Ramon Mujal - Academia.edu (original) (raw)

Papers by Ramon Mujal

Science and engineering of composite materials, Aug 1, 2013

Mass production of tires and their subsequent storage after use are serious environmental problem... more Mass production of tires and their subsequent storage after use are serious environmental problems that are being tried to be solved in various ways. One of these is the mixture of these old used tires [ground rubber tire (GTR)] with various thermoplastic and thermostable polymers. The present work aimed to obtain materials suitable for the electric industry from the mixture of polystyrene (PS) with old used tires (GTR), starting from the requirement of minimum recycling costs, i.e., by using vulcanized GTR without any prior treatment but acting on the particle sizes with a simple and inexpensive screening. In order to do so, dielectric, mechanical, thermal, and microstructure analyses were performed for a large number of compounds, which were obtained using three GTR particle sizes (p < 200 μm, 200 μm < p < 500 μm, and p > 500 μm) and seven concentrations of GTR in the compound (0%, 5%, 10%, 20%, 40%, 50%, and 70%). All these data have allowed an accurate characterization of the properties of the new compounds, and according to these results, possible electrical applications have been explored.

ABSTRACT The study of the magnetic characteristics and constructive shapes of conductive material... more ABSTRACT The study of the magnetic characteristics and constructive shapes of conductive materials, allows a better use of Its electrical characteristics, reducing the maintenance and extending the life of the electrical machines. The improvements obtained on the torque with low currents using rotor with spiral sheets are analysed on this paper. To have a complete study, several rotors and stators have been built to verify the electromagnetic variations on the three-phase asynchronous motors where they combine different constructive and mechanical characteristics of the related elements: changing inertias, constructive materials, and the geometrical shapes and disposition of the sheets. These different types of motors have been first tested in the laboratory, them, are simulated using computer aided tools (Matlab-Simulink). In particular four stators (1000 rpm, 1500 rpm, 1500 rpm-type A, and 3000 rpm) having the same constructive parameters, have been tested with the following rotors: solid rotor, solid rotor with diamagnetic rings, drag cup, and simple and double squirrel cage rotor. All these results have been compared to those obtained with the seven variants of spiral sheet rotor, presented on this paper. It has been demonstrated that It is possible to considerably reduce the starting currents and therefore reducing the maintenance and extending the life of motors, without any negative consequence on the starting torque.

També inclou la versió en castellà2011/201

Anales de la Universidad de Chile, Aug 17, 2010

Science and engineering of composite materials, May 1, 2015

Mass production of tires as well as its difficult storage or elimination is a real environmental ... more Mass production of tires as well as its difficult storage or elimination is a real environmental problem. Various methods for recycling tires are currently used, such as mechanical crushing, which puts vulcanized rubber, steel, and fibers apart. The rubber may be used in several industrial applications such as flooring, insulations, and footwear. The present paper focuses on finding a new application for old used tires [ground tire rubber (GTR)]. To this end, tires dust has been mixed with various thermoplastic polymers such as polyvinyl chloride (PVC), high-density polyethylene (HDPE), ethylene vinyl acetate (EVA), and polypropylene (PP). We have checked the maximum GTR concentration values admitted by these compounds while keeping dielectric properties within acceptable values and therefore remaining suitable for industrial applications in the manufacturing of insulators for electrical wires. In particular, tires dust with particles size p < 200 μm has been mixed with the polymers in four different GTR concentrations of 5%, 10%, 20%, and 50% to establish its performance through dielectric tests performed within a range of temperatures from 30°C to 120°C, and with frequencies from 1 × 10-2 to 3 × 10 6 Hz, and analyzing conductivity, permittivity, dielectric loss factor, and relaxations. At last, the fracture surfaces of the composite samples have been evaluated using scanning electron microscopy (SEM).

Materials, Dec 6, 2020

Currently, the huge use of tires generates large quantities of waste material which represents a ... more Currently, the huge use of tires generates large quantities of waste material which represents a severe environmental problem. The common technique used for processing waste tires is crushing using mechanical methods and separating tire components like fibers, metals, and rubber from the used tire. The aim of this research is the recycling of this rubber from crushed tires, called ground tire rubber (GTR). With this aim, the manuscript analyses key mechanical properties of the thermoplastic composites produced by blending of crushed and micronized small particles of waste rubber tires with several industrial thermoplastic polymers. These types of composites are defined based on the total amount GTR in percent by weight, in the composite, and also, the particle sizes used in each case, so these aforementioned two variables (microparticle size and amounts) along with seven common industrial polymers define a series of composites for which the mechanical properties were tested, studied, analyzed and finally presented. Finally, the results obtained show that this proposed recycling method could be a way to enhance some specific polymer properties and could contribute to reducing the total of end of life used tire stocks environmental problem.

Renewable energy & power quality journal, Apr 1, 2003

The solar photovoltaic power, solar thermal power, wind power, biomass, biofuels, energy from was... more The solar photovoltaic power, solar thermal power, wind power, biomass, biofuels, energy from waste power & small hydro power stations, etc. are part of the installations that allow the use of a huge number of different energies, called renewable energies, clean energies or new energies. In fact the innovation resides fundamentally in technologies applied today to obtain energy, and the role assigned to these methods of power generation in the world of energy generation. This paper presents the development of this type of energies emphasizing its use to generate electricity. The advantages and trade-offs will be analyzed, as well as short and mid term expectations, studying their incidence on the environment. Moreover, the main renewable energies will be described: Minihydroelectric power stations, solar thermal stations, solar photovoltaic stations, wind power stations biomass and urban waste power stations.

Automática e instrumentación, Feb 14, 2019

Peer ReviewedPostprint (author's final draft

International Journal of Electrical Power & Energy Systems, Feb 1, 2012

The improvements obtained on the torque with low currents using rotor with spiral sheets are anal... more The improvements obtained on the torque with low currents using rotor with spiral sheets are analyzed in this paper. To have a complete study, several rotors and stators have been built to verify the electromagnetic variations on the three-phase asynchronous motors where they combine different constructive and mechanical characteristics of the related elements: changing inertias, constructive materials, and the geometrical shapes and disposition of the sheets. These different types of motors have been first tested in the laboratory, then, are simulated using computer aided tools (Matlab-Simulink). In particular four stators (1000, 1500, 1500-type A, and 3000 rpm) having the same constructive parameters, have been tested with the following rotors: solid rotor, solid rotor with diamagnetic rings, drag cup, and simple and double squirrel cage rotor. All these results have been compared to those obtained with the seven variants of spiral sheet rotor, presented in this paper.

En esta ponencia se expondran los pasos a seguir para la creacion de una guia en formato Web para... more En esta ponencia se expondran los pasos a seguir para la creacion de una guia en formato Web para la elaboracion de material multimedia (CD, DVD, pagina Web). La propuesta surgio del Instituto de Ciencias de la Educacion y del Servicio de Bibliotecas de la Universidad Politecnica de Cataluna debido al creciente aumento en la elaboracion de material multimedia por parte del profesorado y delante de la necesidad de compaginar, unificar criterios y ayudar a los docentes que se inician en la elaboracion de estos materiales. Esta guia se ha encargado a un grupo de profesores de diversos Departamentos dirigidos por Ramon Mujal del Departamento de Ingenieria Electrica, y en ella se ha intentado sintetizar y resumir en un formato multimedia las dudas, problemas o inquietudes con las cuales nos enfrontamos al iniciar trabajos de este tipo.