J.L. Míguez

J.L. Míguez
University of Vigo | UVIGO · Department of Mechanical Engineering, Heat Engines and Machines, and Fluids

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92
Publications
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Publications

Publications (92)
Article
Among the different modelling strategies applied for the simulation of packed bed biomass combustion during the last two decades, the present paper detailed describes two models based on two of the most commonly used approaches and tests their performance through the simulation of a 60-kW wood pellet boiler. This contributes to analyze the behavior...
Article
In several studies about ball-cratering test, a gap remains: how the ball surface texture influences the dynamic of the particles through the contact? In this paper, the influence of ball surface texture in the dragging of abrasive particles on micro-abrasion tests was studied, and the resulting wear mechanisms have been analyzed. The tests were co...
Article
This article presents a detailed description of the first functional new approach to simulate the bed physics in biomass boilers in an Eulerian mathematical framework. In particular, this article describes the analysis of the context of the collapse due to gravitational forces, the design of an automated algorithm that is responsible for its simula...
Article
The use of biomass is growing as it is considered as a renewable energy by a society with increasing ecological awareness. Biomass has the advantage of being easily used in existing installations with non-renewable solid fuels, either as a final fuel or as a transition fuel. However, biomass use presents serious operational problems, such as slaggi...
Article
The limited success in the promotion of biomass use through technologically advanced heating networks in economically depressed areas has been, in part, attributed to the insufficient understanding of the transformation patterns of the energy for use of indigenous resources. In this regard, Organic Rankine cycle (ORC) is proved to be reliable techn...
Article
Ash-related issues such as fouling and slagging are likely the main operational problems of most commercial solid fuel burners. To study this kind of system, a full 3D-transient bed model embedded into the commercial CFD code ANSYS-Fluent was developed to describe the main processes that occur inside the bed. The model employs several sub-models th...
Article
In this work, we study the operation of a water heater storage tank using CFD modelling and analyse its limitations in order to propose a redesign that improves its characteristics. The study method is based on calculating the main variables that affect the thermal performance using the finite volume method. With this method, the Navier-Stokes equa...
Article
This work proposes a method based on CFD techniques for the study of thermal water heater tanks. The method is based on using the Navier-Stokes equations to calculate the internal movements of the fluid and the transport of energy through the flow. The Boussinesq approximation is applied to solve the fluid movements that occur by natural convection...
Article
This paper presents a comprehensive model for simulating the combustion of large biomass particles. The model implements a set of Eulerian variables that represent the components of solid biomass in a commercial CFD code. The evolution of these variables represents the thermal conversion of biomass and its interaction with the gas flow. The model c...
Article
Physical Vapour Deposition (PVD) is a process usually used for the production of advanced coatings regarding its application in several industrial and current products, such as optical lens, moulds and dies, decorative parts or tools. This process has several variants due to its strong evolution along the last decades. The process is commonly assis...
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Sustainable development is acquiring high attendance in higher education. In fact, one of the targets for the Sustainable Development Goals announced by the United Nations in September 2015 aims to ensure that all learners acquire the knowledge and skills needed to promote sustainable development, including, among others, thorough education on sust...
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It is thought that there are 14 million standardised sea containers out of order, equal to 23.3 million twenty-foot equivalent unit (TEU), which could be devoted for other purposes. The COR-TEN® steel containers are the best, due to the features of the materials, to be used in applications intended for the accommodation of people. One of the uses i...
Article
A biomass combustion model with a thermally thick approach is presented and applied to the simulation of a commercial biomass domestic boiler. A subgrid scale model is used to divide the particles into several grid points, each representing one of the different combustion stages. These grid points determine the variables of the solid phase located...
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Tri-generation plants will have an important role in the near future in the residential sector where heating and cooling demands come into play throughout the year. Depending on the building’s location, the characteristics of its enclosure and its use, the thermal loads and demands will be different. This article analyses and compares a combined co...
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This experimental work studies a small-scale biomass combustor (5-12 kW) with an underfed fixed bed using low air staging ratios (15%-30%). This document focuses on the influence of the operative parameters on the combustion process, so gaseous emissions and the distribution and concentration of particulate matter have also been recorded. The facil...
Article
Learning by doing is essential in engineering education, along with topics such as systems automation and control and energy efficiency. This article presents work including all of these different topics. A micro-cogeneration facility located at the University of Vigo is studied. The experimental plant is automated after detecting the most importan...
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Micro combined heating and power (micro-CHP) systems are becoming more than important, and even essential, if we pretend to take full advantage of available energy. The efficiency of this kind of systems reaches 90% and important savings in energy transport processes can occur. In this research, an internal combustion engine (ICE)-based micro-CHP s...
Article
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Advantages, such as thermal storage improvement, are found when using PCMs (Phase Change Materials) in storage tanks. The inclusion of three different types of materials in a 60 ℓ test tank is studied. Two test methodologies were developed, and four tests were performed following each methodology. A thermal analysis is performed to check the therma...
Article
The increasing use of smartphone technology in people's daily lives and its continuous development lead to the inevitable use of mobile applications because of their easy access anytime and anywhere. In this study, a new Android application for smartphones is developed and presented for the remote control of a micro-cogeneration system from a mobil...
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One of the main barriers for the successful utilization of new biomass feedstocks in commercial pellet boilers is the lack of knowledge of the combustion behavior of such fuels, particularly in terms of ash slagging, which can potentially damage boiler and limit combustion efficiency. The VI Framework European project Domoheat studied the combustio...
Article
This paper presents a transient model for the simulation of biomass combustion in a fixed bed boiler fed through particle drop. The method combines classical CFD techniques, which are used to simulate the gas phase, with a set of Eulerian variables defined to model the solid phase and Lagrangian trajectories that model the particle drop. Several su...
Article
Information and communications technologies (ICT) are being used in engineering fields due to multiple advantages that motivate their introduction in university teaching. A course on thermal engineering has been taught for the past 3 years as part of the industrial engineering degree at the University of Vigo. Energy savings and efficiency are comm...
Article
Background: Musculoskeletal disorders (MSDs) are diseases of high prevalence. The extent to which our work is causing or aggravating them is still questioned because their causes are heterogeneous and usually combined in the same person, and can be attributed to any of them. Objective: The objective of this paper is to compare Spain with the res...
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Full-text available
The present study aims to evaluate the effect of different operating conditions on fouling composition after woody biomass combustion in an experimental low-power fixed-bed boiler. The boiler was built specifically for research purposes and allows easy removal of areas susceptible to fouling and the control, modification and registry of combustion...
Article
Calibrating a simulation model is one of the most difficult tasks required to validate an energy conservation measure. To obtain an accurate calibration, it is necessary to collect all the performance data and estimate the missing information. In this study, a unique building with a heating and cooling system consisting of a ground-source heat pump...
Article
Abstract The thermally thick treatment of fuel particles during the thermal conversion of solid biomass is required to consider the internal gradients of temperature and composition and the overlapping of the existing biomass combustion stages. Due to the implied mixture of scales, the balance between model resolution and computational efficiency i...
Article
This paper presents the technical study of a commercial sailboat conversion, originally manufactured with an internal combustion engine (ICE), into electrical hybrid propulsion system with fuel cell and batteries. Batteries are charged with electrical energy from grid when boat remains at port. The used hydrogen is generated with the electrolysis o...
Article
This work focuses on the combustion performance of cheap low quality fuels as an alternative to existing pellets and chips for a small-scale combustion. The market is keen on using locally available fuels but a lack of information on their performance in boilers and legislation can be prevented them from doing so. The approval of the regulation tha...
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The biomass market has experienced an increase in development, leading to research and development efforts that are focused on determining optimal biofuel combustion conditions. Biomass combustion is a complex process that involves divergent parameters and thus requires the use of advanced analysis methods. This study proposes combining grey relati...
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The European Higher Education Area (EHEA) requires the student a more autonomous work. This autonomy is related to the outcome of the self-regulated learning process. The self-regulation involves a self-management skill set coping with any adverse contingency and entails the knowledge of the available abilities and the personal control to put in ac...
Article
A new system to collect and analyse some of the condensable products of biomass pyrolysis is developed and tested. Pyrolysis of olive stone, oak pellet, pine pellet and major components of biomass (cellulose, hemicellulose and lignin) is performed by means of a thermogravimetric analysis (TGA). Some of the pyrolysis oil generated during the pyrolys...
Patent
Full-text available
The invention relates to a method and a device for determining specific emissions as an exhaust gas characteristic of an internal combustion engine. Said method is characterized in that the exhaust gas mass flow (3) is determined as the first operating parameter and the engine power output (2) as the second operating parameter, the nitrous oxide ma...
Article
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Purpose ‐ The purpose of this paper is to propose an interpretation of the grey relational grade taking into account its variation range on the basis of the error propagation theory. Design/methodology/approach ‐ The paper uses error propagation theory to calculate the uncertainty of the grey relational grade, exploring how errors are propagated th...
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doi:10.3390/ma6083530 materials ISSN 1996-1944 www.mdpi.com/journal/materials Article Abstract: The aim of this paper is to research new thermally-efficient concrete walls, analyzing the mechanical behavior of a self-compacting concrete to manufacture an uncoated solid structural panel, with the incorporation of a micro-encapsulated phase change ma...
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The basic pyrolysis behaviour of eight different biomass fuels has been tested in a thermogravimetric analyser under dynamic conditions (5, 20 and 50 °C min−1 heating rates) from room temperature up to 1,000 °C. Their decomposition was successfully modelled by three first-order independent parallel reactions, describing the degradation of hemicellu...
Article
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Although the Stirling engine was invented in 1816, this heat engine still continues to be investigated due to the variety of energy sources that can be used to power it (e.g., solar energy, fossil fuels, biomass, and geothermal energy). To study the performance of these machines, it is necessary to develop and simulate models under different operat...
Article
This study is conducted to determine, from an energetic point of view, the reasons for the success of Galician granaries (the most important traditional “dry storage” structure, also called a “horreo”, typical in the northwest of Spain). Granaries (horreos) are bioclimatic conservation structures with various forms that have been used for over 2000...
Article
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In this work, a CFD-based model is proposed to analyse the effect of phase change materials (PCMs) on the thermal behaviour of the walls of a cubicle exposed to the environment and on the resistance of the walls to climate changes. The effect of several days of exposure to the environment was simulated using the proposed method. The results of the...
Article
This work studied the importance of wood pellets, chips and wood logs for small- and medium-scale heat production. Pellet use can contribute substantially to reaching the renewable heat and electricity goals set by the European Union (EU) Renewable Energy Directive. Consequently, to integrate into European energy markets, pellet use must be a key p...
Article
The aim of this work is to study the structure of the reaction front thickness and its dependence on the air mass flow rate. Thus, a few modifications are introduced in an existing fixed-bed combustor to continuously measure the position of the surface of the bed. In addition, based on the temperature measured by thermocouples, other processes are...
Article
A multi-net fault diagnosis system, designed to provide power estimation and fault identification, is presented. Eight different faults: misfiring of each of the three cylinders, shaft imbalance, clogged intake and a leaking start plug for each cylinder were separately induced in the engine. Only the vibration and exhaust temperature sensors were u...
Article
The Network Simulation Method (NSM) has been used to study the variations with velocity of suction, hall effect, Reynolds and Hartmann number, particle concentration and Eckert number on the unsteady MHD Couette Flow and heat transfer of a dusty and electrically conducting fluid between parallel plates in the presence of an external uniform magneti...
Article
The position of pellet fuel particles in a burner largely determines their combustion behaviour. This paper addresses the simulated motion of circles and spheres, equivalent to pellet, and their final position in a packed bed subject to a gravitational field confined inside rigid cylindrical walls. A simplified Monte Carlo statistical technique has...
Article
Fixed-bed combustion in a tube reactor is a useful procedure to exploit a large variety of biomasses obtaining accurate in-bed data. In this paper, the ignition front propagation velocity is experimentally studied in a counter-current process for eight different biomass fuels with a wide range of origins, compositions and packing properties. Air ma...
Article
This paper presents a combined grey relational and fuzzy analysis for the evaluation of the environmental feasibility of burning mixtures of pellet and RDF (Refuse Derived Fuel) in a small pellet boiler-stove. RDF is obtained from Municipal Solid Waste (MSW) and contains a biomass fraction and a non-organic fraction (plastic). As a first step, both...
Article
This paper presents a computational fluid dynamic analysis of a small-scale commercial biomass pellet boiler. Combustion of the particles in the bed plays a key role in the analysis of this kind of systems, and a stand-alone code was used in this work to provide the inlet conditions for the CFD analysis. Model predictions were compared with the exp...
Article
This paper presents a computational fluid dynamics model of a methanol burner. Special emphasis was placed on the study of the liquid atomization and combustion process. Linearized Instability Sheet Atomization (LISA model) was employed to simulate the fuel atomization process. Predictions of droplet diameters, droplet trajectories, temperatures an...
Article
In a way similar to the automotive industry, outboard emissions limits are being constantly revised, which strongly effects the development of the new engines and their compliance. During the last ten years, conventional two-stroke outboard engines, which are used for fishing and recreational boats, have thus been replaced by four-stroke engines or...
Article
The aim of the present work is to study the viability of a cofiring system in a small-scale biomass plant using a mixture of wood pellet and refuse derived fuel (RDF pellet). RDF comes from municipal solid waste, and a valorization process via combustion is a useful way of solving the problem of the accumulation of nonrecyclable wastes. In this pap...
Article
Economic development in recent decades has been characterised by the increased use of fossil fuels. Clearly, a significant amount of this energy does not fall in line with the principles of sustainable development, either because of its contaminating effect or because of its non-renewable nature.Today, Navarre generates around 60% of its electricit...
Article
The implementation of the emissions market should imbue renewable energies with a greater degree of competitiveness regarding conventional generation. In order to comply with the Kyoto protocol, utilities are going to begin to factor in the cost of CO2 (environmental costs) in their overall generating costs, whereby there will be an increase in the...
Article
In this paper, it is proposed to incorporate the analysis of the dynamic performance of the process into the design and engineering stage of projects as a means of analysing and resolving this type of problem. The following contributions are made with this objective in mind:(a)The barriers in the way of dynamic analysis are identified.(b)Software t...
Article
The objective of this study is to compare the engine performance and emission results of biodiesel derived from used cooking oil when applied in different proportions in outboard engines. Results revealed that the use of biodiesel resulted in lower emissions of CO (up to 12%) with an increase in emissions of NOx (up to 20%, except in one case which...
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Full-text available
The present work is an approach to the analysis of cofiring systems with pelletized forest and pelletized refused-derived fuel (RDF). RDF is obtained from municipal solid wastes and contains a biomass fraction and a nonorganic fraction (plastic). As a first step, characterization of both fuels is given to define their properties. A special feeding...
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This paper presents the engineering design and theoretical exergetic analyses for a container-housed reciprocating engine. The exergy analysis conducted was based on the first and second laws of thermodynamics for power generation systems.Using thermographic inspection, the heat dissipated by each one of the 28 elements under consideration in the e...
Article
Installations involving fluids often present problems in terms of the dynamic performances of their different parts. These problems can be analysed and dealt with at the design stage. This means that both the technologists who design the thermohydraulic process and those who carry out the regulation and control must be involved in the process from...
Article
Containerised cogeneration sets, CCSs, are an efficient answer for remote developing regions which do not have alternative energy sources and for those applications requiring mobility and the quick installation of energy plants. Nevertheless, CCSs can present over-heating problems as a result of inefficient ventilation. The heat dissipated by each...
Article
The combustion of pellets in small stoves is a complex issue in which many factors must be considered. The University of Vigo has developed a 24 kWt fixed bed stove pilot plant for studying pellet combustion in which different configurations and operational conditions can be tested. An extensive experimental study using the statistical analysis app...
Article
The use of renewable energy offers a decrease in external energy dependence; a boost to local and regional component manufacturing industries; promotion of regional engineering; increased R&D, decrease in impact of electricity production and transformation; increase in the level of services for the rural population; creation of employment, etc.To a...