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Combustion of fuel with oxidizer inside a combustion chamber of an internal combustion engine forms inevitable oxides of nitrogen (NOx) due to high temperature at different locations of the combustion chamber. This study aims to quantify NOx formed inside the combustion chamber using two fuels, a conventional diesel (n-heptane) and a biodiesel (methyl oleate).

This research uses a computational fluid dynamics simulation of chemically reacting fluid flow to quantify and compare oxides of nitrogen (NOx) in a compression ignition (CI) engine. The study expends species transport model of ANSYS FLUENT. The simulation model has provided the temperature profile inside the combustion chamber, which is subsequently used to calculate NOx using the NOx model. The simulation uses a single component hydrocarbon and oxygenated hydrocarbon to represent fuels; for instance, it uses n-heptane (C₇H₁₆) for diesel and methyl-oleate (C₁₉H₃₆O₂) for biodiesel. A stoichiometric air–fuel mixture is used for both fuels. The simulation runs a single cylinder CI engine of 650 cm³ swept volume with inlet and exhaust valves closed.

The pattern for variation of velocity, an important flow parameter, which affects combustion and subsequently oxides of nitrogen (NOx) formation at different piston locations, is similar for the two fuels. The variations of in-cylinder temperature and NOx formation with crank angles have similar patterns for the fuels, diesel and biodiesel. However, the numerical values of in-cylinder temperature and mass fraction of NOx are different. The volume averaged static peak temperatures are 1,013 K in case of diesel and 1,121 K in case of biodiesel, while the mass averaged mass fractions of NOx are 15 ppm for diesel and 141 ppm for biodiesel. The temperature rise after combustion is more in case of biodiesel, which augments the oxides of nitrogen formation. A new parameter, relative mass fraction of NOx, yields 28% lower value for biodiesel than for diesel.

This work uses a new concept of simulating simple chemical reacting system model to quantify oxides of NOx using single component fuels. Simplification has captured required fluid flow data to analyse NOx emission from CI engine while reducing computational time and expensive experimental tests.

This paper aims to present a genuine code developed for multi-objective optimization of selected parameters of a turboprop unmanned air vehicle (UAV) for minimum landing-takeoff (LTO) nitrogen oxide (NOx) emissions and minimum equivalent power specific fuel consumption (ESFC) at loiter (aerial reconnaissance phase of flight) by using a genetic algorithm.

The genuine code developed in this study first makes computations on preliminary sizing of a UAV and its turboprop engine by analytical method for a given mission profile. Then, to minimize NOx emissions or ESFC or both of them, single and multi-objective optimization was done for the selected engine design parameters.

In single objective optimization, NOx emissions were reduced by 49 per cent from baseline in given boundaries or constraints of compressor pressure ratio and compressor polytropic efficiency in the first case. In second case, ESFC was improved by 25 per cent from baseline. In multi-objective optimization case, where previous two objectives were considered together, NOx emissions and ESFC decreased by 26.6 and 9.5 per cent from baseline, respectively.

Variation and trend in the NOx emission index and ESFC were investigated with respect to two engine design parameters, namely, compressor pressure ratio and compressor polytropic efficiency. Engine designers may take into account the findings of this study to reach a viable solution for the bargain between NOx emission and ESFC.

UAVs have different flight mission profiles or characteristics compared to manned aircraft. Therefore, they are designed in a different philosophy. As a number of UAV flights increase in time, fuel burn and LTO NOx emissions worth investigating due to operating costs and environmental reasons. The study includes both sizing and multi-objective optimization of an UAV and its turboprop engine in coupled form; compared to manned aircraft.

The purpose of this study is to estimate the nitrogen oxide (NOx), carbon monoxide (CO) and hydrocarbon (HC) emissions and their environmental and economic aspects during the actual landing and take-off operations (LTO) of domestic and international flights at a small-scale airport. In this regard, the aircraft-induced NOx, CO and HC emissions analyses, the global warming potential (GWP) estimations of exhaust emissions and the life cycle assessment (LCA)-based environmental impact (EI) estimations of exhaust emissions, and the eco-cost estimation of exhaust emissions are measured.

Estimations and calculations are performed in parallel with the International Civil Aviation Organisation’s Engine Emission Databank and Intergovernmental Panel on Climate Change approaches. Also, to assess the environmental effect of the pollutants, the GWP and the EI analyses which is based on the LCA approaches are used. Finally, the eco-cost approach has been used to discuss the economic aspects of these emissions.

The total emissions of air pollutants from aircraft are estimated as 601.067 kg/y for HC, 6,074.905 kg/y for CO and 4,156.391 kg/y for NOx at the airport. Also, emissions from international flights account for 79% of emissions from all flights. The Airbus A321 type of aircraft has accounted for more than half of the total HC, CO and NOx emissions. The total amount of emissions from the B738 type of aircraft is estimated as 24%. It is noticed that the taxi phase constitutes 52% of the total HC, CO and NOx emissions. Because of this, it is selected the five different alternative taxi times to observe the effects of pollution role of taxiing time in detail and re-estimated accordingly. According to the re-estimated results with variations in taxiing time, when the taxiing time at the airport is 24 min instead of the original value, this case contributes to a decrease in total LTO emissions of approximately 4%. Also, when the taxiing time is decreased by 2 min, HC, CO and NOx emission amounts decrease by approximately 3.9%, 5.9% and 1.2%, respectively. At this point, the polluting role of taxiing time will be helpful to reduce the aircraft-induced HC, CO and NOx emissions for other larger-scale airports. On the other hand, it is estimated that the GWP of the A321 is 1,066.29 t CO₂e whilst the GWP of B738 is 719.50 t CO₂e. The eco-cost values of the A321, B738, A320 and CL60-type of aircraft are estimated as almost 61,049.42, 41,086.02, 18,417.43 and 6,163.59 Euros, respectively.

With the detailed results of this study, the polluting role of taxiing time on total HC, CO and NOx emissions in a small-scale airport will be helpful to reduce aircraft-induced emissions for other larger-scale airports. Also, in the future, this study and its results will be helpful to create an emission inventory at the airport examined.

In this study, different from some previous studies, air pollutants from aircrafts are evaluated with different aspects such as the EI and eco-cost and GWP. Also, this study will be making a helpful contribution to the literature as it covers the more diversity of the different types of aircrafts in the analyses.

Stainless steel pickling is a major generator of NOx emissions and is also a major producer of nitrate effluents. Hydrogen peroxide technologies have been developed and proven to suppress NOx emissions and also to replace nitric acid in the pickling process and hence remove the problem of nitrate effluent discharge. Presents case histories to illustrate the effectiveness of hydrogen peroxide both for NOx suppression and for nitric acid‐free pickling when pickling stainless steels.

The purpose of this research is to explore a concept of the management of professionals that can withstand critical questioning.

A case study is analysed with use of key concepts from Polanyi.

The instrumental approach to knowledge, so frequently used in knowledge management, neglects important issues. The conventional question: “How should we organize knowledge?” neglects the question: “How should knowledge impact organization?”. With use of Polanyi's concept of knowledge, a richer interdependency between knowledge and organization can be conceived. Findings were drawn from an ethnographic case study in the IT sector to illustrate how professionals can successfully negotiate the content, meaning and development of their tasks and practices. The attempt to create a safe haven, supporting professional and personal development, illustrates how the tacit dimension has emancipatory potential.

Contributes to clarifying the richness of Polanyi's social thought and the uses of the concept of the “tacit” to organization when it is not functionally misunderstood but appreciated in its full critical force.

The demand for energy is increasing massively due to urbanization and industrialization. Due to the massive usage of diesel engines in the transportation sector, global warming is increasing rapidly. The purpose of this paper is to use hydrogen as the potential alternative for diesel engine.

A series of tests conducted in the twin cylinder four stroke diesel engine at various engine speeds. In addition to the hydrogen, the ultrasonication is applied to add the nanoparticles to the neat diesel. The role of nanoparticles on engine performance is effective owing to its physicochemical properties. Here, neat diesel mixed 30% of biodiesel along with the hydrogen at the concentration of 10%, 20% and 30% and 50 ppm of graphite oxide to form the blends DNH10, DNH20 and DNH30.

Inclusion of both hydrogen and nanoparticles increases the brake power and brake thermal efficiency (BTE) of the engine with relatively less fuel consumption. Compared to all blends, the maximum BTE of 33.3% has been reported by 30% hydrogen-based fuel. On the contrary, the production of the pollutants also reduces as the hydrogen concentration increases.

Majority of the pollutants such as carbon monoxide, carbon dioxide and hydrocarbon were dropped massively compared to diesel. On the contrary, there is no reduction in nitrogen of oxides (NOx). Highest production of NOx was witnessed for 30% hydrogen fuel due to the premixed combustion phase and cylinder temperatures.

The different performance tests were conducted on diesel engine compression ignition (CI) mode and CRDi engine.

The CI engine was suitably modified to CRDi engine with Toroidal re-entrant combustion chamber (TRCC) and was run in dual-fuel (DF) mode. Hydrogen (H₂) was supplied at different flow rates during the suction stroke, and 0.22 Kg/h of hydrogen fuel flow rate (HFFR) was found to be optimum. Diesel and biodiesel were used as pilot fuels. The CRDi engine with DF mode was run at various injection pressures, and 900 bar was found to be optimum injection pressure (IP) with 10o before top dead center (bTDC) as fuel injection timing (IT).

These operating engine conditions increased formation of oxides of nitrogen (NOx), which were reduced by exhaust gas recycle (EGR). With EGR of 15%, CRDi engine resulted in 12.6% lower brake thermal efficiency (BTE), 5.5% lower hydrocarbon (HC), 7.7% lower carbon monoxide (CO), 26% lower NOx at 80% load as compared to the unmodified diesel engine (CI mode).

The current research is an effort to study and evaluate the performance of CRDi engine in DF mode with diesel-H₂ and BCPO-H₂ fuel combinations with TRCC.

LARGE fleets of supersonic commercial aircraft will only fly the airways when engineers control engine emission of oxides of nitrogen (NOx) into the stratosphere. The technology is being acquired now, well in advance of the high speed civil transport planned for the 21st century.

The aim of this paper is to quantify the impact of transboundary air pollutants, particularly those related to urban traffic, on health outcomes. The importance of focusing on the health implications of transboundary pollution is due to the fact that these emissions originate from another jurisdiction, thus constituting international negative externalities. Thus, by isolating and quantifying the impact of these transboundary air pollutants on domestic health outcomes, the authors can understand more clearly the extent of these externalities, identify their ramifications for health and emphasise the importance of cross-country cooperation in the fight against air pollution.

The authors employ panel data regression analysis to look at the relationship between emissions of transboundary air pollution and mortality rates from various respiratory diseases among a sample of 40 European countries, over the period 2003–2014. In turn, the authors use annual data on transboundary emissions of sulphur oxides (SOx), nitrogen oxides (NOx) and fine particulate matter (PM_2.5), together with detailed data on the per capita incidence of various respiratory diseases, including lung cancer, asthma and chronic obstructive pulmonary disease (COPD). The authors consider a number of different regression equation specifications and control for potential confounders like the quality of healthcare and economic prosperity within each country.

The results show that transboundary emissions of PM_2.5 are positively and significantly related to mortality rates from asthma in our sample of countries. Quantitatively, a 10% increase in PM_2.5 transboundary emissions per capita from neighbouring countries is associated with a 1.4% increase in the asthma mortality rate within the recipient country or roughly 200 deaths by asthma per year across our sample.

These findings have important policy implications for cross-country cooperation and regulation in the field of pollution abatement and control, particularly since all the countries under consideration form a part of the UN's Convention on Long-Range Transboundary Air Pollution (CLRTAP), a transnational cooperative agreement aimed at curtailing such pollutants on an international level.

The purpose of this paper is to review the applications of the chemical reactor network (CRN) approach for modeling the combustion in gas turbine combustors and classify the CRN construction methods that have been frequently used by researchers.

This paper initiates with introducing the CRN approach as a practical tool for precisely predicting the species concentrations in the combustion process with lower computational costs. The structure of the CRN and its elements as the ideal reactors are reviewed in recent studies. Flow field modeling has been identified as the most important input for constructing the CRNs; thus, the flow field modeling methods have been extensively reviewed in previous studies. Network approach, component modeling approach and computational fluid dynamics (CFD), as the main flow field modeling methods, are investigated with a focus on the CRN applications. Then, the CRN construction approaches are reviewed and categorized based on extracting the flow field required data. Finally, the most used kinetics and CRN solvers are reviewed and reported in this paper.

It is concluded that the CRN approach can be a useful tool in the entire process of combustion chamber design. One-dimensional and quasi-dimensional methods of flow field modeling are used in the construction of the simple CRNs without detailed geometry data. This approach requires fewer requirements and is used in the initial combustor designing process. In recent years, using the CFD approach in the construction of CRNs has been increased. The flow field results of the CFD codes processed to create the homogeneous regions based on construction criteria. Over the past years, several practical algorithms have been proposed to automatically extract reactor networks from CFD results. These algorithms have been developed to identify homogeneous regions with a high resolution based on the splitting criteria.

This paper reviews the various flow modeling methods used in the construction of the CRNs, along with an overview of the studies carried out in this field. Also, the usual approaches for creating a CRN and the most significant achievements in this field are addressed in detail.