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为了研究传热对微型发动机燃烧室内甲烷催化燃烧特性的影响,采用CH4和空气的预混合气体,对在活塞上表面和燃烧室顶部涂有Pt-La/γ-Al2O3催化剂的传热情况下的微型发动机的催化燃烧特性进行了实验研究及数值模拟,详细对比分析了3种典型的管壁材料(Si,Fe和矾土),有、无催化涂层及绝热与传热情况下的微型发动机燃烧室内CH4的催化燃烧特性。结果表明:对于Pt-La/γ-Al2O3催化下自由活塞式的微型发动机,受尺度减小引起的传热损失对催化燃烧过程影响不大;有催化情况下的燃烧效率明显高于无催化,催化燃烧具有更高的燃烧室内温度,可以实现更高的动力和电能输出,微型发动机(MEMS微推进系统)具有更高的输出功率和能量密度;管壁材料为导热系数较小的矾土的催化燃烧效率略高于导热系数较大的Si;微型发动机燃烧室的壁面材料应采用具有承受应力高、适应温度广、机械性能及抗变形能力强等优点的耐火陶瓷。
In order to investigate the effect of heat transfer on the catalytic combustion of methane in a combustion chamber of a micro-engine, a premixed gas of CH4 and air was used to simulate the heat transfer of Pt-La / γ-Al2O3 catalyst coated on the top surface of the piston and the top of the combustion chamber Micro-engine catalytic combustion characteristics of the experimental study and numerical simulation, a detailed comparative analysis of three typical wall materials (Si, Fe and bauxite), with and without catalytic coating and heat insulation and heat transfer of the micro-engine Catalytic Combustion Characteristics of CH4 in Combustion Chamber. The results show that the heat transfer loss caused by reduced scale has little effect on the catalytic combustion process for the free-piston micro-engine catalyzed by Pt-La / γ-Al2O3. The catalytic combustion efficiency is obviously higher than that of the non-catalytic, Catalytic combustion has a higher combustion chamber temperature, higher power and electric energy output can be achieved, and the micro-engine (MEMS micro-propulsion system) has higher output power and energy density. The wall material is made of alumina with smaller thermal conductivity The catalytic combustion efficiency is slightly higher than that of Si with large thermal conductivity; the wall material of the micro-engine combustion chamber should be made of refractory ceramics with the advantages of high bearing stress, wide temperature adaptation, strong mechanical properties and anti-deformation ability.