delay in a compression ignition engine. Two sets of tests were conducted, i.e. a set of constant injection timing tests with start of fuel injection at 10° crank angle degree (CAD) before top dead center (BTDC) and a set of constant ignition timing tests while also keeping the 10° CAD BTDC injec...

This paper examines the effect of equalizing ignition delay in a compression ignition engine. Two sets of tests were conducted, i.e. a set of constant injection timing tests with start of fuel injection at 10° crank angle degree (CAD) before top dead center (BTDC) and a set of constant ignition timing tests while also keeping the 10° CAD BTDC injec...

Screening of a variety of bioderived furanic molecules was performed in order to improve our understanding of how this class of molecules respond during compression-ignition combustion, after blending with diesel fuel. Reducing carbon emissions is possible through the use of “2nd generation” carbon neutral biofuels, the sources of which are from no...

Soils hold three quarters of the total organic carbon (OC) stock in terrestrial ecosystems and yet we fundamentally lack detailed mechanistic understanding of the turnover of major soil OC pools. Black carbon (BC), the product of the incomplete combustion of fossil fuels and biomass, is ubiquitous in soils globally. Although BC is a major soil carb...

Biofuels may reduce road transport carbon intensity; however, it is uncertain whether displacing fossil diesel would alter the engine-derived particulate toxicity. The primary objective of this work was to determine whether there is a fuel effect on the comparative in vitro toxicity of biodiesel exhaust particulates relative to those from fossil di...

Air rifle and air pistol target shooting are included in major intentional and national sports competitions and are also highly popular sport pastimes. Published scientific studies of pellet drag are very rare, in contrast to a large number of scientific studies published on aerodynamic drag of sports balls and other sports projectiles. Measurement...

Particulate matter (PM) is emitted from a range of combustion sources, can vary greatly in properties, and is able to penetrate deep into the human lungs, conveying carcinogenic PAHs present on the particle surface. Alcohol based biofuels have been shown to potentially reduce PM emissions when displacing fossil fuels. To improve understanding of th...

Polycyclic aromatic hydrocarbons (PAHs) are potentially carcinogenic pollutants emitted by diesel engines, both in the gas phase and adsorbed onto the surface of particulate matter (PM). There remains limited understanding of the complex and dynamic competing mechanisms of PAH formation, growth and oxidation in the gas phase, and their adsorption o...

An investigation into the exhaust emissions of carcinogenic polycyclic aromatic hydrocarbons (PAHs) from a diesel engine was reported. The study is reinforced by the experimental results obtained from a tube reactor aimed at examining the PAH formation processes from these fuels. The paper cantered on the 16 priority PAHs suggested by the United St...

This paper concerns the effect of unsaturation of hydrocarbons (single, double, and triple bonds) on soot particle characteristics (mass, number, and size) and on the carcinogenicity of soot particles. The soot particles were produced from oxygen-free pyrolysis of five hydrocarbons, namely: propane, propylene, ethane, ethylene, and acetylene. The c...

A significant amount of harmful emissions pass unreacted through catalytic after-treatment devices for IC engines before the light-off temperature is reached, despite the high conversion efficiency of these systems in fully warm conditions. Further tightening of fleet targets and worldwide emission regulations will make a faster catalyst light-off...

Better understanding of combustion and formation of exhaust gas pollutants of fuels is needed in order to meet stringent regulation standards of a diesel engine. The cetane number is one of the most-cited indicators of diesel fuel quality. This paper presents experimental studies with a wide range of fuels to investigate the effect of cetane number...

This paper reports an experimental investigation into the effects of fuel composition on the exhaust emission of toxic polycyclic aromatic hydrocarbons (PAHs) from a diesel engine, operated at both constant fuel injection and constant fuel ignition modes. The paper quantifies the US EPA (United State Environmental Protection Agency) 16 priority PAH...

Current biofuels for diesel engines are largely derived from food crops and there is significant concern, recognised by legislation, that such fuels do not result in net reductions of greenhouse gas emissions when considering the entirety of the production to usage lifecycle. A potential alternative approach is to utilise the lipid content of organ...

Air rifles and air pistols find widespread use in formal and recreational sports events. Despite their widespread use in sport, they have rarely been studied scientifically. The influence of air rifle pellet geometry on aerodynamic drag was investigated experimentally and theoretically at Mach number of 0.58 (approximately 200 m/s) and Reynolds num...

Lipids extracted from spent coffee grounds (SCG) are a potentially promising feedstock for biodiesel production if the relatively high free fatty acid (FFA) portion of the oil can be successfully converted into methyl esters, and the resulting biodiesel found to have acceptable combustion and emissions performance. This study presents experimental...

Spent coffee grounds (SCG) are a potentially valuable source of lipids for sustainable production of biofuels. However, there are several feedstock properties and solvent extraction parameters that can impact on the oil yield and quality, potentially reducing the possible environmental benefits of deriving oils from this waste stream. This study pr...

Spent coffee grounds (SCG) are the main residues of the coffee beverage industry, and a potentially valuable source of energy-dense lipids. The present study investigates the effect of temperature, pressure and duration on the pressurized solvent extraction of lipids from dried SCG to evaluate their impact on oil extraction efficiency, composition...

Concerns as to the adverse effects of diesel engine exhaust on urban air quality have resulted in increasingly stringent emissions legislation, with the prospect of many major global cities potentially banning diesel vehicles. Emissions of nitrogen oxides (NOx) and particulate matter (PM) are linked to increases in premature mortality, and the simu...

Spent coffee grounds (SCG) are a potentially sustainable source of C16-C18 triglycerides. This study investigates known solvent extraction technologies with a wide range of solvents for lipid extraction from SCGs, and determines the effect of solvent selection and process temperature on the extraction efficiency and composition of the obtained oil....

The influence of carbon number of seven hydrocarbons (methane, ethane, propane, n-butane, i-butane, heptane and toluene) on PAH formation was investigated in a laminar tube reactor. The hydrocarbons underwent oxygen-free pyrolysis within the temperature range of 1050-1350 °C at a fixed carbon concentration of 10,000 ppm on C 1 basis. Particulate an...

Spent coffee grounds (SCGs) and roasted defective coffee beans (RDCBs), are a potentially sustainable source for biofuel production if the processing of these residues, and the recovery of energy-dense lipids, can be undertaken in an energy efficient way. A necessary step in solvent extraction of lipids is prior drying of the feedstock, and this ca...

The co-combustion of diesel fuel with H2 presents a promising route to reduce the adverse effects of diesel engine exhaust pollutants on the environment and human health. This paper presents the results of H2-diesel co-combustion experiments carried out on two different research facilities, a light duty and a heavy duty diesel engine. For both engi...

Lignocellulosic materials have been identified as potential carbon–neutral sources of sustainable power production. Catalytic conversion of lignocellulosic biomass results in liquid fuels with a variety of aromatic molecules. This paper investigates the combustion characteristics and exhaust emissions of a series of alkylbenzenes, of varying number...

The conversion of lignocellulosic biomass to liquid fuels presents an alternative to the current production of renewable fuels for IC engines from food crops. However, realising the potential for reductions in net CO2 emissions through the utilisation of, for example, waste biomass for sustainable fuel production requires that energy and resource i...

Engineering systems such as gas turbines and internal combustion engines utilise gaseous fuels which produce toxic substances when they are burnt. Among these substances are solid soot particles and gas phase polycyclic aromatic hydrocarbons (PAHs). The link between soot and PAHs has long been established. Firstly, PAHs assemble themselves into lar...

Future fuels for compression ignition engines will be required both to reduce the anthropogenic carbon dioxide emissions from fossil sources and to contribute to the reductions in the exhaust levels of pollutants, such as nitrogen oxides and particulate matter. Via various processes of biological, chemical and physical conversion, feedstocks such a...

This paper presents a study undertaken on a naturally aspirated, direct injection diesel engine investigating the combustion and emission characteristics of CH4-CO2 and CH4-CO2-H2 mixtures. These aspirated gas mixtures were pilot-ignited by diesel fuel, while the engine load was varied between 0 and 7 bar IMEP by only adjusting the flow rate of the...

This paper presents a H2-diesel fuel co-combustion study undertaken on a supercharged, direct injection, diesel engine investigating the combustion characteristics and emissions production at a range of engine loads (IMEP), EGR levels and intake air boosting conditions. The utilisation of EGR and intake air boost with H2-diesel fuel co-combustion a...

The paper presents an experimental investigation of combusting methane-hydrogen mixtures, pilot-ignited by diesel fuel, on a naturally aspirated, direct injection compression ignition engine. The tests were performed with two diesel fuel flow rates for pilot-ignition, and the engine was supplied with different quantities of methane-hydrogen mixture...

This review article deals with the use of isotopic tracers in the field of combustion science. A number of researchers have reported the use of isotopic techniques, which have been employed to solve a wide range of combustion problems. Radioactive and stable isotopes have been utilized as tracers, including isotopes of carbon (¹³C and ¹⁴C), oxygen...

This paper presents the results of an experimental study that was carried out to determine the conversion rates to particulate matter (PM) of several liquid fuel hydrocarbon molecules and specific carbon atoms within those molecules. The fuels investigated (ethanol, n-propanol, i-propanol, acetone, and toluene) were blended in binary mixtures with...

This paper presents the results of an experimental study that was carried out to determine the conversion rates to particulate matter (PM) of several liquid fuel hydrocarbon molecules and specific carbon atoms within those molecules. The fuels investigated (ethanol, n-propanol, i-propanol, acetone, and toluene) were blended in binary mixtures with...

The use of algal biomass for the production of sustainable biofuels has attracted significant interest due to the fast reproduction rates and high lipid content of many microalgal species. However, existing methods of extracting algal cellular lipids are complex and expensive, with regards to both energy input and economic costs. This work explores...

Development of new fuels and engine combustion strategies for future ultra-low emission engines requires a greater level of insight into the process of emissions formation than is afforded by the approach of engine exhaust measurement. The paper describes the development of an in-cylinder gas sampling system consisting of a fast-acting, percussion-...

The autoignition timing of 1-Hexene was controlled in a Homogeneous Charge Compression Ignition (HCCI) engine by reacting the fuel with ozone-containing air prior to its combustion. The experiments were conducted in a single cylinder research engine instrumented with an cylinder pressure sensor. The fuel was chemically characterised using Nuclear M...

Effects of oxygen content of fuels on combustion characteristics and emissions were investigated on both an optical single cylinder direct injection (DI) diesel engine and a multi-cylinder engine. Three fuels were derived from conventional diesel fuel (Finnish City diesel summer grade) by blending Rapeseed Methyl Ester (RME) or Diglyme and Butyl-Di...

Investigations that rank the tendencies of single-component fuels to form soot have given useful insights into how molecules and local molecular structure influences the conversion of carbon in fuel to soot. These studies can provide fundamental understanding of how functional group chemistry influences the products formed during pyrolysis or combu...

An experimental study on three different oxygenated fuels, namely Oxy1, Oxy2, and Oxy3 respectively, was conducted on both an optical single cylinder DI diesel engine, to investigate their effects on spray, ignition, and combustion development. Those three fuels were derived from the conventional diesel fuel (Finnish City diesel summer grade) by bl...

This paper presents the results of combustion experiments conducted in a single cylinder compression ignition engine with several fuel molecules which can be produced from lignocellulosic biomass through a variety of processing routes. The lignocellulosic fuel molecules tested were ethyl levulinate, butyl levulinate, ethyl valerate, butyl valerate,...

Renewable alternatives to fossil fuels are necessary for the reduction of anthropogenic greenhouse gas emissions, the increased atmospheric concentrations of which are resulting in global climate change. Biodiesel, fatty acid esters prepared from the reaction of triglycerides with alcohols, is a potentially sustainable fuel for compression ignition...

The metabolic engineering of photosynthetic microbes for production of novel hydrocarbons presents an opportunity for development of advanced designer biofuels. These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace. Current biofuels, such as...

The paper is concerned with particulate formation from the fuels oleic acid and methyl oleate. In particular the paper reports, quantitatively, the propensity of individual carbon atoms in these two molecules in being converted to particulate. The conversion of individual carbon atoms to particulate was traced by ‘labelling’ individual carbon atoms...

Numerous engineering applications require generation of droplets on demand which are of high uniformity and constant size. The common method to produce droplets is to drive liquid at high pressure through a small orifice/nozzle. The liquid stream disintegrates into small droplets. However this method normally requires large volumes of liquid and is...

This paper presents experimental studies carried out on a modern direct injection compression ignition engine supplied with a range of straight vegetable oils to investigate the effect of oil fatty acid composition on combustion and emissions. Seven oils, those of corn, groundnut, palm, rapeseed, soybean, sunflower and the micro-algae species Chlor...

Copyright © 2014 SAE International.Improvements in the efficiency of internal combustion engines and the development of renewable liquid fuels have both been deployed to reduce exhaust emissions of CO 2 . An additional approach is to scrub CO 2 from the combustion gases, and one potential means by which this might be achieved is the reaction of com...

The paper presents an experimental investigation of hydrogen-diesel fuel co-combustion carried out on a naturally aspirated, direct injection diesel engine. The engine was supplied with a range of hydrogen-diesel fuel mixture proportions to study the effect of hydrogen addition (aspirated with the intake air) on combustion and exhaust emissions. Th...

Fuels are continuing to be derived from fossil sources, but as production technology improves, biofuels and synthetic fuels are expected to emerge as scalable long-term sources of liquid fuels. Efforts are being made to ensure that this next-generation of fuels is cleaner burning than the last. In order to inform the production and processing of cl...

Improvement of the diesel engine and optimization of the combustion process continues to be an important aspect of efforts to meet new emissions regulations. The most important factors which directly influence the performance of a diesel engine are related to the spray formation and vaporization of the liquid fuel upon injection into the cylinder....

Substitution of conventional feedstock with waste based alternatives is one route towards both remediation and reducing costs associated with production of algal biomass. This work explores whether exhaust gases and wastewater can replace conventional feedstock in the production of biomass from Chlorella sorokiniana. Exhaust gases were used to augm...

Successfully designing and making effective of use of the next generation of liquid fuels, which will be derived from a range of biomass and fossil sources, requires an understanding of the interactions between structurally similar and dissimilar fuel components when utilised in current engine technology. Interactions between fuel components can in...

In developing future fuels there is an opportunity to make use of advances in many fields of science and engineering to ensure that such fuels are sustainable in both production and utilization. One such advance is the use of synthetic biology to re-engineer photosynthetic micro-organisms such that they are able to produce novel hydrocarbons direct...

A primary motivation for the development of future fuels is to halt the increasing concentration of atmospheric carbon dioxide. As such, a fuel that can potentially be produced from a feedstock of alcohols and atmospheric carbon dioxide is an attractive proposition. Symmetrical carbonate esters may thus offer a sustainable means of converting alcoh...

Future fuels will be developed from a variety of biomass and fossil sources, and this presents an opportunity to design new fuels that carry a much reduced environmental burden. To this end, understanding how the molecular structure of a fuel impacts on the processes of combustion and emissions production is critical in selecting suitable feed-stoc...

At present, biodiesel is primarily comprised of fatty acid methyl esters (FAMEs) obtained by the transesterification of a variety of vegetable oils with methanol. However, transesterification can be carried out with a wide variety of alcohols other than methanol. This paper presents experimental studies carried out on a diesel engine supplied with...

The fuel economy and emissions performance of a Diesel engine is strongly influenced by the fuel injection process. This paper presents early results of an experimental investigation into diesel spray development carried out in a novel in-house developed optical pressure chamber capable of operating at pressure up to 50 bar and temperatures up to 9...

Current developments in fuels and emissions regulations are resulting in an increasingly severe operating environment for diesel fuel injection systems. The formation of deposits within the holes or on the outside of the injector nozzle can affect the overall system performance. The rate of deposit formation is affected by a number of parameters, i...

Diesel fuels usually comprise a wide range of compounds having different molecular structures which can affect both the fuel's physical properties and combustion characteristics. In future, as synthetic fuels from fossil and sustainable sources become increasingly available, it could be possible to control the fuel's molecular structure to achieve...

Two direct injection spark ignition (DISI) engines with identical combustion chamber geometries and fuel injection systems were used to investigate fuel economy, exhaust emissions, the in-cylinder flow field, the fuel spray behaviour and combustion characteristics with early inlet valve closure (EIVC) strategies aimed at reducing parasitic inductio...

The present paper describes a method of controlling the time of ignition in homogeneous-charge compression ignition (HCCI) combustion. In the described experiments some control of ignition timing in HCCI combustion is achieved through alteration of the fuel molecular structure using a chemical reaction of the fuel with ozone, prior to introduction...

The combustion characteristics of several volatile ether molecules were studied under diffusion and homogeneous charge combustion modes in a compression ignition engine. Volatile ethers of low molecular mass are organic molecules that could be used as fuel for compression ignition engines. The physical and chemical characteristics of such ethers co...

Nanosized particles emitted from automotive engines continue to attract concern because of their adverse health effects and their impact on the environment. Automotive engines are a major source of fine and ultrafine particles emitted into the atmosphere. Through stricter emission regulations and the introduction of advanced technologies, the speci...

The subject of this paper is a series of experiments conducted on a single-cylinder research engine investigating the influence of molecular structure on the combustion behaviour of fatty acid alcohol ester (biodiesel) molecules under diesel engine conditions. The fuels employed in these experiments comprised various samples of pure individual fatt...

As an experiment investigation, the effects of ethanol blended gasoline fuel with different injection method on nano-sized particle emission characteristics were examined in a 0.5L spark-ignited single-cylinder engine with a compression ratio of 10. Because this engine nano-particles are currently attracting interest due to its adverse health effec...

Current developments in fuels and emissions regulations are resulting in increasingly severe operating environment for the injection system. Formation of deposits within the holes of the injector nozzle or on the outside of the injector tip may have an adverse effect on overall system performance. This paper provides a critical review of the curren...

Biodiesel is a renewable fuel which can be used as a direct replacement for fossil diesel fuel as a calorific source in diesel engines. It consists of fatty acid mono-alkyl esters, which are produced by the transesterification reaction of plant oils with monohydric alcohols. The plant oils and alcohols can both be derived from biomass, giving this...

Synthetic bio-fuels, which can be obtained through the gasification of biomass into synthesis gas and the subsequent catalytic reaction of the synthesis gas into liquid fuel molecules, could play a key-role in providing a sustainable source of automotive fuels during the coming decades. This paper presents an attempt to understand the effect of mol...

The effect on the intake flow field, air fuel mixing processes, thermodynamic performance and emissions output has been investigated for a range of valve operating profiles. A standard speed load point of 2000 rpm and 2.7 bar IMEP 720° has been reached by throttling the intake whilst running standard cam profiles, by early closing of both inlet val...

Two-colour pyrometry, thermodynamic analysis, and exhaust emissions analysis have been used to improve understanding of the formation of soot during combustion in a high speed direct-injection automotive diesel engine. Three fuel blends were used: a Base Fuel commercially available in Northern Europe; a blend of the Base Fuel (70%) and esterified r...

There is a great deal of interest in new technologies to assist in reducing the CO2 output of passenger vehicles, as part of the drive to meet the limits agreed by the EU and the European Automobile Manufacturer's Association ACEA, itself a result of the Kyoto Protocol. For the internal combustion engine, the most promising of these include gasolin...

This paper reports the outcome from a systematic investigation carried out on HCCI (Homogeneous Charge Compression Ignition) combustion of a diesel type fuel. The n-heptane was chosen in this study to study the HCCI combustion characteristics of diesel engines with premixed charge by port fuel injection. Measurements were carried out in a single-cy...

The piston bowl design is one of the most important factors that affect the air-fuel mixing and the subsequent combustion and pollutant formation processes in a direct-injection diesel engine. The bowl geometry and dimensions, such as the pip region, bowl lip area, and toroidal radius, are all known to have an effect on the in-cylinder mixing and c...

In modern, high-speed, direct injection diesel engines for passenger vehicles, there is extensive impingement of the fuel sprays on to the piston bowl walls. Recent trends towards smaller engine sizes, equipped with high-pressure common-rail fuel injection systems, have tended to increase the spray/piston wall interaction. This paper describes test...

A strong in-cylinder tumbling flow, which was produced by partially shrouding the lower periphery of the inlet valves, was measured in a three-valve twin-spark spark ignition (SI) engine using digital particle image velocimetry (PIV). Characteristics of the bulk flow, cyclic variation, frequency spectrum of velocity fluctuation, large- and small-sc...

The piston bowl design is one of the most important factors that affect the air/fuel mixing and the subsequent combustion and pollutant formation processes in a direct injection diesel engine. The bowl geometry and dimensions, such as the pip region, the bowl lip area and the torus radius, are all known to have an effect on the in-cylinder mixing a...

Diesel soot particles were extracted from both the exhaust pipe and the pre-chamber of a naturally aspirated single-cylinder engine. The micrographs and size distributions of the soot spherules were analyzed by means of transmission electron microscopy (TEM). Little difference was found in either morphology or oxidation rate between the soot sample...

In order to take advantage of different properties of fuel components or fractions, a new concept of fuel stratification has been proposed by the authors. This concept requires that two fractions of standard gasoline (e.g., light and heavy fractions) or two different fuels in a specially formulated composite be introduced into the cylinder separate...

The piston bowl design is one of the most important factors that affect the air/fuel mixing and the subsequent combustion and pollutant formation processes in a direct injection diesel engine. The bowl geometry and dimensions, such as pip region, bowl lip area, and torus radius are all known to have an effect on the in-cylinder mixing and combustio...