Organizational technology acceptance and use: a relational perspective

Theoretical background. Hypotesis. Research design. Results. Discussion and conclusions. Appendix 1: Descriptive network statistics. Appendix 2: Questionnaire. Appendix 3: Graphical representation of the networks

Organizational technology acceptance and use: a relational perspective

Theoretical background. Hypotesis. Research design. Results. Discussion and conclusions. Appendix 1: Descriptive network statistics. Appendix 2: Questionnaire. Appendix 3: Graphical representation of the networks.Theoretical background. Hypotesis. Research design. Results. Discussion and conclusions. Appendix 1: Descriptive network statistics. Appendix 2: Questionnaire. Appendix 3: Graphical representation of the networks.LUISS PhD Thesi

Application of Sorption Enhanced Water Gas Shift for Carbon Capture in Integrated Steelworks

Abstract In integrated steelworks a large fraction of total CO2 is emitted from the power plant, where carbon- rich blast furnace gas (BFG) is burned to produce electricity by means of a steam cycle or a gas-steam combined cycle. The aim of the present paper is to assess the potential of Sorption Enhanced Water Gas Shift (SEWGS) process for CO2 capture from blast furnace gas. Firstly, a reference combined cycle applied to blast furnace steel plant is defined. Mass flow rate and composition of the steel plant off-gas used as fuel in the combined cycle have been derived from a large integrated steel plant. Then, the application of the SEWGS process is investigated and compared to a reference monoethanolamine (MEA)-based post-combustion absorption option. Two different SEWGS plant layouts are proposed together with two different sorbents. SEWGS achieves 85% of CO2 avoided with electric efficiency of 39% with the advanced sorbent

De la définition à la mise en forme de feutres imprégnés expansés à base de formules résineuses répondant aux exigences de REACH

Ces travaux ont été réalisés dans le cadre d’un projet industriel avec l’entreprise Roxel visant à la substitution de la résine phénolique, impactée par la règlementation Reach, dans un matériau composite expansé : le Roxalte®. Ce matériau est composé d’un feutre de basalte imprégné de résine phénolique qui s’expanse sous l’effet de la température par l’action de microsphères expansibles contenu dans le mélange (Expancel®). Pour s’adapter aux différentes utilisations du Roxalte®, des systèmes époxy répondant aux exigences de Reach ont été sélectionnés. Le premier objectif de cette thèse est la substitution de la résine phénolique. Le second objectif est de fournir une méthodologie pour la réalisation de mousses. La caractérisation physicochimique de la résine phénolique ainsi qu’une étude des relations structure/propriétés ont orienté la sélection vers un système faisant état de très hautes Tg : le Tris(4-hydroxyphenyl) methane triglycidyl ether (TETM) allié au durcisseur amine diaminodiphénylsulfone (DDS). La solution de remplacement immédiate a alors consisté à utiliser le système époxy [TETM/DDS] ainsi qu’un grade d’Expancel® adapté à l’intervalle de polymérisation de la résine. L’optimisation du cycle de réticulation a permis d’atteindre une Tg égale à 330 °C. La seconde étape a consisté à optimiser le moussage en calant la cinétique de réticulation sur la cinétique d’expansion par la détermination des temps de gel du système époxy et des temps d’expansion des microsphères. En dernier lieu, le composite expansé a été mis en œuvre grâce à l’ajout de solvant non réactif (acétone). Le deuxième volet de ces travaux a porté sur l’étude du moussage en utilisant le bicarbonate de sodium (BS) comme agent gonflant. La dualité exothermique/endothermique du procédé (exothermie de la réticulation et endothermie de la décomposition du BS) a été étudiée. Des suivis cinétique en mode isothermes et anisotermes ont été réalisés sur deux systèmes époxy (TETM/DDS et TETM/IPDA), sur le BS et sur les mélanges TETM/DDS+BS et TETM/IPDA+BS. L’ajout de fibres de basalte a fait état de différence notable sur la morphologie des mousses à base des systèmes époxy et du BS et les phénomènes de coalescence des bulles et de diffusion du gaz ont été mis en évidence. Une meilleure répartition des fibres et des bulles avec le système [TETM/IPDA] a été observé

CAESAR: SEWGS integration into an IGCC plant

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A novel time discretization method for solving complex multi-energy system design and operation problems with high penetration of renewable energy

Modelling and optimising modern energy systems is inherently complex and often requires methods to simplify the discretization of the temporal domain. However, most of them are either (i) not well suited for systems with a high penetration of non-dispatchable renewables or (ii) too complex to be broadly adopted. In this work, we present a novel method that fits well with high penetration of renewables and different spatial scales. Furthermore, it is framework-independent and simple to implement. We show that, compared to the full time discretization, the proposed method saves >90% computation time with <1% error in the objective function. Moreover, it outperforms commonly used methods of modelling through typical days. Its practical usefulness is demonstrated by applying it to a case study about the optimal hydrogen production from renewable energy. The increased modelling fidelity results in a significantly cheaper design and reveals operational details otherwise hidden by typical days

A Machine Learning-Aided Equilibrium Model of VTSA Processes for Sorbents Screening Applied to CO2 Capture from Diluted Sources

The large design space of the sorbents' structure and the associated capability of tailoring properties to match process requirements make adsorption-based technologies suitable candidates for improved CO2 capture processes. This is particularly of interest in novel, diluted, and ultradiluted separations as direct CO2 removal from the atmosphere. Here, we present an equilibrium model of vacuum temperature swing adsorption cycles that is suitable for large throughput sorbent screening, e.g., for direct air capture applications. The accuracy and prediction capabilities of the equilibrium model are improved by incorporating feed-forward neural networks, which are trained with data from rate-based models. This allows one, for example, to include the process productivity, a key performance indicator typically obtained in rate-based models. We show that the equilibrium model reproduces well the results of a sophisticated rate-based model in terms of both temperature and composition profiles for a fixed cycle as well as in terms of process optimization and sorbent comparison. Moreover, we apply the proposed equilibrium model to screen and identify promising sorbents from the large NIST/ARPA-E database; we do this for three different (ultra)diluted separation processes: direct air capture, yCO2 = 0.1%, and yCO2 = 1.0%. In all cases, the tool allows for a quick identification of the most promising sorbents and the computation of the associated performance indicators. Also, in this case, outcomes are very well in line with the 1D model results. The equilibrium model is available in the GitHub repository https://github.com/UU-ER/SorbentsScreening0D

Application of Hydrogen Selective Membranes to IGCC

AbstractThis study considers the integration of Pd-based H2-selective membranes in integrated gasifier combined cycles (IGCC) from both technical and economical point of view. The selected gasification system is based on Shell technology. Two different dry feeding systems are investigated: the first is a state-of-the- art nitrogen-based lock hopper charger while the second uses CO2 as pressurization gas. The net electric efficiency of the two plants is evaluated as a function of the hydrogen recovery factor (HRF) and the membrane feed pressure in order to minimize the membrane surface area. 90% HRF and 54bar feed pressure are the best operating parameters which correspond to a net electric efficiency of 39% both for N2 and CO2 feeding system. The cost of CO2 avoided is calculated as a function of a parameter named MI which represents the membrane development in terms of performances and costs. Results show that an improvement of membrane technology is necessary to match the state-of-the-art CO2 capture plant, even though membranes show good potentiality for cost abatement

Gas permeation through carbon membranes:Model development and experimental validation

With a growing interest in carbon membranes for gas separation, understanding their performance and behaviour is essential for proper design of the membrane separation. Currently not many models exist that correctly describe transport through carbon membranes due to its complex nature. This work attempts to implement a general modelling approach which describes several key transport phenomena inside carbon membranes. The approach assumes a membrane wall to be a bundle of pores with parallel transport mechanisms using the pore size distribution as a weight factor to sum the different transport phenomena. This work adapts this approach specifically for carbon membranes, additionally accounting for molecular sieving and pore blocking effects. Imposing realistic boundary conditions, the model is solved using global optimization algorithms. For testing, four different CMSMs have been produced with hydroquinone and novolac precursors. Pure- and mixed gas permeation tests are done for these CMSMs with H2, N2, and CO2 and the model is fit to this permeation data. Fitting results with pure gas measurements show the model is able to predict the contributions of different mass transport mechanism for the different membranes. This is validated by comparing these results to gas-pair permselectivity data. The model is furthermore fit to mixed gas data. Existence of multi-component effects shows that the model could be further improved. Overall, the model presented in this work is shown to be able to describe complex mass transport behaviour for various different carbon membranes.</p