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Fabrication and characterization of thermochemical hydrogen sensor with laminated structure
Kim, Seil,Song, Yoseb,Lim, Hyo-Ryoung,Kwon, Young-Tae,Hwang, Tae-Yeon,Song, Eunpil,Lee, Songjun,Lee, Young-In,Cho, Hong-Baek,Choa, Yong-Ho Elsevier 2017 International journal of hydrogen energy Vol.42 No.1
<P><B>Abstract</B></P> <P>In this study, we reported the simple and cost-effective fabrication of thermochemical hydrogen (TCH) sensors composed of chalcogenide thin films and Pt/Al<SUB>2</SUB>O<SUB>3</SUB> powders. Chalcogenide thin films of two types, composed of Bi<SUB>2</SUB>Te<SUB>3</SUB> (monomorphic-type) and Bi<SUB>2</SUB>Te<SUB>3</SUB> Sb<SUB>2</SUB>Te<SUB>3</SUB> (four-leg PN junction-type), were prepared by electrochemical deposition. The Pt/Al<SUB>2</SUB>O<SUB>3</SUB> powder, which acts as a heating catalyst, was synthesized by impregnation of an Al<SUB>2</SUB>O<SUB>3</SUB> powder with an aqueous solution of platinum (IV) chloride pentahydrate. Its heating process was optimized via a hydrogen-sensing evaluation to control the size of the Pt particles. The monomorphic-type TCH sensor showed an output signal of 14.2 μV in response to 10 vol% hydrogen gas, whereas an output signal of 39.6 μV was obtained from a four-leg PN junction–type TCH sensor. Even though the n–p junction-type had the same deposition area as that of the monomorphic-type, the output signal of the n–p junction TCH sensor was greater by a factor of 2.8. In addition, the monomorphic-type TCH sensor had an inferior response time (T<SUB>90</SUB>) of 31 s and a longer recovery time (D<SUB>10</SUB>) of 38 s; the four-leg PN junction-type TCH sensor had a lowest response time of 27 s and a fastest recovery time of 9 s (in 3% H<SUB>2</SUB>/air at room temperature).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermochemical hydrogen sensor composed of chalcogenide thin film and Pt/Al<SUB>2</SUB>O<SUB>3</SUB> catalyst was fabricated. </LI> <LI> Voltage signal of the n–p junction type sensor was higher than monomorphic type sensor. </LI> <LI> Heat dissipation of n–p junction type sensor was superior to that of monomorphic type one. </LI> <LI> Response and recovery time of n–p junction type sensor were 27.4 and 9.6 s in 3% H<SUB>2</SUB>/air. </LI> </UL> </P>
김형민,김은필,Kim, Hyung Min,Kim, Eunpil 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.3
A jet injected normally into a cross flow has been found to have the cross section of a horseshoe shape. It occurs by a twin vortex motion in the region downstream of the jet injection. Such a flow is inherently and highly three-dimensional and numerical calculations should play an important role. The three-dimensional momentum equations with buoyancy effect and energy equation are solved to obtain the velocity distributions, center-line trajectories, cross sectional shape and entrainment. The density difference is sufficiently small, so that the Boussinesq approximation is considered to be valid. The SIMPLE algorithm is applied in a staggered grid system of a calculational domain for the numerical method.