Search Results (610)

This article aimed to assess the accuracy of the COPERT model in predicting CO₂ emissions and energy consumption in real operating conditions, represented by the WLTP homologation tests. Experimental data obtained for a Euro 6 vehicle were compared with the values estimated by the COPERT model, assuming identical speed conditions. MLP and SANN artificial neural networks were also used to create a model describing the complex relationships between emissions, speed, and energy consumption. The results indicate an apparent overestimation of CO₂ and energy consumption values by the COPERT model, especially in the low-speed range typical of urban traffic. The minimum energy consumption values were observed at speeds of 50–70 km/h, indicating the existence of an optimal drive system operation zone. The neural models showed high efficiency in predicting the tested parameters—the best results were obtained for the MLP 6-10-1 architecture, whose correlation coefficient exceeded 0.98 in the validation set. The paper highlights the need to calibrate the COPERT model using local experimental data and integrate artificial intelligence methods in modern emission inventories. Full article

Piston engines used for powering automobiles as well as machinery and equipment have traditionally relied on petroleum-derived fuels. Subsequently, renewable fuels began to be used in an effort to reduce the combustion of hydrocarbon-based fuels and the associated greenhouse effect. Researchers are currently developing technologies aimed at eliminating fuels containing carbon in their molecular structure, which would effectively minimize the emission of carbon oxides into the atmosphere. Ammonia is considered a highly promising carbon-free fuel with broad applicability in energy systems. It serves as an excellent hydrogen carrier (NH₃), free from many of the storage and transportation limitations associated with pure hydrogen. Safety concerns regarding the storage and transport of hydrogen make ammonia an increasingly important fuel also due to its larger hydrogen storage capacity. This manuscript investigates the use of ammonia for powering a dual-fuel engine. The results indicate that the addition of ammonia improves engine performance; however, it may also lead to an increase in NO_x emissions. Due to the limitations of ammonia as a fuel, approximately 40% of the energy input must still be provided by diesel fuel to achieve optimal engine performance and acceptable NO_x emission levels. The presented research findings highlight the significant potential of NH₃ as an alternative fuel for compression-ignition engines. Proper control of the injection strategy or the adoption of alternative combustion systems may offer a promising approach to reducing greenhouse gas emissions while maintaining satisfactory engine performance parameters. Full article

This study investigates the performance and combustion behavior of a spark ignition engine retrofitted to operate on compressed natural gas (CNG), with a focus on a newly developed stratified charge pre-chamber design. The engine was modified to include an auxiliary intake valve that enables partial enrichment of the pre-chamber mixture without the need for a dedicated fuel injector. This hybrid approach combines the mechanical simplicity of passive systems with the enhanced combustion control of active pre-chambers. Both experimental tests and computational fluid dynamics (CFD) analyses were carried out under partial load conditions (8 Nm) and engine speeds ranging from 900 to 1700 rpm. The results demonstrate improvements in indicated mean effective pressure (IMEP), combustion stability, and flame propagation speed—particularly at lower engine speeds where stratified combustion effects are more pronounced. However, increasing engine speed resulted in reduced volumetric efficiency and elevated exhaust temperatures, indicating potential for further optimization via turbocharging or advanced scavenging techniques. Overall, the findings validate the effectiveness of the proposed design in enhancing thermal efficiency and ignition stability in CNG-fueled engines, especially under urban driving conditions. Full article

Hybrid electric vehicles are essential in the automotive industry. Combining electric propulsion with biofuels to power the electric motor and the internal combustion engine offers enormous potential to reduce fuel consumption and polluting emissions. However, to operate efficiently, HEVs require an EMS that decides whether the vehicle is propelled by the combustion engine or the electric motor while managing power generation and the battery charge state. This work analyzes the use of biodiesel as a fuel in hybrid electric vehicles (HEVs). For this purpose, the mechanical behavior of a diesel engine was experimentally determined using a B10 blend to evaluate its power, torque, emissions, and operating behavior, such as temperatures and pressures. The engine used was a 2.5 L four-stroke with 131 hp at 3600 rpm to complete the efficiency map considering power, torque, and combustion. Finally, an energy management strategy based on an efficiency map is proposed. The results show that it is possible to use a specific operating range of the combustion engine with maximum efficiency while maintaining an optimal battery state of charge (SOC). Full article

Despite its higher density, viscosity, and lower calorific value, biodiesel has been explored as an alternative energy source to diesel fuel. This study investigated biodiesel produced from croton macrostachyus (CMS) seed, a non-edible feedstock. The research aimed to experimentally analyze cylinder pressure, heat release rate, and ignition delay, as well as engine performance and emission characteristics, at a constant speed of 2700 rpm under varying loads (0–80%) using diesel, B10, B15, B20, and B25 blended fuels. Among the tested blends, B25 exhibited superior performance, achieving the highest peak cylinder pressure (CP) of 58.21 bar and a maximum heat release rate (HRR) of 543.9 J/CA at 80% engine load. Conversely, B20 at 60% engine load, followed by B25 and pure diesel at 80% engine load, demonstrated the shortest ignition delay (ID) and the most advanced start of combustion (SoC). Compared to the biodiesel blends, pure diesel showed: a 5.5–14% increase in brake thermal efficiency (BTE), a 17–26% decrease in brake-specific fuel consumption (BSFC), and a 7–12% reduction in exhaust gas temperature (EGT). Regarding emissions, carbon monoxide (CO) and hydrocarbon (HC) emissions were lower for pure diesel, while carbon dioxide (CO₂) and nitrogen oxide (NOx) emissions were higher for biodiesel blends, attributed to their inherent oxygen content. In conclusion, CMS biodiesel displays promising characteristics, suggesting its potential suitability for use in internal combustion engines. Full article

This paper presents the effectiveness of representing the process of creating and burning a combustible mixture in vibroacoustic parameters of a compression ignition engine. Empirical engine tests allowed us to conduct analyses in terms of the operating conditions, fuel parameters, and fuel type. The influence of dimethyl ether on combustion efficiency was quantified using performance indicators, emission parameters, and vibration estimates (compared to diesel fuel). Mathematical models of combustion and its variability were created using the mean, peak-to-peak amplitude, root mean square error, and peak amplitudes of vibration accelerations, which were also represented using vibration graphics. Dimethyl ether positively influenced engine performance, emissions, and vibration reduction. The proposed method can predict combustion irregularities and detect their sources in engine designs with high kinetic energy, hybrid combustion modeling, and fuel composition identification. Dimethyl ether reduced hydrocarbons by 96–99%, particulate matter by 37–60%, and carbon monoxide by 2.5–19.5%, whereas nitrogen oxides increased by 1–8% (relative to diesel fuel). Emission models were created with accuracies of 0.88–0.96 (hydrocarbons), 0.80–0.98 (particulate matter), 0.95–0.99 (carbon monoxide), and 0.97–0.99 (nitrogen oxides). Dimethyl ether application reduced the mean amplitude of the vibrations in the range of 5.7–60.6% and the peak-to-peak amplitude in the range of 18.2–72.4%. The standard deviation of combustion was decreased by 8.8–49.1% (mean) and by 28.8–39.5% (peak-to-peak). The vibroacoustic models’ accuracy scores were 0.90–0.99 (diesel fuel) and 0.72–0.75 (dimethyl ether). Full article

Negative inlet pre-swirl has been identified as a potentially effective method to improve the theoretical work that has been performed. However, it should be noted that a large negative inlet swirl may adversely affect the pressure ratio of the compressor due to the different centrifugal forces generated by the movement of the airflow within the large-angle pre-swirl guide vane flow channel. In order to achieve a large inlet negative pre-swirl, a new guide vane with a contraction channel is proposed for a 40° pre-swirl angle fan. This contraction guide vane is of the tandem type, and it includes a first-stage enlarged guide vane and a second-stage contraction guide vane channel. Comprehensive CFD numerical simulations and experimental studies have been conducted to analyze the key design parameters, and the total pressure loss and efficiency of the new guide vanes were analyzed and compared under various operating conditions. It was found that this new guide vane can significantly reduce the total pressure loss coefficients. Compared with the conventional guide vanes, the inlet velocity distribution is more uniform development of inlet velocities, and a significant reduction in flow separation is found for this new guide vane. The guide vane with a ring width ratio of 1.5 reduced 53.11% of the total pressure loss coefficient. In addition, the efficiency of the fan has been shown to increase by more than 2.29% under various operating conditions, due to the improved internal flow of the fan under large flow conditions, under all operating conditions, with an overall improvement in the total pressure ratio of about 5%. Full article

The RED II Directive requires European Union member states to increase the share of renewable energy in the transport sector to at least 14% by 2030. In January 2024, Poland replaced E5 gasoline (95 octane) with E10, which contains up to 10% bioethanol derived from second-generation sources such as agricultural residues. The transition to E10 raises concerns about the ability of engine management systems to adapt to its different air–fuel ratio (AFR) requirements. The AFR for E10 (13.82) is 1.98% lower than for E5 (14.25) and 3.88% lower than for pure gasoline (14.7). Research conducted on a spark-ignition engine (with AFR regulation) using an exhaust gas analyzer demonstrated that during the combustion of E5 and E10 fuels with correctly adjusted AFR and operation at λ = 1, the use of E10 potentially increases CO₂ and NO_x emissions despite reductions in CO and HC. However, when calibrated for E5 and operated with E10 fuel, an increase in CO₂ and HC concentrations in the exhaust gases is observed, along with a reduction in CO and NO_x. This phenomenon is attributed to operation with lean mixtures, at λ = 1.02. This study investigates both the theoretical and experimental impact of this fuel transition. Fuel systems typically adjust engine operation based on exhaust gas analysis but cannot recognize fuel type, leading to incorrect λ values when the AFR differs from the ECU’s programming. Effective adaptation would require additional fuel composition sensors and editable ECU mappings. For older vehicles or small non-road engines, manual adjustments to injection or carburetor systems may be necessary. Full article

This study evaluates the performance and emissions characteristics of a compression ignition engine fueled with biodiesel blends derived from used cooking oil (UO) and sunflower oil (SF) at concentrations of 5%, 10%, 20%, and 50%. Tests were conducted under different load conditions (20%, 50%, and 100%) across engine speeds ranging from 1500 to 3600 rpm, focusing on effective power, torque, brake specific fuel consumption (BSFC), and emissions of NOx, CO, HC, particulate matter (PM), smoke, and CO₂. Consistent engine operating conditions were maintained for all fuel blends. The results indicated that increasing the biodiesel concentration led to a decrease in brake power and torque—up to 3.18% reduction for SF50 compared to diesel—due to the lower calorific value of biodiesel. For SF biodiesel, the BSFC increased with higher biodiesel content, while for UO biodiesel the results varied across concentrations. Emissions analysis revealed lower CO and HC at 2500 rpm for all biodiesel blends relative to diesel, while NOx emissions varied depending on fuel type and concentration. In terms of particles, both PM and smoke were measured, and while PM showed different results across blends, smoke was lower for all blends compared to diesel. Our overall analysis shows that biodiesel blends up to 20% can be effectively used in diesel engines without substantial modifications, offering a balance between performance and reduced emissions. Full article

Thermoelectric heat dissipation systems offer unique advantages over conventional systems, including vibration-free operation, environmental sustainability, and enhanced controllability. This study examined the benefits of incorporating a thermoelectric cooler (TEC) into conventional heat sinks and investigated strategies to improve heat dissipation efficiency. A theoretical model introducing a dimensionless evaluation index ($r_q$) is proposed to assess the system’s performance, which measures the ratio of the heat dissipation density of a conventional heat dissipation system to that of a thermoelectric heat dissipation system. Here, we subjectively consider 0.9 as a cutoff, and when $r_q<0.9$, the thermoelectric heat dissipation system shows substantial superiority over conventional ones. In contrast, for $r_q>0.9$, the advantage of the thermoelectric system weakens, making conventional systems more attractive. This analysis examined the effects of engineering leg length ($L^{*}$), the heat transfer allocation ratio ($r_h$), and temperature difference ($\mathsf{\Delta }T$) on heat dissipation capabilities. The results indicated that under a fixed heat source temperature, heat sink temperature, and external heat transfer coefficient, an optimal engineering leg length exists, maximizing the system’s heat dissipation performance. Furthermore, a detailed analysis revealed that the thermoelectric system demonstrated exceptional performance under small temperature differences, specifically when the temperature difference was below 32 K with the current thermoelectric (TE) materials. For moderate temperature differences between 32 K and 60 K, the system achieved optimal performance when ${\mathrm{r}}_h\ge -2.4+1.37e^{0.019\Delta T}$. This work establishes a theoretical foundation for applying thermoelectric heat dissipation systems and provides valuable insights into optimizing hybrid heat dissipation systems. Full article

E-fuels, or synthetic fuels produced from green hydrogen and captured CO₂, are a promising solution for achieving climate neutrality by replacing fossil fuels in transportation and industry. They help reduce greenhouse gas emissions and efficiently utilize renewable energy surpluses. This study aims to assess the current state and future potential of e-fuel production technologies, focusing on their scalability and market integration. A comprehensive literature review and market trend analysis, including modeling based on historical data and growth forecasts, were used to estimate market penetration. Results indicate that e-fuels could reach a 10% market share within the next 5 years, potentially reaching 30% in 20 years, particularly in aviation, maritime transport, and the steel industry. Ongoing projects expected to be completed this decade may cover about 20% of the global liquid fuel demand for transportation. However, challenges such as high costs, scalability, and recent project terminations due to funding shortages highlight the need for substantial investment, regulatory support, and innovation. Global collaboration and policy alignment are essential for the successful development and integration of e-fuels as a critical pathway to decarbonization. Full article

Ethyl alcohol is a known additive to automotive gasoline. In commercially available gasolines, its concentration is between 5 and 10%. Since ethyl alcohol can be considered as a renewable fuel, efforts are being made to further increase its content in gasoline. This article describes the results of comparison experiments on a Euro 5 direct injection spark-ignition car engine fueled with conventional gasoline and gasoline with 30% v/v ethyl alcohol content (E30). The test results showed that a significant share of ethanol in the fuel did not affect most of the regulated emissions of gaseous components (namely: CO, HC, NO), i.e., a three-way catalyst effectively removed these components, regardless of the fuel composition. Slightly lower CO₂ emissions with the E30 fuel were noticeable. A significant difference, however, in lower particulate number emissions for the fuel with high-ethanol content was seen. At high engine load, the use of the E30 fuel resulted in a tenfold reduction in particulate number emissions. This might be considered as a very valuable effect of ethanol since direct injection spark-ignition engines are typically characterized by higher particulate emissions compared to engines equipped with other types of injection systems. Full article

Efficient path planning is vital for multi-UAV inspection missions, yet the comparative effectiveness of different optimization strategies has not received much attention. This paper introduces the first application of the Genetic Algorithm (GA) and Hill Climbing (HC) to multi-UAV inspection of indoor pipelines, providing a unique comparative analysis. GA exemplifies the global search strategy, while HC illustrates an enhanced stochastic local search. This comparison is impactful as it highlights the trade-offs between exploration and exploitation—two key challenges in multi-UAV path optimization. It also addresses practical concerns such as workload balancing and energy efficiency, which are crucial for the successful implementation of UAV missions. To tackle common challenges in multi-UAV operations, we have developed a novel repair mechanism. This mechanism utilizes problem-specific repair heuristics to ensure feasible and valid solutions by resolving redundant or missed inspection points. Additionally, we have introduced a penalty-based approach in HC to balance UAV workloads. Using the Crazyswarm simulation platform, we evaluated GA and HC across key performance metrics: energy consumption, travel distance, running time, and maximum tour length. The results demonstrate that GA achieves a 22% reduction in travel distance and a 23% reduction in energy consumption compared to HC, which often converges to suboptimal solutions. Additionally, GA outperforms HC, Greedy, and Random strategies, delivering at least a 13% improvement in workload balancing and other metrics. These findings establish a novel and impactful benchmark for comparing global and local optimization strategies in multi-UAV tasks, offering researchers and practitioners critical insights for selecting efficient and sustainable approaches to UAV operations in complex inspection environments. Full article

To enhance the performance of aviation piston engine starters in high-altitude environments, this study investigated their transient starting characteristics under low-temperature and low-pressure conditions using a high-altitude simulation chamber. Experiments were conducted across ambient temperatures from −60 to 15 °C and pressures from 35 to 95 kPa. The results show that the ambient temperature significantly impacts the transient characteristics of the motor, particularly at the initiation stage, whereas pressure has a weaker effect. For every 5 °C drop in temperature, the peak starting current increases by 1.95 A. From 15 to −60 °C, the maximum difference in the starting current pulse width is 11.64 ms. Furthermore, as the ambient temperature decreases, the average current after the motor stabilizes increases, and the average speed decreases. Full article