n-Octanol (C₈H₁₇OH) is an advanced biofuel derived from ligno-cellulosic biomass that is suitable for compression ignition technology with several properties closer to fossil diesel. This study analyses the performance and emissions of a direct-injection (DI) diesel engine fueled with n-octanol/diesel blends containing 10% (OCT10), 20% (OCT20) and 30%(OCT30) by volume of n-octanol using a 3 × 3 full-factorial experimental design matrix that considers blend composition of n-octanol in diesel, exhaust gas recirculation (EGR) rates of 10%, 15% and 20% and injection timings of 19°, 21° and 23° crank angle (CA) before top dead centre (bTDC) as factors. Models for oxides of nitrogen (NOx), smoke, brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) were developed using response surface methodology (RSM) and were found to be significant statistically. The variation of EGR had a considerable effect on both BTE and BSFC of the engine followed by blend composition and injection timing. Best performance (BTE = 37.06%, BSFC = 0.23kg/kWh) was delivered by OCT10 at 10% EGR and 23°CA while the lowest performance (BTE = 30.95%, BSFC = 0.28kg/kWh) was by OCT30 at 20% EGR and 19°CA. Injection timing was found to have the highest effect on NOx emissions while EGR affected smoke opacity to the maximum. NOx was found to decrease from 1790 ppm (for OCT10 at 10% EGR and 23°CA) to as low as 410 ppm (for OCT30 at 20% EGR and 19°CA). Smoke opacity was found to decrease from 94.2% (for OCT10 at 20% EGR and 19°CA) to as low as 43% (for OCT30 at 10% EGR and 23°CA). Desirability approach was used to determine the best combination of blend composition of n-octanol, EGR and injection timing for minimising smoke, NOx and BSFC simultaneously. 17% by volume of n-octanol/diesel blend injected at 20° CA bTDC and 10% EGR was predicted to be optimum which delivered a simultaneous reduction of NOx (−47.4%), smoke (−21.08%) and BSFC (−8%) during confirmatory tests with a reasonable accuracy of within 4%. This method is robust and could be employed to other small engines for developing models that can predict engine characteristics with reasonable accuracy.

正辛醇（C ₈ H ₁₇OH）是一种源自木质纤维素生物质的先进生物燃料，适用于压缩点火技术，具有与化石柴油更接近的多种性能。这项研究分析了使用正辛醇/柴油混合物（含量为正辛醇的体积百分比为10％（OCT10），20％（OCT20）和30％（OCT30））的直喷式（DI）柴油发动机的性能和排放。一个3×3全因子实验设计矩阵，其中考虑了柴油中正辛醇的混合物组成，排气再循环（EGR）率为10％，15％和20％，喷射定时为19°，21°和23°曲柄上止点（bTDC）之前的夹角（CA）作为因素。氮氧化物（NOx），烟雾，制动热效率（BTE）和制动比油耗（BSFC）是使用响应曲面方法（RSM）开发的，在统计学上具有显着意义。EGR的变化对发动机的BTE和BSFC都有很大影响，其次是混合气成分和喷射正时。OCT10在10％EGR和23°CA时表现出最佳性能（BTE = 37.06％，BSFC = 0.23kg / kWh），而OCT30在20％时表现最佳（BTE = 30.95％，BSFC = 0.28kg / kWh） EGR和19°CA。发现喷射正时对NOx排放的影响最大，而EGR最大程度地影响了烟的不透明度。发现NOx从1790 ppm（对于10％EGR和23°CA的OCT10）降低到410 ppm（对于20％EGR和19°CA的OCT30）。发现烟的不透明度从94降低。2％（对于20％EGR和19°CA的OCT10，低至43％（对于10％EGR和23°CA的OCT30）。使用可取性方法确定正辛醇，EGR和喷射正时的混合成分的最佳组合，以同时减少烟气，NOx和BSFC。的17％预测在20°CA bTDC和10％EGR时注入正辛醇/柴油混合物是最佳的，这在确认性测试期间可同时减少NOx（−47.4％），烟气（−21.08％）和BSFC（−8％）准确度在4％以内。该方法是鲁棒的，并且可以用于其他小型发动机，以开发可以以合理的精度预测发动机特性的模型。