Vpliv tlaka v izpušnem sistemu na delovno sposobnost motorja z notranjim zgorevanjem

Müller, Neža (author), Seljak, Tine (mentor)

V sistemih za zajem ogljikovega dioksida je zaradi procesnih pogojev in tlačnih uporov potreben tlak višji od atmosferskega. Ta običajno zahteva, da se CO2, ki iz procesov zgorevanja izhaja pri atmosferskem tlaku, ponovno komprimira. Da bi se izognili ponovni kompresiji smo virtualno zasnovali motor z notranjim zgorevanjem, ki za kompresijo izpušnih plinov uporabi ekspanzijski takt motorja in s tem produkte zgorevanja komprimira neposredno, brez ekspanzije na atmosferski tlak ter z izkoriščanjem zaostalega tlaka v valju. Tako izpušni plini niso ekspandirani do atmosferskega tlaka, kot je to navadno značilno za delovanje batnih motorjev, ampak je na izstopu predpisan povišan tlak. Ker ima vsaka sprememba delovnega procesa v batnih motorjih lahko velik vpliv na delovno sposobnost motorja, smo s programsko opremo AVL Cruise M, ki simulira delovanje motorja, preverili, kako povišan tlak na izstopu vpliva na delovno sposobnost motorja in sestavo izpušnih plinov. Izkaže se, da neposredna kompresija do določene vrednosti tlaka na izstopu iz valja lahko izkorišča zaostali tlak v valju, vendar ob nespremenjenih parametrih delovanja, enakih krivuljah polnilnih in izpušnih ventilov ter enaki karakteristiki turbopuhala, neposredna kompresija znatno zmanjšuje delovno sposobnost motorja ter zahteva namenske prilagoditve.

• Language: Slovenian
• Keywords: atmosferski motor, turbopolnilnik, izpušni sistem, zaostali izpušni plini, tlak na izstopu, razmernik zraka, ločevanje ogljikovega dioksida
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [N. Müller]
• Year: 2022
• Number of pages: XXII, 54 str.
• PID: 20.500.12556/RUL-137648
• UDC: 621.432.2(043.2)
• COBISS.SI-ID: 113991683
• Publication date in RUL: 24.06.2022

MÜLLER, Neža, 2022, Vpliv tlaka v izpušnem sistemu na delovno sposobnost motorja z notranjim zgorevanjem [online]. Bachelor’s thesis. Ljubljana : N. Müller. [Accessed 5 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=137648

Secondary language

• Language: English
• Title: Performance analysis of internal combustion engine at different exhaust system pressures

Abstract

The process of separating carbon dioxide by absorption requires a pressure higher than atmospheric. To avoid re-compression, we virtually designed a reciprocating engine which instead of relying on the expansion of the working medium to atmospheric pressure, uses the residual pressure at the end of the power stroke to supply the pressure for downstream processing of exhaust gases. This means that the exhaust gases are not expanded to atmospheric pressure, as is usually the case with reciprocating engines, but rather the pressure at the outlet is elevated according to the requirements of the absorption process. Since any manipulation of the work process can have a significant impact on the engine's performance, we evaluated the impact of direct compression of exhaust gases with AVL Cruise M software to simulate how the exhaust stroke outlet pressure affects the engine's performance and the composition of the exhaust gases. The results reveal that a direct compression approach for exhaust gas treatment can indeed exploit the residual pressure up to a certain level depending on the operating point. If valve timings, turbocharger characteristics and operating point of the engine are kept unchanged, this severly impacts the performance of the engine, indicating that optimization of the engine would be required to make the direct compression approach viable.

• Keywords: naturally aspirated engine, turbocharger, exhaust system, exhaust residuals, outlet pressure, air–fuel ratio, carbon capture