Search Results

The previous study indicates that the detonation waves generated by acetylene/oxygen mixture can converge in the combustion chamber. In order to verify the destructive effect of detonation wave convergence on piston materials, the detonation bomb device was modified to fundamentally investigate the material failures of aluminum alloy for pistons. The results show that the specimens are destroyed in the middle and edge region after dozens of detonations, which is consistent with the typical characteristics of the piston failures in engines. Therefore, the hypothesis that failures of piston material is caused by the detonation wave convergence is verified.

Compared with conventional flow field, metal foam has been increasingly used for gas distributor in the PEM (proton exchange membrane) fuel cell due to its high porosity and conductivity, which significantly enhances the species transport under high current density condition. In this study, the cell performances with metal foam and graphite parallel flow field are compared under normal and subzero temperature conditions. Besides, electrochemical impedance spectroscopy (EIS) is recorded to characterize the Ohmic, polarization and polarization resistance. Under normal condition, the cell with metal foam exhibits three times better performance than the one with parallel flow field. Meanwhile, the effects of inlet gas humidity and flow rates on cell performance are also studied, indicating that the cathode flooding easily occurs due to its difficult water removal. However, the high flow rate can greatly ease the cathode water flooding.

Recent toxicological and epidemiologic studies have shown that diesel emissions have been a significant toxic air contaminant. Catalyzed DPF (CDPF) not only significantly reduces the PM mass emissions (>90%), but also further promotes carrier self-regeneration and oxidize more harmful gaseous pollutants by the catalyst coated on the carrier. However, some ultrafine particles and potentially harmful gaseous pollutants, such as VOCs species, originally emitted in the vapor-phase at high plume temperature, may penetrate through the CDPF filter. Furthermore, the components and content of catalyst coated on the CDPF could influence the physicochemical properties and toxicity intensity of those escaping ultrafine particles and gaseous pollutants. In this work, (1) we investigated the influence of precious metal content as a variable parameter on the physicochemical properties and catalytic activities of the small CDPF samples.