| Reduction in fuel consumption and exhaust emissions are two major objectives in engine development. DME is an excellent alternative fuel for vehicle and it has been paid widespread attention because it can be made of coal which accords with the energy structure in China. DME flue mixed with hydrogen will be helpful to improve engine performance. With the support of NSFC (NO. 50676056), this study launched steam reforming of DME to produce hydrogen and fuel reforming (REGR) technologies of dimethyl ether engine. Main contents including:1 The performance of Dimethyl ether (DME) hydrolysis active components and methanol reforming active components were studied. The results showed that:①Among DME hydrolysis active components, HZSM-5 catalysts have higher DME conversion and H2 production rate thanγ-Al2O3 catalyst at lower temperature. When the temperature exceeds 450℃,γ-Al2O3 catalyst has higher H2 production rate than HZSM-5 catalysts (nSiO2/nAl2O3=25,100).②γ-Al2O3 catalyst possesses higher stability than HZSM-5 catalysts.③When the temperature exceeds 300℃, CuMn2O4 catalyst has high H2 production among different methanol reforming active components.④CuMn2O4 that was calcined by 700℃exhibited higher activity DME conversion and H2 production rate than CuMn-spinel that was calcined by 500℃and 900℃.2 The effects of temperature, steam-to-DME mole rate and air speed onγ-Al2O3/CuMn2O4 bi-functional catalyst were studied. The results showed that:①As the increase of temperature, the DME conversion and H2 production rate ofγ-Al2O3/CuMn2O4 increase. The Initial temperature of DME is 300℃,and the DME conversion is almost 100% when the temperature exceeds 400℃.②As the increase of steam-to-DME mole rate, the DME conversion and H2 production rate ofγ-Al2O3/CuMn2O4 go up. When the water-ether ratio is higher than 5:1, the DME conversion and H2 production rate are stabilized.③As the increase of air speed, the DME conversion and H2 production rate ofγ-Al2O3/CuMn2O4 are invariant first and then decreased.3 In DME engine test bench, CO2 was added in the intake air to simulate EGR, different proportions of DME and H2 were added in the intake air to simulate fuel-reforming and REGR of DME. The performance of DME engine using REGR tgechnology was studied. The results showed that:①When the torque is 70 N.m, as the increase of H2 additive amount, the peak in-cylinder pressure goes up, and the show up of the peak in-cylinder pressure is retarded.②As the increase of H2 additive amount, the peak heat release rate becomes narrower and higher and the show up of the peak heat release rate is retarded.③As the increase of H2 additive amount, the maximum rate of pressure rise increases and the start of ignition retards.④As the increase of the load, the peak heat release rate becomes wide and the peak of diffusion combustion increased. The increase of the H2 additive amount leads to the decrease of the diffusion combustion.In this research, in-depth mechanism of the steam reforming and the performance of DME engine with REGR technologies have be studied, which will lay a good foundation for the application of DME engine. |
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