ABSTRACT Asphaltenes represent the heaviest fraction of crude oils, being recognized by their tendency to self-associate and precipitate. Asphaltene precipitation and subsequent deposition can cause problems in all stages of production. The objective of this paper is to model Brazilian crude oil and asphaltene systems using the PC-SAFT equation of state. Asphaltenes were extracted from crude oil through the addition of different n-alkanes. The PC-SAFT was capable of accurately predicting liquid density for toluene and asphaltenes and boiling point elevation for crude oil at different concentrations of toluene. Asphaltene precipitation from model oil allowed us to evaluate the influence of binary interaction parameters on modeling results. The influence of precipitant agent (n-hexane and n-heptane) on the asphaltene phase behavior was analyzed, showing that n-hexane was able to precipitate more asphaltenes than n-heptane, as expected. Furthermore, simulated results are in agreement with experimental observations: the average relative errors are 3.75 % and 10.25 % for the weight percentage of precipitated asphaltene using n-hexane and n-heptane as precipitant, respectively.

Abstract Data Centers are growing steadily worldwide, and they are expected to continue growing up to 53% in 2020. Energy efficiency, in high power consumption, is a key venue. There are methodologies to measure this efficiency, one example is using the PUE (Power Usage Effectiveness) index. In this paper is proposed a new index for measuring efficiency at the design stage, the EUED (Energy Usage Effectiveness Design). This index allows to evaluate systems using “free cooling” and adiabatic system. A comparison is performed considering the equipment in the worst situation. The thermodynamics parameter enthalpy is used to calculate the results. This new methodology allows to determine differences between the cities of São Paulo and Curitiba (1.21%) and between Rio de Janeiro and Curitiba (10.61%). The values for the EUED index were 1.245 kW/kW for Curitiba, 1.260 kW/kW for São Paulo and 1.377 kW/kW for Rio de Janeiro, respectively, reaching a difference of 16.86% for Curitiba, 16.19% for São Paulo and 10.31% for Rio de Janeiro in relation to PUE COA (Power Usage Effectiveness Constant Outdoor Air). The advantage of the EUED is that it works with the 8,760 hours in the design phase, using psychometric elements to determine when to use free cooling and evaporative system, and more importantly varying the COP according to environmental characteristics.

A técnica de espectrofotometria na região do infra-vermelho próximo (NIR) é usada nesse trabalho para avaliar e controlar de forma contínua e em linha a evolução do tamanho médio de partícula em polimerizações de estireno em suspensão. Os resultados obtidos mostram que os espectros de NIR são sensíveis a modificações das condições de operação, podendo dessa forma prover informações sobre a evolução dinâmica da distribuição de tamanhos de partícula e sobre a estabilidade da suspensão durante a polimerização. Observa-se que a manipulação das variáveis normalmente utilizadas para modificar as curvas de distribuição de tamanhos, tais como a velocidade de agitação e a concentração de agente estabilizante, não causa modificações significativas na cinética da polimerização. Finalmente, experimentos mostram que a monitoração e controle contínuo da polimerização com a técnica de NIR permite projetar e obter distribuições de tamanho com valores médios pré-especificados, o que aponta para potencial desenvovlvimento de aplicações industriais.

This work presents the application of near-infrared (NIR) spectroscopy to the in-line monitoring of particle size in styrene suspension polymerizations. Results show that NIR spectra are sensitive to the different operational conditions and may provide information about particle dynamics and suspension stability. It is observed that the manipulation of important variables to the control of particle size distributions, such as stirrer speed and stabilizer concentration, does not cause any change to the polymerization kinetics. Finally, suspension polymerization experiments are carried out with in-line spectrophotometer, in order to obtain a specified average particle size, and results point out to potential industrial applications.