Kinetics of absorption of carbon dioxide in aqueous ammonia solutions

AbstractIn the present work the absorption of carbon dioxide into aqueous ammonia solutions has been studied in a stirred cell reactor, at low temperatures and ammonia concentrations ranging from 0.1 to about 7 kmol m−3. The absorption experiments were carried out at conditions where the so-called pseudo first order mass transfer regime was obeyed–and hence the kinetics of the reaction between carbon dioxide and ammonia could be derived. The results were interpreted according to the well-established zwitterion mechanism

THEORETICAL VALIDATION OF TEST RESULTS FOR THE PRESSURE DROP VALUES OF CIRCULAR PINS WITH A MAXIMUM LENGTH TO DIAMETER RATIO OF 3.0 USING EXISTING EQUATIONS AND TEST DATA FOR HEAT EXCHANGER APPLICATION

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Pins are a very common type of extended surface used in the field of heat transfer; their main use being in the electronics field. In this report, the use of pins as an extended surface is considered for a Heat Exchanger application in the aerospace field. The Heat Exchanger uses forced convective heat transfer mechanism for the dissipation of heat and the implicated fluid is air. For this application the pin layout and design is completely unique in that the pin’s maximum length to diameter ratio is 3.0 and the layout of the pins produces an X T value of 7, which has not been explored in any previous work. The Length: Diameter ratio of these new pins is very small when compared to the Length: Diameter ratios of tubes currently used in heat exchangers to enhance heat transfer. Moreover, the distance between the pins in this arrangement is much greater than those for the tubes. Testing has been performed on this pin design and the theoretical validation of those test results is one of the main aspects discussed in this report. Due to the innovative nature of the pin designs, there is insufficient existing test data or established equations that can be used. Assumptions are made in order to be able to apply the current equations for pressure drop calculations with valid justifications. The theoretical results for the total pressure drop show an average deviation of 6% from the test results for mass flow rates between 0.14 kg/s and 0.36 kg/s. The maximum pressure drop was found to be caused by the pins and it was in the range of 89%-91%of the total. In this article, the limitations of existing equations are discussed and the gap in the theoretical knowledge regarding novel pin designs is highlighted.mp201

Hollow fiber membrane contactor as a gas-liquid model contactor

Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coefficient from first principles. Moreover, in the case of gas-liquid membrane contactor, the gas-liquid exposure time can be varied easily and independently without disturbing the gas-liquid interfacial area. These features of the hollow fiber membrane contactor make it very suitable as a gas-liquid model contactor and offer numerous advantages over the conventional model contactors. The applicability and the limitations of this novel model contactor for the determination of physico-chemical properties of non-reactive and reactive gas-liquid systems are investigated in the present work. Absorption of CO 2 into water and into aqueous NaOH solutions are chosen as model systems to determine the physico-chemical properties for non-reactive and reactive conditions, respectively. The experimental findings for these systems show that a hollow fiber membrane contactor can be used successfully as a model contactor for the determination of various gas-liquid physico-chemical properties. Moreover, since the membrane contactor facilitates indirect contact between the two phases, the application of hollow fiber model contactor can possibly be extended to liquid-liquid systems and/or heterogeneous catalyzed gas-liquid systems

El vestido de boda: La problematización de la condición femenina en un monólogo teatral de Emilia Pardo Bazán

This is the published version. Copyright 2007 Johns Hopkins University Press.Para divulgar sus ideas sobre la cuestión femenina, Emilia Pardo Bazán se acercó también a la escena y escribió, entre otras obras, el monólogo teatral El vestido de boda (1898). El género monológico se acopló perfectamente al discurso feminista de la autora, ya que le permitió construir a una protagonista que se expresaba libremente, sin que otro locutor le pusiese freno. La originalidad de El vestido de boda reside, sobre todo, en el uso que hace Pardo Bazán de la sátira y de la ironía para manipular las expectativas del público burgués al que iba destinada la pieza. Explotando hábilmente una serie de convenciones teatrales, la escritora resalta el culto a las apariencias de la sociedad española decimonónica, gran obstáculo a la emancipación de la mujer burguesa