Ulpiano Ruiz-Rivas

University Carlos III de Madrid | UC3M · Department of Thermal and Fluids Engineering

En los hornos de soleras múltiples, ocurren procesos físicos-químicos multivariables, no lineales y con dinámicas que varían en el tiempo. La automatización de la postcombustión se realiza mediante controladores Proporcional-Integral-Derivativo (PID), sin tener en cuenta modelos matemáticos que relacionen las variables de interés. Este artículo pre...

Planners, policy makers, activists, corporations, and other parties must ensure that transitions away from fossil fuel dependence are not only environmentally sound but also socially just. Socially unjust disparities may impact communities that have long borne myriad burdens of our energy system, as well as those facing the impacts of shifting away...

The incidence of energy poverty in the Global South is identified by the lack of basic access to modern fuels and energy carriers. Impoverished people have traditional biomass and human power as their only sources of energy. This situation of deprivation of basic resources, in which (according to estimates of international agencies) almost one thir...

Energy poverty in the Global South generally focuses on the lack of basic access to modern fuels and energy carriers. Impoverished people rely primarily on traditional biomass as a source of energy. This situation of basic resource deprivation, in which almost one third of the world's population lives, masks other relevant features of the problem....

Recent research has looked into the potential for energy savings from adopting setpoint temperatures based on adaptive comfort. The recently suggested Adaptive-Comfort-Control-Implementation Script (ACCIS), a computational method that expands the use of air conditioning to adaptive comfort, can be used to accomplish this. The user's setup and an In...

The possibility for energy savings from implementing setpoint temperatures based on adaptive comfort has recently been investigated. This can be achieved by using the recently proposed Adaptive-Comfort-Control-Implementation Script (ACCIS), that is a computational approach which extends the air-conditioning usage to adaptive comfort. According to b...

This paper presents a critical review of the multidisciplinary work done on energy poverty in developing regions, a topic that presents remarkable differences with energy poverty in OECD countries. These efforts have resulted in the establishment of strategies to fight against energy poverty and to expand basic energy supplies (to leave no one behi...

In this work, a conceptual framework based on Fuzzy Logic for identifying Energy Poverty situations in Getafe (Spain) is presented. The resulted model uses twelve input variables for obtaining the level of Energy Poverty. The input variables were defined around the three key drivers commonly used for the Energy Poverty characterization: low incomes...

This paper focuses on the need for sustainable energy engineering degrees and the problems found in establishing appropriate curricula contents. Proposals are made for developing adapted energy engineering degrees. Relevant contents are provided for these curricula, which should train engineers to deal with current and future problems. This need fo...

Purpose This paper aims to present a new master’s programme for promoting energy access and energy efficiency in Southern Africa. Design/methodology/approach A transdisciplinary approach called “participatory integrated assessment of energy systems” (PARTICIPIA) was used for the development of the curriculum. This approach is based on the two em...

Free access to the article until August 10, 2017, using the following link: https://authors.elsevier.com/a/1VFYv1H~cz-wMo In this paper a microporous membrane is used in combination with rectangular microchannels in the absorber of an absorption chiller, working in two different configurations: cooled by a water flow and adiabatically. In the non...

RENet es un proyecto de cooperación internacional al desarrollo enmarcado dentro del Programa EDULINK: ACP-EU Higher Education Cooperation, financiado por la Unión Europea e implementado por el secretariado ACP. RENet centra su objetivo general en el fortalecimiento de la educación superior de calidad, la creación de capacidad docente/investigadora...

La formación en zonas en desarrollo de profesionales especialistas en temas energéticos es un aspecto clave de la agenda de desarrollo, explicitado en los ODS. Se ha desarrollado un trabajo ingente en la elaboración de cursos universitarios vinculados con la energía. Sin embargo, los planes de estudios suelen ser muy deudores de los existentes en l...

Free access to the article until November 9, 2016, using the following link: http://www.sciencedirect.com/science/article/pii/S0140700716302572 The simulation of the heat and mass transfer in a H2O–LiBr microchannel desorber endowed with a microporous membrane is presented. The heat and mass transfer processes are modelled by means of selected cor...

The thin-layer drying kinetics of Granny Smith apples is determined by thermogravimetric analysis of the drying process at constant temperatures ranging from 20 °C to 50 °C, using intervals of 5 °C. The experimental drying curves obtained in the TGA were fitted to the Wang-Singh equation, which was found to describe precisely the drying process occ...

In this paper a microporous membrane is used in combination with rectangular microchannels of 3 cm length in the absorber of an absorption chiller working in two different configurations: cooled by a water flow and adiabatically. A previous model developed by the authors serves as the basis to simulate the heat and mass transfer between solution an...

Free access to the article until March 25, 2016, using the following link: http://authors.elsevier.com/a/1SUgE1H~cztAPH Abstract: A microporous membrane is used in combination with rectangular microchannels in the absorber of an absorption chiller with the aim of reducing the size of this cooling technology. The simulation of the heat and mass tra...

A theoretical study on the maximum evaporation rate obtainable in a small-scale indirect solar dryer is presented, considering evaporation of free water. A mathematical model of the evolution of the temperature and the specific humidity of the airflow along the drying chamber is presented. Based on the results, some simplifications are proposed and...

Renewable heat, from solar thermal collectors, or process waste heat, can be used to fed absorption cooling chillers for cooling or refrigeration purposes. This combination allows for an optimal implementation of solar thermal systems in buildings, because excess heat during summer season can be used to produce air conditioning. One of the main com...

Absorption cooling chillers can use waste heat or renewable heat from solar thermal collectors for cooling purposes. The optimal implementation of solar thermal energy in buildings can be obtained when solar energy is used in the summer period for air conditioning. Thus, the electricity consumption peak in summer due to the use of air-conditioning...

A Monte Carlo model was proposed to characterize the fuel particles motion in a large-scale fluidized bed. The model describes the global motion of a fuel particle with a proper circulation throughout the bed, analyzing its behavior both in the freeboard and inside the bed. The model was validated with experimental results of the lateral mixing of...

The characteristic parameters of devolatilization, the activation energy and the frequency factor, can be obtained following different experimental approaches. In the Distributed Activation Energy Model (DAEM), these parameters are derived from several TGA curves that are typically obtained for constant, low heating rate experiments. Then, the resu...

The motion of a large non-reacting object in the freeboard of a bubbling fluidized bed was characterized experimentally and compared with Monte Carlo simulations. A tracking technique was developed to study the object motion both when it is immersed in the dense bed and in the freeboard. Monte Carlo simulations, based on the kinematic equations of...

This paper aims to evaluate the potential for electricity and ethanol production in Central America using sweet sorghum as an energy crop. Three scenarios were built to analyse sweet sorghum production in terms of the land where it can be cultivated: cropland, sugarcane land in fallow and land in continuous production (intercropping system). The la...

The motion of a large neutrally-buoyant object immersed in a 2D bubbling fluidized bed was simulated using a Monte Carlo method. The object vertical trajectory within the bed was simulated for a range of dimensionless gas velocities using a simple 1D model. The main characteristics of the object motion were obtained from the trajectory simulation a...

obtención del producto final, ya que mejora la preservación del producto y economiza su transporte. En la producción agrícola y forestal existe un gran escalón entre la producción a nivel industrial y la de pequeña escala. A escala industrial se posee la tecnología necesaria para el procesado de los productos. En la mayoría de los casos está basada...

A model is developed to study the influence of design parameters (dimensions, air mass flow rate) in the performance of an indirect solar drier for batch drying. The aim of the work is to cover a wide range of configurations and sizes with a simple model. The model covers the air heating in the collector and the vapour mass transfer in the drying c...

A model is developed to study the influence of design parameters (dimensions, air mass flow rate) in the performance of an indirect solar drier for batch drying. The aim of the work is to cover a wide range of configurations and sizes with a simple model. The model covers the air heating in the collector and the vapour mass transfer in the drying c...

The thermal decomposition of biomass (pine pellets) and sewage sludge was studied using thermogravimetric analysis under an inert atmosphere and the Distributed Activation Energy Model (DAEM) was employed. The activation energy and the frequency factor that characterize the kinetics were determined for both samples. A simplification of the process...

A model is developed to study the influence of design parameters (dimensions, air mass flow rate) in the performance of an indirect solar drier for batch drying. The aim of the work is to cover a wide range of configurations and sizes with a simple model. The model covers the air heating in the collector and the vapour mass transfer in the drying c...

En el curso 2009/10, con la adaptación al Espacio Europeo de Educación Superior (EEES), las asignaturas relativas a la Cooperación al Desarrollo y las Tecnologías Apropiadas que el Grupo de Tecnologías Apropiadas de la Universidad Carlos III de Madrid impartía desde el curso 2003/04 se transforman en dos nuevas asignaturas llamadas, Aplicaciones...

This work presents a theoretical study of the energetic performance of a moving bed heat exchanger (MBHE), which consists of a flow of solid particles moving down that recovers heat from a gas flow percolating the solids in cross-flow. In order to define the solid conduction effects, two solutions for the MBHE energy equations have been studied: an...

The motion of a large object in a bubbling fluidized bed is experimentally studied using digital image analysis. A wide range of fluidized bed applications involves the motion of large objects within the bed, such objects being reactants, catalysts, agglomerates, etc. The experiments were run in a 2D bubbling fluidized bed with glass spheres as bed...

The motion of a large object in a bubbling fluidized bed was experimentally studied using digital image analysis (DIA). The experiments were performed in a 2-D bubbling fluidized bed with glass spheres as bed material. The object motion was measured using non-intrusive tracking techniques, while independent measurements of the dense phase velocity...

RESUMEN La docencia reglada en temas de cooperación dentro de nuestras propias universidades es un aspecto central de la Cooperación Universitaria para el Desarrollo. En el presente trabajo se recoge la experiencia desarrollada por el Grupo de Tecnologías Apropiadas de la Universidad Carlos III de Madrid, tras seis años impartiendo asignaturas de l...

La estructura de un chorro con coflujo y sometido a forzado axial es estudiada experimentalmente en e! campo cercano. El flujo es isotermo e incompresible. Las medidas experimentales han consistido en visualizaciones del flujo en planos longitudinales y transversales y medidas simultáneas de dos componentes del vector velocidad, mediante PIV (Parti...

This work presents an experimental analysis of the hydrodynamic and thermal performance of micro-heat exchangers. Two micro-heat exchangers, characterized by microchannels of 100 × 100 and 200 × 200 μm square cross-sections, were designed for that purpose. The fluid used was deionized water and there was no phase change along the fluid circuit. The...

This work provides an energy and exergy optimization analysis of a moving bed heat exchanger (MBHE). The exchanger is studied as a cross-flow heat exchanger where one of the phases is a moving granular medium. The optimal MBHE dimensions and the optimal particle diameter are obtained for a range of incoming fluid flow rates. The analyses are carrie...

This work presents a study to optimize the performance of a heat regenerator composed by two coupled moving bed heat exchangers (MBHE). A MBHE is used to recover heat, from a hot gas stream, and the other one is used to preheat an air stream. A direct application might be a gasifier. The heat exchangers performance was studied in two cases, conside...

This work presents an experimental study to characterize ascending bubbles and granular velocity in the dense phase of a 2-D fluidized bed. Three different non-intrusive techniques based on images obtained with a high speed camera are developed, and applied to the images. First the bubble paths are characterized with time-average concentration maps...

The performance of a novel rotating distributor fluidized bed is presented. The pressure drop and the standard deviation of pressure fluctuations were used to find the minimum fluidization velocity, Umf, and to characterize the quality of fluidization at different rotational speeds of the distributor plate. Experiments were conducted in the freely...

The MBHE proposed can be analyzed as a crossflow heat exchanger where one of the phases is a moving granular medium. In the present work the exergy analysis of the MBHE is carried out over operation data of the exchanger obtained in two ways: a numerical simulation of the stationary problem and a simplified analysis. The numerical simulation is car...

A new non-intrusive method for measuring the throughflow velocity crossing the dome of erupting bubbles in freely bubbling 2-D fluidized beds is presented. Using a high speed video-camera, the dome acceleration, drag force and throughflow velocity profiles are obtained for different experiments, varying the superficial gas velocity. The acceleratio...

This work presents an experimental study of the vortex structures that appear in the shear layer of co-flowing water jets subjected to a strong axial forcing. Quantitative, forcing-phase-locked measurements of the velocity in the near field were obtained using two-component Particle Image Velocimetry (PIV). Two-dimensional vorticity, strain and pre...

Multigrid particle image velocimetry (PIV) is an open path in the search for high-resolution PIV methods. It is based on an iterative scheme that uses the information of initial processing to adapt the method parameters in order to improve the measurements. This is mainly performed by reducing the size of the interrogation windows and shifting them...

The trajectories of heavy particles (ρparticle/ρfluid>>1) are simulated in a two-dimensional free vortex flow. The results show that heavy particles, even with small diameters, cannot properly trace the fluid and develop a centrifugal motion. This behaviour leads to a rapid depletion of particles in the vortex core, which, in seed-dependent measure...

This work presents a new family of PIV velocity data derivative filters based on local adaptation of the coefficients of a linear explicit filter (FIR). The main aim of the adapting scheme is the improvement of the spatial first differentiation frequency bandwidth, which is accomplished reducing the truncation error of the scheme and the noise ampl...

A study of the evolving shear layer in the near field of ReD=7000, co-flowing water jets is presented. The inner jet is subjected to a strong axial forcing and to a small, controlled azimuthal perturbation. This flow configuration is characterised by a strong lateral expansion of the inner jet in the near field, controlled by the forcing parameters...

An experimental study is presented of the vortex structures that appear in the shear layer of laminar, co-flowing air jets subjected to strong axial forcing. A set of flow visualisation experiments has been performed to elucidate the nature of the different structures and the mechanisms leading to their appearance and further interactions. The axia...