In-cylinder soot radiation heat transfer in direct-injection diesel engines. (December 2015)

• Record Type: Journal Article
• Authors: Benajes, Jesús; Martín, Jaime; García, Antonio; Villalta, David; Warey, Alok
• Is Part Of: Energy conversion and management. Volume 106(2015)
• Page Start: 414
• Page End: 427
• Publication Date: 2015-12
• Subjects: BMEP brake mean effective pressure -- CA crank angle -- CMOS Complementary Metal Oxide Semiconductor -- CO2 carbon dioxide -- DI Direct Injection -- ECN engine combustion network -- EGR exhaust gases recirculation -- EVC exhaust valve close -- FWHM full width at half maximum -- GHG green house gas -- HSIP High Speed Imaging Pyrometer -- HT heat transfer -- Ib, λ spectral intensity of black body -- ICE internal combustion engines -- Isoot spectral intensity -- IVC inlet valve close -- KL optical thickness -- Ks conical shape -- mf mass of fuel injected -- OP Optoelectronic Pyrometer -- Pinj injection pressure -- LHV lower heating value -- RoHR heat release rate -- SoI start of injection -- SoE start of energizing -- TDC top dead center -- VGT variable geometry turbocharger -- XO2 oxygen fraction -- α absorptivity coefficient -- ελ spectral emissivity -- λ wavelenght -- ρ density -- Ω solid angle; Soot -- In-cylinder heat transfer -- Radiation -- Optical pyrometer; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2015.09.059
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: Optoelectronic pyrometer provides similar results compared with a conventional method. Lower injection pressure results in higher radiation. Higher ambient temperature and higher in-cylinder gas density produce higher radiation. Larger lift-off length reduces the soot volume fraction and the spectral intensity. An increase on swirl number, load and CA50 provide a lower total radiation. Lower values of EGR implies a decreased on radiation intensity. Abstract: The efficiency and CO2 are one of the main concerns of automotive manufacturers. There are several strategies under investigation to solve this problem. In the present work, the research effort has been focused on improving knowledge of in-cylinder heat transfer and its impact on engine efficiency. In particular, soot radiation was studied since it can be considered a significant source of the efficiency losses in modern diesel engines. Considering previous studies, the portion of total chemical energy released during combustion lost due to radiation heat transfer varies widely from 0.5% up to 10%, depending on engine parameters and combustion process. Thus, the main objective of this work was to evaluate the amount of energy lost to soot radiation relative to the input fuel chemical energy during the combustion event under different operating conditions in a completely controlled environment provided by an optical engine. Under these simplified conditions, two-color method was applied by using high speed imaging pyrometer with cameras (two dimensional results) and optoelectronic pyrometer (zero dimensional results). Once a detailed comparison between both diagnostics was performed, optoelectronic pyrometer was used to characterize radiant energy losses in a fully instrumented 4-cylinder direct-injection light-duty diesel engine. In particular swirl ratio, EGR and combustion phasing effects on radiation heat transfer were evaluated.