Papers by Salvador de las Heras
Self-thermal insulation of containers by the precipitation and formation of a gas film at the walls for thermal energy storage
Journal of Thermal Science and Engineering Applications
Passive thermal self-insulation of the inside walls of containers when they are deliberately coat... more Passive thermal self-insulation of the inside walls of containers when they are deliberately coated by nucleation sites and the fluid is diluted with a certain gas. It is well known -in heat transfer engineering, the drastic thermal insulating effect produced when a film of vapour (film boiling) covers the surface of the heater, and if measures are not taken the burnout of the heated surface occurs. This, until now, undesired phenomenon, however, may be harnessed for thermal storage. Here, it is proposed that a self-passive film-gas blanketing the inside surfaces of the container may be promoted by the dilution of a given gas in the fluid in which the heat is to be stored (e.g, molten salts, water, phase change materials, etc.) and deliberately covering the inside surface of the container with nucleation sites. The amazing achievements in last years in micro/nano surface modification allow the control in size, number and roughness of the nucleation sites making the idea of self-ther...
Magnetic Traveling Waves Induced by Mini-Coils for Sweeping Dust of Mars Solar Arrays
2018 International Energy Conversion Engineering Conference, 2018
In this work consideration is given to dust removal from surface of Mars solar arrays by harnessi... more In this work consideration is given to dust removal from surface of Mars solar arrays by harnessing the magnetic properties of the dust. Here, it is speculated a possible technique by which localized and properly spaced magnetic potential wells generated by mini coils varying with time and space along the surface solar array and generating a sort of magnetic traveling wave could move magnetic dust particles step by step between the coils towards a landfill where may be disposed. The magnetic field of the coils could be generated by using the photoelectrical current of the solar array.
High granularity model of a photovoltaic array under complex shadow conditions
This paper presents a model of Photovoltaic (PV) array under complex partially shading conditions... more This paper presents a model of Photovoltaic (PV) array under complex partially shading conditions integrating characteristics of shadow area and combination of direct and indirect radiations. The area of the shadow on PV module is deducted through of image processing. The Hybrid Bond-Graph (HBG) facilitates the energy exchange between the different parts of the PV module justifying the high granularity of the tool. The proposed model is validated through experimental tests under shading conditions
Enhanced Kalman Filter-Based Identification of a Fuel Cell Circuit Model in Impedance Spectroscopy Tests
Lecture Notes in Electrical Engineering, 2020
Simulation Practice and Theory, 1999
The paper deals with the dynamic analysis of double acting actuators, both linear and rotary ones... more The paper deals with the dynamic analysis of double acting actuators, both linear and rotary ones. Two dierent formulations to model a pneumatic circuit, composed of an actuator and a digital valve, are presented. In the ®rst one an air thermodynamic transformation is assumed and the simulation is carried out in the MATLAB-Simulink environment, while in the second one also the energy equation is introduced, so that the thermic exchange between the chambers and the external ambient is considered. Furthermore models of actuators, both linear and rotary, using the bondgraph method are presented; the energy and continuity equations are implement by using two C-®elds. Finally simulations results, obtained in the two dierent environments, are compared and discussed.
Supersaturated Solar Ponds for Enhanced Thermal Insulation by the Spontaneous Formation of a Thin Film Gas at the Bottom
Journal of Energy Resources Technology
In this work the novel approach of supersaturated solar ponds to enhance thermal insulation of th... more In this work the novel approach of supersaturated solar ponds to enhance thermal insulation of the pond by the spontaneous formation of a thin film gas blanketing its bottom which is covered by active nucleation sites is discussed. Utilizing a simplified physical model an expression for the heat transfer and the increase of temperature at the bottom of the solar pond was derived.
A Short Survey for a Thermo-Ducted Kitchen Hood Wasted Heat Self-Powered
ASME Journal of Engineering for Sustainable Buildings and Cities
In this note, a brief survey is given to the possibility for a thermo-ducted kitchen hood where e... more In this note, a brief survey is given to the possibility for a thermo-ducted kitchen hood where exhaust fan or other mechanical devices are no longer needed, and then, in addition, no sound is generated. The aim of this thermo-ducted kitchen hood is a device self-powered by its own wasted heat produced from the simmering or cooking process by re-injecting properly this heat at the top of the hood and then exacerbating an induced thermal convective loop able to extract moisture, odors, and oils generated.
Journal of the European Radon Association, 2021
Diffusion coefficients of radon through minerals and rocks are characterised by Arrhenius linear ... more Diffusion coefficients of radon through minerals and rocks are characterised by Arrhenius linear plots, i.e., increasing with temperature. It has been observed, for example, that rocks with a mild heating (<100°C) translate into a radon release that can be enhanced 100–1,000 times than the normal release at STP (Standard Temperature Pressure (STP). Therefore, it is reasonable to think that if the soil is deliberately heated creating a thermal gradient, it could be possible, at least from a theoretical point of view, to thermally pump radon from soil because the radon atoms will escape preferentially from cold regions (low diffusion coefficient) towards hot regions (high diffusion coefficients) if a radon sink is located. In this short note, this approach for soil radon removal is investigated.
Bénard-Marangoni convection and its significance with regard to film boiling heat transfer from 9... more Bénard-Marangoni convection and its significance with regard to film boiling heat transfer from 9 micro heat sinks is discussed. In recent works cooling performance of micro heat sinks has been 10 studied showing that two-phase cooling could be more efficient than single-phase cooling. However, 11 in those previous works was also found that the critical heat flux (CHF) i.e., the transition from 12 a nucleate boiling regime to an almost insulating film boiling regime was the main limitation 13 of two-phase cooling. Here, it is shown that owing to the induced thermal gradient along the 14 fin and the very small fin-spacing, Bénard-Marangoni convection (which was neither considered 15 nor mentioned so far) can play an important role and in fact driven the entire film boiling 16 heat and mass transfer process. The reason behind this lies in the fact that in film boiling the 17 interfacial vapor-liquid velocity is the capital factor rather than the bulk velocity, and this can be 18 at le...
A comprehensive wind tunnel test program was conducted to evaluate control of Hot Gas Ingestion (... more A comprehensive wind tunnel test program was conducted to evaluate control of Hot Gas Ingestion (HGI) on a 9.2% scale model of the McDonnell Aircraft Company model 279-3C advanced Short Takeoff and Vertical Landing (STOVL) configuration. The test was conducted in the NASA-Lewis Research Center 9 foot by 15 foot Low Speed Wind Tunnel during the summer of 1987. Initial tests defined baseline HGI levels as determined by engine face temperature rise and temperature distortion. Subsequent testing was conducted to parametrically evaluate HGI control using: Lift Improvement Devices (LIDs), forward nozzle splay angle, combination of LIDs and forward nozzle splay angle, and main inlet blocking. The results from this test program demonstrate that HGI can be effectively controlled and that HGI is not a barrier to STOVL aircraft development.
In this work a novel approach is investigated for Particle Image Velocimetry (PIV) which is a tec... more In this work a novel approach is investigated for Particle Image Velocimetry (PIV) which is a technique used as optical method for instantaneous flow visualization. So far traditional PIV is based in the injection of small seed-particles which are entrained by the flow and illuminated so that particles are visible and the motion of the seeding particles is used to calculate speed and direction of the flow. Here, the seed-particles are replaced by magnetic clusters and instead to be illuminated are subjected to alternating magnetic field which result in local hyperthermia of the cluster owing to the dissipative power from the motion in the viscous medium. The heat radiation emitted by the particles may be detected by infrared cameras which impressive achievement in the last decade permit to analyze dynamic events. Because the most recent advances in detection and tracking in thermal infrared imagery, Thermal-PIV by the use of hyperthermal magnetic clusters allow a unique feature, nam...
The mechanical effect of moisturization on airborne COVID-19 transmission and its potential use as control technique
Environmental Research, 2021
Mounting evidence from scientific community seems to suggest that COVID-19 virus can potentially ... more Mounting evidence from scientific community seems to suggest that COVID-19 virus can potentially spread by airborne transmission. As a result, methods and techniques for preventing environmental contagious, such as ventilation or air filtration have been proposed. Here, it is investigated the effect of moisturization on airborne COVID-19 transmission from a mechanical point of view in which comparatively large water droplets promote the growth -by collision and coalescence, of suspended airborne COVID-19 and then accelerating its gravitational settling. Utilizing a classical raindrop collisional model from cloud science and the available experimental data an expression for the removal time of suspended airborne COVID-19 as function of the relative humidity was derived. The mechanical model is in good agreement with the recent reported experimental research in which high temperature and high relative humidity reduce COVID-19 contagious and then is a point in favor of the mechanic model of the effect of moisture in the COVID-19 airborne transmission. The results encourage further research on the deliberate moisturization of room air (by using ceiling mounted humidifiers) as a potential technique for control of airborne COVID-19 transmission.
Induced Ring-like Deposits Around Suspended Radioactive Particles by Marangoni Stress and its Possible Use as Detection Technique
Special Publications, 2019
In this work Marangoni-thermal convection promoted by the heat from the radioactive decay of radi... more In this work Marangoni-thermal convection promoted by the heat from the radioactive decay of radiogenic particles suspended in fluids is analysed. It was found that owing to the outward flow induced from the radioactive particle, the surrounding material could be pushed outwards from the particle. As a result a power-law distribution of concentration surrounding the particle appears which could reveal the presence of suspended radiogenic particles or can be used as a preliminary visual technique for detection.
IFAC Proceedings Volumes, 2002
The problem of robustness in fault detection has been treated basically using two kinds of approa... more The problem of robustness in fault detection has been treated basically using two kinds of approaches: actives and passives. Most of the literature in robust fault detection is focused on the problem of active approach based on decoupling the effects of the uncertainty from the effects of the faults on the residual. On the other hand, the passive approach is based of propagating the effect of the uncertainty on the residuals and then using adaptive thresholds. In this paper, the passive approach based on adaptive thresholds produced using a model with uncertain parameters bounded in intervals, also known as an "interval model", will be presented in the context of parity equations and observers methodologies, deriving their corresponding interval versions. Finally, an example based on an industrial actuator used as a FDI benchmark in the European project DAMADICS will be used for testing and comparing the proposed approaches.
2010 IEEE 15th Conference on Emerging Technologies & Factory Automation (ETFA 2010), 2010
This paper describes the methodology and solution to automate and monitor a sewage treatment plan... more This paper describes the methodology and solution to automate and monitor a sewage treatment plant from an industry dedicated to the manufacture of wood panels. The control system designed, not only governs all elements of performance of the plant, but also oversees its proper functioning. It also has a human-machine interface with a daily working and emergency program, accompanied by an information system supported by records and alarms to facilitate human decisions making if were necessary. The proposed solution, not only increases the reliability and safety of the process with respect to plants or other type semi-automatic operation, but also reduces costs by improving process efficiency and minimizes costs in maintenance and monitoring.
Bond graph and external modeling for FDI design of smart actuators
IEEE International Conference on Systems, Man and Cybernetics
ABSTRACT External model leads on concepts of services and user operating modes and requires infor... more ABSTRACT External model leads on concepts of services and user operating modes and requires information from fault detection and isolation algorithms to propose to the operator various modes and explains how to go from one to another. The bond graph methodology as a graphical modelling language becomes a complementary tool for those purposes. In this way, by adding a bond graph methodology, it becomes possible to obtain physical knowledge of the actuators, and to improve their monitoring, and consequently to insure the best safety using its causal properties. The methodology is applied to an intelligent industrial actuator used as a benchmark in the EU FP5 grant DAMADICS project.
E. Codina Macià J. Mª. Bergadà Grañó S. De Las Heras Jimenez© los autores, 1998;© Edicions UPC, 1... more E. Codina Macià J. Mª. Bergadà Grañó S. De Las Heras Jimenez© los autores, 1998;© Edicions UPC, 1998. Quedan rigurosamente prohibidas, sin la autorización escrita de los titulares del" copyright", bajo las sanciones establecidas en las leyes, la reproducción ...
Water Supply, 2009
The division of a network in different sectors is a usual practice in Water Companies. It improve... more The division of a network in different sectors is a usual practice in Water Companies. It improves the management of the network in different senses. Sectors have more homogenous characteristics and need specific cares and treatments that is not the same all through the network. Specifically for leakage detection and assessment it is interesting to know the performance of the sector before any leakage detection strategy is applied. In this paper a characterisation methodology for the sectors is presented. This methodology is based on the knowledge provided by the company but has been analysed using clustering techniques. The main objective of the classification was to give a scope of the different types of sectors present in the network. A decision table based on the relevant descriptors was built. This allowed choosing three interesting pilot sectors for the leakage detection methodology study.
IEEE Transactions on Control Systems Technology, 2008
Model-based fault detection relies on the use of a model to check the consistency between the pre... more Model-based fault detection relies on the use of a model to check the consistency between the predicted and the measured (or observed) behavior of a system. However, there is always some mismatch between the modeled and the real process behavior. Then, any model-based fault detection algorithm should be robust against modeling errors. One possible approach to take into account modeling uncertainty is to include all the uncertainty in system parameters using an interval model that allows generating an adaptive threshold. In this paper, the use of interval models in robust fault detection considering three schemes (simulation, prediction, or observation) is presented and discussed. The main contribution is to present a comparative study that allows identifying the benefits and drawbacks of using each scheme. This study will provide a guideline for the use of the proposed fault detection schemes in real applications. Finally, an intelligent servoactuator, proposed as a benchmark in the context of European Research Training Network DAMADICS, is used to illustrate the application and the comparative study of these interval-based fault detection schemes.
Introduction to the DAMADICS actuator FDI benchmark study
Control Engineering Practice, 2006
This paper provides the description and presentation of the actuator benchmark used in fault diag... more This paper provides the description and presentation of the actuator benchmark used in fault diagnosis studies within the DAMADICS European Research Training Network presented in the papers of this special issue. The benchmark system is openly available, is FDI method-independent and based on an in-depth study of the phenomena that can lead to likely faults in valve actuator systems. The
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Papers by Salvador de las Heras