Recent studies have demonstrated stable generation of power from pure ammonia combustion in a micro gas turbine (MGT) with a high combustion efficiency, thus overcoming some of the challenges that discouraged such applications of ammonia in the past. However, achievement of low NOx emission from ammonia combustors remains an important challenge. In this study, combustion techniques and combustor design for efficient combustion and low NOx emission from an ammonia MGT swirl combustor are proposed. The effects of fuel injection angle, combustor inlet temperature, equivalence ratio, and ambient pressure on flame stabilization and emissions were investigated in a laboratory high pressure combustion chamber. An FTIR gas analyser was employed in analysing the exhaust gases. Numerical modeling using OpenFOAM was done to better understand the dependence of NO emissions on the equivalence ratio. The result show that inclined fuel injection as opposed to vertical injection along the combustor central axis resulted to improved flame stability, and lower NH₃ and NOx emissions. Numerical and experimental results showed that a control of the equivalence ratio upstream of the combustor is critical for low NOx emission in a rich-lean ammonia combustor. NO emission had a minimum value at an upstream equivalence ratio of 1.10 in the experiments. Furthermore, NO emission was found to decrease with ambient pressure, especially for premixed combustion. For the rich-lean combustion strategy employed in this study, lower NOx emission was recorded in premixed combustion than in non-premixed combustion indicating the importance of mixture uniformity for low NOx emission from ammonia combustion. A prototype liner developed to enhance the control and uniformity of the equivalence ratio upstream of the combustor further improved ammonia combustion. With the proposed liner design, NOx emission of 42 ppmv and ammonia combustion efficiency of 99.5% were achieved at 0.3 MPa for fuel input power of 31.44 kW.

最近的研究表明，在微型燃气轮机（MGT）中通过纯氨燃烧稳定地发电具有很高的燃烧效率，因此克服了过去阻碍氨这种应用的一些挑战。然而，实现来自氨燃烧器的低NOx排放仍然是重要的挑战。在这项研究中，提出了一种燃烧技术和燃烧器设计，以实现氨MGT旋流燃烧器的高效燃烧和低NOx排放。在实验室高压燃烧室中研究了燃料喷射角，燃烧器入口温度，当量比和环境压力对火焰稳定和排放的影响。FTIR气体分析仪用于分析废气。使用OpenFOAM进行了数值建模，以更好地了解NO排放对当量比的依赖性。结果表明，倾斜的燃料喷射与沿燃烧器中心轴的垂直喷射相反，可改善火焰稳定性，并降低NH₃和氮氧化物的排放。数值和实验结果表明，控制燃烧室上游的当量比对于贫浓氨燃烧室的低NOx排放至关重要。在实验中，NO当量在上游当量比为1.10时具有最小值。此外，发现NO排放随环境压力而降低，特别是对于预混燃烧。对于本研究采用的浓稀混合气燃烧策略，预混合燃烧中的NOx排放量要比非预混合燃烧中的低，这表明混合均匀性对于氨燃烧产生的低NOx排放至关重要。开发出原型衬管来增强燃烧器上游当量比的控制和均匀性，从而进一步改善了氨燃烧。利用建议的衬里设计，