Experimental and numerical study of flame structure and emissions in a micro gas turbine combustor

Experimental and numerical study of flame and emission characteristics in a tubular micro gas turbine combustor is reported. Micro gas turbines are used for distributed power (DP) generation using alternative fuels in rural areas. The combustion and emission characteristics from the combustor have to be studied for proper design using different fuel types. In this study methane, representing fossil natural gas, and biogas, a renewable fuel that is a mixture of methane and carbon-dioxide, are used. Primary air flow (with swirl component) and secondary aeration have been varied. Experiments have been conducted to measure the exit temperatures. Turbulent reactive flow model is used to simulate the methane and biogas flames. Numerical results are validated against the experimental data. Parametric studies to reveal the effects of primary flow, secondary flow and swirl have been conducted and results are systematically presented. An analysis of nitric-oxides emission for different fuels and operating conditions has been presented subsequently.

Analysis of Exhaust Gas Content for Selected Biofuel-Powered Combustion Engines with Simultaneous Modification of Their Controllers

The use of renewable resources for powering self-ignition engines in European Union countries involves a high demand for renewable energy which is not accompanied by the development of its production infrastructure. The application of biofuel in vehicle powering is supposed to provide reductions in greenhouse gas emissions and an increase in the share of renewable energy resources in the total energy consumption. The study includes the analyses of power unit exhaust components, such as oxygen, carbon monoxide, nitric oxides, carbonizers, carbon dioxide and a quantity of exhaust particles contained in exhaust gases. Tests using an exhaust gas analyzer and a vapor analyzer were conducted. Three high-pressure engines, characterized by direct fuel injection, were tested. The vehicle computer software adjustments included increasing the fuel dose and the air load. Mixtures of diesel oil and fatty acid methyl esters were used in the tests. Based on the results, a statistical analysis was performed and an assessment model was developed to understand the functioning of the research objects fueled with these mixtures, with simultaneous software changes in the vehicle computers. On the basis of the conducted analysis, it was found that only 30% of fatty acid methyl ester additives to diesel oil reduced the performance parameters of the drive units.

Experimental Investigation on Performance, Combustion, Emission and Vibration Analysis of Diesel Engine Fuelled with Rice Bran Biodiesel and n-Butanol Additive

Substantial growth in emissions, hike in fuel prices, and exhaustion of fossil fuels has given rise to the need for substitute fuels for diesel engines, which are renewable and demote the emission. Also, strict international emission standards force researchers to seek alternative fuels. Vegetable oils are promising alternative biodiesel for a diesel engine, amongst them, rice bran is underutilized, a non-edible source that doesn’t create any food security hurdle. The paper focused to investigate the performance, combustion, emission, and vibration characteristics of diesel engine fuelled with rice bran biodiesel and n- butanol additive (5% constant) at CR 17.5. The engine characteristics of seven biodiesel blends (B5n5, B10n5, B15n5, B20n5, B25n5, B30n5, and B40n5) were measured at various loads under constant speed and compared with diesel fuel. The performance characteristics were observed in moderate quantities as compared to diesel whereas the emissions were found reduced drastically than diesel fuel except for nitric oxides (NOx) emissions. The measured engine cylinder vibration for all blends indicates similar results as diesel fuel hence leads to smooth combustion. The investigation shows that blends from B20n5 to B30n5 have the potential to be used in a diesel engine without any modification.

Effect of Hard Coal Combustion in Water Steam Environment on Chemical Composition of Exhaust Gases

This academic paper revolves around the results of research on the change in emission parameters of the used heating boiler following the introduction of the overheated water stream, which had an impact on different emission parameters. The research results provide an insight into the hard coal combustion process, which had a significant impact on the change in the chemical composition of exhaust gases: it contributed to the lower mass concentration of the emitted dust and black carbon (PM) as well as nitric oxides (NOx) while, at the same time, playing a significant role in increasing the mass concentration of the emitted carbon oxide (CO). Two types of devices were used for the purposes of conducting the research at hand: a boiler with an automatic fuel feeding system with one combustion chamber and a boiler with a combustion chamber and an afterburning chamber fitted over it. Apart from the measurements of mass concentration of the emitted harmful substances, the research also focused on measurements of temperature inside the combustion and afterburning chambers, as well as the temperature of exhaust gases and their oxygen content. As part of the research, water steam was introduced to the combustion and afterburning chambers at the flow rate of 0.71 kg/h and 3.60 kg/h for boilers operating at a minimum power of 30% and a nominal power of 100%. An original steam generator with an overheated water steam production range from 0.71 kg/h to 3.60 kg/h was used to create and feed the water steam. The efficiency of the combustion process was calculated using the obtained results for each operating configuration of a given boiler.

Biofixation of Air Emissions and Biomass Valorization – Evaluation of Microalgal Biotechnology

This research appraised the simultaneous biofixation of carbon dioxide (CO 2 ) and nitric oxides (NO x ) by microalgae species Chlorella vulgaris , Haematococcus pluvialis , and Scenedesmus subspicatus . The experimental design was established by five treatments with gas concentrations between control – 0.04% of CO 2 , 5 to 15% of CO 2 , and 30 to 100 ppm of NOx. Parameters such as pH, growth, productivity, lipids, protein, carbon/ nitrogen ratio, and astaxanthin were evaluated. For all species, the maximal growth was achieved with 5% of CO 2 and 30 ppm of NO x . Regarding protein content, for all the three species, better results were obtained at higher concentrations of CO 2 and NOx. These results prove the microalgae capacity for CO 2 and NO x biofixation and reuse of biomass as a source of high value-added products, such as lipids, proteins, and astaxanthin. These findings support the indication of these species for flue gas treatment process and use in biorefineries systems.

Associations between ambient air pollutants and hospital admissions: more needs to be done

Deaths from air pollution in the UK are higher by a factor of 10 than from car crashes, 7 for drug-related deaths and 52 for murders, and yet awareness seems to be lacking in local government. We conducted an 18-year retrospective cohort study using routinely collected health care records from Ninewells Hospital, Dundee, and Perth Royal Infirmary, in Tayside, Scotland, UK, from 2000 to 2017. Hospitalisation events and deaths were linked to daily nitric oxides (NOX, NO, NO2), and particulate matter 10 (PM10) levels extracted from publicly available data over this same time period. Distributed lag models were used to estimate risk ratios for hospitalisation and mortality, adjusting for temperature, humidity, day of the week, month and public holiday. Nitric oxides and PM10 were associated with an increased risk of all hospital admissions and cardiovascular (CV) admissions on day of exposure to pollutant. This study shows a significant increase in all cause and CV hospital admissions, on high pollution days in Tayside, Scotland.

Performance of Combustion and Emissions Characteristics of Ethanol Dual Injection Spark Ignition Engine

Ethanol dual injection (DualEI) is a new technology to maximise the benefits of ethanol fuel to the spark-ignition engine. In this study, the combustion and emissions characteristics in a DualEI spark-ignition engine with a variation of the direct injection (DI) ratio and engine speed were experimentally investigated. The volume ratio of DI was varied from 0% (DI0%) to 100% (DI100%), and two engine speeds of 3500 and 4000 RPM were tested. The spark timing for maximum brake torque (MBT) was first determined, and then the results of the effect of DI ratio on the engine performance at the MBT conditions were discussed and analysed. The results showed that the MBT timing for the DI and spark timings were 330 and 30 CAD bTDC, respectively. At the MBT timing, the indicated mean effective pressure slightly increased from 0.47 to 0.50 MPa when the DI ratio increased from DI0% to DI100%. However, the maximum combustion pressure significantly decreased by 8.32%, and volumetric efficiency increased by 4.04%. This was attributed to the reduced combustion temperature due to the cooling effect of ethanol fuel enhanced by the DI strategy. The indicated specific carbon monoxide and hydrocarbons significantly increased due to poor mixture quality caused by fuel impingement associated with the overcooling effect. However, the indicated specific nitric oxides significantly decreased due to the temperature reduction inside the combustion chamber. Results showed the potential of DualEI to increase the compression ratio and consequently increase the engine thermal efficiency without the risk of engine knock.

Effect of Intake Air Temperature and Premixed Ratio on Combustion and Exhaust Emissions in a Partial HCCI-DI Diesel Engine

Homogeneous charge compression ignition (HCCI) is considered an advanced combustion method for internal combustion engines that offers simultaneous reductions in oxides of nitrogen (NOx) emissions and increased fuel efficiency. The present study examines the influence of intake air temperature (IAT) and premixed diesel fuel on fuel self-ignition characteristics in a light-duty compression ignition engine. Partial HCCI was achieved by port injection of the diesel fuel through air-assisted injection while sustaining direct diesel fuel injection into the cylinder for initiating combustion. The self-ignition of diesel fuel under such a set-up was studied with variations in premixed ratios (0–0.60) and inlet temperatures (40–100 °C) under a constant 1600 rpm engine speed with 20 Nm load. Variations in performance, emissions and combustion characteristics with premixed fuel and inlet air heating were analysed in comparison with those recorded without. Heat release rate profiles determined from recorded in-cylinder pressure depicted evident multiple-stage ignitions (up to three-stage ignition in several cases) in this study. Compared with the premixed ratio, the inlet air temperature had a greater effect on low-temperature reaction and HCCI combustion timing. Nonetheless, an increase in the premixed ratio was found to be influential in reducing nitric oxides emissions.