Browsing by Author "Macoun, David"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Comparison of hydrogenated vegetable oil and biodiesel effects on combustion, unregulated and regulated gaseous pollutants and DPF regeneration procedure in a Euro6 car
    (Elsevier B.V., 2019-12-15) Pechout, Martin; Kotek, Martin; Jindra, Petr; Macoun, David; Hart, Jan; Vojtíšek-Lom, Michal
    The effects of traditional biodiesel (fatty acid methyl-esters, FAME) and a hydrotreated vegetable oil (HVO) were comprehensively investigated on a production Euro 6 diesel car, including fuel injection rate and timing, combustion analysis, emissions of regulated and unregulated pollutants, and regeneration of the diesel particle filter. The use of both biofuels is a part of the efforts to reduce emissions of greenhouse gases and health-relevant pollutants and to improve energy security and sustainability. HVO, albeit more expensive, offers benefits relative to FAME in terms of oxidation stability, injector fouling, energy content and cetane number. The car was fitted with an on-board instrumentation and subjected to a range of driving cycles on a chassis dynamometer. The fuel consumption calculated from instantaneous emissions data based on exhaust gas composition measured by an on-board FTIR and calculated exhaust flow matched directly measured fuel consumption within several percent on all fuels; differences in the consumption among the fuels correspond to different heating values. The combustion onset and maximum heat release rate were comparable for diesel and FAME but were advanced on HVO due to its higher cetane number, causing, at times, multiple distinct heat release peaks, suggesting that optimization of fuel injection timing for HVO might be beneficial. Emissions of methane and ammonia were negligible, of N2O were measurable and slightly lower for HVO than for other fuels, of formaldehyde were limited to cold engine accelerations and highest for FAME and negligible for HVO, of NO and NO2 were high on all fuels during all operating conditions except for the type approval test. The results confirm several relative advantages of HVO over RME, with penetration into engine lubricating oil during particle filter regeneration to be further investigated. The effects of HVO lubricity and other long-term effects were not evaluated here.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Porovnání metod pro testování propustnosti pro vodní páry
    (2015-02-10) Macoun, David; Heinisch Tereza, Ing.; Skolitel : 55347 Laurin Josef, doc. Ing. CSc.; Konzultant : 55195 Havelka Antonín, doc. Ing. CSc.; Konzultant2 : 56834 Pittnerová Radka, Ing.
    Diplomová práce se zabývá porovnáním dostupných metodik pro testování propustnosti textilií pro vodní páry. Hlavním cílem práce je otestovat vliv klimatických podmínek nastavených dle asijských, amerických a evropských norem na výši paropropustnosti textilií, které standardně používají výrobci outdoorových materiálů a oděvů. Textilie byly testovány na zařízení Permetest dle evropské normy ISO 11092 a následně v klimatické komoře Vötsch, kde bylo možné nastavit různé klimatické podmínky. Všechna měření byla prováděna v laboratořích Katedry hodnocení textilií Technické univerzity v Liberci. V práci je vyhodnocen vliv teploty a relativní vlhkosti doby měření na výsledné hodnoty paropropustnosti za 24 hodin.
  • Thumbnail Image
    Item
    Vliv technologických parametrů vstřikování na relaxaci napětí v plastových dílech
    (Technická Univerzita v Liberci, 2010-01-01) Macoun, David; Lenfeld, Petr
    This diploma thesis deals with the effect of technological parameters by injection on relaxation strain at semi-crystallic thermoplastic ( Liten MB 87 and Ultraform W2320 003) in dependence on the speed of injection, stress and temperature of form. Relaxation strain is achieved on TIRATEST 2300 machine. The theoretical part focuses on viscoelastic properties of polymers and practical results of viscoelastic behaviour.
  • Thumbnail Image
    Item