Measurement of the neutron proton spin correlation parameter Azz at forward angles

The n-p spin correlation parameter Azz was measured at an energy of 68 MeV and 7 angles in the range of 22.5° - 57.3° CM with a statistical accuracy better than 0.01. In the measured range, Azz is most semsitive to є1, the mixing parameter of the deuteron states 2S1 and 2D1. Therefore the measurement is expected to reduce significantly the uncertainties of the phases in the energy range below 100 MeV, when a new global Phase Shift Analysis (PSA) is performed. This should help to find a more accurate answer to the strength of the tensor force in the NN-interaction. The experiment was performed in the low energy area C (NEC) of the Paul Scherrer Institute )PSI) in Villigen, Switzerland

Single-phase media hydrodynamics and heat transfer in heat exchangers with twisted profile tubes

A profiled heat exchanger tube is the one in which some features have been incorporated into the tube geometry for heat transfer enhancement. They offer a perspective method of steam turbine shell-and-tube heat exchangers improvement. Twisted profile tubes (TPT) are widely used in power engineering. This paper presents some results of experimental and theoretical research of hydrodynamics and heat transfer in TPTs. It is revealed that the heat transfer coefficient for water flow in a TPT increases up to 80% compared to that of a plain tube. With a rise of media Reynolds number, the heat transfer rate in a TPT decreases in comparison to that of a plain tube, but for air flow in a TPT the heat transfer coefficients ratio does not depend on the Reynolds number value. Water flow hydraulic losses in TPTs increase from 15 to 100% depending on the tube profile parameters. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Contribución al estudio de la hidrodinámica y transferencia simultánea de masa en biorreactores airlift de tres fases: producción de un consorcio microbiano degradador de petróleo

Los biorreactores multifásicos son sistemas en los cuales una fase orgánica es adicionada a la fase acuosa (por ejemplo agua contaminada con petróleo). Estos sistemas son relativamente recientes y todavía poco estudiados. En este trabajo, se estudió la hidrodinámica en biorreactores de 10 L tipo airlift (BAL) de tres fases, lo que permitió: (i) seleccionar la configuración geométrica del BAL que generó los mejores números de Reynolds de la fase acuosa (Reaq); (ii) proponer un Re representativo del BAL, que relacionó la hidrodinámica con la transferencia de masa de la fase orgánica (constituida por hexadecano (HXD)) a la fase acuosa; éste se definió como la diferencia entre el Re de la fase HXD (ReHXD) y Reaq, (Reaq- HXD); (iii) caracterizar las zonas de operación del BAL usando Reaq-HXD como criterio. La configuración geométrica con la relación de diámetros (tubo concéntrico/BAL) que generó los mejores Reaq fue 0.65 y la de alturas fue 0.77. El Reaq-HXD fue el mismo en la zona de ascenso y descenso para Ug mayores de 0.6 cm s-1 (alrededor de 3000). Con la configuración geométrica seleccionada y con el Reaq-HXD como criterio característico de las zonas de estudio en los BAL se estudió la transferencia de masa en biorreactores de 10 L, lo que permitió: (i) desarrollar una nueva técnica analítica para la determinación dinámica de la tasa de transferencia de HXD (TTH); (ii) proponer el cociente entre las tasas de transferencia de HXD y oxígeno TTH/TTO como el criterio de ingeniería que considera la tasa con la que se transfieren los dos sustratos involucrados en un proceso biotecnológico de degradación aerobia de HXD y (iii) asociar el criterio TTH/TTO con las velocidades de la fase gaseosa y facilitar su aplicación práctica. TTH/TTO fue menor a 0.03 a lo largo de los 14 días de cultivo mostrando que no hubo limitaciones por oxígeno. Se aplicó el criterio del cociente TTH/TTO a un proceso biotecnológico, lo que permitió: (i) incrementar la eficiencia (rendimiento y productividad) de la producción del consorcio microbiano y (ii) el escalamiento descendente (BAL de 0.5 y 10 L, factor de escala 20) de la producción del consorcio microbiano. La mayor productividad del consorcio (1.02 ± 0.03 g SS (L h)-1) fue alcanzada usando una estrategia de Ug variable, que considera el cociente TTH/TTO y requiere un menor gasto de energía. Una de las aportaciones principales de este trabajo es el estudio de un bioproceso con transferencia de masa y reacción (degradación de HXD y crecimiento microbiano) simultánea. El uso del cociente TTH/TTO permitió mejorar la productividad del consorcio microbiano degradador de petróleo, que puede ser utilizado como inóculo para la remediación de agua y suelos (al menos en el horizonte A, que es la capa de suelo superficial) contaminados.Multiphasic bioreactors are systems in wich an organic phase is added to the aqueous phase (i.e. oil-contaminated water). The development of these reactors are relatively recent and they are still poorly understood. In this work, The hydrodynamic in 10 L three-phase airlift bioreactors (ALB) was studied. Our results allowed: (i) to select the geometrical configuration for that ALB with better aqueous-phase Reynolds numbers (Reaq); (ii) to propose a representative Re for ALB able to associate hydrodynamics with the organic phase (constituted by hexadecane (HXD)) mass transfer to the aqueous phase as the difference between the HXD phase Re (ReHXD) and Reaq, (Reaq-HXD) and, (iii) to characterize the ALB operation zones using Reaq-HXD. The diameters relation (draft tube/ALB) that generated the highest Reaq was 0.65 andthe de height relation was 0.77. Reaq-HXD was the same for riser and downcomer at Ug higher than 0.6 cm s-1 (around 3000). Mass transfer studies in three phases 10-L airlift type bioreactors, allowed us: (i) to develop a new dynamic technique for determining the rate of transfer of HXD (HTR) and (ii) to propose the ratio transfer rates between oxygen and HXD HTR/OTR as the engineering criterion that considers the rate at which the two of the substrates involved in a biotechnological process of aerobic degradation of HXD are transferred into the aqueous phase to be consumed. HTR/OTR was lower than 0.03 along 14-days culture showing no oxygen limitations. The ratio HTR/OTR was applied to a biotechnological process, which allowed: (i) to increase efficiency (performance and productivity) of the microbial consortium production and (ii) scaling down (scaling factor 20) the production of microbial consortium. The largest consortium productivity (1.02 ± 0.03 g SS (L h)-1) was reached using a variable Ug strategy, by considering HTR/OTR ratio at lower total energy consumption. One of the main contributions of this work is the study of a bioprocess with simultaneous mass transfer and reaction (HXD degradation and microbial growth) considerations. The use ratio HTR/OTR simultaneous mass transfer) allows to enhance the oil-degrading consortium, able to remediate soil and water oil-contaminated, productivit

STUDY OF MOTOR OIL COOLING AT LOW REYNOLDS NUMBER IN MULTI-PORT NARROW CHANNELS

Mini and micro-scale channels have drawn researchers\u27 attention in the past three decades. The use of these channels in a heat exchanger is due to the several advantages they provide. Motor oil was chosen as the working fluid since it is greatly utilized in automotive applications. In current investigations, experiments were performed to verify the aptness of cooling the oil through a cross-flow minichannel heat exchanger. The inlet temperature of the motor oil was kept constant at 75oC, while the air inlet temperatures were varied within the range of 20oC - 40oC. The range of oil Reynolds number was found to be between 0.85 to 3.5 whereas the air velocities were between 6 m/s and 18 m/s. Correlations were developed between the Nuoil and Reoil and Proil. The effect of Reoil on the heat transfer coefficient, NTU, and effectiveness were investigated. The results were compared with the findings of another viscous fluid where a similar test specimen was used and same trends were observed