Performance analysis and optimization of thermal barrier coated piston diesel engine fuelled with biodiesel using RSM

The current research investigates diesel and simarouba biodiesel blends (10%, 20%, & 30% by volume) in conventional and Low Heat Rejection (LHR) diesel engines, each rated at 4.4 kW. While optimization techniques like Response Surface Method and Taguchi have been extensively studied, the impact of LHR and optimization on LHR engine performance and emissions is rarely explored. Converting the conventional engine to LHR involved applying 300 μm of stabilized zirconia to the piston crown to enhance combustion efficiency. Performance and emissions were analyzed at rated injection pressure (200 bar) and timing (23° before top dead center - btdc). Experiments were continued on LHR engine by varying injection timings (advancing - 26°btdc and retarding - 20°btdc). Advanced injection timing showed significant improvement in performance of Low heat rejection engine. MINITAB statistical tool is used to optimize engine performance using Response Surface Method. The 20% blend showed improved performance in both engines. The optimum values for Low heat rejection engine responses are 26.8%, 0.32 kg/kW-h, 0.018%, 59.59 ppm, and 1419.03 ppm for brake thermal efficiency, brake specific fuel consumption, carbon monoxide, and unburnt hydrocarbons, respectively. Confirmation experiments aligned well with model predictions, indicating the potential of LHR engines to enhance thermal efficiency and reduce emissions.