Open Access
Study of the degradation of heat exchanger materials in the acidic environment of Teide National Park
(2019) Catalán Ros, Leyre; Pérez Artieda, Miren Gurutze; Berlanga Labari, Carlos; Garacochea Sáenz, Amaia; Rodríguez García, Antonio; Domínguez, Vidal; Montañez, Ana Carolina; Padilla, Germán D.; Pérez, Nemesio M.; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC; Ingeniería
Supplying power to volcanic monitoring stations constitutes a challenge due to both the access difficulties and the acidic environment associated with volcanoes. ELECTROVOLCAN project is developing thermoelectric generators that make use of the temperature of the available fumaroles to directly supply electricity to the stations in a robust, compact and reliable way. The main element of thermoelectric generators are the thermoelectric modules, based on Seebeck effect. Nonetheless, since the efficiency of these modules increases with the temperature difference between their sides, the introduction of heat exchangers becomes essential. The present study analyses the behavior of different materials used in the construction of the heat exchangers in the acidic environment of Teide National Park.
Open Access
Development and experimental validation of a thermoelectric test bench for laboratory lessons
(OmniaScience, 2013) Rodríguez García, Antonio; Astrain Ulibarrena, David; Martínez Echeverri, Álvaro; Aranguren Garacochea, Patricia; Pérez Artieda, Miren Gurutze; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
The refrigeration process reduces the temperature of a space or a given volume while the power generation process employs a source of thermal energy to generate electrical power. Because of the importance of these two processes, training of engineers in this area is of great interest. In engineering courses it is normally studied the vapor compression and absorption refrigeration, and power generation systems such as gas turbine and steam turbine. Another type of cooling and generation less studied within the engineering curriculum, having a great interest, it is cooling and thermal generation based on Peltier and Seebeck effects. The theoretical concepts are useful, but students have difculties understanding the physical meaning of their possible applications. Providing students with tools to test and apply the theory in real applications, will lead to a better understanding of the subject. Engineers must have strong theoretical, computational and also experimental skills. A prototype test bench has been built and experimentally validated to perform practical lessons of thermoelectric generation and refrigeration. Using this prototype students learn the most effective way of cooling systems and thermal power generation as well as basic concepts associated with thermoelectricity. It has been proven that students learn the process of data acquisition, and the technology used in thermoelectric devices. These practical lessons are implemented for a 60 people group of students in the development of subject of Thermodynamic including in the Degree in Engineering in Industrial Technologies of Public University of Navarra.
Open Access
The importance of the assembly in thermoelectric generators
(IntechOpen, 2018) Araiz Vega, Miguel; Catalán Ros, Leyre; Herrero Mola, Óscar; Pérez Artieda, Miren Gurutze; Rodríguez García, Antonio; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería
Generally, in the optimization of thermoelectric generators, only the heat exchangers or the thermoelectric modules themselves are taken into account. However, the assembly of the generator as a whole is of vital importance since a bad contact or a thermal bridge can waste the performance of an optimal generator. In this sense, the present chapter analyzes experimentally the use of different interface materials to reduce the thermal contact resistance between the modules and the heat exchangers, the influence of the pressure distribution in the assembly as well as the effect of different insulating materials in order to reduce the thermal bridge between the exchangers. Thus, it has been demonstrated that a good assembly requires the implementation of thermal interface materials to ensure the microscopic contact between the heat exchangers and the modules, besides a uniform clamping pressure. Nevertheless, since this is normally achieved with screws, they represent a source of thermal bridges in conjunction with the small distance between the exchangers. In order to reduce heat losses due to thermal bridges, which can represent up to one-third of the incoming heat, an increment of the distance between the exchangers and the use of an insulator is recommended.
Open Access
Revisión sobre nitruraciones láser de aleaciones de titanio
(CENIM, 2010) Pérez Artieda, Miren Gurutze; Fernández Carrasquilla, Javier; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
Una técnica comúnmente utilizada para la mejora de la resistencia a desgaste de las aleaciones de titanio es la nitruración de la superficie, utilizando la deposición física o química de vapor, la implantación iónica o el refundido de la superficie en atmósferas que contienen nitrógeno. En esta revisión se estudian los sistemas de nitruración con tecnología láser, utilizados para tratar la superficie de diferentes aleaciones de titanio. Las aleaciones de titanio son un material alternativo al acero, muy atractivo para aplicaciones que requieren alta resistencia a temperaturas elevadas, puesto que tienen una relación resistencia-dureza elevada y buena resistencia a corrosión. En aplicaciones que requieren buena resistencia a desgaste, las aleaciones de titanio suponen un problema, debido a sus pobres características tribológicas. La utilización de aleaciones de titanio junto con un tratamiento de nitruración adecuado, podría permitir la sustitución del acero en diferentes aplicaciones, consiguiendo una disminución en el peso de los componentes fabricados.
Open Access
Revisión sobre recubrimientos láser de aleaciones de aluminio
(CENIM, 2008) Pérez Artieda, Miren Gurutze; Fernández Carrasquilla, Javier; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
En este artículo se presenta un trabajo de revisión bibliográfica, centrado en los procesos de recubrimiento y tratamiento superficial láser realizados en aleaciones de aluminio. Estos procesos láser son técnicas de modificación superficial que permiten la obtención de propiedades adecuadas en la superficie de componentes cuyas características internas no se ven afectadas. La ventaja principal que caracteriza la tecnología láser es la elevada velocidad de calentamiento y enfriamiento que se produce durante los procesos. Esto, provoca la formación de fases fuera del equilibrio, con microestructuras nuevas. En el artículo se aprecia que los resultados obtenidos, sin embargo, varían no sólo con el tipo de aleación utilizada como substrato y con el material de aporte sino, también, con la ruta de fabricación seguida por el propio material. Además, se analizan los diferentes parámetros que tienen influencia en el proceso y se contrastan las características obtenidas por distintos investigadores, con el objeto de condensar en un documento la información más importante en este campo.
Open Access
New opportunities for electricity generation in shallow hot dry rock fields: a study of thermoelectric generators with different heat exchangers
(Elsevier, 2019) Catalán Ros, Leyre; Aranguren Garacochea, Patricia; Araiz Vega, Miguel; Pérez Artieda, Miren Gurutze; Astrain Ulibarrena, David; Institute of Smart Cities - ISC
Despite being one of the largest renewable sources, geothermal energy is not widely utilized for electricity generation. In order to leverage shallow hot dry rock (HDR) fields, the present paper proposes an alternative to enhanced geothermal systems (EGS): thermoelectric generators. Based on the conditions of Timanfaya National Park, a prototype has been built to experimentally analyze the feasibility of the proposed solution. The prototype is composed by a two phase closed thermosyphon (TPCT) as hot side heat exchanger, two thermoelectric modules, and it considers different cold side heat exchangers: fin dissipators assisted by a fan and loop thermosyphons, both with various geometries. Experiments have demonstrated that loop thermosyphons represent the best alternative due to their low thermal resistance and, especially, due to their lack of auxiliary consumption, leading to a maximum net power generation of 3.29 W per module with a temperature difference of 180 °C (200 °C in the hot side and 20 °C as ambient temperature), 54% more than with fin dissipators. Hence, there exists a new opportunity for electricity generation in shallow hot dry rock fields: thermoelectric generators with biphasic thermosyphons as heat exchangers, a patented and robust solution.
Open Access
Computational and experimental study of a complete heat dissipation system using water as heat carrier placed on a thermoelectric generator
(Elsevier, 2014) Aranguren Garacochea, Patricia; Astrain Ulibarrena, David; Pérez Artieda, Miren Gurutze; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
The heat dissipation systems which have liquids as heat carriers outperform conventional dissipation systems at thermoelectric generators (TEGs). However, new elements need to be introduced such as pumps, secondary heat exchangers and piping. A predictive computational model of a dissipation system involving refrigerant liquids has been implemented. The accuracy of the model is 93 % for all its outputs: the total thermal resistance, the hydraulic losses and the auxiliary power consumption. The validation of the model has been done with a prototype mainly composed by a multi-channel heat exchanger, a fan-coil, a pump and several sensors: temperature, pressure and flow meters. A study on the influence of the water and the air mass flow over the total thermal resistance has been conducted. The total resistance dependence on the air mass flow shows the importance of including the secondary heat exchanger into the thermal and hydraulic calculations. The smallest resistance does not always obtain the highest net power generation, the high demanding power of the auxiliary equipment needed to obtain this resistance influences negatively on the net power generation. Among the experimental points, the optimum scenario obtains a 40 % additional power generation with respect to the smallest resistance point.