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This work is aimed to study the wax deposition process on the internal surface of oil production pipelines and the influence of parameters such as flow rate and pipe wall temperature on the deposit thickness for a light crude oil with high paraffinic content considering three different temperature boundary conditions on the pipe wall; two of which assumed a profile temperature on the boundary, fact that has not been considered in previous works, and the third a constant value. The analysis was conducted assuming pseudo steady conditions on the fluid phase. The finite differences method was applied to solve the differential equation system and the solution was implemented numerically using the C++ programming language. The model was validated with the experimental results reported by Singh et al. (2000) and subsequently used to simulate the growth of the paraffin deposits as a function of flow rate and pipe temperature. The results showed that increased flow rates reduce the maximum deposit thickness, as it spreads on a longer distance in the pipe when considering a constant wall temperature or the axial thermal gradient with a positive slope, and the opposite effect is observed when considering the axial thermal gradient with a negative slope.

Combustion is the most commonly used technology to produce energy from biomass; nevertheless, there are still thermal efficiency problems in current biomass combustion furnaces and a lack of knowledge about the properties of residual biomasses that could be used as fuels. Aiming to contribute to knowledge of the potential of residual biomass for energy generation, this work reports on the implementation of a 2D computational model to study the combustion performance of several solid biomass fuels, and its application in the analysis of Lippia origanoides bagasse combustion. The model uses an Eulerian–Lagrangian approach; in the continuous phase, governing equations are solved, and in the dispersed phase, particles are tracked and the mass, momentum, species and energy transfer between the phases are calculated. The model was validated against experimental data from a combustor fueled by three biomasses: wood pellets, olive stone and almond shell. The results show deviations of less than 13%, with few exceptions, which indicates a good degree of agreement with experimental measurements compared with those reported by other studies on the subject. Furthermore, it was found that the stems of Lippia origanoides bagasse show similar performance to that of other biomass used as solid fuel, while the leaves present lower performance.

Biomass is an important renewable energy source that has great potential as a substitute for fossil fuels in the short and medium-term, which has led to the development of various methods for its energy conversion, of which combustion is the most widely used. This process has several environmental advantages compared to traditional energy sources, however, there is still a long way to go in terms of process efficiency and emission reduction. In this context, CFD computational models are a powerful tool that allows to study and improve the performance of combustion systems in a safe, fast and economical way, compared to experimental studies. OpenFoam is one of the most important CFD software currently available, however, there are few works that use it to simulate the combustion of solid biomass. In this work an application of the software in modeling of a biomass boiler fueled by grape marc is reported, this model allows predict important parameters like CO, H2O and velocity fields in a 2D domain.

En el presente artículo se muestra el desarrollo de una estrategia de cálculo para la simulación del campo del flujo en intercambiadores de calor siguiendo la metodología de los volúmenes finitos utilizando una formulación uno-dimensional. El método aplicado consiste en establecer las ecuaciones de conservación de la masa, energía y cantidad de movimiento a un elemento diferencial en cada una de las corrientes involucradas en el sistema a analizar. Tales ecuaciones, se integran a lo largo del intercambiador de calor, que junto con las ecuaciones de estado, y las ecuaciones que permiten evaluar ciertos parámetros empíricos, constituyen un sistema de ecuaciones no lineales a resolver. En este artículo se presenta un estudio sobre el uso de las estrategias de integración del sistema de ecuaciones secuencial paso a paso, solución simultánea, y el método SIMPLE y su influencia en el error y el tiempo de cálculo. Los resultados indican que el método de cálculo más efectivo en tiempo de cómputo y con error más pequeño es el método secuencial asumiendo que la temperatura de pared es constante.