Energy Conversion and Management-X最新文献

This paper investigates the techno-economic implications on air travel when fossil-based kerosene is phased out of the market, specifically focusing on the comparison between liquid hydrogen, liquid methane and renewable kerosene for ten exemplary flight routes to estimate the cost of air travel per passenger and 100 km distance travelled $\left(\frac{{€}_{2020}}{PAX100km}\right)$ for every fuel type. By considering the entire supply chain, including hydrogen production from renewable sources, synthesis, oversea transport, domestic distribution, and utilization, this study addresses the overarching question of whether it is more economical to change the fuel source or the fuel itself to reduce fossil kerosene usage in the aviation industry. It is demonstrated that aircraft acquisition costs play a minor role compared to fuel supply costs and specific fuel demand. The study shows that for electricity-based fuels, liquid hydrogen is the most economic option, even with a potential energy penalty, followed by liquid methane and renewable kerosene. The results for an aircraft with a capacity 180 passengers are 3.08, 4.57 and 5.11 $\frac{€}{PAX100km}$ for liquid hydrogen, liquid methane and renewable kerosene, respectively. Challenges regarding storage and isolation requirements for cryogenic fuels in aviation are discussed, with assumptions made that these obstacles can be overcome to realize economic benefits. Additionally, the study suggests potential shifts in aircraft size selection by airlines to mitigate rising fuel prices in the future. The study advocates for the aviation industry's openness to new fuels like liquid hydrogen and liquid methane to alleviate the cost increase associated with phasing out fossil kerosene.

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.

Proton exchange membrane (PEM) electrolyser stands as a promising candidate for sustainable hydrogen production from renewable energy sources (RESs). Given the fluctuating nature of RESs, accurate modelling of the PEM electrolyser is crucial. Nonetheless, complex models of the PEM electrolyser demand substantial time and resource investments when integrating them into a large-scale power system. The majority of introduced models in the literature are either overly intricate or fail to effectively reproduce the dynamic behaviour of the PEM electrolyser. To this end, this article aims to develop a model that not only captures the dynamic response of the PEM electrolyser, crucial for conducting flexibility studies in the power system, but also avoids complexity for seamless integration into large-scale simulations without comprising accuracy. To verify the model, it is validated against static and dynamic experimental data. Compared to the investigated experimental cases, the model exhibited an average error of 0.66% and 3.93% in the static and dynamic operation modes, respectively.

The Mediterranean basin has been characterized by a net flow of fossil commodities from the North African shore to Southern Europe and the Middle East for decades; however, decarbonizing the energy system implies to substantially modify this situation, turning the current “black dialogue” into a “green dialogue” (i.e., based on the exchange of renewable electricity and green hydrogen). This paper presents a feasibility study conducted to estimate the potential green hydrogen production by electrolysis in three Tunisian sites. It shows and compares several plant layouts, varying the size and typology of renewable electricity generators and electrolyzers. The work adopts local weather data and technical features of the technologies in the computations, and accounts for site specific topographical and infrastructural constraints, such as land available for construction and local power grid connection capacities. It shows that configurations able to produce large quantities of green hydrogen may not be compliant with such constraints, basically nullifying their contribution in any hydrogen strategy. Finally, results show that the LCOH lies in the range 1.34 $/kg_H2 and 4.06 $/kg_H2 depending on both the location and the combination of renewable electricity generators and electrolyzers.

Mint species are grown worldwide and known for their medicinal and aromatic properties however, studies on its energy assessment are very scarce. This study quantifies the energy input–output relationship of herbs and essential oil production of different mint species (M. arvensis, M. piperita, M. spicata, M. cardiaca and M. citrata) which were commercially grown in subtropical India. This study proposes for life cycle assessment and their effects on environment. The energy inputs and outputs were significantly varied with mints species. Results showed that mints essential oil production used more energy than herbs, and M. citrata utilizes the highest energy in both cases. Fire wood requirements for essential oil extraction accounts maximum (59.16 %) energy input. Mint herbs and essential oil yields were recorded higher in M. citrata (23.14 t ha⁻¹), and M. arvensis (143.2 kg ha⁻¹), respectively. Energy yields were estimated highest in M. cardiaca (herbs), and M. arvensis (essential oils), and required net calorific values were tested by automated advanced oxygen bomb calorimeter. Overall, M. arvensis showed the best results in energy production (0.07 kg MJ⁻¹), profitability (0.27), net return (17156.40 MJ ha⁻¹), and energy use efficacy (1.27) for mint herbs production. However, for essential oil production M. cardiaca performed well. This study revealed that mint herbs production was more energy efficient than essential oils extraction although essential oil production is fiscally secure.

Bioethanol burners are significantly expanding devices in Europe, still considered preferably as the design element while its possible importance in the energy system of the household used to be neglected. The aim of this study was to determine the operating techno-environmental parameters as the heat output and the flue gas composition of the bioethanol fireplace with vortex flame. The measurement methodology was based on actual valid standard EN 16647 Fireplaces for Liquid Fuel. In general, three ethanol-based fuels were tested in combination with one bioethanol burner equipped with different regulation rings changing burner opening area. The average reached heat energy output ranged between 3.97 and 2.22 kW with maximal burner opening area (without the usage of regulation rings) for different fuels. By usage of the regulation rings, the heat energy output was reduced to 35 – 40 % of the nominal average heat output. Simultaneously the time of the burning of one fuel dose can be increased by regulation ring usage up to 195 % of the combustion time without the regulation ring. By placing the regulation rings on the burner bowl opening area, the flue gas composition was affected positively in terms of CO and negatively in terms of NO_x.

The aim of this research is to glance the feasible scientific theory and performance investigations of steady-state hydraulic automatic transmission vehicle. Numerous studies that inform about new powertrain designs in steady-state conditions look at how well manual transmission vehicles operate. However, one of the most cutting-edge of conventional automotive vehicle power transmission for modern automobile designs is hydraulic automatic transmission. Consequently, in this research the realistic methodical scheme is achieved using classical optimization techniques, utilizing spatial case functions that signify engine and torque convertor performance curve in automatic transmission vehicle. The advantage is to test the vehicle performance that meets the experimental or numerical design enactment considering the exceptional correlation coefficient obtained at global extreme. Analysis comprises, engine's joint work with hydraulic torque converter examined in relation to vehicle speediness, observing the matching between engine and convertor based on the fundamental operational performances resembling, full use of engine power, economic fuel consumption, and the requirements of vehicle operation. Finally the vehicle powertrain feasibility is confirmed by, the maximum speed of the vehicle and fuel consumption in extra urban driving 274.5 km/hr and 5.5 L/100 km respectively. This shows, there is 4 % and 7 % deviation from vehicle evidence speed and fuel consumption respectively.

As an emerging source of clean electrical power, Thermoelectric generation (TEG) finds its applications in heat removal and electricity generation as an efficient improvement tool for thermal devices utilizing fossil fuels. TEG exhibits low power density and its temperature distribution is usually non-uniform over thermal conductive surfaces. Due to the non-uniformity of heat flow and loose surface contact, non-uniform temperature distribution (NTD) appears on TEG surfaces and the TEG control problem becomes complex, multi-solution, nonlinear, and highly sensitive to operating conditions. The bypass diode activation of TEG systems streamlines the power flow in a string of series-connected modules, generating multiple peak points. Classical techniques fail to address these issues of multiple maxima and lose efficiency. To solve this problem, a novel SI-based optimization algorithm, Runge Kutta Method (RUN), is applied as MPPT control. To gauge the performance of the proposed controller several distinct case studies are used, including varying temperatures gradient, NTD, 24-hour thermal profile stochastic temperature, and experimental verification. Additionally, MPPT rating analysis, economic assessment, and statistical studies are done for comparison with other state-of-the-art control techniques. The minimum tracking and settling times have been improved by RUN to 180 ms. For the additional hardware implementation, the maximum levelized cost of energy (LCOE) is about 0.16 $\frac{\$}{\mathrm{kWh}}\left(\frac{1.07\yen }{\mathrm{kWh}}\right).$ The power tracking efficiency of RUN can be above 99 % with energy harvest improvements of 6.3 %.

In 3D-printing, sodium silicate (SS) can be used as an inorganic binder for wood-based composites due to its better rheological properties, high strength, and affordability. Investigating the recyclability of 3D-printed composites is necessary to understand the reusability of demolished additively manufactured construction waste. In this work, the bio-oil through pyrolysis was produced using pine and SS composites and further characterized to observe the effects of the pyrolysis temperatures and the proportion of SS in composites. Pine and SS composites with 0, 33.33, 50, and 66.67 % of the SS on a mass basis were prepared and cured to mimic the 3D-printed composites. Then, pyrolysis of cured composites was performed in a bench-scale fixed bed pyrolysis reactor at four temperatures (450–600 °C). From the pyrolysis of composites with 66 % SS at 600 ℃, a maximum condensed liquid yield of 68 % (wt.%, dry basis) was obtained. Further, it was observed that the selectivity towards hydrocarbons and alkyl phenols increased by increasing the proportion of SS in the composite, but methoxy phenols decreased, which enhanced bio-fuel production. A maximum hydroxyl concentration of 6.54 mmol g⁻¹ was observed for the bio-oil from pyrolysis of SS-based composite at 600 ℃. This study shows the feasibility of upcycling the 3D-printed wood composites through pyrolysis to generate bio-oil that can be used for bio-based resin synthesis and bio-fuel applications.

In recent years, efforts have been made to increase the proportion of electricity demand met by Renewable Energy Sources (RESs). Distributed Energy Resources (DERs) play a crucial role in this frame, particularly in Microgrids (MGs) where DERs and clusters of loads are interconnected. This paper presents an Energy Management System (EMS) developed for a low-voltage MG installed in Italy, connecting Photovoltaic (PV) units, a Wind Turbine (WT), a Battery Energy Storage System (BESS), a Combined Heat and Power (CHP) unit and loads: the EMS aims to optimize the day-ahead scheduling of the MG, considering both economic and power quality criteria. The mathematical model incorporates the capability curves of the inverters connected to DERs and allows for curtailment of PV and WT units, with curtailment costs assessed using the Levelized Cost of Electricity (LCOE). Penalties for the absorption of reactive power from the external network are considered and evaluated in accordance with the current regulatory framework. Optimal Power Flow (OPF) equations are integrated into the EMS model, too. A preliminary analysis, carried out on a simplified MG, evaluates the impact of linearizing the DERs capability curves and OPF equations on the EMS’s outcomes. Finally, a sensitivity analysis evaluates the impact of different operational constraints and of different objective function formulations on the operation of the MG, discussing key energy and economic results.