To utilize sustainable biofuel, the current study proposes a novel combustion technique that directly burns liquid ethanol without a spray system. Two swirling air flows are induced by tangentially injected the gas from two concentric tubes at different stages. The liquid ethanol is fed by a liquid tank at the center. At the beginning methane flame assists in preheating the system to vaporize liquid ethanol and ignite the vapor. Thereafter methane is switched off, and liquid ethanol can be continuously vaporized through self-burning released heat. The heat and mass transfer processes are examined to illustrate such self-sustained burning–heating–evaporating system. The ethanol flow rate is gradually increased to provide different heat output. The flame structures, temperature distributions and pollutant emissions are carefully examined. The results show that the ethanol can be steadily burned to provide heat output between 0.7 and 2.5 kW. Generally a blue flame is obtained, and the NO_x and CO concentrations are ultralow. By increasing ethanol flow rate to exceed 8 mL/min, an unsteady, sooting flame is observed owing to incomplete evaporation and poor mixing. A parametric study is conducted to evaluate the influences of liquid tank position, flow rate and tip structure on the combustion characteristics. Additionally, an optimal operation condition is proposed. The current study provides a promising method to burn low-boiling liquid fuel in a clean, efficient and compact way.

为了利用可持续的生物燃料，当前的研究提出了一种新颖的燃烧技术，无需喷雾系统即可直接燃烧液态乙醇。切向注入来自两个不同阶段的两个同心管的气体会引起两个回旋的气流。液体乙醇由中央的储液罐供入。在开始时，甲烷火焰有助于预热系统，以蒸发液体乙醇并点燃蒸汽。此后，关闭甲烷，液态乙醇可以通过自身燃烧释放的热量不断蒸发。考察了传热和传质过程，以说明这种自我维持的燃烧-加热-蒸发系统。乙醇流速逐渐增加以提供不同的热量输出。仔细检查火焰结构，温度分布和污染物排放。结果表明，乙醇可以稳定燃烧以提供0.7至2.5 kW的热量输出。通常会获得蓝色火焰，而NO_x和CO浓度极低。通过将乙醇流速增加到超过8 mL / min，由于蒸发不完全和混合不良，会观察到不稳定的烟灰。进行了参数研究，以评估液罐位置，流量和喷嘴结构对燃烧特性的影响。另外，提出了最佳操作条件。当前的研究提供了一种以清洁，有效和紧凑的方式燃烧低沸点液体燃料的有前途的方法。