Experimental investigation of tetrahydrofuran combustion in homogeneous charge compression ignition (HCCI) engine: Effects of excess air coefficient, engine speed and inlet air temperature

In this study, the effects of tetrahydrofuran (THF) which is nontoxic and generated from renewable environmentally friendly lignocelluloses, and n-heptane/THF blends on combustion, performance and emission characteristics were investigated at various lambda, engine speed and inlet air temperatures. Wide ranges of lambda value and engine speed were investigated and the results were presented in comparison to n-heptane as reference fuel. The combustion parameters such as cylinder pressure, heat release rate, in-cylinder gas temperature, CA10, CA50, thermal efficiency, ringing intensity, maximum pressure rise rate and imep, the performance parameters such as brake torque, power output, specific fuel consumption and HC and CO emissions were determined. Operating range of the HCCI engine was also determined. The results showed that, increasing the lambda value decreased both the in-cylinder pressure and the heat release rate for all test fuels. The addition of tetrahydrofuran led to retard combustion phasing. Thermal efficiency increased about 54% for F60N40 compared to n-heptane at 60 degrees C inlet air temperature, 1200 rpm engine speed and lambda = 2.2. The results also showed that HC and CO emissions increased with the increase of tetrahydrofuran. Furthermore, tetrahydrofuran caused to expand HCCI operating range towards to knocking and misfiring boundaries. (C) 2019 Energy Institute. Published by Elsevier Ltd. All rights reserved.