Simulation of solar cells using in electrocars

Tato práce se zabývá problematikou výroby a využití elektrické energie v elektromobilech pomocí fotovoltaických článků. V této práci je uveden model fotovoltaického systému složeného ze tří fotovoltaických polí umístěných na modelu elektromobilu s maximálním ohledem na využitelnou plochu a efektivitu celého systému. Také jsou zde uvedeny výpočty doby nabíjení akumulátoru, získané energie z fotovoltaických polí – porovnání praktického zisku energie a také celkové elektrické parametry a bilance modelu elektromobilu. Cílem práce bylo navržení modelu elektromobilu, který by sloužil jako vzor pro elektromobily skutečné velikosti s využitím obnovitelného zdroje elektrické energie.The thesis deals with the question of the production of electric energy in electromobiles by the means of photovoltaic cells and its using. The thesis presents the model of photovoltaic system composed of the three photovoltaic fields incorporated in the electromobile model and it considers its maximum usable surface and efficiency. The thesis also includes the calculations concerning the charging time of accumulator, the amount of energy gained from photovoltaic fields – comparison of practical energy gain, the electric parameters in general and the overall performance of electromobile model. The aim of the thesis was to design an electromobile model which would serve as a model for actual-sized electromobiles using the renewable source of electric energy.

Different way how to use solar radiation for the electric energy production

Tato práce řeší problematiku využití sluneční energie konverzí na elektrickou energii. V práci je podrobnějším způsobem rozebráno několik způsobů konverze. Především jsem se zaměřil na fotovoltaickou přeměnu a také termální přeměnu sluneční energie s využitím parních turbin pro výrobu energie. V následujících částech se zaměřuji na problematiku fotovoltaiky, fotovoltaické systémy, dále pak na termální sluneční elektrárny, jejich instalace a využití.The thesis deals with the problem of potential use of solar energy through the conversion into electric energy. The thesis analyses in great detail several types of conversion. My special concern included photovoltaic conversion and thermal conversion of solar energy using steam turbines for energy production. In the subsequent parts, I focus on the problem of photovoltaic, photovoltaic systems, and solar thermal power plants, their installation and use.

Injection moulding of α- and β-polypropylenes: Morphology consequences

The specific effects of mould temperature (MT) and holding pressure (HP) on the structure of neat and β-nucleated isotactic polypropylenes have been studied. Commercially available isotactic polypropylene was modified by 0.03 wt.% of β-specific nucleator. From both original (α-iPP) and β-nucleated (β-iPP) materials test specimens were injection-moulded using two sets of processing parameters. In the T-set the MT was varied within a range of 40-120 °C by 10 °C steps, while in the P-set the HP was changed from 5 to 13 MPa in 1 MPa steps. Polarized-light microscopy showed a strong effect of MT but minute influence of HP on the morphology of α- and β-iPP specimens. The increase of MT positively influenced the crystallinity and the β-form content, particularly in the skin of specimens as wide-angle X-ray scattering displayed. On the contrary, the rising HP depressed the crystallinity within the bulk of specimens proportionally

Ethylene copolymers with crystallizable side chains

Metallocene-catalyzed copolymers of ethylene and α-olefins were investigated by X-ray scattering and differential scanning calorimetry. Evaluated α-olefin comonomers consisted of 8, 12, 18, or 26 carbons. As indicated from the small-angle X-ray scattering, ethylene-hexacosene copolymer with comonomer content of 3 mol % may contain second crystallites. Because no other reflections were observed in the wide-angle X-ray scattering patterns, the side-chain crystallites should have the same crystal lattice dimensions as the prevailing main-chain crystallites. Since this potential side chains crystallization can only be found in the ethylene-hexacosene copolymer with 3 mol % of comonomer, a critical concentration of long-chain comonomer should be reached for this secondary crystallite formation. It was also found that the thickness of the interlamellar amorphous layer stays virtually constant regardless of the changes in comonomer content and side-chain length. © 2011 American Chemical Society

Preparation of PE/PP Blends with Microfibrillar-Phase Morphology

Polyethylene/polypropylene blend extrudates with microfibrillar-phase morphology (polypropylene microfibrils reinforcing polyethylene matrix phase) were prepared through continuous extrusion with semihyperbolic-converging die enabling elongation and orientation of macromolecules in flow direction. Structure and thermal properties of extruded profiles were examined using electron microscopy, wide-angle X-ray scattering and differential scanning calorimetry. Tensile tests proved that extrudates with microfibrillar-phase morphology show significantly. higher mechanical properties than conventional extrudates. Presented concept offers possibility of expensive multicomponent medical devices with metal-inlays replacement

Injection-moulded alpha- and beta-polypropylenes: II. Tensile properties vs. processing parameters

Resuming our comprehensive study, present Part II directs attention towards the effects of mould temperature and holding pressure on the tensile properties of neat and beta-nucleated isotactic polypropylenes. A commercial-grade of isotactic polypropylene was modified with a beta-specific nucleator. From both the original material (alpha-iPP) and the beta-nucleated material (beta-iPP), tensile test specimens were injection-moulded. Stress-strain measurements performed at room temperature revealed a positive influence of higher mould temperatures but negligible effect of holding pressure on the elastic modulus of injection-moulded specimens. It was suggested that at optimum processing conditions the elastic modulus of both alpha- and beta-iPP may be comparable. The softening effect of beta-form manifested itself in systematically lower yield stress values of beta-iPP as compared to alpha-iPP. The yield strain of both alpha- and beta-iPP decreased with the increase of mould temperature and the decrease of holding pressure. Prolonged solidification times at higher mould temperatures negatively influenced the strain at break of the specimens; the values of beta-iPP exceeded by several folds those of alpha-iPP. The stress at break of beta-iPP decreased correspondingly to strain at break. On the contrary, the increase of strain at break in a-iPP was followed by a decrease of stress at break. (c) 2006 Elsevier Ltd. All rights reserved

Injection-moulded alpha- and beta-polypropylenes: I. Structure vs. processing parameters

The paper studies the effects of mould temperature and holding pressure on the structure of neat and beta-nucleated isotactic polypropylenes. Commercially available isotactic polypropylene was modified with a beta-specific nucleator based on N,N'-dicyclohexylnaphthalene-2,6-dicarboxamide in the concentration of 0.03 wt.%. From both the original material (alpha-iPP) and the beta-nucleated material (beta-iPP), dog bone-shaped test specimens were injection-moulded, using two sets of processing parameters. In the T-set the mould temperature was varied within the range of 40-120 degrees C in 10 degrees C steps, while in the beta-set the holding pressure was changed from 5 to 13 MPa in 1 MPa steps. Other processing parameters were kept on the same level. Polarized-light microscopy showed a strong effect of mould temperature on the morphology of alpha-iPP specimens; the skin thinned out and the spherulite size increased with mould temperature rise. On the other hand, in the case of alpha-iPP only the skin thickness was correspondingly affected, while the spherulite size remained virtually constant, independent of the mould temperature changes. At the same structure level, both alpha-iPP and beta-iPP specimens were insensitive to holding pressure variations. Polymorphic composition derived from wide-angle X-ray scattering displayed similar range of changes induced by variations of the processing parameters for both materials. The increase of mould temperature positively influenced the crystallinity and the P-form content, particularly in the skin of specimens. On the contrary, higher holding pressure depressed the crystallinity proportionally within the bulk of specimens. (c) 2005 Elsevier Ltd. All rights reserved