Search results for "Power density"
showing 10 items of 57 documents
High Accuracy Modelling of Hybrid Power Supplies
2011
This chapter proposes a modelling approach based on the PSIM/Simulink co-simulation toolbox for hybrid power supplies, featuring high accuracy. Hybrid source performances are fully tested during behavioural simulations. The importance of high-accuracy modelling is investigated and modelling guidelines for both power sources and load are given for further applications. The Simulink model is analyzed and the efficiency of the proposed approach is verified by the comparison between simulation and experimental results. In the last few years, hybrid power supplies are investigated for a wide variety of application areas: two primary sources are coupled to take advantages of both, overcoming thei…
Fuel cells for household appliances: Experimental test of power management algorithms
2013
In this paper, fuel cell - based hybrid power supplies for household appliances are addressed. The profile of residential power consumption is evaluated during working, non-working days in both summer and winter periods. The worst-case load power demand is therefore highlighted. A 5kW Nuvera PowerFlow proton exchange membrane fuel cell for household appliances is tested. On the basis of the characterization of the fuel cell stack under test, stand-alone and fuel cell - battery active hybrid power supply architectures are both considered. Experimental validation of three power management algorithms is proposed in terms of hydrogen consumption, cost and energy saving. Power management algorit…
Investigation of electrode material – redox couple systems for reverse electrodialysis processes. Part II: Experiments in a stack with 10–50 cell pai…
2013
Abstract The performances of reverse electrodialysis depend on several factors, including the nature of the electrode material and of the redox processes adopted to make possible the conversion between chemical potential and electric power. In this paper the possible utilization of various redox processes (reduction/oxidation of iron species, oxidation and reduction of water, oxidation of chlorine and reduction of water) was studied in a stack equipped with 10–50 cell pairs and by focused electrolyses in a three compartment cell. The effect of selected redox processes on power density output and eventual contamination of saline solutions flowing in the stack was evaluated in detail. The eff…
INTEREST OF BEAM QUALITY IN MATERIALS TREATMENTS BY HIGH POWER LASER
1991
The aim of the study is the increasing of performances of the YAG Lasers. For this, we use the principle established by Boquillon and Taisne : an X geometry of the resonator. In this case the number of emitted modes is lower than for the linear conception and the beam quality is greater. So, reached power density can be 7 times higher than for the classical cavity and consequently cutting speed can be about 2 times higher than for the linear one. Concerning welding, thick materials need a lot of energy and our system is not competitive. however it exists an interest for thin joining with an easely formed key hole and later a more important penetration.
Reverse electrodialysis with saline waters and concentrated brines: A laboratory investigation towards technology scale-up
2015
Abstract The use of concentrated brines and brackish water as feed solutions in reverse electrodialysis represents a valuable alternative to the use of river/sea water, allowing the enhancement of power output through the increase of driving force and reduction of internal stack resistance. Apart from a number of theoretical works, very few experimental investigations have been performed so far to explore this possibility. In the present work, two RED units of different size were tested using artificial saline solutions. The effects of feed concentration, temperature and flowrate on process performance parameters were analysed, adopting two different sets of membranes. These experiments all…
Maximum Net Power Density Conditions in Reverse Electrodialysis Stacks
2018
Reverse Electrodialysis (RED) harvests electrical energy from a salinity gradient. The maximum obtainable net power density (NPD) depends on many physical and geometric variables. Some have a monotonic (beneficial or detrimental) influence on NPD, and can be regarded as “scenario” variables chosen by criteria other than NPD maximization. Others, namely the thicknesses HCONC, HDIL and the velocities UCONC, UDIL in the concentrate and diluate channels, have contrasting effects, so that the NPD maximum is obtained for some intermediate values of these parameters. A 1-D model of a RED stack was coupled here with an optimization algorithm to determine the conditions of maximum NPD in the space o…
The REAPower Project: Power Production From Saline Waters and Concentrated Brines
2019
Aim of this chapter is that of describing in detail the REAPower project from the very beginning up to the testing of the pilot plant built at the end of the project.
Reverse electrodialysis with NH4HCO3-water systems for heat-to-power conversion
2017
Abstract A Reverse ElectroDialysis Heat Engine (REDHE) system operating with “thermolytic” ammonium hydrogen-carbonate (NH4HCO3) aqueous solutions as working fluids is studied. The engine is constituted by (i) a RED unit to produce electric power by mixing the solutions at different salinity and (ii) a thermally-driven regeneration unit including a stripping and an absorption column to restore the initial salinity gradient thus closing the cycle. In the present work only the RED unit and the stripping column are taken into account. In particular, a simplified integrated process model for the whole cycle was developed: it consists of (i) a lumped parameter model for the RED unit validated wi…
Bipolar membrane reverse electrodialysis for the sustainable recovery of energy from pH gradients of industrial wastewater: Performance prediction by…
2021
Abstract The theoretical energy density extractable from acidic and alkaline solutions is higher than 20 kWh m−3 of single solution when mixing 1 M concentrated streams. Therefore, acidic and alkaline industrial wastewater have a huge potential for the recovery of energy. To this purpose, bipolar membrane reverse electrodialysis (BMRED) is an interesting, yet poorly studied technology for the conversion of the mixing entropy of solutions at different pH into electricity. Although it shows promising performance, only few works have been presented in the literature so far, and no comprehensive models have been developed yet. This work presents a mathematical multi-scale model based on a semi-…
Spectral characteristics of steady-state Lévy flights in confinement potential profiles
2016
The steady-state correlation characteristics of superdiffusion in the form of Levy flights in one-dimensional confinement potential profiles are investigated both theoretically and numerically. Specifically, for Cauchy stable noise we calculate the steady-state probability density function for an infinitely deep rectangular potential well and for a symmetric steep potential well of the type U(x)∞x2m. For these potential profiles and arbitrary Levy index α, we obtain the asymptotic expression of the spectral power density.