Microemulsions are thermodynamically stable alternatives to diesel, which could be directly used in the engine, without any modification. Surfactant‐free water‐in‐diesel microemulsions with 60.0–70.0% (vol/vol) diesel, 29.0–39.5% (vol/vol) butanol, and 0.5–2.0% (vol/vol) water were formulated, and their properties were compared against standard specifications of diesel fuel oil (ASTM D975). The calorific values of the microemulsion fuels (41.23–44.75 MJ/kg) were higher than the volume‐fraction weighted averages (39.20–40.75 MJ/kg). The cloud points (−0.5 to −3.5°C) were lower than expected (0°C). The specific gravities (0.825–0.831), viscosities (2.16–2.39 mm²/s), and sulfur contents (27–45 mg/kg) were also within the permissible limits. Some of the microemulsions showed improved cetane indices (cetane index up to 49.5), while the microemulsions with higher butanol percentages, for which cetane index reduced to 38, would require the use of cetane improvers. Since these microemulsions satisfied the ASTM specifications, they could be potentially used as a cleaner alternative to diesel.

中文翻译：

---

酒精对水包柴油微乳液燃料性能的影响

微乳剂是柴油的热力学稳定替代品，可直接用于发动机而无需任何修改。配制了不含表面活性剂的柴油中水微乳液，其中包含60.0–70.0％（体积/体积）柴油，29.0–39.5％（体积/体积）丁醇和0.5–2.0％（体积/体积）水，其性能与柴油的标准规格（ASTM D975）进行了比较。微乳液燃料的热值（41.23–44.75 MJ / kg）高于体积分数加权平均值（39.20–40.75 MJ / kg）。浊点（-0.5至-3.5°C）低于预期（0°C）。比重（0.825–0.831），粘度（2.16–2.39 mm ²/ s），硫含量（27-45 mg / kg）也在允许的范围内。一些微乳液显示十六烷指数有所改善（十六烷指数高达49.5），而丁醇百分比降低至38的丁醇含量较高的微乳液将需要使用十六烷值改进剂。由于这些微乳液满足ASTM规范，因此它们有可能被用作柴油的清洁替代品。