Pre- and post-combustion emission reduction techniques for engine fuelled with diesel/DEE blends by three approaches

Abstract

ABSTRACT Experiments were conducted on a single-cylinder four-stroke diesel engine coupled to an eddy current dynamometer. In the first approach, baseline data generation for optimization of injection timing, injection pressure, number of holes, and combustion chamber types was done. Further, exhaust gas recycle (EGR) was added at the rate of 5%, 10%, 15%, and 20% to these optimized diesel engine operating parameters. Adopting diesel particulate filter (DPF) and diesel oxidation catalyst (DOC), NOx emission was measured. In the second approach, test runs were conducted on diesel engine by injecting 5%, 10%, 15%, and 20% diethyl ether (DEE). EGR, DPF, and DOC were adopted to reduce NOx. In the third approach, experiments were conducted by injecting DEE into inlet manifold at injection timings, viz., 5°BTDC, TDC, 5°ATDC, and 10°ATDC and with injection duration of 18°, 22.5°, 27°, 31.5°, and 36° CA. The 20% EGR, DPF, and DOC were fixed when manifold injection of DEE to observe the further reduction in NOx level. The first approach resulted in the highest brake thermal efficiency of the engine and was found to 31.25% and 27.36% without EGR and with 20% EGR. Lowest smoke and CO levels obtained were 11 ppm and 0.094% with both DPF and DOC. Reduction of NOx by 25% was achieved by combined mode of EGR, DPF, and DOC. The second approach resulted in a brake thermal efficiency of 29.25% and was obtained when the engine was powered with 20% DEE. With 20% EGR, HC and CO reduced by 40% and 8% adopting DPF and by 10% and 45% adopting DOC. NOx emission reduced by 10% adopting DPF and reduced by 6% using DOC. Finally, in the third approach, a Brake thermal efficiency of 30.84% was obtained with manifold injection of DEE and reduced to 29.3% when 20% EGR was adopted. DPF reduced smoke by 37 HSU and DOC by 1 HSU. Lowest NOx emission of 760 ppm was obtained for engine injecting DEE in manifold having 20% EGR, DPF, and DOC. Comparing results of all the test runs under three approaches, the optimum condition suggested to an existing diesel engine to be fueled with 20% DEE/diesel ratio having 80% load, operating with 20% exhaust gas recirculation rate adopting both DPF and DOC. The performance and emission values at this suggested condition are found to be as brake thermal efficiency of 27.5%, peak pressure 69 bar, ignition delay of 10.2 deg CA, combustion duration of 44 deg CA, smoke of 11 HSU, HC of 33 ppm, CO of 0.16%, and NOx of 680 ppm.