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Gas–liquid separators are one type of surface facility among those used in oil fields. In this paper, the study of gas–liquid separation in a cylindrical cyclone separator (GLCC) using computationa...

espanolRESUMEN En este documento, se describe el desarrollo e implementacion de un modelo de simulacion molecular que describe la nucleacion del proceso de condensacion de componentes pesados del gas natural mezclas de alcanos lineales (Ci - C6 y C9) a condiciones de transporte (10 - 40 bar). Especificamente, se uso el metodo de Monte Carlo con sesgo configuracional, el campo de fuerza llamado de atomo unido para equilibrio de fases (TraPPE-UA) y la tecnica de muestreo sombrilla. El crecimiento de las gotas fue evaluado con el modelo de Young considerando numeros de Knudsen por debajo de 0.1. Los resultados de simulacion obtenidos para la nucleacion y crecimiento de gota fueron comparados con datos experimentales reportados en la literatura con el fin de validar los modelos implementados. Las simulaciones predicen un tamano de la gota de 2.09 μm el cual esta de acuerdo con los resultados experimentales. EnglishABSTRACT This paper describes the development and implementation of a molecular simulation model to predict the nucleation process during the condensation of heavy components of the gas natural mixtures of linear alkane (C1 - C6 and C9) at transport conditions (10-40 bar). Specifically, it was used the Monte Carlo method with configurational-bias, the united-atom force field known as "Transferable Potentials for Phase Equilibria (TraPPE-UA)," and the Umbrella sampling technique. The growth of the droplets was evaluated with the model of Young considering numbers of Knudsen below 0.1. The simulation results obtained for the droplet nucleation and growth were compared with experimental data reported in the literature with the aim of validating the implemented models. The simulations predict a droplets size of 2.09 μm which is in good agreement with the experimental results.

espanolDebido a los graves problemas presentados a causa del amplio uso de biocombustibles de primera generacion, los biocombustibles de segunda generacion se presentan como una posible mejor alternativa para la sustitucion de los combustibles convencionales provenientes del petroleo. En el presente articulo se presenta un estudio del desempeno de motores diesel alimentados con bio-oil hidrotratado proveniente de biomasa lignocelulosica, el cual es un biocombustible de segunda generacion; para esto se desarrollo un modelo termodinamico cero-dimensional de la combustion que predice los parametros de desempeno del motor. Dicho modelo fue validado contra datos experimentales de presion en camara de dos motores diesel alimentados con mezclas diesel/biodiesel y diesel/bio-oil hidrotratado observandose una buena correlacion entre los datos simulados y experimentales, con errores relativos promedio en los valores pico de presion de 0,5 y 1% respectivamente. Los resultados muestran que el bio-oil hidrotratado, al utilizarse en pequenas proporciones, puede convertirse en un sustituto parcial del combustible diesel convencional. EnglishDue to the serious problems encountered because of the extensive use of first-generation biofuels, second generation biofuels are presented as a possible best alternative for replacing conventional fuels from oil. This paper presents a theoretical study of the performance of diesel engines fueled with hydrotreated bio-oil from lignocellulosic biomass, which is a second generation biofuel. For this, a thermodynamic zero-dimensional combustion model simulation was carried out; it predicts the performance parameters of the engine. This model was validated against experimental data of two diesel engines fueled with diesel-biodiesel and diesel/hydrotreated bio-oil blends, and a good correlation between simulated and experimental data was observed, with average relative errors, in pressure peak values, of 0.5 and 1% respectively. The results show that hydrotreated bio-oil in small proportions could become a partial substitute for conventional diesel fuel.

In our previous articles (Energy & Fuels 2017, 31, 133–139 and Energy & Fuels 2017, 31, 8997–9005), it was presented that the asphaltenes of the Colorado field have different chemical structures, and these change the properties of crystallization of the paraffins. In this paper, we present a new way to understand the effects of the chemical structure of the asphaltenes on crude oil rheology, which includes correlating the average molecular parameters (AMPs) and the concentration of the asphaltenes with rheological properties using chemometric methods such as the partial least squares method. The asphaltenes were separated from six crude oil samples (average °API of 38) and were characterized using nuclear magnetic resonance to determine their main molecular parameters. Rheological properties including viscosity, yield stress, and gel temperature were experimentally determined for each of the crude oil samples and their respective maltenes. The results of a multivariate analysis show that the AMPs of the a...

In a previous article (Molina V., D.; Energy Fuels 2017, 31, 133−139; DOI: 10.1021/acs.energyfuels.6b01887) the structural differences of asphaltenes in Colombian light crude oils from the same field, i.e., the Colorado oilfield, were presented. Colorado crude oil is a light crude with very low content of asphaltenes (

espanolRESUMEN Las fuerzas de adhesion entre asfalto y diferentes minerales fueron obtenidas empleando el microscopio de fuerza atomica (AFM). El AFM permite el estudio de la interaccion entre dos moleculas en la misma superficie o en interfaces y su comportamiento. En esta investigacion, varias muestras de asfalto con diferentes propiedades fueron puestas en contacto con puntas modificadas para el AFM. Estas puntas fueron fabricadas con minerales comunmente encontrados en los agregados empleados en mezclas asfalticas, como son en dioxido de silicio (SiO2) y el carbonato de calcio (CaCO3). El trabajo de adhesion fue obtenido empleando curvas de fuerza - distancia para cada sistema asfalto-mineral. La medicion directa de las fuerzas desarrolladas entre asfalto y agregado en la interface empleando tecnicas nanoscopicas proveen un mejor entendimiento del sistema y sus caracteristicas. Esto, sin duda alguna contribuira en la seleccion de combinaciones asfalto - agregado empleadas en mezclas asfalticas que desarrollen enlaces mas fuertes, produciendo sistemas mas resistentes a las diferentes fallas relacionadas al fenomeno de adhesion que pueden generarse en pavimentos asfalticos. EnglishABSTRACT The adhesion forces between bitumen and minerals were measured, using Atomic Force Microscopy (AFM). The AFM enables the study of the interactions between two molecules in a same surface or at interfaces and their behavior. In this case, bitumen samples with different properties were placed in contact with AFM modified tips. The tips were fabricated with minerals found in aggregates used in asphalt mixtures, like silicon dioxide (SiO2) and calcium carbonate (CaCO3). The work of adhesion was obtained measuring adhesion forces for each bitumen-mineral pair. The direct measurement of forces between asphalt and aggregates at interface level through nanoscopic techniques provides a better insight of the system and its characteristics. This will help to improve the selection of bitumen-aggregate combinations used in asphalt mixtures, obtaining systems with higher bond strength, therefore more resistant to failures. portuguesRESUMO As forcas de adesao entre o asfalto e diversos minerais foram obtidas atraves microscopio de forca atomica (AFM) O AFM possibilita o estudo entre duas moleculas na mesma superficie ou em interfaces e seu comportamento. Varias amostras de asfalto com diversas propriedades foram colocadas em contato com pontas modificadas para o AFM, nesta pesquisa. Essas pontas foram fabricadas com minerais geralmente encontrados nas adicoes empregadas em misturas asfalticas, tais como dioxido de silicio (SiO2) e o carbonato de calcio (CaCO3). O trabalho de adesao obteve-se empregando curvas de forca (distância para cada sistema asfalto-mineral). A medicao das forcas desenvolvidas entre asfalto e adicao na interface utilizando tecnicas nanoscopicas dao uma melhor compreensao do sistema e suas caracteristicas. Isso, sem duvida nenhuma, ira contribuir na selecao de combinacoes asfalto - adicoes utilizadas em misturas asfalticas que desenvolvam ligacoes mais fortes, produzindo sistemas mais resistentes as diversas falhas relacionadas com o fenomeno de atrito que podem ser geradas em pavimentos asfalticos.

espanolResumen La separacion fisica de liquidos y gases es una de las operaciones de produccion, procesamiento y tratamiento en la industria petrolera, necesaria para prevenir danos en equipos rotativos, evitar corrosion en tuberias y cumplir con las especificaciones de calidad del gas natural para uso domestico. Cuando la presion de operacion aumenta, la diferencia de densidades entre las fases disminuye, lo cual dificulta el proceso de separacion. Se realiza la revision del estado del arte, desde los anos 90 hasta el presente, de las diferentes metodologias para separar las fases liquida y gaseosa del gas natural, asi como las variables de diseno con aplicacion a sistemas que operan a alta presion; prestando especial enfasis en los avances encontrados utilizando Dinamica de Fluidos Computacional. Los resultados muestran que, aunque los separadores centrifugos y los separadores supersonicos son mas compactos y de facil mantenimiento comparados con los separadores gravitacionales, estos ultimos continuan siendo la estrategia mas favorable cuando se combinan alta presion y baja cantidad de liquido (menos del 4% vol), como es el caso del gas natural. Conclusion adjudicada, en parte, a la falta de estudios experimentales/numericos que involucren al gas natural en equipos alternativos al separador gravitacional portuguesResumo A separacao fisica de liquidos e gases e uma das principais operacoes de producao, processamento e tratamento na industria do petroleo, necessaria para evitar danos ao equipamento rotativo, para evitar a corrosao nos tubos e para cumprir as especificacoes de qualidade do gas natural para uso domestico. Quando a pressao de operacao aumenta, a diferenca de densidade entre as fases diminui, o que torna o processo de separacao dificil ou, em alguns casos, impossivel. Neste trabalho, e realizada a avaliacao do estado da arte de diferentes metodologias para separar as fases liquida e gasosa do gas natural e as variaveis de design com aplicacao para sistemas que operam a alta pressao a partir dos anos 90 ate a data atual; com enfase especial nos avancos encontrados usando a Dinâmica dos Fluidos Computacional. Os resultados mostram que, embora ambos os separadores centrifugos e supersonicos sao mais compactos e de facil manutencao comparado com separadores gravitacionais, o ultimo continua a ser a estrategia favorecida quando a alta pressao e de baixa quantidade de liquido sao combinados (menos de 4% vol), como e o caso do gas natural; Conclusao concedida, em parte, a falta de estudos experimentais/numericos envolvendo gas natural em equipamentos alternativos ao separador gravitacional EnglishAbstract The Physical separation of liquids and gases is one of the main operations of production, processing and treatment in the oil industry; it is necessary to prevent damage to rotating equipment, to avoid corrosion in pipes and to achieve with the natural gas quality specifications for domestic use. When the operating pressure increases, the density difference between the phases decreases, which makes the separation process difficult or in some cases impossible. In this work, the state of the art of the different methodologies to separate the liquid and gaseous phases of natural gas is reviewed , as well as the design variables applied to systems that operate at high pressure from the 90's to the present; with special emphasis on the advances found using Computational Fluid Dynamics. The results show that, although both centrifugal and supersonic separators are more compact and easy to maintain compared to gravitational separators, gravitational separators remain the most favorable strategy when combining high pressure and low liquid load (less than 4%vol), as is the case of natural gas. Conclusion awarded, in part, to the lack of experimental/numerical studies involving natural gas in alternative equipment to the gravitational separator

This study embraces the evaluation of the rheological and magneto-rheological properties of heavy and extra-heavy crude oils by applying nanotechnology and magnetism as technological solutions in reducing viscosity. Mixtures of heavy oils with ferrofluids were used to study the viscous effects induced by the action of external magnetic fields. The rheological evaluation covered rotational and oscillatory tests as a function of time and temperature. In the magneto-rheological characterization, there were analyzed the magnetoviscous effects. The results revealed that the crude oils are viscoelastic materials that follow the Generalized Maxwell Model over a wide range of temperatures (-5 to 60 °C). It was also proved that the synergy between the carrier liquid and the nanoparticles promoted a significant reduction of viscosity (~98–99%) and viscoelasticity, which was directly related to the simultaneous action of the solvent and the asphaltene adsorption onto the nanoparticles surface. Critical concentrations of nanoparticles (0.2 wt% and 0.6 wt%) were proved to promote the maximum decrease in viscosity (additional ~ 0.3–0.5% or 1000-3000 cP) and the elastic storage modulus, which was crucial evidence of their effect on hindering the aggregation mechanisms of asphaltenes. In the heavy oil–ferrofluid mixtures, a magneto-rheological effect was demonstrated. The magnetic field attenuated the initial relaxation processes, leading to an increase in the viscosity and shear stress. The phenomenon was attributed to the formation of magnetic chains, such as that observed in magneto-rheological fluids. These results were supported by Scanning Electron Microscopy, which showed the formation of magnetic-field induced thick columnar assemblies of nanoparticles-asphaltene complexes.

This paper describes the development and implementation of a molecular simulation model to predict the nucleation process during the condensation of heavy components of the gas natural mixtures of linear alkane (C1 - C6 and C9) at transport conditions (10-40 bar). Specifically, it was used the Monte Carlo method with configurational-bias, the united-atom force field known as "Transferable Potentials for Phase Equilibria (TraPPE-UA)," and the Umbrella sampling technique. The growth of the droplets was evaluated with the model of Young considering numbers of Knudsen below 0.1. The simulation results obtained for the droplet nucleation and growth were compared with experimental data reported in the literature with the aim of validating the implemented models. The simulations predict a droplets size of 2.09 μm which is in good agreement with the experimental results. RESUMEN En este documento, se describe el desarrollo e implementación de un modelo de simulación molecular que describe la nucleación del proceso de condensación de componentes pesados del gas natural mezclas de alcanos lineales (Ci - C6 y C9) a condiciones de transporte (10 - 40 bar). Específicamente, se usó el método de Monte Carlo con sesgo configuracional, el campo de fuerza llamado de átomo unido para equilibrio de fases (TraPPE-UA) y la técnica de muestreo sombrilla. El crecimiento de las gotas fue evaluado con el modelo de Young considerando números de Knudsen por debajo de 0.1. Los resultados de simulación obtenidos para la nucleación y crecimiento de gota fueron comparados con datos experimentales reportados en la literatura con el fin de validar los modelos implementados. Las simulaciones predicen un tamaño de la gota de 2.09 μm el cual está de acuerdo con los resultados experimentales.

The simulation of an industrial boiler in CFD (Computational Fluid Dynamics) is usually done by stages due to the extensive size and the different physical phenomena that occur in different locations of the equipment. In this work, the simulation of an industrial grate boiler is done in three stages, one for the primary air circuit, another one for the secondary air circuit and the final one is the furnace. The combustion of sugarcane bagasse is a complex phenomenon that involves moisture vaporization, devolatilization and char combustion, in order to account for those phenomena, bagasse particles were modeled in a Eulerian-Lagrangian approach. The simulations were performed in commercial software ANSYS FLUENT and the devolatilization model were programmed in C language as a User Defined Function (UDF). When the results of the simulations were compared with experimental data, a satisfactory agreement was observed. Simulations were performed with primary and secondary air inlets modifications in order to optimize the boiler performance, the results of those simulations showed significant improvement in the combustion parameters. La simulación de una caldera industrial en CFD se realiza, usualmente, por etapas debido al gran tamaño y a los diferentes fenómenos físicos que ocurren dentro del equipo. En este trabajo, la simulación de una caldera industrial de parrilla se realiza en tres etapas, la primera es el circuito de aire primario, la segunda es el circuito de aire secundario y la tercera corresponde a la caldera. La combustión de bagazo de caña es un fenómeno complejo que involucra vaporización de la humedad, devolatilización y combustión del carbón, de forma que para evaluar esos fenómenos las partículas de bagazo fueron modeladas en un marco Euleriano-Lagrangiano. Las simulaciones fueron desarrolladas en el software comercial ANSYS FLUENT y la tasa de devolatilización fue programada en lenguaje C como una función definida por el usuario. Cuando los resultados de las simulaciones se compararon con datos experimentales, se observó una concordancia satisfactoria. Se realizaron simulaciones con modificaciones en las entradas de aire primario y secundario buscando optimizar el funcionamiento de la caldera y los resultados de esas simulaciones presentaron una mejoría significativa en los parámetros de combustión.

En la industria de la panela (denominada azúcar sin centrifugar por la FAO), se estima que los evaporadores de múltiple efecto (EME), permiten un mayor control e incrementan en un 36 % la eficiencia global del proceso. No obstante, la implementación de estas tecnologías requiere que, además del ajuste técnico del proceso, también se mantenga la calidad de la panela obtenida en los sistemas de evaporación abierta. Condición que ha develado un vacío tecnológico respecto a la influencia de las complejas reacciones que ocurren durante la evaporación y concentración del jugo sobre las características de la miel de caña y la panela. Con el fin de llenar parte de este vacío tecnológico, el objetivo del trabajo aquí presentado fue determinar el efecto de las variables de evaporación: presión y flujo calórico sobre la calidad de la miel de caña y la panela. Para lograrlo, se trabajó un diseño experimental completamente al azar con un arreglo factorial 4x3, cuatro repeticiones y la variedad de caña CC 85-46, sin floculante, coadyuvante, ni antiespumante. Los resultados mostraron que los sistemas presurizados y con densidades de flujo calórico bajo (17 kW/m2), afectan negativamente la calidad de la panela en aspectos como color, pH, índice glucósido y solidificación, hasta el punto de no cumplir con los requerimientos de la Resolución 779 del Ministerio de Protección Social colombiano respecto a sacarosa y azúcares reductores.

The implementation of multi-effect evaporators on panela (unrefined whole cane sugar) production process requires, besides the technological adjustment, to maintain product characteristics; this condition revealed the lack of knowledge of the effect of evaporation pressure on the quality of panela. In order to fill part of this gap, this study sought to determine the effect of both theconcentration of antifoam and the use of a flocculant (Heliocarpus popayanensis Kunth) and an adjuvant (lime) on the quality of sugar honey and panela, when evaporation is performed at different atmospheric pressures. In order to achieve this, the present study worked on two completely randomized experimental designs with four replications, a density of evaporation heat flow of 27.78 kW/m2 and juice from the CC85-46 variety. In the first design, two variables were studied: evaporation pressure and use of flocculant and adjuvant with a 4x2x2 factorial arrangement without antifoam.In the second design, variables evaporation pressure and quantity of antifoam with a 4x3 factorial arrangement without flocculant nor adjuvant were studied. The results show that the quality of the product deteriorates in pressurized systems (glucoside coefficient increases up to 200%), is not affected by the use of 50 μL of antifoam per liter of clarified juice and improved by the use of flocculant (turbidity is reduced by 55%). Solidification and hardness improve with the addition of the adjuvant, but this increased 48% color and 24% turbidity.

This paper reviews the impact of asphaltenes on wax crystallization and on the properties of crude oils, and the consequences thereof on the flow assurance of waxy crude oil. It initially includes studies of the crystallization of both pure n-alkanes as well as the mixtures thereof, because they have led to an understanding of how their precipitation occurs along with their transitions of crystalline phases, particularly, by studies of X-ray diffraction (XRD). This is followed by the studies and results of crystallization in crude oils and/or the fractions thereof and how their properties are affected in the presence of asphaltenes. The results on the influence of asphaltenes are inconclusive and sometimes contradictory: some confirm that their presence decreases pour point, others affirm that it increases it and yet others say there is no effect. Similar results have been reported for properties such as crystallization point, phase transition and rheological properties. The influence of the chemical structure of asphaltenes on the change in crude oil properties has not been generalized either. It has been inferred that is possibly due to the interaction between aliphatic chains of asphaltenes and waxes, and it has been established that there is synergy in coprecipitation due to evidence in the analysis of organic deposits.

El estudio del proceso de combustión en motores Diésel ha sido, durante años, un tema de gran interés debido principalmente a la creciente necesidad de mejorar el rendimiento de los motores, reducir el consumo de combustible y reducir la emisión de contaminantes. Los estudios experimentales presentan la desventaja de requerir grandes recursos económicos y tiempo en su realización, razón por la cual se utilizan modelos computacionales que permiten estudiar el proceso de combustión de una forma más económica y práctica. En este artículo se presenta una revisión de varios de los modelos de combustión en motores Diésel más relevantes, desarrollados a nivel nacional e internacional, con el fin de dar al lector una visión de la evolución y el estado actual de este tipo de modelos.

En la industria de la panela (denominada azúcar sin centrifugar por la FAO), se estima que los evaporadores de múltiple efecto (EME), permiten un mayor control e incrementan en un 36 % la eficiencia global del proceso. No obstante, la implementación de estas tecnologías requiere que, además del ajuste técnico del proceso, también se mantenga la calidad de la panela obtenida en los sistemas de evaporación abierta. Condición que ha develado un vacío tecnológico respecto a la influencia de las complejas reacciones que ocurren durante la evaporación y concentración del jugo sobre las características de la miel de caña y la panela. Con el fin de llenar parte de este vacío tecnológico, el objetivo del trabajo aquí presentado fue determinar el efecto de las variables de evaporación: presión y flujo calórico sobre la calidad de la miel de caña y la panela. Para lograrlo, se trabajó un diseño experimental completamente al azar con un arreglo factorial 4x3, cuatro repeticiones y la variedad de caña CC 85-46, sin floculante, coadyuvante, ni antiespumante. Los resultados mostraron que los sistemas presurizados y con densidades de flujo calórico bajo (17 kW/m²), afectan negativamente la calidad de la panela en aspectos como color, pH, índice glucósido y solidificación, hasta el punto de no cumplir con los requerimientos de la Resolución 779 del Ministerio de Protección Social colombiano respecto a sacarosa y azúcares reductores. In the industry of panela (called uncentrifuged sugar by the FAO), is estimated that multiple-effect evaporators (EME), allow greater control and increases by 36 % the overall efficiency of process. However, the implementation of these technologies requires the technical adjustment of the process; it keeps the quality of panela obtained in open systems evaporation too. Condition has unveiled a technological gap with respect to influence of the complex reactions that occur during water evaporation and concentration of sugars on the characteristics of sugar cane and brown sugar. To fill part of this technological gap, the objective of the work presented here was determine the effect of the variables of evaporation, pressure and heat flux on the quality of sugar cane and the panela. To achieve this, it worked one experimental design, completely at randomized with 4x3 factorial arrangement, four repetitions and the variety of cane CC 85-46, without flocculant, adjuvant or antifoam. The results showed that heat flow densities of 17 kW/m² and pressurized systems, adversely affect quality of panela in areas such as color, pH, glycoside and solidification rate, to the point of not meeting the requirements of resolution 779 of the Colombian Ministry of Social Protection from sucrose and reducing sugars.

The flow of a ferrofluid between two parallel infinitely long plates generated by a rotating magnetic field has been studied analytically and numerically using spin diffusion theory for a broad range of frequencies and intensities of the magnetic field. This work was motivated by interest in obtaining better agreement between the theoretical predictions and the experimental observations of the dependence of the flow magnitude on the amplitude and frequency of the magnetic field. These discrepancies have been attributed to the use of asymptotic solutions to assess velocity profiles obtained to moderate magnetic field strength and to the need to use a more accurate magnetization equation to high amplitudes and frequencies of the magnetic field. For such reasons, the objective of this work was to evaluate the effect of the magnetization equations derived by Shliomis [Sov. Phys. JETP 34, 1291 (1972)] (Sh-72) and by Martsenyuk, Raikher, and Shliomis [Sov. Phys. JETP 38, 413 (1974)] (MRSh-74) on the flow predic...

La implementación de evaporadores multiefecto en el proceso panelero requiere, además del ajuste tecnológico, mantener las características del producto; esta condición develó el desconocimiento del efecto de la presión de evaporación sobre la calidad de la panela. Para llenar parte de este vacío, se buscó determinar el efecto tanto de la concentración de antiespumante como del uso de floculante (Heliocarpus popayanensis Kunth) y coadyuvante (cal) sobre la calidad de la miel y la panela, cuando la evaporación se realiza a presiones diferentes a la atmosférica. Para ello, se trabajó en dos diseños experimentales completamente al azar, con cuatro repeticiones, una densidad de flujo calórico de evaporación de 27,78 kW/m² y jugo de la variedad CC85-46. En el primero se estudiaron las variables presión de evaporación y uso de floculante y coadyuvante, con un arreglo factorial de 4x2x2 y sin antiespumante. En el segundo, se estudiaron las variables presión de evaporación y cantidad de antiespumante, con un arreglo factorial de 4x3 y sin floculante ni coadyuvante. Los resultados permiten concluir que la calidad del producto se deteriora en sistemas presurizados (se incrementa el coeficiente glucósido hasta en 200%), no se afecta con el uso de hasta 50 mL de antiespumante por litro de jugo clarificado y mejora con el uso de floculante (se disminuye la turbidez en 55%). La solidificación y la dureza mejoran con el coadyuvante, pero este incrementa 48% el color y 24% la turbidez. The implementation of multi-effect evaporators on panela (unrefined whole cane sugar) production process requires, besides the technological adjustment, to maintain product characteristics; this condition revealed the lack of knowledge of the effect of evaporation pressure on the quality of panela. In order to fill part of this gap, this study sought to determine the effect of both the concentration of antifoam and the use of a flocculant (Heliocarpus popayanensis Kunth) and an adjuvant (lime) on the quality of sugar honey and panela, when evaporation is performed at different atmospheric pressures. In order to achieve this, the present study worked on two completely randomized experimental designs with four replications, a density of evaporation heat flow of 27.78 kW/m² and juice from the CC85-46 variety. In the first design, two variables were studied: evaporation pressure and use of flocculant and adjuvant with a 4x2x2 factorial arrangement without antifoam. In the second design, variables evaporation pressure and quantity of antifoam with a 4x3 factorial arrangement without flocculant nor adjuvant were studied. The results show that the quality of the product deteriorates in pressurized systems (glucoside coefficient increases up to 200%), is not affected by the use of 50 μL of antifoam per liter of clarified juice and improved by the use of flocculant (turbidity is reduced by 55%). Solidification and hardness improve with the addition of the adjuvant, but this increased 48% color and 24% turbidity.

This study evaluated the efficiency of pans in furnaces to jaggery making. It was modified the geometry of thermal energy´s transfer area of pans to asses such efficiency. The background of open pans (typically flat) was changed for a geometry similar to parallel channels with different cross sections arranged in the direction of movement of the combustion gases. The furnace efficiency was determined for different positions and heights of new pans in the oven. The results showed that new design improved energy transfer, especially geometry with triangular cross section where the height between the floor of the duct and the bottom of the pan was 8cm. There was a significant improvement in the efficiency of utilization of thermal energy, resulting in a saving of 28.48% of fuel.

El objetivo de este trabajo es estudiar el proceso de deposicion de parafinas sobre la superficie interna de las tuberias de produccion de petroleo y la influencia de parametros como la velocidad de flujo y la temperatura de la pared sobre el espesor del deposito para un crudo ligero con alto contenido parafinico considerando tres condiciones de frontera sobre la pared de la tuberia; dos de las cuales suponen un perfil de temperatura en la frontera, hecho que no ha sido considerado en trabajos anteriores, y la tercera un valor constante. El analisis se realizo suponiendo condiciones seudo-estables en la fase fluida. El metodo de diferencias finitas se aplico para resolver el sistema de ecuaciones diferenciales y la solucion se llevo a cabo numericamente utilizando el lenguaje de programacion C++. El modelo fue validado a partir de los resultados experimentales reportados por Singh et al. (2000) y posteriormente utilizados para simular el crecimiento de los depositos de parafina como una funcion de la velocidad de flujo y la temperatura de la tuberia. Los resultados mostraron que el aumento de la velocidad de flujo reduce el maximo espesor del deposito, pero este se extiende sobre una distancia mas larga sobre la tuberia cuando se considera una temperatura de pared constante o cuando se considera el gradiente de temperatura axial con pendiente positiva; mientras que se observa el efecto contrario cuando se considera el gradiente de temperatura axial con pendiente negativa.