Ciclo de mejora en la asignatura Proyectos de la rama de ingeniería

La experiencia aquí descrita se enmarca en el Curso General de Docencia Universitaria perteneciente al Programa de Formación e Innovación Docente del Profesorado (FIDOP) de la Universidad de Sevilla. El objeto de esta contribución consiste en la caracterización de una experiencia real derivada de la aplicación de la metodología basada en los ciclos de mejora a una asignatura de la rama de ingenierías. En primer lugar, se caracterizará el contexto en el que se ha desarrollado de la experiencia, procediéndose posteriormente a exponer los detalles correspondientes al diseño, aplicación y evaluación del mencionado ciclo de mejora. Este trabajo concluye la recapitulación de los hechos que han permitido la reformulación de los principios didácticos del autor

Contribución a la simulación de la combustión HCCI en motores de combustión interna alternativos mediante modelos multizona

Falta resumen y palabras clavesEntre los desafíos a los que debe hacer frente la industria del motor de combustión interna alternativo (MCIA) cabe destacar tanto la reducción de emisiones como el aumento del rendimiento, ambos derivados de las cada vez más exigentes normativas en vigor en distintas áreas geográficas. Entre las medidas de mejora puestas en marcha por el sector de los MCIA cabe destacar la búsqueda de tecnologías alternativas a los tradicionales motores de encendido provocado (MEP) y diésel, es decir, de encendido por compresión (MEC), siendo la combustión en modo HCCI (Homogeneous Charge Compression Ignition) una de las opciones más prometedoras. Dado que los modelos multizona han demostrado, tras una oportuna calibración, ser capaces de reproducir la combustión en modo HCCI con suficiente precisión, a la vez que los recursos computacionales requeridos no son excesivos, el presente trabajo pretende contribuir al estado del arte mediante la elaboración de un nuevo modelo multizona fenomenológico, asociado a la combustión en modo HCCI tanto del gasoil como del biodiésel. Mediante este trabajo se aborda en primer lugar el estudio experimental de los efectos ejercidos sobre la combustión en modo HCCI por distintos métodos de preparación de la mezcla entre el combustible y el aire. Concretamente se analizan las implicaciones tanto de la inyección temprana (early HCCI) como de la inyección tardía (late HCCI), lo que permite la identificación de las distintas tendencias asociadas a la combustión en modo HCCI ante cambios en diferentes parámetros operativos. En paralelo a la realización del estudio experimental se ha construido un modelo numérico multizona, el cual se basa en sendas leyes funcionales para el modelado del comportamiento tanto del inicio de la combustión como de la tasa de liberación de calor. Combinando el previamente mencionado modelo multizona y los datos obtenidos durante la fase de experimentación en el laboratorio se ha procedido a la calibración de las leyes funcionales del inicio de la combustión y de la tasa de liberación de calor. De esta forma se ha obtenido un modelo fenomenológico predictivo que es capaz de reproducir la combustión en modo HCCI, como demuestra la bondad de los resultados obtenidos para la curva de presión, la tasa de liberación de calor y las emisiones de óxidos de nitrógeno

Experimental investigation and modelling of biodiesel combustion in engines with late direct injection strategy

The combination of alternate fuels, such as biodiesel, and low-temperature combustion (LTC) constitutes a promising solution to reduce pollutant emission and to avoid dependence on fossil fuels. However, this concept requires additional research to optimise LTC of biodiesel over wider operating ranges, specifically including the implementation of numerical models to assist in the development of these engines. In this work, an experimental analysis was carried out assessing both thermal performance and emissions derived from the LTC of diesel/biodiesel blends with late direct injection. Furthermore, this analysis allowed implementing a predictive tool to characterise in-cylinder pressure trace under this operation strategy. This model was coupled with an empirical law to simulate heat release during the combustion process. Least squares method was applied to fit this empirical law to experimental data involving different conditions in terms of percentages of rapeseed biodiesel in the fuel blend, rotational speed, fuel/air equivalence ratio and percentages of external exhaust gas recirculation. To build the predictive model, a multiple regression methodology was used to correlate the law parameters with the operating conditions. Finally, a validation process based on the simulation of in-cylinder pressure trace was developed, revealing that the predictions agreed well with the experimental data. This suggests that the proposed model is able to satisfactorily predict the LTC of diesel/biodiesel blends within the test range.Junta de Andalucía - Consejería de Economía AT17-5934-USUniversidad de Cádiz PB2022-04

Thermodynamic Model for Performance Analysis of a Stirling Engine Prototype

In this study, the results of simulations generated from different thermodynamic models of Stirling engines are compared, including characterizations of both instantaneous and indicated operative parameters. The aim was to develop a tool to guide the decision-making process regarding the optimization of both the performance and reliability of Stirling engines, such as the 2.9 kW GENOA 03 unit—the focus of this work. The behavior of the engine is characterized using two different approaches: an ideal isothermal model, the simplest of those available, and analysis using the ideal adiabatic model, which is more complex than the first. Some of the results obtained with the referred ideal models deviated considerably from the expected values, particularly in terms of thermal efficiency, so a set of modifications to the ideal adiabatic model are proposed. These modifications, mainly related to both heat transfer and fluid friction phenomena, are intended to overcome the limitations due to the idealization of the engine working cycle, and are expected to generate results closer to the actual behavior of the Stirling engine, despite the increase in the complexity derived from the modelling and simulation processes.Ministerio de Economía y Competitividad ENE2013-43465-

Thermal Modeling of the Port on a Refining Furnace to Prevent Copper Infiltration and Slag Accretion

Fire refining of blister copper is a singular process at very high temperatures (~1400 K), which means the furnace is exposed to heavy thermal loads. The charge is directly heated by an internal burner. The impurities in the charge oxidize with the flux of hot gases, creating a slag layer on the top of the molten bath. This slag is periodically removed, which implies liquid metal flowing through the furnace port. To address its malfunction, a re-design of the furnace port is presented in this work. Due to the lack of previous technical information, the convective heat transfer coefficient between the slag and the furnace port was characterized through a combination of an experimental test and a three-dimensional transient model. Finally, the original design of the furnace port was analyzed and modifications were proposed, resulting in a reduction of the average temperature of the critical areas up to 300 K. This improvement prevents the anchoring of the accretion layer over the port plates and the steel plate from being attacked by the copper

Techno-Economic Assessment of an Innovative Small-Scale Solar-Biomass Hybrid Power Plant

The current context of the climate emergency highlights the need for the decarbonization of the energy sector by replacing current fossil fuels with renewable energy sources. In this regard, concentrating solar power (CSP) technology represents a commercially proven alternative. However, these types of plants are associated with high production costs and difficulties in controlling production during temporary variations in solar resource availability. In order to minimize these drawbacks, this study proposes the hybridization of CSP technology with direct biomass combustion, with the particularity of an innovative process scheme that does not correspond to traditional series or parallel configurations. This paper focuses on the techno-economic evaluation of this novel configuration in a small-scale power plant. To achieve this, both solar resource and biomass production, which are dependent on the selected location, were analyzed. Additionally, the plant was characterized from both technical and economic perspectives. The obtained results allowed for the characterization of the Levelized Cost of Energy (LCOE) based on various parameters such as the size of the solar field and biomass boilers, as well as limitations on biomass consumption.Agencia Andaluza de la Energí