324 research outputs found
Catalytic upgrading of hydrothermal liquefaction biocrudes: Different challenges for different feedstocks
Hydrothermal liquefaction (HTL) followed by catalytic hydrotreating of the
produced biocrude is increasingly gaining ground as an effective technology for
the conversion of biomass into liquid biofuels. A strong advantage of HTL
resides in its great flexibility towards the feedstock, since it is able to
treat a large number of different organic substrates, ranging from dry to wet
residual biomass. Nevertheless, the characteristics of biocrudes from different
typologies of organic materials result in different challenges to be met during
the hydrotreating step, leading to differences in heteroatoms removal and in
the typology and composition of the targeted products. In this work, biocrudes
were catalytically hydrotreated with a commercial NiMo/Al2O3 catalyst at
different temperatures and pressures. Sewage sludge biocrude was found to be
very promising for the production of straight-chain hydrocarbons in the diesel
range, with considerable heteroatoms removal even at mild hydrotreating
conditions. Similar results were shown by algal biocrude, although complete
denitrogenation is challenging. Upgraded biocrudes from lignocellulosic
feedstock (miscanthus) showed high yields in the gasoline range, with a
remarkable content of aromatics. Operating at a higher H2 pressure was found to
be crucial to prevent coking and decarboxylation reactions.Comment: Accepted manuscript for publication in Renewable Energ
Online Condition Monitoring of Rotating Machines by Self-Powered Piezoelectric Transducer from Real-Time Experimental Investigations
This paper investigates self-powering online condition monitoring for rotating machines by the piezoelectric transducer as an energy harvester and sensor. The method is devised for real-time working motors and relies on self-powered wireless data transfer where the data comes from the piezoelectric transducer’s output. Energy harvesting by Piezoceramic is studied under real-time motor excitations, followed by power optimization schemes. The maximum power and root mean square power generation from the motor excitation are 13.43 mW/g(2) and 5.9 mW/g(2), which can be enough for providing autonomous wireless data transfer. The piezoelectric transducer sensitivity to the fault is experimentally investigated, showing the considerable fault sensitivity of piezoelectric transducer output to the fault. For instance, the piezoelectric transducer output under a shaft-misalignment fault is more than 200% higher than the healthy working conditions. This outcome indicates that the monitoring of rotating machines can be achieved by using a self-powered system of the piezoelectric harvesters. Finally, a discussion on the feasible self-powered online condition monitoring is presented
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