Yingjia Zhang

Kinetics of Hydrogen Abstraction and Addition Reactions of 3-Hexene by ȮH Radicals

Rate coefficients of H atom abstraction and H atom addition reactions of 3-hexene by the hydroxyl radicals were determined using both conventional transition-state theory and canonical variational transition-state theory, with the potential energy surface (PES) evaluated at the CCSD(T)/CBS//BHandHLYP/6-311G(d,p) level and quantum mechanical effect corrected by the compounded methods including one-dimensional Wigner method, multidimensional zero-curvature tunneling method, and small-curvature tunneling method. Results reveal that accounting for approximate 70% of the overall H atom abstractions occur in the allylic site via both direct and indirect channels. The indirect channel containing two van der Waals prereactive complexes exhibits two times larger rate coefficient relative to the direct one. The OH addition reaction also contains two van der Waals complexes, and its submerged barrier results in a negative temperature coefficient behavior at low temperatures. In contrast, The OH addition pathway dominates only at temperatures below 450 K whereas the H atom abstraction reactions dominate overwhelmingly at temperature over 1000 K. All of the rate coefficients calculated with an uncertainty of a factor of 5 were fitted in a quasi-Arrhenius formula. Analyses on the PES, minimum reaction path and activation free Gibbs energy were also performed in this study.

CO and H2O Time-Histories in Shock-Heated Blends of Methane and Ethane for Assessment of a Chemical Kinetics Model

This work was funded in part by a Graduate Research Fellowship, NSF grant DGE-1252521 and by the TEES Turbomachinery Laboratory.

Chapter 175 – The experimental study on the performance of a small-scale oxygen concentrator by psa

Publisher Summary This chapter analyzes an experimental study on the performance of a small-scale oxygen concentrator by pressure swing adsorption (PSA). A small-scale adjustable rich oxygen concentrator by PSA is designed and manufactured to study influences of nozzle size, purge quantity on characteristics of the production oxygen, such as its pressure, purity and volume flux. The purity of oxygen produced by this device could reach above 90% and up to 96% in volume. The flux of rich oxygen product could be adjusted intelligently in the range of 0.51/min–3.51/min. It is found that the small-scale concentrator could operate in optimum performance, with the purity of oxygen being above 90%. The relationship between the HPAP and the Qe is a typical curve of Langmuir. The optimal operating pressure of the experiment device is 0.18Mpa to 0.2MPa. The ratio of the purge quantity Qp to the flow of the product oxygen Qo is maintained above 2.5. The smaller the nozzle diameter, the higher the HPAP. The optimal nozzle diameter is from 0.8mm to 1.2mm while the adsorption time is 10 seconds. The highest purity of the production oxygen is about 96% in volume by using this small-scale concentrator while the flow of the production oxygen is of 2.0l/min. The small-scale concentrator is quite suitable for hospital, domestic usage, and oxygen bar. The device is quite usable in hospital, domestic application, oxygen bar and other places in shortage of oxygen. It would have great economic benefit in the future.