Gas Recirculation Research Articles

Production and characterization of two-step condensation bio-oil from pyrolysis

The goal of this project is to investigate the potential of fuel production directly from slow pyrolysis of straw pellets without further refining. A two-step condensation was used to separate liquids from the volatiles. The thermal process chosen is slow pyrolysis at 500°C to couple the fuel production with carbon capture by maximizing the char production alongside bio-oils collection. Condensation parameters were tuned to improve the pyrolysis oil quality. To assess the oil quality some requirements on marine fuels, bio-oils and boiler fuels were taken as reference. Three condensation conditions were inspected: the best pyrolysis overall process was repeated three times for a total of five pyrolysis processes (lately referred to as runs). As expected, the bio-oil characteristic changed with the condensation temperature. As a result of lowering the bio-oil condensation temperature, the bio-oil results less viscous, less dense, with lower heating value and with higher water content. The final bio-oil produced was almost compliant to ISO 8217:2017 for residual marine fuels K 380, apart from water content and acid number, while it was almost compliant for the standard EN 16900:2017 for industrial boilers fuels, apart for the kinematic viscosity. It was assessed that the char is produced with an average yield of 27 w% on dry basis, while bio-oil has a yield between 5 and 10 w%. It is possible to recover an average of 72 % of the total energy contained in the straw in the valuable products, gas, char and bio-oil. The carbon captured with charcoal was around 49 w% of the total present in straw. The pyrolysis experiments were performed using an innovative semi-batch, packed-bed reactor with gas re-circulation and a new two-fraction condensation appliance that is DTU patented. The innovation is both in the reactor, where the gas is directly heated and flushed back into the pyrolyser, and in the condensation section, where the bio-oil is separated from the water fraction during the pyrolysis. The company Stiesdal SkyClean A/S showed interest in further development and scale up of this pyrolysis and condensation system.

Characteristics of gel entrainment induced by gas recirculation in coaxial gas–liquid jets

Characteristics of gel entrainment induced by gas recirculation in coaxial gas–liquid jets

A novel, cassette-based nitric oxide delivery system with an advanced feedback control algorithm accurately delivers nitric oxide via the anesthesia machine independent of fresh gas flow rate and volatile anesthetic agent

Nitric oxide (NO), a selective pulmonary vasodilator, can be delivered via conventional ICU and anesthesia machine ventilators. Anesthesia machines are designed for rebreathing of circulating gases, reducing volatile anesthetic agent quantity used. Current cylinder- and ionizing-based NO delivery technologies use breathing circuit flow to determine NO delivery and do not account for recirculated gases; therefore, they cannot accurately dose NO at FGF below patient minute ventilation (MV). A novel, cassette-based NO delivery system (GENOSYL® DS, Vero Biotech Inc.) uses measured NO concentration in the breathing circuit as an input to an advanced feedback control algorithm, providing accurate NO delivery regardless of FGF and recirculation of gases. This study evaluated GENOSYL® DS accuracy with different anesthesia machines, ventilation parameters, FGFs, and volatile anesthetics. GENOSYL® DS was tested with GE Aisys and Dräger Fabius anesthesia machines to determine NO dose accuracy with FGF < patient MV, and with a Getinge Flow-i anesthesia machine to determine NO dose accuracy when delivering various volatile anesthetic agents. Neonatal and adult mechanical ventilation parameters and circuits were used. GENOSYL® DS maintained accurate NO delivery with all three anesthesia machines, at low FGF with recirculation of gases, and with all volatile anesthetic agents at different concentrations. Measured NO2 levels remained acceptable at ≤ 1 ppm with set NO dose ≤ 40 ppm. GENOSYL® DS, with its advanced feedback control algorithm, is the only NO delivery system capable of accurately dosing NO with anesthesia machines with rebreathing ventilation parameters (FGF < MV) regardless of anesthetic agent.

Utilization of hydrogen and methane as energy carriers with exhaust gas recirculation for sustainable diesel engines

Hydrogen and methane as secondary fuels in diesel engines can be promising solutions to meet energy demand. The current study investigated the effect of the specialty gases of different compositions on diesel engine performance and exhaust gases. Four gases with various compositions of exhaust gas recirculation (Carbon monoxide, Carbon dioxide, and Nitrogen) and fuels (Hydrogen and Methane) were used at various mass flow rates of 10, 20, and 25 LPM (liter per minute), and various engine speeds of 2000, 2500, 3000, and 3500 rpm (revolutions per minute). The procured results revealed that adding specialty gases improved brake thermal efficiency and power. Similarly, the brake-specific fuel consumption was also massively retarded compared to diesel due to the influence of the hydrogen and methane composition. However, the fuel with the higher nitrogen reported less BTE (brake thermal efficiency) and comparatively higher exhaust gas temperature owing to the higher presence of nitrogen in their composition. Regarding emissions, including exhaust gas recirculation dropped the formation of pollutants efficiently compared to diesel. Among various fuels, Case 1 (30 % H2, 5 % CH4, 5 CO2, and 60 % CO) reported the lowest emission of NOx, and Case 2 (25 % H2, 5 % CH4, 5 CO2, 30 % CO, and 35 % N2) of CO and CO2 emissions. Generally, specialty gases with a variable composition of exhaust gas recirculation gases can be a promising sustainable replacement for existing fossil fuels.

ВПЛИВ РУДНОВУГІЛЬНИХ КОМПОЗИЦІЙ У СКЛАДІ ШИХТИ НА ФОРМУВАННЯ ТЕРМІЧНО РЕЗЕРВНОЇ ЗОНИ ДОМЕННОЇ ПЕЧІ

The object of research is the technology of iron smelting when using ore-coal compositions. The purpose of the work is the effect of changing the composition of the blast furnace charge on the thermal state of the formation of the thermal reserve zone. Research methods - theoretical studies are based on the basic principles of physical chemistry and the theory of metallurgical processes. Experimental studies were carried out in laboratory and industrial conditions. Scientific novelty - there is a "coupling phenomenon" between recovery and gasification - this is a close contact between small particles of iron oxides and carbon, which is formed in the ore-coal composite, which ensures an increase in the efficiency of blast furnace smelting. Reduction of fuel consumption and, accordingly, the amount of gases per unit charge of modern blast furnace smelting, the height of the reserve zone is reduced; this zone is not observed in the vertical elements of the furnace with the maximum ore load. Practical significance - the use of ore-coal composites provides a high speed of iron recovery and carbon gasification reactions and a low initial temperature of carbon gasification of 250-420ºС, which is ensured by gas recirculation in the under burden, due to the short distance between the parts of iron-containing and carbon composites and their sizes, where the distance between them is short and the limit of the reaction is "visible" to both.

Nonlinear feedforward controller design of gasoline engine air-path system for reducing engine torque overshoot

In gasoline engines, the amount of fresh air in the cylinder becomes temporarily excessive owing to the slow response in exhaust gas recirculation (EGR) gas under a high EGR ratio. This phenomenon should be avoided, as it causes an engine torque overshoot because the amount of fuel also increases to follow the stoichiometric ratio, and can cause discomfort to the driver. In this study, we investigate reducing torque overshoot using a feedforward controller, which is a simple and effective method for improving the response of a control system. The feedforward controller is typically designed based on the inverse of the plant model. However, designing a feedforward controller for a high-order and nonlinear plant, such as an engine air-path system, can be challenging. Therefore, we exploit the fact that if a given nonlinear system satisfies the flatness property, a feedforward controller based on the inverse model can be easily obtained. The effectiveness of the proposed feedforward controller is evaluated through simulations.

Problems of operating heating boilers of increased environmental efficiency

Purpose. Ensuring reliable operation of heating heat-generating devices with recirculation and exhaust gas heat recovery. Methodology. The normative methods of thermal calculation for surface heat exchange devices and the software according to the requirements of regulatory methods for this type of equipment for processing the results of our own experimental studies on heat exchange during deep cooling of combustion products of gas-consuming boilers were used. Findings. Calculation studies on the thermal operation modes during the heating period under the conditions of recirculation and heat recovery of flue gases of gas-fired water-heating boiler plants not equipped with air heaters were carried out. The main characteristics were determined of the thermal and humidity operation state for the air-supply ducts of these installations under the conditions of recirculation of flue gases’ part into the blown air. Regularities of temperature and dew point changes in the mixture of admixed gases and air under the conditions of using traditional heat recovery technologies and without them in different boiler modes and with different parts of recirculated gases were established. Problems of ensuring the operability and reliability of such boiler plants are highlighted. It is shown that these problems are related to condensate formation on the internal surfaces of air ducts and their freezing in some operating modes during in the cold period of the heating season. It is also shown that an effective solution to existing problems can be the use of air heaters in heat recovery systems to preheat the blown air before its mixing with recirculation gases. Originality. For the first time, the thermal and humidity operation modes of the air-supply ducts of heating boiler plants with increased environmental efficiency, which is ensured by boiler exhaust gases recirculation into the blown air, have been investigated. Practical value. The obtained research results will be used in the design of systems of recirculation and heat recovery of heat-generating devices’ exhaust gases to improve their environmental and thermal efficiency.

Evaluation of the controlled hydrodynamic cavitation as gas mass transfer system for ex-situ biological hydrogen methanation

The present work represents the first study focused on controlled hydrodynamic cavitation applied as gas transfer system to supply the methanogenic archaea with exogenous H2 and CO2. Starting from a generic mixed inoculum sampled from a thermophilic full-scale anaerobic digester, a bubble column bioreactor was coupled with a rotating hydrodynamic cavitator and fed with different H2/CO2 loading rates. Process efficiency and long-term effects on process stability and microbial population were evaluated. Gas sparging through the controlled hydrodynamic cavitation device is feasible under the operating conditions tested, resulting in almost 100% efficiency in H2 utilization and recording a CH4 volumetric content more than 99% in the gas leaving the reactor, without any gas recirculation from the headspace. The experimental trials lasted about 160 days and the behavior of the bioreactor showed a substantial stability over the time. Metagenomic and FISH analyses were carried out at the end of the experimental trials, revealing a remarkable increase of hydrogenotrophic methanogens species, related to the selection-effect of H2 on community composition. The findings provide previously unidentified insights into long-term effect on process stability and microbial community diversity in the biological hydrogenotrophic methanation process coupled with a gas–liquid mass transfer system based on controlled hydrodynamic cavitation technology.

Measurements of fluoride production in Resistive Plate Chambers

Resistive Plate Chambers (RPCs) are operated with a gas mixture made of C2H2F4, SF6 and iC4H10. It is well known that under the effect of a high electric field and radiation, the C2H2F4 molecule breaks into several compounds and free fluoride ions, which can accumulate under gas recirculation and could be harmful for the long-term detector operation. Furthermore, if High Pressure Laminate (HPL) electrodes are employed, the gas mixture is humidified and, in presence of water, the free fluoride ions become hydrofluoric acid (HF), a very reactive compound. The F− production depends on several factors such as radiation rate, gas flow, detector current and gas mixture. In this study we developed and tested two different set-ups for the F− concentration measurements by using an Ion Selective Electrode (ISE) station. The measurement on the F− production were performed on 2 mm gas gap bakelite RPC detector irradiated at the CERN Gamma Irradiation Facility (GIF++) with different absorption factors. Several gas mixtures were tested to understand how the formation of HF is affected. The F− production of the standard gas mixture was compared with the one of the standard gas mixture with the addition of 30% CO2 at several gamma rates. Different concentrations of SF6 were also investigated to understand if and how the SF6 could affect the F− production. Finally, two gas mixtures containing HFO1234ze, C2H2F4 and He or CO2 were used to study the RPC F− production in presence of the HFO1234ze, which is less stable in atmosphere with respect to the C2H2F4.

OPERATION FEATURES OF ENVIRONMENTALLY EFFICIENT BOILER PLANTS OF MUNICIPAL THERMAL POWER ENGINEERING

The work is devoted to research on the improvement of thermal energy production technologies in gas-consuming heating boiler installations while improving their environmental performance and increasing the operation reliability. The work purpose is to study the heat and humidity modes of the air-supply ducts of boiler plants with exhaust gases recirculation systems into the blown air. The main objectives of the study are: to determine the thermal parameters of a heating boiler with a 2 MW heating capacity with a exhaust gases recirculation system mixed with blown air into its furnace space under conditions of using heat recovery technologies and without them; determination and analysis the heat and humidity parameters of this mixture in different operating modes of boiler plants. Known thermal calculation methods of boiler plants and data from our own experimental studies of heat transfer during deep cooling of boiler plant exhaust gases were used. The thermal calculation results of the heating boiler with a system for exhaust gas recirculation into its furnace space mixed with blown air are presented. The regularities of changes in the adiabatic combustion temperature and heat-humidity characteristics of the above mixture depending on the boiler heat load in different its operation modes during the heating period and the share of flue gas recirculation from 10 to 20 % were established. The research results show that the introduction of recirculation gases leads to a decrease by 150 – 250 °С of the adiabatic combustion temperature tad due to the need to consume fuel heat for heating the introduced ballast and the greater of the recirculation share s the lower the level of the indicated temperature. The research results also showed that gas recirculation causes insignificant (in the range of 0.5 – 4.7 °С) changes in the temperature of the boiler exhaust gases. Based on the data obtained, the change regularities in the heat-humidity characteristics (temperature and dew point) of the mixture of recirculated gases and air in different boiler operating modes during the heating period and under the studied recirculation shares were established. It is shown that recirculation causes condensate formation on the surfaces of air ducts in all operating modes of boiler and in some modes their icing is possible. To prevent these negative phenomena, it is necessary to apply measures to increase the temperature of the gas-air mixture by a value not less than Δtsum = 15 – 35 °С.

A versatile cryogenic system for liquid argon detectors

Detectors for direct dark matter search using noble gases in the liquid phase as a detection medium need to be coupled to liquefaction, purification and recirculation systems. A dedicated cryogenic system has been assembled and operated at the INFN-Naples cryogenic laboratory with the aim to liquefy and purify the argon used as an active target in liquid argon detectors to study the scintillation and ionization signals detected by large SiPM arrays. The cryogenic system is mainly composed of a double wall cryostat hosting the detector, a purification stage to reduce the impurities below one part per billion level, a condenser to liquefy the argon, and a recirculation gas panel connected to the cryostat equipped with a custom gas pump. The main features of the cryogenic system are reported as well as the performance, long term operation and stability in terms of the most relevant thermodynamic parameters.

Low-Grade Syngas Biomethanation in Continuous Reactors with Respect to Gas–Liquid Mass Transfer and Reactor Start-Up Strategy

In order to utilize a wider range of low-grade syngas, the syngas biomethanation was studied in this work with respect to the gas–liquid mass transfer and the reactor start-up strategy. Two reactors, a continuous stirred tank (CSTR) and a bubble column with gas recirculation (BCR-C), were used in the experiment by feeding an artificial syngas of 20% H2, 50% CO, and 30% CO2 into the reactors at 55 °C. The results showed that the CH4 productivity was slightly increased by reducing the gas retention time (GRT), but was significantly improved by increasing the stirring speed in the CSTR and the gas circulation rate in the BCR-C. The best syngas biomethanation performance of the CSTR with a CH4 productivity of 22.20 mmol·Lr−1·day−1 and a yield of 49.01% was achieved at a GRT of 0.833 h and a stirring speed of 300 rpm, while for the BCR-C, the best performance with a CH4 productivity of 61.96 mmol·Lr−1·day−1 and a yield of 87.57% was achieved at a GRT of 0.625 h and a gas circulation rate of 40 L·Lr−1·h−1. The gas–liquid mass transfer capability provided by gas circulation is far superior to mechanical stirring, leading to a much better performance of low-grade syngas biomethanation in the BCR-C. Feeding H2/CO2 during the startup stage of the reactor can effectively stimulate the growth and metabolism of microorganisms, and create a better metabolic environment for subsequent low-grade syngas biomethanation. In addition, during the thermophilic biomethanation of syngas, Methanothermobacter is the dominant genus.

Influence of nozzle structure on the combustion performance of a graphitic hydrogen-chlorine synthesis combustor

The growing semiconductor sector is driving up demand for high-purity gas-phase HCl. Large combustion zones and low HCl concentrations are problems for HCl manufacturing systems. Based on the realizable k-ε model, the eddy breakup combustion model, and the participating media radiation model, the computational fluid dynamics simulation was used as the primary means in this study. The influence of four structural factors, nozzle jet hole diameter, jet angle, and opening angle—another is nozzle mounting height, on the combustion effect of the synthesis combustor was investigated. The extent of the high-temperature zone in the synthesis combustor and the purity of the hydrogen chlorine at the outlet were used as the main evaluation criteria. The results of numerical simulations demonstrate that the better the gas mixing and combustion in the combustor, the lower the nozzle mounting height should be. Small nozzle diameters and large nozzle jet angle increase gas flow velocity in the recirculation zone close to the inner wall of the combustor. Additionally, the recirculation zone will appear in the combustor as a result of the nozzle's presence. The area of the high-temperature zone within the combustor decreases as internal gas velocity increases. On the other hand, the recirculation gas flow is not significantly impacted by the angle at the condition that the jet holes open. The results of the investigation provide a reference for the design of the miniaturization of the combustor in the non-premixed combustion synthesis of gases process.

Influence of Off Gas Recirculation on the Intermediate Temperature SOFC With Partial Oxidation Reformer

Abstract Solid oxide fuel cell (SOFC) is a clean and efficient energy utilization technology. Partial oxidation reforming (POX) can be used to simplify the SOFC system structure, but its lower hydrogen production rate deteriorates the system performance. A wise method may be combining anode off gas recirculation (AOGR) and cathode off gas recirculation (COGR) with POX. Thus, their influence on the coupled system of intermediate temperature SOFC and POX is researched in detail in this paper. Results show that the reforming process gradually changes from exothermic to endothermic as AOGR rate increases. Meanwhile, its oxygen demand declines sharply and the process can even be self-sustained without external air input at the AOGR rate of 0.5 and 0.6. The application of AOGR can improve electrical efficiency by up to 51%, but at the expense of thermal efficiency. Excessive AOGR rates will result in decreased cell voltage and insufficient energy supply to the after-burner, so it should be restricted within a reasonable range and the best recommended value is 0.5. The application of COGR has little effect on fuel line parameters, so it causes little deterioration in electrical efficiency while improving thermal efficiency. Besides, the cell voltage is also insensitive to it. The combination of AOGR and COGR can obtain better fuel economy and larger cogeneration scale simultaneously at the cost of a tiny electrical output power, while an optimal balance between three efficiencies is also achieved.

Experimental and Numerical Study on the Effect of NO2 on n-Butanol/Biodiesel Dual-Fuel Combustion in a Compression Ignition Engine.

Nitrogen dioxide (NO2) is an active species of exhaust gas recirculation gas, and it has a significant impact on the autoignition and combustion processes of fuels. This study presented a comprehensive investigation of the effect of NO2 on the combustion characteristics of the n-butanol/biodiesel dual fuel. Experiments were conducted on a single-cylinder engine with 0, 100, 200, and 400 v/v ppm NO2 addition at two fuel injection ratios. The findings of the experiments indicated that adding NO2 resulted in an earlier start of heat release and an increase in peak in-cylinder pressure as compared to experiments where no NO2 was added. The evolutions of n-butanol, biodiesel, and OH radicals were evaluated using the computational fluid dynamics software coupled with the n-butanol–biodiesel–NO2 mechanism. The results revealed that when 400 v/v ppm NO2 was added, the consumption of n-butanol and biodiesel occurred earlier, and the formation of OH radicals was approximately an order of magnitude higher before the biodiesel was injected. Furthermore, reaction rate and flux analyses were performed to understand the effect of NO2 addition on the reaction process. When NO2 was added, 35% of the HO2 radicals reacted with NO which converted from NO2 via the reaction NO + HO2 ⇌ NO2 + OH, promoting the formation of OH radicals in the reaction system. The addition of NO2 can also enhance the consumption of CH3 radicals via the reaction CH3 + HO2 ⇌ CH3O + OH.

Effects of Intake Components and Stratification on the Particle and Gaseous Emissions of a Diesel Engine.

It is of great significance to improve the performance of diesel engines by adjusting the intake components and their distribution. In this work, various proportions of exhaust gas recirculation (EGR) gas and oxygen (O2) have been introduced to the intake charge of a diesel engine and the effects of different intake components and stratification conditions on pollutant emissions, especially for particles, have been explored. The results show that the introduction of O2 into the intake charge is beneficial to alleviate the deterioration of particles and hydrocarbon (HC) emissions caused by high EGR rates. Compared with the pure air intake condition, the introduction of moderate O2 at high EGR rate conditions can simultaneously reduce nitrogen oxides (NOx) and particles, when the intake oxygen content (IOC) is 0.2 and the EGR rate is 20%, the NOx and particles are reduced by 45.66% and 66.49%, respectively. It is worth noting that different intake components have a significant impact on the particle size distribution (PSD) of diesel engines. In addition, the in-cylinder O2 concentration distribution formed by the stratified intake is advantageous for further improving the combined effect of NOx, particles and HC emissions relative to the homogeneous intake. At a condition of 0.2 IOC and 20% EGR rate, the NOx, particles, and HC emissions are about 8.8%, 14.3%, and 26% lower than that of intake components nonstratification, respectively.

Comparative analysis of thermal economy of two SOFC-GT-ST triple hybrid power systems with carbon capture and LNG cold energy utilization

This paper studies the coupling of fuel cell power generation technology and conventional thermal power generation technology, constructs the thermodynamic model of combined cycle power generation of fuel cell, gas turbine and steam turbine, and analyzes the thermodynamic performance of the system from the important links such as compressor pressure ratio, steam carbon ratio, fuel utilization, fuel cell operating temperature and gas recirculation. Since natural gas as fuel will emit a lot of greenhouse gases, two new low-carbon power generation systems including composite power system, carbon capture and liquified natural gas cold energy utilization are proposed. In this paper, the post-combustion carbon capture which is more practical and conducive to the safe operation of the system is used. The adsorbents used in the two carbon capture methods are MDEA and CaO respectively. In the MDEA carbon capture process, flash tower and split flow process are added to reduce energy consumption. In the calcium looping carbon capture process, CO2 reflux process is set to optimize the calcination temperature, and two-stage waste heat boilers are set to recover a large amount of waste heat of CO2 and clean flue gas respectively. After that, to further save energy consumption, a method of cascade utilization of liquified natural gas cold energy is proposed. It can not only increase power output, but also provide natural gas at normal temperature and pressure for the system and the outside. The calculation results show that the efficiency of the optimized combined cycle system of fuel cell, gas turbine and steam turbine reaches 70.32%. In terms of energy saving, the system efficiency of MDEA carbon capture process is 1.81% higher than that of calcium looping carbon capture process, and calcium looping carbon capture process has more advantages in economic cost. In addition, the cascade utilization of liquified natural gas cold energy provides additional 410.86 kW, 382.64 kW electric energy and more directly usable natural gas for the two systems. The research results of this paper can provide meaningful guidance for the design of low-carbon and high-efficiency power generation system based on fuel cell.

Study of the Effect of Gasification Pressure on the Composition of the Producer Gas From Coal

The paper presents the results of studies of the effect of gasification pressure on the composition of the producer gas from different types of coals. Calculations of gasification process with determining the main indicators for different coals depending on the pressure and the recirculation fraction of the producer gas were carried out. The results of studies have shown that the elevated pressure and fuel heating by recirculation gases in combination with high values of gasification temperature and the use of oxygen or steam-oxygen blowing promotes to increase the calorific value of the producer gas, to reduce the time of the process and the gasifier sizes, which leads to improvement of conditions and intensification of the process.

ПІДВИЩЕННЯ НАДІЙНОСТІ КОТЕЛЬНИХ УСТАНОВОК З РЕЦИРКУЛЯЦІЄЮ ТА ТЕПЛОУТИЛІЗАЦІЄЮ ДИМОВИХ ГАЗІВ

The efficiency studies result of blown air and cooled exhaust gases heaters of boiler plants, designed to prevent condensate formation in their air and gas exhaust ducts are presented. Gas-heating and water-heating heaters of different types were considered, designed for drying mixtures of: a) exhaust gases and b) blown air and recirculation gases. The ranking of the studied heaters by metal capacity and compactness of heat-exchange surfaces is performed.

Emissões de gases de um motor agrícola de ignição por compressão utilizando misturas de óleo Diesel, biodiesel e etanol

ABSTRACT: Partial fuel replacement strategies arising from fossil sources used in compression ignition engines involve mixtures of mineral Diesel oil, biodiesel and ethanol to minimize the gas emissions. In this study, experimental assessments were performed on a multi-cylinder, turbocharged aftercooler, compression-ignition, agricultural tractor engine provided with electronic injection management and an exhaust gas recirculation (EGR) gas treatment system. Diesel oil containing low (BS10 -10 ppm) and high sulfur concentrations (BS500 - 500 ppm) was utilized, with 10% of biodiesel as a constituent established by Brazilian legislation, in blends with 5, 10, 15 and 20% of the total volume, made up of anhydrous ethanol with additives. Thus, there were eight fuels blends and two reference conditions (without ethanol). The emissions of CO, HC, NOx and the HC+NOx gases were estimated, corresponding to the eight operating modes (M) of the ABNT NBR ISO 8178-4 standard. From the findings, it was evident that with the rise in the ethanol concentrations in the fuel blends there was a corresponding increasing in the CO, NOx and HC+NOx emissions. The HC, on the contrary, exhibited a pattern of higher emissions for the high-sulfur fuels (BS500) at low loads. No difference was observed for the NOx emissions at high loads. In the other operation modes, different behaviors were expressed for the BS10, which sometimes showed an increase, while at other times a reduction in the NOx emissions. Regarding the BS500, the NOx emission increased when the ethanol concentrations rose. As the specific emissions of the NOx were higher than those of the HC (in g.kW-1.h-1), the behavior exhibited by the HC+NOx showed similarity to that of the NOx. When the directly analysis of the operating modes was taken into consideration, the use of ethanol triggered an upswing in the emissions, exceeding the threshold of MAR-1 and EURO V standards.