The flow field plates with a minimum channel dimension of 400 ��m were fabricated using double-sided micro photochemical etching. The fabrication sequence is shown in Figure 4. The cleaned and dried stainless steel substrate (SS316L) (a) was spin-coated with one SU-8 photoresist layer with a thickness of 10 ��m on both sides (b). Then, the flow field patterns on the mask were transferred to the photoresist layers using UV-based lithography techniques (c), and developed using a 1% sodium carbonate developer (d). The flow field patterns were obtained after etching in FeCl3-HCl for 30 min (e), and the residual photoresist was removed using NaOH solution at 50��C (f).Figure 4.Etching process of the flow field plate.2.3.
Set-up of the Test LoopIn this study, the effects of CO2 bubbles were characterized using the inlet-to-outlet pressure drop and the two-phase flow behavior in the channels of anode flow field. On the other hand, the performance of the ��DMFC was examined using an electronic load. Figure 5 shows the schematic drawing of the experimental test loop. In the test l
The key step in controlling car exhaust emissions was the introduction of ��autocatalysts�� roughly twenty-five years ago. Initially, a platinum-based (Pt) oxidation catalyst was used with an air pump which provided excess air in the exhaust gas to oxidize HCs and CO to less harmful CO2 and H2O [3]. By the early 1980s, it had been discovered that CO and HCs could be oxidized and NOx reduced simultaneously over a single ��three-way catalyst�� (TWC) containing Pt and Rh [4].
The correct operating TWC conditions require: i) the total absence of lead in gasoline, which would poison the catalyst; ii) the gaseous mixture has to be set precisely at the stoichiometric value (air/fuel weight ratio equal to 14.6).The latter requirement can be matched using an oxygen gauge, located in the exhaust gas. The signal delivered by this gauge, also called the lambda gauge, measures the stoichiometry of the emission mixture and determines whether the combustion products are oxygen rich or lean.Lambda gauges for stoichiometric engines are based on ceramic type metal oxides, usually yttrium stabilized zirconia (YSZ). The YSZ is compacted into a dense ceramic and relies on Cilengitide the generation of mobile oxygen ions (O2-) at the elevated temperatures within the tailpipe, typically in excess of 400 ��C.
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