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۱Theoretical investigation into nano structures of boron substituted C20 fullerene and H2Adsorption on them
نویسنده(ها): ، ،
اطلاعات انتشار: اولین همایش ملی نانومواد و نانو تکنولوژی، سال
تعداد صفحات: ۴
The MPW1PW91\6–31++G** density functional calculations were used to obtain minimum geometries and interaction energies between the molecular hydrogen and nanostructures of fullerenes C20cage),C20(bowl), C20H10(bowl), CC18H10B2(bowl) by Gaussian 98 package. In each case, H2molecule is adsorbed above the pentagonal andhexagonal sites. Using NBO analysis, the relative energies, Adsorption energy, and HOMO–LUMO gaps (HLG) are obtained. All results shownthat B atom substitution in hexa site in C20 bowl) may be suitable for th adsorption of hydrogen molecule.<\div>

۲Role of different insert shapes on performance of tubular heat exchangers
اطلاعات انتشار: ششمین کنفرانس مبدلهای گرمایی، سال
تعداد صفحات: ۱۴
An experimental assessment on heat transfer enhancement inside a circular straight tubular heat exchanger equipped with different insertsis presented. The investigated parameters are (1) six different shapes of inserts: perforated–tape, jagged–tape, twisted–tape, helical–screw, vortex–generator, and offset–strip (2) seven volumetric flow rates: 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 lit\min. Test results indicate that the thermal–hydraulic performance of the heat exchanger is strongly related to the shape of inserts. The tube fitted with the vortex–generator insert offers the highest values of the heat transfer coefficient and pressure drop compared to the other studied inserts<\div>

۳Influences of different arrangements of delta–winglets on thermal–hydraulic performance of vortex–generator insert
اطلاعات انتشار: ششمین کنفرانس مبدلهای گرمایی، سال
تعداد صفحات: ۱۲
Heat transfer enhancement in a tube using the vortex–generator (VG) insert with different arrangements of delta–winglets is investigatedin the current study.Fourteen VG insertswith the longitudinaland forward arrangementof delta–wingletsare made from thealuminum sheets with length of 350 mm, width of 14.5 mm, and thickness of 0.6 mm.The heat transfer and pressure drop results achieved from the use of VG insertsinside the tube are compared with those obtained for the plain tube.It is found that at the transitional flow through the plain tube, Notter–Rouse equation predicts the current experimental Nusseltnumber better than Gnielinski equation.Also, the experimental results reveal that the use of VG inserts inside the tube yields higher heat transfer coefficient and pressure drop than the plain tube, and these parameters augment with increasing the number of delta–winglet. The appropriate tradeoff between the enhanced heat transfer and the friction is found by using a special arrangement of delta–winglets on the VG insert which presents the highest heat transfer coefficient as well as the maximum values of considered performance evaluation criterion (PEC). The maximum PEC of 1.41 is found for this VG insert atthe maximum Reynolds number<\div>

۴A Laboratory Study of Oil Recovery by Nitrogen WAG injection in Berea Sandstone Rock
نویسنده(ها): ، ، ،
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۸
This work concerns to experimentally investigate the nitrogen immiscible WAG injection in Berea sandstone rocks which has been rarely attended in the available literature. Flooding tests wereconducted on a 30 cm length Berea sandstone core sample at reservoir conditions and theinfluences of injection rate and WAG ratio on breakthrough time, early recovery and ultimaterecovery were investigated. Relatively long core size makes it attractive to be a more reliablerepresentation of flow through reservoir rocks. Nitrogen, 5000 ppm NaCl brine, and Kerosene were used as working fluids. The results revealed that among 4 different flow rates implemented in the experiments, 0.4 cc\min is optimum. Three screening factors, higher early and final recoveryand lower gas production (after breakthrough) are considered for selecting the optimal rate. In addition, the results of the experiments performed at different WAG ratio, and at optimum rate,showed that there is an optimum WAG ratio, 2, in which the oil recovery is maximized. This workillustrates that if the parameters influencing WAG injection are thoroughly investigated, it can achieve a high recovery in Berea sandstone even with a cost–effective choice of Nitrogen in immiscible conditions where no other better alternative is economically available<\div>
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