An appraisal of the P.moriformis microalga oil as fuel for diesel engines with and without exhaust gas recirculation (EGR)

Abstract

Introduction. The examination of diesel engines using algal oils as fuel is running very slow. A narrative review of the literature with a special focus on articles that discuss compression-ignition (CI) engine trials on microalgal oils (MOs) was done showing that over the period of 2000 to 2017, only the oils obtained from three different species of green microalga, namely Chlorella protothecoides, Tetraselmis suecica, and Botryococcus braunii were evaluated as diesel substitutes. Moreover, we detected a complete lack of data and information in the scholarly journals on the performance and emission characteristics of CI engines with the introduced EGR systems that ran on MOs. The bench mounted engine was running on low load (BMEP = 0.397 MPa), average load (BMEP = 0.595 MPa) and high load (BMEP = 0.794 MPa) modes at n = 2000 rpm and used high purity P. moriformis microalgal oil, diesel fuel, and their 30% and 70% blends as fuel. Variation of BSFC rates, net efficiency, and emissions of four different chemical compounds (smoke, NOx, HC, CO2) were established. The aforementioned parameters were repeatedly assessed for the engine running at low load conditions with the advancement or retardation of start of fuel injection timing 2 degrees of crankshaft rotation angle from -16° to +4° of CA relative to top dead centre. This study addresses the suitability of high purity microalgal oil to meet the needs as a renewable fuel substitute for diesel engines. It is a part of larger scale investigation done by authors on numerous synergistic improvements in cultivation of microalga P.moriformis in humid climate countries as well as on production and appraisal of microalgal biofuels.