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161.
A convenient experimental method for measuring the thermal conductivity of uranin (fluorecein sodium, C20H10O5Na2) is described. Two similar blocks of uranin, produced from a strong uranin/water solution, were exposed to one-dimensional steady-state conduction. It was found that, for a mean bulk temperature ranging from ambient up to 55°C, the uranin has a constant thermal conductivity of 0.43 W/mK. Above these temperatures, the material begins to soften and the thermal conductivity is seen to decrease 相似文献
162.
The plane one-dimensional and radially symmetric problems of injection of superheated steam into a porous medium saturated with gas are considered. Self-similar solutions are constructed on the assumption that in this case four zones are formed in the porous medium, namely, a gas flow zone, superheated and wet steam zones, and a water slug zone formed due to steam condensation. On the basis of the solution obtained, both the effects of the boundary pressure, mass flow rate, and temperature of the injected superheated steam and the effect of the initial state of the porous medium on the propagation of the hydrodynamic and thermal fields in the porous medium are studied. 相似文献
163.
We formulate conservation laws governing steam and nitrogen injection in a one-dimensional porous medium containing water.
Compressibility, heat conductivity and capillarity are neglected. We study the condensation front and shock waves arising
in the flow. We find that there are four possible types of solutions for the initial and boundary conditions of interest.
We describe a simple construction in the temperature saturation plane that determines the complete solution for the given
conditions. Applications of the theory developed here are in clean up of soil contaminated with nonaqueous phase liquids.
We show that a substantial cold gaseous zone develops in all solutions of practical interest, thus counteracting downward
migration of the pollutant. 相似文献
164.
This work focuses on heat and mass transfers with phase change in porous media. The experimental analysis was carried out in an aerodynamic return-flow wind tunnel, with very small cylinders of cellular concrete. For the local analysis, the samples were fitted with thermocouples and pressure sensors. A method of temperature and pressure field visualization is developed to highlight the dynamics of transport phenomena. We show two specific phenomena: (1) liquid outflow generated by the overpressure and (2) vaporization of the water inside a two-phase zone that progressively pervades the sample. 相似文献
165.
166.
167.
采用共沉淀法制备了CuO/ZnO/CeO2/ZrO2甲醇水蒸气重整催化剂,探讨了陈化时间对催化剂性能的影响.结果发现,延长陈化时间能增加催化剂的表面铜原子数和改善催化剂的还原性能,但与此同时也降低了催化剂的储放氧性能.延长陈化时间,CuO/ZnO/CeO2/ZrO2催化剂的氢产率随表面铜原子数的增加而成线性增长.另一方面,重整尾气中的CO含量也随着储放氧能力的下降而增加.综合考虑产氢率和重整尾气中CO含量,最佳陈化时间为2h,此时,CuO/ZnO/CeO2/ZrO2催化剂表现出了最佳性能. 相似文献
168.
水蒸气气氛煤中温催化气化动力学研究 总被引:1,自引:0,他引:1
水蒸气气氛煤中温催化气化动力学研究 《燃料化学学报》2013,41(10):1166-1172
以碳酸钾为催化剂,用热天平的等温热重法研究了四种不同变质程度煤焦常压下水蒸气催化气化反应动力学。在加和不加碳酸钾条件下,测定了温度为700~850℃煤焦的化学反应控制条件下的碳转化率与时间的关系。碳酸钾催化剂的加入对变质程度越高煤的气化催化作用越大。加碳酸钾的碳转化率与时间的关系用混合模型和修正随机孔模型可以良好的拟合关联,均相模型关联较差。利用修正随机孔模型拟合关联出了四种煤焦催化水蒸气气化反应的活化能和指前因子,活化能为90.317~167.861kJ/mol,指前因子和活化能之间具有补偿效应。 相似文献
169.
R. Francke J. Heine G.-V. Röschenthaler 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):377-380
Abstract Selected acyclic and cyclic phosphites (RO)2PX (1-5) were reacted with activated ketones (CF3)2CO (6) and Z-CF3C(O)CH=C(OH)CF3 (7a) / E-CF3C(O)CH=C(OSiMe3)CF3 (7b) in order to study the influence of R and X on the product formation. A new type of insertion, a 1,4 group shift and cyclo-addition reactions yielding five membered rings and bicyclic fused systems were observed. In most cases phosphonates and their λ5[sgrave]5 P derivatives were obtained. The ketones in question can be considered versatile reactants in phosphorus chemistry. 相似文献
170.
采用HJ535-2009《水质氨氮的测定纳氏试试剂分光光度法》测定水样氨氮时,当水样浑浊或有颜色时用蒸馏法对样品进行预处理,但该处理方法测定结果偏低,远远超出误差允许范围。提出以0.45μm滤膜过滤样品后进行测定,并在比色过程用过滤水样作色度校准。方法改进后对标准样品进行测定,测定结果与标准值相一致。采用改进后的方法对实际样品进行测定,加标回收率为96.7%,测定结果的相对标准偏差为3.60%(n=6)。该法测试数据稳定、结果可靠,适合于汛期地表水中氨氮的测定。 相似文献