1. A review of the use of Rankine cycle systems for hydrogen productionUrška Novosel, Jurij Avsec, 2020, izvirni znanstveni članek Opis: The vast majority of steam power plants in the world are based on the Rankine cycle. It is a wellknown, trustworthy process that uses water or water vapour as a working medium, which supplies heat from various primary energy sources: fossil fuels, renewable energy sources (solar energy, energy from wood biomass, etc.) or a combination of both. With the Rankine cycle, energy sources other than electricity can be produced, which can be used as the primary energy source for various applications. The present article focuses on the production of hydrogen in addition to electricity; therefore, two energy sources are obtained from the same system with a few modifications of the existing power plant for further exploitation. There are several processes for hydrogen production using the Rankine cycle; in the present article, two processes are focused on: using part of the electricity produced and obtaining hydrogen by electrolysis of water or using part of high quality steam (basically heat energy) in combination with electricity and obtaining hydrogen by a thermochemical copper-chlorine process. Each of these processes has its advantages and disadvantages, which are presented in the present article with an example model of a power plant.
Ključne besede: Rankine cycle, hydrogen production, electrolysis, thermochemical process
Objavljeno v DKUM: 01.12.2023; Ogledov: 483; Prenosov: 5
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2. Hydrogen production using a thermochemical cycleJurij Avsec, Urška Novosel, Dušan Strušnik, 2022, izvirni znanstveni članek Opis: Sustainable methods of clean fuel production are needed throughout the world due to depleting oil reserves and the need to reduce carbon dioxide emissions. The technology based on fuel cells for electricity production or the transport sector has already been developed. However, a key missing element is a large-scale method of hydrogen production. The copper-chlorine (CuCI) combined thermochemical cycle is a promising thermochemical cycle that can produce large amounts of cheap hydrogen. A particularly promising part of this process is its use in combination with nuclear or thermal power plants. This paper focuses on a CuCl cycle and describes the models used to calculate thermodynamic and transport properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure HCl and CuCl2. The mathematical model developed for the solid phase takes into account vibrations of atoms in molecules and intermolecular forces. This mathematical model can be used for the calculation of the thermodynamic properties of polyatomic crystals on the basis of the Einstein and Debye equations. The authors of this paper developed the model in the low temperature and high temperature region. All the analytical data have been compared with some experimental results and show a relatively good match. For the solid phase, the authors developed a model to calculate thermal conductivity based on electron and phonon contributions.
Ključne besede: thermodynamics, energy, hydrogen production, solid phase, fluid phase
Objavljeno v DKUM: 30.10.2023; Ogledov: 375; Prenosov: 6
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5. CATALYTIC GENERATION OF HYDROGEN FROM BIOMASS DERIVED LACTIC ACID VIA AQUEOUS PHASE REFORMINGMonika Bosilj, 2015, magistrsko delo Opis: Hydrogen production from aqueous phase reforming (APR) of organic acids in aqueous phase and from residue of a biomass decomposition process over 3 wt% Pt/ZrO2 has been studied in the absence and presence of barium ions. The results have been compared with Pt/TiO2, Pt/C and Ni/C catalysts. Having identified barium hydroxide as a promising reagent in combination with Pt/ZrO2 catalyst for the hydrogen production out of organic acids, the method for the lactic acid conversion was extended. Lactic acid (LA) was analysed as a major compound in an aqueous solution after a biomass digestion process with Ba(OH)2.
Gaseous and aqueous products after APR reaction of LA mixture with barium hydroxide were identified by different analytical techniques. Gaseous products consisted mainly of permanent gases such as hydrogen, carbon dioxide and methane. The results showed that mixture of LA in combination with both barium hydroxide and Pt/ZrO2 catalyst had the highest hydrogen production rate and the highest selectivity to hydrogen, whereas low gaseous product amount were observed from mixture of LA and only barium hydroxide or Pt/ZrO2 catalyst. Methane and higher amount of carbon dioxide were detected in gas phase products particular in the presence of Pt/ZrO2 catalyst in the mixture.
Aqueous products consisted mainly of pyruvic acid, acetic acid and salts, such as acetate and propionate. The complete conversion of LA after APR was reached in mixture of LA and Ba(OH)2∙8H2O over Pt/ZrO2 catalyst. Mixture of LA and Ba(OH)2∙8H2O or Pt/ZrO2 catalyst gave lower conversion of LA.
Amount of gaseous products, selectivity to hydrogen and LA conversion were affected by higher reactant mixture concentration. In comparison to low concentrated mixtures, high concentrated mixtures contained larger amounts of barium but the same amount of Pt/ZrO2 catalyst. BET analyses showed much smaller pore volume of spent Pt/ZrO2 catalyst, which was used in APR reaction of high concentrated (1.5 mol/L) mixture. Therefore, lower gas product amounts, lower selectivity to hydrogen and only 63 % conversion of LA were effects of deactivated Pt/ZrO2 catalyst.
The results showed that hydrogen generation from APR of LA and conversion of LA in aqueous phase are hardly influenced by the Pt/ZrO2 catalyst presence, which in combination with barium ions, promotes the catalytic APR reaction.
Ključne besede: biomass, hydrogen production, aqueous phase reforming, lactic acid
Objavljeno v DKUM: 20.02.2015; Ogledov: 2120; Prenosov: 172
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7. Recent Canadian advances in nuclear-based hydrogen production and the thermochemical Cu-Cl cycleGreg F. Naterer, S. Suppiah, M. Lewis, K. Gabriel, İbrahim Dinçer, Marc A. Rosen, Michael Fowler, G. Rizvi, E. B. Easton, B. M. Ikeda, M. H. Kaye, L. Lu, I. Pioro, P. Spekkens, P. Tremaine, J. Mostaghimi, Jurij Avsec, J. Jiang, 2009, izvirni znanstveni članek Opis: This paper presents recent Canadian advances in nuclear-based production of hydrogen by electrolysis and the thermochemical copper-chlorine (Cu-Cl) cycle. This includes individual process and reactor developments within the Cu-Cl cycle, thermochemical properties, advanced materials, controls, safety, reliability, economic analysis of electrolysis at off-peak hours, and integrating hydrogen plants with Canada's nuclear power plants. These enabling technologies are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production from the next generation of nuclear reactors.
Ključne besede: nuclear-based hydrogen production, thermochemical copper-chlorine cycle, electrolysis
Objavljeno v DKUM: 31.05.2012; Ogledov: 2038; Prenosov: 101
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