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Research Papers: Internal Combustion Engines

# Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

[+] Author and Article Information
Vittorio Manente

Combustion Engine Division, Lund University, Lund 22100, Swedenvittorio.manente@energy.lth.se

Bengt Johansson, Pert Tunestal

Combustion Engine Division, Lund University, Lund 22100, Sweden

J. Eng. Gas Turbines Power 132(8), 082802 (May 26, 2010) (7 pages) doi:10.1115/1.4000291 History: Received May 21, 2009; Revised June 02, 2009; Published May 26, 2010; Online May 26, 2010

## Abstract

Exhaust gas recirculation (EGR) sweeps were performed on ethanol partially premixed combustion (PPC) to show different emission and efficiency trends as compared with diesel PPC. The sweeps showed that when the EGR rate is increased, the efficiency does not diminish, HC trace is flat, and CO is low even with 45% of EGR. $NOx$ exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions, a sweep in the timing of the pilot injection and pilot-main ratio was done at $∼16.5 bars$ gross IMEP. It was found that with a pilot-main ratio of 50:50, and by placing the pilot at −60 with 42% of EGR, $NOx$ and soot are below EURO VI levels; the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the start of injection at −35 top dead center, the efficiency is maximized, on the other hand, when the injection is at −25, the emissions are minimized, and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

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## Figures

Figure 4

NOx, CO, HC, and soot as a function of EGR at 14.39 bars fuel MEP and 16.28 bar fuel MEP

Figure 13

Gross indicated specific NOx and soot as a function of SOIp and pilot-main ratio

Figure 14

Gross indicated efficiency a function of SOIp and pilot-main ratio

Figure 1

Gross IMEP, combustion, thermal, and gross indicated efficiency as a function of EGR at 14.39 bars fuel MEP and 16.28 bars fuel MEP

Figure 2

Burning rate profile at low, medium, and high EGR rate at 14.39 bars fuel MEP and 16.28 bars fuel MEP

Figure 3

Exhaust, heat transfer, and conversion losses as a function of λ and EGR at 16.28 bars fuel MEP

Figure 5

NOx-soot tradeoff during the EGR sweep

Figure 6

IMEP gross as a function of the SOI at two different EGR rates

Figure 7

Pressure rise rate as a function of the SOI at two different EGR rates

Figure 8

Indicated, thermal, and combustion efficiencies as a function of the SOI at 0% and 28.35% EGR

Figure 9

Exhaust, emission, and heat transfer losses as a function of the SOI and EGR rate (the three losses were normalized with the displacement volume to facilitate the comparison with IMEP and fuel MEP)

Figure 10

NOx, CO, HC versus SOI at 0% and 28.35% EGR

Figure 11

IMEP gross as a function of SOIp and pilot-main ratio

Figure 12

Gross indicated specific CO and HC as a function of SOIp and pilot-main ratio

Figure 15

Thermal and combustion efficiencies a function of SOIp and pilot-main ratio

Figure 16

Maximum pressure rise rate and ignition delay as a function of SOIp and pilot-main ratio

## Errata

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