Influence of Exhaust Gas Recirculation and Fuel Injection Timings on a Diethyl Ether–Diesel Blend-Fueled Compression Ignition Engine

Abstract Environmental pollution and energy scarcity have led to the search for novel alternative fuels to compression ignition (CI) engines. In the present study, diesel and its blend with diethyl ether (DEE40, 40% DEE in diesel, v/v) are compared to investigate the effect of exhaust gas recirculation (EGR) and injection timings using conventional diesel combustion (CDC) mode. Experiments were conducted in a four-stroke direct-injection CI engine to characterize the performance, combustion, and exhaust emissions at various engine operating conditions. As a result of the study, it was observed that the start of the main injection (SoMI) of 2 deg before top dead center (bTDC) and 20% EGR were optimized for better performance and nitric oxide (NO) emissions with a penalty of hydrocarbon (HC) emissions. DEE40 showed lower maximum cylinder pressure (Pmax) and maximum heat release rate (HRRmax) than diesel due to the lower calorific value (CV) and higher cetane number (CN) of DEE. The difference in Pmax for both test fuels was higher with increasing engine load. The superior fuel properties of DEE40 compensated for the lower CV of DEE, showing higher brake thermal efficiency (BTE) and lower brake-specific energy consumption (BSEC) compared to diesel. DEE40 showed an improved coefficient of variance (CoV) and combustion stability at higher loads, especially with 20% EGR. NO and HC emissions are lower for DEE40 blends at all engine operating conditions. Carbon monoxide (CO) emissions in diesel–DEE blends rely on the dominance of latent heat of vaporization over the fuel-bound oxygen and CN. Upon EGR application, CO emissions were adversely impacted by 20% EGR rates. However, NO emissions improved. Therefore, it is recommended to blend DEE (up to 40% v/v) in diesel for higher BTE without adversely impacting the exhaust emissions.