Abstract The current study investigates the combustion performance of straight algae oil (AO) in a 7-kW lab-scale gas turbine burner enabled by a novel twin-fluid injector, named Swirl-burst (SB) injector. The chemical structure (fatty acid profile), the physical, and chemical properties of AO are acquired to understand the combustibility of the oil as a potential biofuel. Effects of equivalence ratio (ER) and atomizing air to liquid mass ratio (ALR) across the injector on the global combustion characteristics are investigated at a constant heat release rate for the oil. The features of interest include visual flame images, product gas temperature, emissions of carbon monoxide (CO), and nitrogen oxides (NOx) at the combustor exit. Results show that mono-unsaturated fatty acid is predominant in the composition of the oil, suggesting possibly short ignition delay. AO has a heating value comparable to that of diesel but with a high kinematic viscosity (approximately 16 times more viscous than diesel). Clean combustion highly depends on fine sprays that lead to fast fuel pre-vaporization, thorough fuel-air mixing, and thus clean premixed combustion. Conventional injectors such as air blast (AB) atomizers cannot finely atomize viscous oils for clean combustion due to the low viscosity tolerance. Fortunately, with the SB injection, clean, complete, and lean-premixed combustion of straight AO has been successfully achieved without fuel preheating at most of the investigated cases, reasonably reflecting the fine atomization capability of the SB injector even for the viscous oil. The blue flames, overlapping temperature profiles, and low emissions of CO and NOx consistently show the clean lean-premixed AO flames. Stable and clean flames are obtained at ERs of 0.60–0.75 (with the optimum ER identified at 0.65, in terms of flame stability and low emissions), and a blow-out limit at the ER of about 0.55. At the ER of 0.65, clean and lean-premixed flames are also acquired for all the tested ALRs (2.0–5.0). Increase in ALR varies the SAA and spray behavior of the SB injection as well as the aerodynamic interaction between fuel and oxidizer. The increasing ALR results in dominantly blue flames and decrease in CO and NOx concentrations, less than 10 ppm at ALRs > 2.5, due to finer atomization and better fuel-air mixing at the higher ALRs, and thus enhanced premixed combustion. Overall, clean and stable lean-premixed combustion of straight AO is achieved without fuel preheating using the novel SB injector despite the high fuel viscosity. The SB injection potentially enables AO itself as a cost-effective and near-zero-emission biofuel.

中文翻译：

---

使用新型双流体喷射器在涡流稳定燃烧器中燃烧直藻油

摘要 目前的研究调查了直藻油 (AO) 在 7 kW 实验室规模燃气轮机燃烧器中的燃烧性能，该燃烧器由一种名为 Swirl-burst (SB) 喷射器的新型双流体喷射器启用。获取 AO 的化学结构（脂肪酸谱）、物理和化学特性，以了解油作为潜在生物燃料的可燃性。当量比 (ER) 和穿过喷射器的雾化空气与液体质量比 (ALR) 对全局燃烧特性的影响在油的恒定热释放速率下进行了研究。感兴趣的特征包括可视火焰图像、产品气体温度、燃烧器出口处的一氧化碳 (CO) 和氮氧化物 (NOx) 排放。结果表明，单不饱和脂肪酸在油的组成中占主导地位，暗示可能有短暂的点火延迟。AO 的热值与柴油相当，但运动粘度高（大约是柴油的 16 倍）。清洁燃烧高度依赖于精细的喷雾，导致燃料快速预汽化、燃料-空气充分混合，从而实现清洁预混燃烧。由于低粘度耐受性，传统喷射器（例如鼓风 (AB) 雾化器）无法精细雾化粘性油以实现清洁燃烧。幸运的是，采用SB喷射，在大多数研究情况下，无需燃料预热即可成功实现直接AO的清洁、完全和稀薄预混燃烧，合理地反映了SB喷射器即使对粘稠油的精细雾化能力。蓝色的火焰，重叠的温度曲线，CO 和 NOx 的低排放始终显示清洁的贫预混 AO 火焰。在 ER 为 0.60–0.75（在火焰稳定性和低排放方面，最佳 ER 确定为 0.65）时获得稳定和清洁的火焰，并且在 ER 处的爆燃极限约为 0.55。在 ER 为 0.65 时，所有测试的 ALR (2.0-5.0) 也获得了清洁和贫油预混火焰。ALR 的增加会改变 SAA 和 SB 喷射的喷雾行为以及燃料和氧化剂之间的空气动力学相互作用。ALR 的增加导致主要为蓝色火焰，CO 和 NOx 浓度降低，ALR > 2.5 时低于 10 ppm，这是由于更高的 ALR 下更精细的雾化和更好的燃料-空气混合，从而增强了预混燃烧。全面的，尽管燃油粘度较高，但使用新型 SB 喷油器无需燃油预热即可实现直接 AO 的清洁和稳定的稀薄预混燃烧。SB 注入可能使 AO 本身成为一种具有成本效益且接近零排放的生物燃料。