A major issue nowadays that concerns the pollution of the environment is the emissions emerging from heavy-duty internal combustion engines. Such concern is dictated by the fact that the electrification of heavy-duty transport still remains quite challenging due to limitations associated with mileage, charging speed and payload. Further improvements in the performance and emission characteristics of conventional heavy-duty diesel engines are required. One of a few feasible approaches to simultaneously improve the performance and emission characteristics of a diesel engine is to convert it to operate on Miller cycle. Therefore, this study was divided into two stages, the first stage was the simulation of a heavy-duty turbocharged diesel engine (4-stroke, 6-cylinder and 390 kW) to generate data that will represent the reference model. The second stage was the application of Miller cycle to the conventional diesel engine by changing the degrees of intake valve closure and compressor pressure ratio. Both stages have been implemented through the specialist software which was able to simulate and represent a diesel engine based on performance and emissions data. An objective of this extensive investigation was to develop several models in order to compare their emissions and performances and design a Miller cycle engine with an ultimate goal to optimize diesel engine for improved performance and reduced emissions. This study demonstrates that Miller cycle diesel engines could overtake conventional diesel engines for the reduced exhaust gas emissions at the same or even better level of performance. This study shows that, due to the dependence of engine performance on complex multi-parametric operation, only one model achieved the objectives of the study, more specifically, engine power and torque were increased by 5.5%, whilst nitrogen oxides and particulate matter were decreased by 30.2% and 5.5%, respectively, with negligible change in specific fuel consumption and CO₂, as average values over the whole range of engine operating regimes. Full article

The electrogenic biofilm and the bio-electrode interface are the key biocatalytic components in bioelectrochemical systems (BES) and can have a large impact on cell performance. This study used four different anodic carbons to investigate electrogenic biofilm development to determine the influence of charge accumulation and biofilm growth on system performance and how biofilm structure may mitigate against pH perturbations. Power production was highest (1.40 W/m³) using carbon felt, but significant power was also produced when felt carbon was open-circuit acclimated in a control reactor (0.95 W/m³). The influence of carbon material on electrogenic biofilm development was determined by measuring the level of biofilm growth, using sequencing to identify the microbial populations and confocal microscopy to understand the spatial locations of key microbial groups. Geobacter spp. were found to be enriched in closed-circuit operation and these were in close association with the carbon anode, but these were not observed in the open-circuit controls. Electrochemical analysis also demonstrated that the highest mid-point anode potentials were close to values reported for cytochromes from Geobacter sulfurreductans. Biofilm development was greatest in felt anodes (closed-circuit acclimated 1209 ng/μL DNA), and this facilitated the highest pseudo-capacitive values due to the presence of redox-active species, and this was associated with higher levels of power production and also served to mitigate against the effects of low-pH operation. Supporting carbon anode structures are key to electrogenic biofilm development and associated system performance and are also capable of protecting electrochemically active bacteria from the effects of environmental perturbations. Full article

The article presents a process of designing the photovoltaic (PHV) converters system for an electric vehicle, shows the scheme of photovoltaic converters usage, the results of electric vehicle motion modeling with photovoltaic converters, and the results of road tests of an electric vehicle with an additional power source based on photovoltaic converters. The photovoltaic converters system and low-voltage system of an electric vehicle have a shared low-voltage battery, which allows the implementation of two schemes of electric vehicle power supply. Initially, the aggregate base was selected, then, taking into account the efficiency of each device included in the design of the new electric vehicle, mathematical modeling was carried out and showed good efficiency results of the photovoltaic converters system. Then, the prototype was manufactured and tested. The aggregate base included the battery of photovoltaic converters assembled in a certain way on the vehicle roof, the MPPT (maximum power point tracking) controller, the buffer storage device in the form of a 12 V battery, and the DC (direct current) converter that allows transmitting electricity from the buffer battery to the high-voltage system. Modeling of the electric vehicle motion considered typical operating modes, including energy costs for the operation of assistant systems of the electric vehicle, as well as including the consumption of low-voltage components. The tests were carried out according to the NEDC (New European Driving Cycle). As a result, implementation of photovoltaic converters with 21% efficiency allowed for the power reserve of the electric vehicle to be increased by up to 9%. Full article

Municipal and agricultural waste treatment is one of the key elements of reducing environmental impact with direct effects on the economy and society. Algal technology has been tested to enable effective recycling and valorisation of wastewater nutrients including carbon, nitrogen and phosphorus. An integrated evaluation and optimisation of the sustainability of an algal bio-refinery, including mass and energy balances, carbon, water and nutrient use and impact analysis, was assessed. A bio-refinery approach of waste remediation using algal cultivation was developed at Swansea University, focusing on nutrient recovery via algal biomass exploitation in pilot facilities. Mass cultivation (up to 1.5 m³) was developed with 99% of nitrogen and phosphorus uptake by microalgal cultures. Nannochloropsis oceanica was used as a biological model and grown on three waste sources. The compounds obtained from the biomass were evaluated for animal feed and as a potential source of energy. The bioremediation through algal biotechnology was examined and compared to alternative nutrient recovery passive and active methods in order to know the most efficient way of excess nutrient management. Conclusions emphasise the high potential of algal biotechnology for waste remediation and nutrients recovery, despite the need for further development and scalable applications of this new technology. Full article

The influence of the mass composition of a water–fuel emulsion on the ecological characteristics of a diesel engine was evaluated. Research was performed on the diesel engine MMZ D-245.10 (4-cylinder, D = 110 mm, S = 125 mm) fueled with an emulsion having a water content of 10%, 20%, and 30% by weight. A noticeable drop of nitrogen oxide emissions with a growth of the mass fraction of water in the emulsion was revealed, which is a consequence of a decrease in the cycle’s average temperature. During research into engine operation using emulsions, its structure-borne noise was evaluated. For all engine operation modes investigated, the lowest noise level was achieved when the engine was running on diesel fuel (DF), and the highest when an emulsion consisting of 70% DF and 30% water was used. Full article

This paper reports an experimental investigation into the effects of fuel composition on the exhaust emission of toxic polycyclic aromatic hydrocarbons (PAHs) from a diesel engine, operated at both constant fuel injection and constant fuel ignition modes. The paper quantifies the US EPA (United State Environmental Protection Agency) 16 priority PAHs produced from combustion of fossil diesel fuel and several model fuel blends of n-heptane, toluene and methyl decanoate in a single-cylinder diesel research engine based on a commercial light duty automotive engine. It was found that the level of total PAHs emitted by the various fuel blends decreased with increasing fuel ignition delay and premixed burn fraction, however, where the ignition delay of a fuel blend was decreased with use of an ignition improving additive the level of particulate phase PAH also decreased. Increasing the level of toluene present in the fuel blends decreased levels of low toxicity of two to four ring PAH, while displacing n-heptane with methyl decanoate increased particulate phase adsorbed PAH. Overall, the composition of the fuels investigated was found to have more influence on the concentration of exhaust PAHs formed than that of combustion characteristics, including ignition delay, peak heat release rate and the extent of the premixed burn fractions. Full article

This study investigated the effects of H₂ and CH₄ concentrations on the ignition delay time and laminar flame speed during the combustion of CH₄/H₂ and multicomponent syngas mixtures using a novel constructed reduced syngas chemical kinetics mechanism. The results were compared with experiments and GRI Mech 3.0 mechanism. It was found that mixture reactivity decreases and increases when higher concentrations of CH₄ and H₂ were used, respectively. With higher H₂ concentration in the mixture, the formation of OH is faster, leading to higher laminar flame speed and shorter ignition delay time. CH₄ and H₂ concentrations were calculated at different pressures and equivalence ratios, showing that at high pressures CH₄ is consumed slower, and, at different equivalence ratios CH₄ reacts at different temperatures. In the presence of H₂, CH₄ was consumed faster. In the conducted two-stage sensitivity analysis, the first analysis showed that H₂/CH₄/CO mixture combustion is driven by H₂-based reactions related to the consumption/formation of OH and CH₄ recombination reactions are responsible for CH₄ oxidation. The second analysis showed that similar CH₄-based and H₂ -based reactions were sensitive in both, methane- and hydrogen-rich H₂/CH₄ mixtures. The difference was observed for reactions CH₂O + OH = HCO + H₂O and CH₄ + HO₂ = CH₃ + H₂O₂, which were found to be important for CH₄-rich mixtures, while reactions OH + HO₂ = H₂O + O₂ and HO₂ + H = OH + OH were found to be important for H₂-rich mixtures. Full article

The article describes a method to analyze the powertrain operation of electrically driven vehicles in cases of insufficient information (i.e., unknown control algorithms, no torque measurements during vehicle tests). The method implies mathematical modeling with involvement of so-called unknown input observers. A variant of such an observer is proposed. Using that observer, studies of a hybrid vehicle and a pure electric vehicle are performed. The models with torque observers simulated tests of said vehicles conducted on a chassis dynamometer and on roads. For the hybrid vehicle, operating regimes of main powertrain components were identified. For the electric vehicle, the identification revealed a coordinated operation of regenerative braking and mechanical braking. Adequacy of the modeling, including identification of the unmeasured torques, was verified through a comparison with experimental data. Full article

This paper deals with the creation of modern high-performance aircraft power units based on the Wankel rotary piston engine. One of the main problems of Wankel engines is high specific fuel consumption. This paper solves the problem of improving the efficiency of this type of engine. The mathematical model of non-stationary processes of transfer of momentum, energy, mass, and the concentration of reacting substances in the estimated volume provides for the determination of local gas parameters in the entire computational region, which are presented as a sum of averaged and pulsation components. The k-ζ-f model is used as the turbulence model; the combustion is described by the coherent flame model (CFM) based on the concept of laminar flame propagation. As a result of the calculation, we obtained the values of temperature, pressure, and velocity of the working fluid in the working chamber cross-sections of a rotary–piston engine. Various options of the rotor recess shape are considered. Based on the data obtained, the rotor design was improved. The offered shape of the rotor recess has reduced emissions of both nitrogen oxides and carbon dioxide. Full article

Modern research in the area of internal combustion engines is focused on researching and investigating the technologies that will improve fuel efficiency and decrease emissions. Application of dual-fuel engines is considered as a potential solution to these problems. In the dual-fuel engine, a natural gas-air mixture is ignited by a small amount of the diesel fuel directly injected into a combustion chamber. Pilot fuel injection parameters can strongly effect the combustion process. The aim of this paper is to investigate the effect of such fuel-supply parameters as pilot fuel mass, pilot fuel injection pressure, pilot fuel injection timing and excess air ratio on the combustion process. Investigation is based on the data obtained during bench tests conducted with the use of measurement equipment. The dependences of engine characteristics from the fuel supply parameters under review were obtained based on the results of the experimental study. Optimal values for every investigated fuel-supply parameter were chosen based on the obtained results. Over the course of the investigation, the coefficient for heat release rate according to the Vibe equation was calculated for each operating point. Full article