Validating CO Emission Reduction from B30 Diesel Engines through Exhaust-Heated Shell-and-Spiral Coil Fuel Preheating System

This fundamental research investigates the proof-of-concept effect of a counterflow Shell-and-Spiral Coil Heat Exchanger (SSCHE) on CO emissions from a B30-fueled single-cylinder 7 HP diesel engine under no-load conditions, without dynamometer loading, and establishes a scientific basis before advancing to prototype development with bypass valve temperature control. CFD simulation using SolidWorks Flow Simulation 2023 predicted fuel outlet temperatures of 55°C, 78°C, and 92°C for engine speeds of 1000, 1250, and 1500 rpm, respectively. The experimental setup on a B30-fueled Jiang FA R175 A diesel engine demonstrated actual fuel outlet temperatures of 40.14±5.77°C, 56.18±18.26°C, and 77.34±7.01°C, with CFD deviations of 27.0%, 28.0%, and 15.9%, respectively. CO emission analysis demonstrated significant reductions: 56.03% at 1000 rpm, 27.98% at 1000 and 1250 rpm, respectively, but showed a 7.79% increase at 1500 rpm. Findings reveal the best CO reduction was observed at fuel outlet temperatures of 40°C–56°C (low to medium rpm) under the no-load conditions tested. The three-point dataset is insufficient to establish a temperature optimum, and future controlled experiments using bypass valve modulation are required to achieve this. Statistical analysis: Cohen’s d = 3.12, 95% CI [96.8–114.4] ppm, p < 0.001 at 1000 rpm (very large effect); Cohen’s d = 2.10, p < 0.001 at 1250 rpm (large effect); and significant increase in CO at 1500 rpm (d = 0.37, p = 0.003). CFD deviations (15.9%–28.0%) attributed to specification-based boundary conditions and steady-state assumptions; the model is treated as a preliminary design tool throughout the study.

B30 biodiesel; CO emission; Numerical experimental validation; Shell-spiral coil; Waste heat recovery

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