The marine sector represents probably the most powerful segment of international transport. Most ships use diesel engines for propulsion. Pollutant emission regulations with their continuous decline of acceptable limits put huge pressure on engine manufacturers. The use of low-quality fuels makes the marine sector a significant contributor to global pollution. The present study shows how turbocharger operating parameters and replacing diesel fuel with biodiesel B20 (20% oil and 80% diesel volumetric fractions) affect the performance, efficiency and pollutant emissions of a four-stroke diesel engine ALCO V16 251F for marine application. A combustion model developed with the AVL BOOST software was used to perform calculations using diesel fuel and biodiesel B20 for different turbocharger characteristics and injection timings. The model was calibrated against experimental data measured on a tested engine at the application site using diesel fuel and operating in a stationary condition of full load at 600, 700 and 800 rpm engine speeds. The results show that the cumulative effects of using an improved turbocharger associated with B20 fuelling under optimized injection timings could provide reductions of 45% for soot and 5% for NO_x, while maintaining the same engine performance obtained with diesel fuel operation.

A new afterburner installation is proposed, fueled with pure hydrogen (100%H₂) or hydrogen–methane mixtures (60% H₂ + 40% CH_4, 80% H₂ + 20% CH₄) for use in cogeneration applications. Two prototypes (P1 and P2) with the same expansion angle (45 degrees) were developed and tested. P1 was manufactured by the classic method and P2 by additive manufacturing. Both prototypes were manufactured from Inconel 625. During the tests, analysis of flue gas (CO₂, CO, and NO concentration), PIV measurements, and noise measurements were conducted. The flue gas analysis emphasizes that the behavior of the two tested prototypes was very similar. For all three fuels used, the CO₂ concentration levels were slightly lower in the case of the additive-manufactured prototype P2. The CO concentration levels were significantly higher in the case of the additive-manufactured prototype P2 when 60% H₂/40% CH₄ and 80% H₂/20% CH₄ mixtures were used as fuel. When pure H₂ was used as fuel, the measured data suggest that no additional CO was produced during the combustion process, and the level of CO was similar to that from the Garrett micro gas turbine in all five measuring points. The NO emissions gradually decreased as the percentage of H₂ in the fuel mixture increased. The NO concentration was significantly lower in the case of the additive-manufactured prototype (P2) in comparison with the classic manufactured prototype (P1). Examining the data obtained from the PIV measurements of the flow within the mixing region shows that the highest axial velocity component value on the centerline was measured for the P1 prototype. The acoustic measurements showed that a higher H₂ concentration led to a reduction in noise of approximately 1.5 dB for both afterburner prototypes. The outcomes reveal that the examined V-gutter flame holder prototype flow was smooth, without any perpendicular oscillations, without chaotic motions or turbulent oscillations to the flow direction, across all tested conditions, keeping constant thermal power.

This study evaluates the potential of a twin-screw compressor as a heat source to harness thermal energy. Thermoelectric generators are a feasible solution for microenergy harvesting from waste heat based on the Seebeck effect. Thermographic infrared images of the compressor were used to assess potential installation spots. The physical mounting of the thermoelectric modules must consider certain hindering aspects. At first, the compressor skid is subject to standards and authorizations for its components, leaving only a couple of spots for screw-mounted module installations. Another inconvenience is the bonds in any thermoelectric material causing them not to withstand lateral mechanical stress in other directions except the c-axis perpendicular to the layers. Therefore, vibration measurements have to be performed beforehand. Numerical simulations were conducted, relying on the acquired thermoelectric modules as well as on the temperature and vibration data measured on the compressor. The thermoelectric generators studied are part of a multisource piezoelectric and thermoelectric energy harvesting system under research and development.

In a world where the energy demand is increasing daily, energy efficiency and renewable energy play a major role. Our research comes to help fighting the biggest problem that our world is facing today, global warming. This study aims to evaluate the energy potential of biofuels obtained from camelina sativa in order to reduce fossil fuel dependence, greenhouse gas emissions and increase energy efficiency. Camelina (Camelina sativa L.) is a cruciferous oilseed plant belonging to the Brassicaceae (mustard) family with the common name false flax and gold of pleasure. Since camelina can grow under different conditions without being a competitor of food land, this energetic plant can be used for production of both, firstand second-generation biofuels. In our study we determined the elemental analysis of the subproducts obtained from camelina sativa, through experimental tests, and we built a mathematical model to determine the calorific power and to simulate the burning of the biofuels into a steam generator in order to analyse the energy potential. The results show us that the biofuels obtained from camelina sativa can represent an alternative to fossil fuels and should be considered in the transition to green energy.

The stability of hydrogen-fueled flames in afterburner systems is crucial for advancing clean energy technologies but is challenged by intense turbulence and flow variability. This study uniquely integrates advanced particle image velocimetry (PIV) techniques to investigate the flow dynamics around a V-gutter flame holder fueled with 100% hydrogen. Detailed velocity measurements were conducted to analyze the standard deviation of V_y, average V_y, average V, and uncertainty of V_y, as well as the mean swirling strength and mean vorticity profiles across multiple horizontal and vertical lines. The results reveal significant flow variability and turbulence intensity near the flame holder, with standard deviation peaks of up to 12 m/s, indicating zones of high turbulence and potential flame instability. The mean swirling strength, peaking at 850,000 [1/s²], and vorticity values up to 5000 [1/s] highlight intense rotational motion, enhancing fuel–air mixing and flame stabilization. The average V_y remained stable near the centerline, ensuring balanced flow conditions, while lateral deviations of up to −10 m/s reflect vortical structures induced by the flame holder geometry. Low uncertainty values, typically below 1 m/s, validate the precision of the PIV measurements, ensuring a reliable representation of the flow field. By providing a detailed analysis of turbulence structures and their impact on hydrogen combustion, this study offers novel insights into the interplay between flow dynamics and flame stability. These findings not only advance the understanding of hydrogen-fueled afterburner systems but also demonstrate the critical role of rotational flow structures in achieving stable and efficient combustion. By addressing key challenges in hydrogen combustion, this study provides a foundation for designing more robust and environmentally sustainable combustion systems, contributing to the transition toward clean energy technologies.