Niculae Negurescu

Improvement of the Automotive Spark Ignition Engine Performance by Supercharging and the Bioethanol Use

The general objective of this paper is application of the supercharging method and bioethanol use at the spark ignition engine for improving performance of power and torque, improving engine efficiency, decrease of the emissions level and increases of the engine specific power. The paper brings an important contribution to pollution problems solving in large urban areas, the solution can being easily implemented on spark ignition engines in running, even on the old designs which can be converted to fit the current rules of pollution. A modern method to increase efficiency and specific power of the spark ignition engines is supercharging. Supercharging is common for diesel engines, but for SI engines becomes restrictive because of the main disadvantages represented by abnormal combustion phenomena with knock, exhaust gases temperature increasing, engine thermal and mechanical stresses increasing. By using modern control methods of the combustion, supercharging becomes an efficient method even for SI engine. The theoretical and experimental investigations were performed on a 1.5L aspirated spark ignition engine with MP injection which was supercharged. The supercharged engine was fuelled with gasoline-bioethanol blends. The use of bioethanol at supercharged SI engine assures an efficient cooling effect of the intake air due to its higher heat of vaporization. The intake air cooling effect leads to a volumetric efficiency increasing and the knock appearance risk is reduced. For to achieve of the research objectives the following methodology was used: modelling of the thermo-gas-dynamics processes inside engine cylinder for the theoretical evaluation of engine energetic performance; experimental investigations carrying out on the test bed of the SI engine in two versions: aspirated engine and supercharged engine fuelled with gasoline- bioethanol blends, respectively. For to achieve of the research objectives the following methodology was used: modelling of the thermo-gas-dynamics processes inside engine cylinder for the theoretical evaluation of energetic and pollution performance for aspirated engine and also for of the supercharged engine fuelled with gasoline-bioethanol blends in order to decrease the experimental investigations volume; experimental investigations carrying out on the test bed of the SI engine in two versions: aspirated engine and supercharged engine fuelled with gasoline-bioethanol blends, respectively; the interfacing of the electronic control units for the supercharged spark ignition engine fuelled with gasoline- bioethanol blends. The obtained results of the research are: development of a physic-mathematical model to simulate thermo-gas-dynamics processes inside engine cylinder; determining the bioethanol influences on the engine cylinder filling; determining the bioethanol influences on the supercharged spark-ignition engine combustion process; engine efficiency increasing by up to 10 %, specific power increasing by up to 33 %, pollutant emission levels reduction (was obtained a reduction of 20 % for NOx emissions, a 10 % reduction of CO emission and a 13 % reduction of HC emission); establishing the optimal correlation between dosage—electric spark advance—boost pressure—exhaust gases temperature—coefficient of excess air on one hand and functional regime of the engine on the other hand. The abnormal combustion phenomena with knock study in this paper were not developed. As a research novelty is the solution for use of gasoline- bioethanol blends at the supercharging SI engine. Original elements of the research are: application of the supercharging procedure to an aspirated car spark ignition engine; use of gasoline- bioethanol blends as an injected fuel in blower downstream with effect of cooling the compressed air. The SI engine supercharging and use of gasoline- bioethanol blends is a good method to efficiency and power performance increasing. The pollutant emissions level decreases due to the improvement of the combustion processes. Bioethanol can be considered as an efficient anti-knock agent.

Aspects of the animal fat use at the diesel engine fuelling

The general objective of the research is analyzes of the preheated gas oil-animal fat blends use at the experimental diesel engine, type CFR- IT9-3M, adequate instrumentation. The engine was fuelled firstly with diesel fuel then with different diesel fuel-animal fats blends (5%, 10%, 15% animal fats content in mixture with diesel fuel). The main animal fat advantages - cetane number and calorific value close to diesel fuel, higher oxygen content it recommend a good alternative fuel for diesel engines. But, the high viscosity and poor vaporization characteristics of animal fats need prior their heating. The results of experimental investigations show the animal fats effects on auto ignition delay, on the combustion parameters and on the pollutants emissions level. Thus, at the animal fats content increase in mixture with diesel fuel, for same engine adjustments, were obtained the follow results: auto ignition delay increases with ~20%; maximum gas pressure decreases with 10%; gas temperature decreases with 8%; indicate efficiency decreases with 10%; NOx emissions level decreases with 30%; CO emission level increases with 28%; HC emissions level increases with 58%; CO2 emission level decreases with 3.5% and smoke emissions decreases with 65%. Was established the animal fats effects on the fuel auto ignition and combustion. Animal fats can be considered a good alternative fuel for diesel engine, assuring the replace of the fossil fuels and resolving the major problem of animal wastes.

Some Aspects Concerning the Period of Automotive Air Filters Replacement on the Basis of their Technical Conditions

The engine air supply system is the main source through which impurities from the atmosphere reach inside the kinematic couplings of the engine. The engine protection is ensured by periodically replacement of the air filters. Determining air filters service life is a difficult problem due to different operation conditions of the vehicles. Therefore, air filters are frequently replaced more often than necessary on the principle that a new filter is better than a replaced one. The present paper aims to determine if the air filters replaced during the preventive maintenance activities have reached the end of their service life or they could still be used. The research is based on measuring the pressure restriction and estimating the mass of dust collected by the air filters.

Theoretical and Experimental Investigations on the LPG Fuelled Diesel Engine

For energetically performance improvement and pollution level decreases of diesel engine different methods were applied, as the modifying of the energetically solution, exhaust gases after-treatment and some alternative fuel use (ethanol, methanol, biodiesel, DME, CNG, LPG e.g.) in different fuelling solution as direct injection or intake fuelling. Thought, the available information’s in the trade literature for a complete analyse of alternative fuel diesel engine performances are insufficient. This happens also because of the operating and design particularities of the diesel engines used for experimental researches. In the paper the authors show the results of an theoretically and experimental investigations achieved on a 1.5 L common rail diesel engine dual fuelled with LPG and diesel fuel by diesel-gas method. The diesel-gas method is simple and can be applied with minimal modifications also for the engines in use. Is very difficult to use only LPG at the diesel engine because it has an auto ignition high endurance (CN = −2 to −3), different fuelling methods being use. By diesel-gas method the LPG is injected in the inlet manifold and forms with the air a homogeneous mixture, ignited by a diesel fuel pilot, the combustion being developed thru the homogeneous mixture from the combustion chamber. The general objective of this paper is the reduction of the diesel engine pollutant emissions by LPG use, without affecting the energetically performances. The specific objectives of this research are the establishment of the optimal LPG cycle dose and setup of the diesel engine optimal adjustments for all engine operating regimes.

LPG as a Fuel for Diesel Engines-Experimental Investigations

The main objective of the paper is to reduce the pollutant emissions of a compression ignition engine, fuelling the engine with liquefied petroleum gas (LPG), aiming to maintain the energetic performances of the engine. To optimise the engine operation a corelation between the substitute ratio of the diesel fuel with LPG and the adjustments for the investigated regimens must be made in order to limit the maximum pressure and smoke level, knock and rough engine functioning, fuel consumption and the level of the pollutant emissions. The test bed situated in the Thermotechnics, Engines, Thermal Equipments and Refrigeration Instalations Department was adapted to be fuelled with liquefied petroleum gas. A conventional LPG fuelling instalation was adopted, consisting of a LPG tank, a vaporiser, conections between the tank and the vaporiser and a valve to adjust the gaseous fuel flow. Using the diesel-gas methode, in the intake manifold of the engine is injected LPG in gaseous aggregation state and the airr-LPG homogeneous mixture is ignited from the flame appeared in the diesel fuel sprays. To maintain the engine power at the same level like in the standard case of fuelling only with diesel fuel, for each investigated operate regimen the diesel fuel dose was reduced, being energetically substituted with LPG. The engine used for experimental investigations is a turbocharged truck diesel engine with a 10.34 dm3 displacement. The investigated working regimen was 40% load and 1750 rpm and the energetic substitute ratios of the diesel fuel with LPG was situated between [0-25%].

Aspects of Experimental Research on Hydrogen Fuelled Automotive Diesel Engine

The use of hydrogen at the diesel engines for improvement energetic and ecologic their performance is the main objective of the paper. The research work has been carried out on truck diesel engine at the 55 % load and 1400 rpm. The engine was fuelled firstly with diesel fuel, then with diesel fuel and hydrogen at different rates between 11–40 L/min. The minimum brake specific energetic consumption decreases with ~9 % and NOx emission decreases with 5.5 % due to combustion improvement at the hydrogen use. The engine energetic and ecologic performances are improved.

Study of the Diesel Engine Cycle Variability at LPG Fuelling

Efficiency improves and pollutant emissions decrease of the automotive diesel engine can be assured by Liquid Petroleum Gas fuelling. Paper target is the study of cycle variability at LPG fuelling, which shows new, important, considerable implication and effects of LPG use at diesel engine, completing the general experimental investigation of engine running at fuelling with alternative fuel for a clean environmental. The K9K EURO 4 diesel engine was mounted on the test bed, equipped with instrumentation and fuelled with LPG by diesel gas method. The investigated engine operating regimes were 55 % and 70 % load at speed of 2000 rpm, at fuelling with diesel fuel and LPG at different substitute ratios. The increase of LPG cycle dose leads to the increase of cycle maximum pressure and maximum pressure cycle dispersion, thus the dispersion of successive running cycle’s increases. This fact may become a limitation criterion for the LPG substitute ratio value.

Effect ofHydrogen Use on Diesel Engine Performance

Necessity of pollutant emissions decreasing, a great interest aspect discussed at 2015 Paris Climate Conference, highlights the necessity of alternative fuels use at diesel engines. Hydrogen is considered a future fuel for the automotive industry due to its properties which define it as the cleanest fuel and due to the production unlimited sources. The use of hydrogen as fuel for diesel engines has a higher degree of complexity because of some hydrogen particularities which lead to specific issues of the hydrogen use at diesel engine: tendency of uncontrolled ignition with inlet backfire, in-cylinder combustion with higher heat release rates and with high NOx level, storage difficulties. Because hydrogen storing on vehicle board implies important difficulties in terms of safety and automotive range, the partial substitution of diesel fuel by hydrogen injected into the inlet manifold represents the most efficient method. The paper presents the results of the experimental researches carried on a truck diesel engine fuelled with diesel fuel and hydrogen, in-cylinder phenomenas study showing the influence of some parameters on combustion, engine performance and pollutant emissions. The paper novelty is defined by the hydrogen fuelling method applied to diesel engine and the efficient control of the engine running.

Experimental investigations of the hydrogen addition effects on diesel engine performance

In the global content regarding the impact on the environmental of the gases emissions resulted from the fossil fuels combustion, an interest aspect discussed on the 21st Session of the Conference of the Parties from the 2015 Paris Climate Conference and the gradual diminution of the worldwide oil reserves contribute to the necessity of searching of alternative energy from durable and renewable resources. At the use of hydrogen as addition in air to diesel engine, the level of CO, HC and smoke from the exhaust gases will decrease due to the improvement of the combustion process. At low and medium partial loads and low hydrogen energetic ratios used the NOX emission level can decrease comparative to classic diesel engine. The hydrogen use as fuel for diesel engine leads to the improving of the energetic and emissions performance of the engine due to combustion improvement and reduction of carbon content. The paper presents, in a comparative way, results of the experimental researches carried on a truck compression ignition engine fuelled with diesel fuel and with hydrogen diesel fuel and hydrogen as addition in air at different engine operation regimes. The results obtained during experimental investigations show better energetic and pollution performance of the engine fuelled with hydrogen as addition in air comparative to classic engine. The influences of hydrogen addition on engine operation are shown.

Theoretical and Experimental Researches Regard the Use of Bioethanol at the Supercharged Spark Ignition Engine

The use of bioethanol as alternative fuel for automotive supercharged spark ignition engines is required especially for to respect the pollutant norms which become more and more severe, especially for NOx emissions.The general objective of the researches is improving of a automotive supercharged spark ignition engine efficiency, improving performance of power and torque and decreasing of the emissions level by the use of bioethanol. Bioethanol is so a very good alternative fuel for SI engines because of its better combustion proprieties comparative to the gasoline as a good cooling agent of the intake air due to its high vaporization heat.The paper presents results of some theoretical and experimental investigations on a 1.5 L supercharged SI engine fuelled with gasoline-bioethanol blends. The investigations show that the improvement of the combustion process by use the bioethanol at the supercharged spark ignition engine leads to the reduction of BSFC, to the accentuated reduction CO and HC due to a lower C content and better combustion properties of the bioethanol. In same time, the NOx emissions level significantly decreases because of the local cooling effect produced by bioethanol vaporization.