The effects of exhaust gas recirculation (EGR) on the performance of diesel engine.

Masters Degree (Mechanical Engineering). University of KwaZulu-Natal. Durban, 2018.The aim of this work was to study the effects of EGR on the performance of a diesel engine using waste plastic pyrolysis oil (WPPO) and conventional diesel (CD). WPPO was developed through the pyrolysis extraction method. The blends were made up of WPPO and conventional diesel mixed in the ratios of WPPO10, WPPO20, WPPO30, WPPO40 and WPPO100. The EGR % flow rate chosen was 0 % to 30 % graduated in intervals of 5 %. The lower blend ratios of WPPO10 and WPPO20 showed lower values of brake specific fuel consumption (BSFC) compared to conventional diesel values and the high blend ratio of WPPO100. The brake thermal energy (BTE) showed increased values for lower blend ratios of WPPO10 and WPPO20 of 8.35 % and 8.15 % respectively with application of an EGR % flow rate of 15 % compared to high blend ratios of WPPO30, WPPO40 and WPPO100. The application of EGR % flow rate was observed to cause no significant change in the engine brake power (BP) for all the test fuels used. The application of EGR % flow rate in increasing rates reduced exhaust gas temperature (EGT), with conventional diesel reporting 440 ⁰C at 5 % EGR flow rate and 340 ⁰C being the lowest at 30 % EGR flow rate. The application of EGR % flow rate reduced the amount of hydrocarbon emissions emitted by the applied test fuels across the board. At EGR flows rate of 5 %, 10 %, 15 %, 20 %, 25 % and 30 %, conventional diesel had 43 ppm, 57 ppm, 70 ppm, 82 ppm and 85 ppm respectively. As the blend ratio increased with increased EGR % flow rate there was an increased rate of NOX emissions. At 20 % EGR flow rate, blends WPPO10, WPPO2O, WPPO30, WPPO40 and WPPO100 had 591ppm, 645 ppm, 750 ppm, 778 ppm and 851 ppm respectively compared to at the 10 % EGR flow rate where their values were 830 ppm, 971 ppm, 1031 ppm, 1151 ppm and 1116 ppm respectively. There was a significant continuous and marginal increase in the percentage of carbon emissions by volume as the load increased across all the test fuels irrespective of the EGR % flow rate. At 80 % engine load the value for WPPOB100 was 2.0 % up from 1.65 % by volume at part engine load, while the value of conventional diesel was 4.1 % at 80 % engine load compared to 2.95 % by volume at part engine load. The application of EGR % flow rate increased the carbon dioxide emission exponentially by almost doubling the values. At 10 % EGR flow rate the value of conventional diesel was 3.85 % compared to WPPOB100 at 6.25 %, WPPOB10 at 4.75 %, WPPOB20 at 4.25 %, WPPOB30 at 3.95 %, and WPPOB40 at 6.65 %