In this paper an environmental impacts of a 3?kW uninterruptible power supply system with polymer membrane fuel cell (FCH-UPS) was evaluated with a life cycle assessment (LCA) method. The analysis was focused on the analysis of the end of life (EOL) scenarios that will help to reduce environmental impacts during manufacturing stage. Numerical model of the FCH-UPS was developed using Gabi software. The scope of analysis was cradle-to-grave with functional unit 1?kWh of produced electric energy. In operating phase two geographical locations are compared where hydrogen is produced with electrolysis on-site. Three EOL scenarios were analysed: base, feasible and realistic scenario. With realistic EOL scenario in average a 72% reduction of all environmental impacts in the manufacturing phase was achieved. EOL phase of 3?kW FCH-UPS represents low environmental impact compared with other phases in the entire life cycle of observed system. CO2 emissions of 3?kW FCH-UPS system was 239?g CO2 per 1?kWh of produced electricity if operating in Norway and 4040?g CO2 per 1?kWh in Morocco due to electricity grid mix. Results show that with circular economy, recyclingand reuse of the materials in EOL phase, an average reduction of 66% in all environmental impact indicators could be achieved in entire life cycle of a 3?kW FCH-UPS system operated in Norway.
COBISS.SI-ID: 16276763
The Fuel Cells and Hydrogen (FCH) technologies will play an important role in a future where greenhouse gasses emissions need to be reduced. Nevertheless, a huge implementation of these technologies must be addressed taking into account an eco friendly scope not only from the manufacturing perspective but also from the end-of-life scope. A classification of the materials has been done considering the importance of each of them. To obtain a complete overview of the problem, different criteria have been compared: the cost, the scarcity of the material and the affections these materials can cause not only to the environment but also to the humans. This classification has been used to identify which are the most critical materials. Moreover, other transversal issues have been studied as the regulations that apply to FCH technologies from a paneuropean perspective and the strategies to face the end-of-life of this equipment. A holistic point of view has been considered in order to see how the process of dismantling and recycling faces different problems and which milestones to achieve in a future with a deep market penetration are.
COBISS.SI-ID: 16334875
The study presents a final step of several years worth of research. An innovative lignocellulosic biomass derived biofuel is for the first time tested and evaluated in a commercial micro gas turbine (MGT) setup. The engine adaptation procedure and fuel formulation tailoring process is fully supported by earlier achievements, published in several high-impact journals and follows the established workflow. At the same time the paper presents an ultimate follow-up contribution to the finished L2-5468 project. The main novelties of this work are: (1) producing liquefied wood with pure ethylene glycol as a solvent and methane sulfonic acid as a catalyst, to obtain a bio-crude with lower viscosity and higher lignocellulosics content than previous tested formulations; (2) upgrading raw liquefied wood by blending it with ethanol to further reduce the viscosity of the mixture and evaluating the stability of ; (3) utilizing a commercially available MGT Auxiliary Power Unit (APU) of 25kW electrical power output, with notably reduced extent of adaptations to use the newly obtained fuel mixture. Emissions revealed that the presence of LW affects CO and NOx in comparison to conventional fuels. CO increased from 600 ppm to 1500 ppm (at 20 kW electrical power). The experimental study reveals that it is possible to achieve efficient MGT operation while utilizing high biocrude to ethanol ratios, however for a long term operation a number of adaptations are necessary.
COBISS.SI-ID: 16230171
Centrifugal fans have several technical applications. Their aerodynamic performance is well-optimized nowadays, but the same does not apply to their acoustic performance. Noise control studies of centrifugal fans are often focused on designed operating conditions or operating conditions close to the onset of instability. This paper seeks to find an alternative geometry of the centrifugal fan impeller which would improve noise control of centrifugal fans in a wide range of operating conditions. In this paper, the term noise control refers to noise level reduction and additionally to manipulating the psychoacoustic properties of noise. The experimental work and numerical calculations focus on the centrifugal fan in vacuum cleaners. The experimental work, based on numerical simulations, is described to investigate the influence of the triangular cross section on the flow channel, formed by two inclined blades in opposite directions, on aerodynamic properties and the psychoacoustic performance of the impeller. The study demonstrates that impellers with a triangular flow channel achieve an aerodynamic performance which is comparable to that of standard impellers. The results also show that impellers with inclined blades deliver superior results in psychoacoustic metrics compared to impellers with upright blades.
COBISS.SI-ID: 16054555
In sufficient concentrations, the pathogenic bacteria L. pneumophila can cause a respiratory illness that is known as the “Legionnaires” disease. Moreover, toxic Shiga strains of bacteria E. coli can cause life-threatening hemolytic-uremic syndrome. Because of the recent restrictions imposed on the usage of chlorine, outbreaks of these two bacterial species have become more common. In this study we have developed a novel rotation generator and its effectiveness against bacteria Legionella pneumophila and Escherichia coli was tested for various types of hydrodynamic cavitation (attached steady cavitation, developed unsteady cavitation and supercavitation). The results show that the supercavitation was the only effective form of cavitation. It enabled more than 3?logs reductions for both bacterial species and was also effective against a more persistent Gram positive bacteria, B. subtilis. The deactivation mechanism is at present unknown. It is proposed that when bacterial cells enter a supercavitation cavity, an immediate pressure drop occurs and this results in bursting of the cellular membrane. The new rotation generator that induced supercavitation proved to be economically and microbiologically far more effective than the classical Venturi section (super)cavitation.
COBISS.SI-ID: 15787803