Influence Of Relevant Process Parameters Research Articles

On-site production of high-purity hydrogen from raw biogas with fixed-bed chemical looping

Chemical Looping Hydrogen processes among others, show an outstanding potential for the decentralized conversion of biogas into high-purity hydrogen. For the first time, a 10 kWth fixed-bed chemical looping system has been coupled directly to a 3 MWth biogas digester in the southern region of Austria in the scope of the Austrian research project Biogas2H2. This experimental lab system resembles a blueprint for a potential future industrial system design. A comprehensive parameter study pointed out the influence of relevant process parameters (temperature, O/R ratio, reduction time, steam quantity in oxidation) on hydrogen purity and process efficiency. At the optimal operating point (850 °C, O/R 1.2), the process efficiency was comparable to the utilization of synthetic biogas in previous investigations within a deviation of 2.9%. Sulfuric compounds were isolated before entering the chemical looping system in order to avoid harmful contamination of the product hydrogen and performance loss, as investigated in preliminary experiments.The generated hydrogen was characterized online by ppm-range gas analysis and exhibited a product gas quality of up to 99.998%, with residual CO and CO2 as only contaminants. The fulfillment of the carbon mass balance within a mean deviation of 9% proved the correct quantification. The results indicate that coupling fixed-bed chemical looping systems to biogas plants enables the production of a fuel cell grade hydrogen and a sufficient process efficiency in upgrading local available biogenic and agricultural residuals to high-purity hydrogen.

Machine learning approach for elucidating and predicting the role of synthesis parameters on the shape and size of TiO2 nanoparticles

In the present work a series of design rules are developed in order to tune the morphology of TiO2 nanoparticles through hydrothermal process. Through a careful experimental design, the influence of relevant process parameters on the synthesis outcome are studied, reaching to the develop predictive models by using Machine Learning methods. The models, after the validation and training, are able to predict with high accuracy the synthesis outcome in terms of nanoparticle size, polydispersity and aspect ratio. Furthermore, they are implemented by reverse engineering approach to do the inverse process, i.e. obtain the optimal synthesis parameters given a specific product characteristic. For the first time, it is presented a synthesis method that allows continuous and precise control of NPs morphology with the possibility to tune the aspect ratio over a large range from 1.4 (perfect truncated bipyramids) to 6 (elongated nanoparticles) and the length from 20 to 140 nm.

Study on the magnetic abrasive finishing process using alternating magnetic field: investigation of mechanism and applied to aluminum alloy plate

In order to achieve the finishing of complex microsurface, the magnetic abrasive finishing process using alternating magnetic field was proposed. In this paper, the mechanism of the magnetic abrasive finishing process using alternating magnetic field was investigated. At the same time, the influence of magnetic particle size and magnetic field frequency on magnetic cluster changes was observed and the relationship between finishing force and alternating magnetic field was analyzed. In addition, the feasibility of ultraprecision finishing of 5052 aluminum alloy plate through this process was studied, and the influence of relevant process parameters on the finishing characteristics was analyzed. The experimental results show that the surface roughness of 5052 aluminum alloy plate improved from 318 to 3 nm Ra in 15 min.

Roll-to-roll thin film coating on fluoropolymer webs – Status, challenges and applications

Thin film deposition on fluoropolymer webs – both in vacuum and at atmospheric pressure – faces several critical challenges such as poor mechanical and thermo-mechanical properties – especially low dimensional stability and low elastic modulus, high and textured surface roughness and low adhesion of thin films.This paper discusses critical process parameters in roll-to-roll processing for both vacuum processes and wet coating processes with respect to the unique properties of fluoropolymer webs. Reactively sputtered oxide layers as well as wet coated ORMOCER® layers are deposited on ETFE, PVDF and ECTFE webs to form single- and multi-layer permeation barrier systems. The influence of relevant process parameters on the layer adhesion and permeation barrier performance is reviewed. Permeation barrier coatings have been selected as main application for this study, because they are very sensitive to substrate surface irregularities and mechanical damage due to low adhesion, high strain or roll-to-roll processing issues and therefore are a good measure for the quality of the coating on the substrate.Both the wet coated ORMOCER® layers and reactively sputtered zinc-tin oxide (ZTO) layers show surprisingly good adhesion on both ETFE and PVDF surfaces. Both ZTO and – with adhesion promotion treatment – also aluminum oxide (Al2O3) layers have the potential for low water transmission rates (WVTR) below 5·10−2g/(m2d) at 38°C/90% r.h. on these substrates. Further reduction of the WVTR is demonstrated with a combination of wet coated ORMOCER® layers and sputtered ZTO layers yielding a WVTR of 1·10−3g/(m2d) at 38°C/90% r.h. These values were achieved using adapted process parameters and layer stack designs such as reduced web tension and lower layer thicknesses. The results shown in this paper demonstrate the potential of coated fluoropolymer webs for functionalization of membrane roofs and façades with flexible thin film solar cells; thermal insulation and solar control functionality; flexible thin film electroluminescent and OLED lighting panels as well as electrochromic devices.

Blow forming of AZ31 magnesium alloy at elevated temperatures

In this work, the forming behaviour of a commercial sheet of AZ31B magnesium alloy at elevated temperatures is investigated and reported. The experimental activity is performed in two phases. The first phase consists in free bulging test and the second one in analysing the ability of the sheet in filling a closed die. Different pressure and temperature levels are applied. In free bulging tests, the specimen dome height is used as characterizing parameter; in the same test, the strain rate sensitivity index is calculated using an analytical approach. Thus, appropriate forming parameters, such as temperature and pressure, are individuated and used for subsequent forming tests. In the second phase, forming tests in closed die with a prismatic shape cavity are performed. The influence of relevant process parameters concerning forming results in terms of cavity filling, fillet radii on the final specimen profile are analysed. Closed die forming tests put in evidence how the examined commercial magnesium sheet can successfully be formed in complicated geometries if process parameters are adequately chosen.