The steady-state theory of ignition of flowing gaseous mixtures by hot surfaces

Ph.D.Pandeli Durbetak

A Study of Anyon Statistics by Breit Hamiltonian Formalism

We study the anyon statistics of a $2 + 1$ dimensional Maxwell-Chern-Simons (MCS) gauge theory by using a systemmetic metheod, the Breit Hamiltonian formalism.Comment: 25 pages, LATE

Rate of injection modelling for gasoline direct injectors

[EN] Awareness of climate change, fossil fuel availability, and pollutants has been growing which have pushed forward the effort in cleaner engines. In this aspect, the gasoline engines have more improving margin than diesel engines. To have a more efficient combustion, injection systems had evolved from old Port Fuel Injectors to modern Gasoline direct injections which are the used by engine manufacturers nowadays. In this study, within the framework of the Engine Combustion Network (ECN), the so named Spray G is modelled. This gasoline direct injector was developed by Delphi with the intention of getting a better understanding of the gasoline spray. The model is focused on the Rate of Injection (ROI) signal, whose results are presented in order to help engine calibration and modelling for an extensive range of configurations without the need for experimental measurements.This article was supported by Generalitat Valenciana through AICO/2018 under the project Nuevos conceptos en inyeccion de gasolina (NCIG) and through Ayudas de la Conselleria de Educacio, Cultura y esports para la promocion y dinamizacion de parques cientificos (PPC/2018. DOCV del 07/11/2017).Payri, R.; Bracho Leon, G.; Gimeno, J.; Bautista-Rodríguez, A. (2018). Rate of injection modelling for gasoline direct injectors. Energy Conversion and Management. 166:424-432. https://doi.org/10.1016/j.enconman.2018.04.041S42443216

Biofuels and thermal barrier:a review on compression ignition engine performance, combustion and exhaust gas emission

The performance of an internal combustion engine is affected when renewable biofuels are used instead of fossil fuels in an unmodified engine. Various engine modifications were experimented by the researchers to optimise the biofuels operated engine performance. Thermal barrier coating is one of the techniques used to improve the biofuels operated engine performance and combustion characteristics by reducing the heat loss from the combustion chamber. In this study, engine tests results on performance, combustion and exhaust emission characteristics of the biofuels operated thermal barrier coated engines were collated and reviewed. The results found in the literature were reviewed in three scenarios: (i) uncoated versus coated engine for fossil diesel fuel application, (ii) uncoated versus coated engine for biofuels (and blends) application, and (iii) fossil diesel use on uncoated engine versus biofuel (and blends) use on coated engine. Effects of injection timing, injection pressure and fuel properties on thermal barrier coatings were also discussed. The material type, thickness and properties of the coating materials used by the research community were presented. The effectiveness and durability of the coating layer depends on two key properties: low thermal conductivity and high thermal expansion coefficient. The current study showed that thermal barrier coatings could potentially offset the performance drop due to use of biofuels in the compression ignition engines. Improvements of up to 4.6% in torque, 7.8% in power output, 13.4% in brake specific fuel consumption, 15.4% in brake specific energy consumption and 10.7% in brake thermal efficiency were reported when biofuels or biofuel blends were used in the thermal barrier coated engines as compared to the uncoated engines. In coated engines, peak cylinder pressure and exhaust gas temperature were increased by up to 16.3 bar and 14% respectively as compared to uncoated condition. However, changes in the heat release rates were reported to be between −27% and +13.8% as compared to uncoated standard engine. Reductions of CO, CO2, HC and smoke emissions were reported by up to 3.8%, 11.1%, 90.9% and 63% respectively as compared to uncoated engines. Significant decreases in the PM emissions were also reported due to use of thermal barrier coatings in the combustion chamber. In contrast, at high speed and at high load operation, increase in the CO and CO2 emissions were also reported in coated engines. Coated engines gave higher NOx emissions by about 4–62.9% as compared to uncoated engines. Combined effects of thermal barrier coatings and optimisation of fuel properties and injection parameters produced further performance and emissions advantages compared to only thermal barrier coated engines. Overall, current review study showed that application of thermal barrier coatings in compression ignition engines could be beneficial when biofuels or biofuel blends are used instead of standard fossil diesel. However, more research is needed combining coatings, types of biofuels and other engine modifications to establish a concrete conclusion on the effectiveness of the thermal barrier when biofuels are used in the compression ignition engine. Reduction of NOx emissions is another important R & D area

Assessment of pollutants emission and aftertreatment efficiency in a GTDi engine including cooled LP-EGR system under different steady-state operating conditions

Nowadays, EGR systems are being incorporated in the research focused on spark-ignition direct-injection engines as a solution to the problems presented by them; i.e. knock risk and high combustion temperature which produces high NOx emission. Since the major part of the investigations are centered on engine performance or engine simulation aside pollutants emission and aftertreatment evaluation, this paper focuses on these topics: gaseous and particle emission analysis and aftertreatment efficiency evaluation when cooled LP-EGR system is applied to a GTDi engine. This work has been performed in a 4-cylinder, turbocharged, direct-injection gasoline engine with 2.0 L displacement. The equipment used in this study are TSI-EEPS for particle measurement and HORIBA MEXA 1230-PM for soot measurement being HORIBA MEXA 7100-DEGR with a heated line selector the system employed for regulated gaseous emission measurement and aftertreatment evaluation. A reduction around 50% of NOx with an increase of HC and CO emissions was found in medium-load operating points. At full-load conditions, the suppression of fuel enrichment including EGR leads in a drastically reduction in CO maintaining similar HC and NOx emissions. Furthermore, PN and soot emissions also decrease as EGR is included and spark timing advanced in all the tested conditions.The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER- ICTS-2012-06)", framed in the operational program of singular scientific and technical infrastructure of the Ministry of Science and Innovation of Spain.Bermúdez Tamarit, VR.; Lujan Martinez, JM.; Climent Puchades, H.; Campos, D. (2015). Assessment of pollutants emission and aftertreatment efficiency in a GTDi engine including cooled LP-EGR system under different steady-state operating conditions. Applied Energy. 158:459-473. https://doi.org/10.1016/j.apenergy.2015.08.071S45947315