Relationship between low-temperature oxidation activity and second-stage ignition delay: Experimental insights on n-pentanol / hydrogenated catalytic biodiesel blends

N-pentanol exhibits promising potential as a sustainable and eco-friendly biomass energy source. However, certain challenges such as ignition difficulty and unstable combustion exist. This study investigates the influence of low-temperature auto-ignition of n-pentanol/HCB (Hydrogenated Catalytic Biodiesel) blends on ignition and combustion characteristics and evaluates the correlation between low-temperature oxidation and second-stage ignition delay. Results show a linear positive correlation between the HCB content in n-pentanol and its low-temperature oxidation reactivity. The stronger the low-temperature oxidation activity of the blends, the shorter the second-stage ignition delay of blends. When the HCB content in blends is below 40 %, the low-temperature oxidation rate initially increases and then decreases. However, the low-temperature oxidation rate increases again when the HCB content exceeds 40 %. Moreover, the relationship between the initial CO2 generation rate and the HCB blending ratio follows an Exp exponential function under different critical compression ratios. Beyond 43.7 % HCB, an acceleration in the high-temperature combustion rate owing to an increase in the low-temperature oxidation rate again. In addition, the minimum ignition limit of n-pentanol/HCB blends was identified with 40 % HCB blends closely resembling diesel conditions and 50 % HCB blends showing a lower ignition limit, characterized by a critical temperature and pressure of 517.3 K and 8.66 bar, respectively. Furthermore, two distinct conditions for the minimum ignition boundary region of n-pentanol/HCB blends were defined, offering practical insights. In summary, a blend with a 50 % HCB ratio provides a promising solution for the low-temperature ignition and stable combustion of n-pentanol, addressing the challenges of simultaneous use in internal combustion engines.