Person:
Aranguren Garacochea, Patricia

person.page.identifierURI

https://academica-e.unavarra.es/handle/2454/48564

Last Name

Aranguren Garacochea

First Name

Patricia

person.page.departamento

Ingeniería

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ISC. Institute of Smart Cities

ORCID

0000-0001-6911-4506

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811009

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Now showing 1 - 10 of 38

Open Access
Experimental evidence of the viability of thermoelectric generators to power volcanic monitoring stations
(MDPI, 2020) Catalán Ros, Leyre; Garacochea Sáenz, Amaia; Casi Satrústegui, Álvaro; Araiz Vega, Miguel; Aranguren Garacochea, Patricia; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería
Although there is an important lack of commercial thermoelectric applications mainly due to their low efficiency, there exist some cases in which thermoelectric generators are the best option thanks to their well-known advantages, such as reliability, lack of maintenance and scalability. In this sense, the present paper develops a novel thermoelectric application in order to supply power to volcanic monitoring stations, making them completely autonomous. These stations become indispensable in any volcano since they are able to predict eruptions. Nevertheless, they present energy supply difficulties due to the absence of power grid, the remote access, and the climatology. As a solution, this work has designed a new integral system composed of thermoelectric generators with high efficiency heat exchangers, and its associated electronics, developed thanks to Internet of Things (IoT) technologies. Thus, the heat emitted from volcanic fumaroles is transformed directly into electricity with thermoelectric generators with passive heat exchangers based on phase change, leading to a continuous generation without moving parts that powers different sensors, the information of which is emitted via LoRa. The viability of the solution has been demonstrated both at the laboratory and at a real volcano, Teide (Canary Islands, Spain), where a compact prototype has been installed in an 82 C fumarole. The results obtained during more than eight months of operation prove the robustness and durability of the developed generator, which has been in operation without maintenance and under several kinds of meteorological conditions, leading to an average generation of 0.49W and a continuous emission over more than 14 km.
Open Access
Enhancement of the power-to-heat energy conversion process of a thermal energy storage cycle through the use of a thermoelectric heat pump
(Elsevier, 2024) Erro Iturralde, Irantzu; Aranguren Garacochea, Patricia; Sorbet Presentación, Francisco Javier; Bonilla-Campos, Íñigo; Astrain Ulibarrena, David; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The principal strategy for achieving a neutral climate entails enhancing the share of renewable energies in the energy mix, in conjunction with promoting innovation in efficient technologies. Thermal energy storage systems have the potential to efficiently handle the intermittent nature of renewable energy sources. Furthermore, these systems can effectively handle shifts in both heat and electrical demand. Thus, efficient power-to-heat technologies are needed to boost thermal energy storage. This manuscript explores the potential of utilising a thermoelectric heat pump system in conjunction with electric resistances for charging a thermal energy storage. In order to achieve elevated temperatures, the thermoelectric system integrates thermoelectric heat pump blocks in a two-stage configuration. Air has been employed as a heat transfer medium for sensible heat storage. Higher airflow rates improve the performance of thermoelectric heat pump system. Moreover, its impact on the optimal voltage supply of the thermoelectric system is observed when it is combined with an electric resistance to achieve elevated temperatures. In comparison to the basic charging process that solely relies on the electric resistance of a thermal energy storage at 120 °C, a significant 30 % increase in power-to-heat energy conversion has been achieved by including the thermoelectric heat pump system. In fact, it efficiently elevates the temperature from the initial ambient temperature of 25 °C to a remarkable 113.1 °C, achieving a coefficient of performance of 1.35 with an airflow rate of 23 m3/h. Therefore, the use of this technology to enhance a complete process of storing excess renewable energy in the form of heat for subsequent use in both heat and electricity through a combined heat and power cycle is demonstrated.
Open Access
Impact of a thermoelectric subcooler heat exchanger on a carbon dioxide transcritical refrigeration facility
(Elsevier, 2022) Casi Satrústegui, Álvaro; Aranguren Garacochea, Patricia; Araiz Vega, Miguel; Alegría Cía, Patricia; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsita
To improve the performance of vapour compression refrigeration cycles, the inclusion of a thermoelectric subcooler for low-medium power units has been the focus of recent studies due to its robustness, compactness and simplicity of operation. In thermoelectric systems, it has been demonstrated that the heat exchangers used in the hot and cold side of the thermoelectric modules have a critical impact in the performance of the system. This influence has not yet been studied for thermoelectric subcooling systems in vapour compression cycles. This work, for the first time, evaluates the impact that the heat exchangers of a thermoelectric subcooler, included in a transcritical carbon dioxide refrigeration cycle, have, in the performance of the refrigeration cycle. The influence is quantified in terms of: optimum working conditions, coefficient of performance and cooling capacity. The results show that, through an optimization of the heat exchangers of the thermoelectric subcooler, the performance improvements on the coefficient of performance using this technology are boosted from 11.96 to 14.75 % and the upgrade in the cooling capacity of the system rises from 21.4 to 26.3 %. Moreover, the optimum gas-cooler working pressure of the system is reduced and the optimum voltage supplied to the thermoelectric modules increases.
Open Access
Computational study of geothermal thermoelectric generators with phase change heat exchangers
(Elsevier, 2020) Catalán Ros, Leyre; Araiz Vega, Miguel; Aranguren Garacochea, Patricia; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería
The use of thermoelectric generators with phase change heat exchangers has demonstrated to be an interesting and environmentally friendly alternative to enhanced geothermal systems (EGS) in shallow hot dry rock fields (HDR), since rock fracture is avoided. The present paper studies the possibilities of the former proposal in a real location: Timanfaya National Park (Canary Islands, Spain), one of the greatest shallow HDR fields in the world, with 5000 m2 of characterized geothermal anomalies presenting temperatures up to 500 °C at only 2 m deep. For this purpose, a computational model based on the thermal-electrical analogy has been developed and validated thanks to a real prototype, leading to a relative error of less than 8%. Based on this model, two prototypes have been designed and studied for two different areas within the park, varying the size of the heat exchangers and the number of thermoelectric modules installed. As a result, the potential of the solution is demonstrated, leading to an annual electricity generation of 681.53 MWh thanks to the scalability of thermoelectric generators. This generation is obtained without moving parts nor auxiliary consumption, thus increasing the robustness of the device and removing maintenance requirements.
Open Access
Auxiliary consumption: a necessary energy that affects thermoelectric generation
(Elsevier, 2018) Aranguren Garacochea, Patricia; Araiz Vega, Miguel; Astrain Ulibarrena, David; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
Waste heat recovery can apply to a wide range of applications, from transportation, or industries to domestic appliances. Thermoelectric generation technology applied to those cases could produce electrical energy and thus improve their efficiency. A validated computational methodology, which simulates the behavior of any thermoelectric generator and calculates the energy consumption of the auxiliary equipment involved, has been used to determine the potential of waste heat harvesting. The usable energy, the net energy, generated has to be maximized, not only the thermoelectric generation has to be maximized, but also the consumption of the auxiliary equipment has to be minimized, or if possible eliminated. Heat exchangers with a liquid as the heat carrier procure high thermoelectric generations, as their thermal resistances are very low, nevertheless when the consumption of their auxiliary consumption is borne in mind, their use is not that promising. The optimal thermoelectric energy obtained from the flue gases of a real industry using these dissipation systems is 119 MWh/year, while the maximum net energy is 73 MWh/year due to the consumption of the auxiliary equipment. The latest scenario does not only represent a 40% reduction from the optimal thermoelectric generation but also a different optimal working point. The complete elimination of the auxiliary equipment using novel biphasic thermosyphons with free convection at the same application produces a net energy of 128 MWh/year. This novel dissipation technology presents an increase on the thermoelectric generation due to its low thermal resistances, but above all due to the elimination of the auxiliary consumption.
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Experimental evaluation of a transcritical CO2 refrigeration facility working with an internal heat exchanger and a thermoelectric subcooler: performance assessment and comparative
(Elsevier, 2022) Casi Satrústegui, Álvaro; Aranguren Garacochea, Patricia; Araiz Vega, Miguel; Sánchez, Daniel; Cabello, Ramón; Astrain Ulibarrena, David; Ingeniería; Ingeniaritza; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The use of carbon dioxide in transcritical state has become one of the most used solutions to comply with the F-Gas directive and reduce greenhouse gases emissions from refrigeration systems at high ambient temperatures. For low-medium power units, the commonly used solutions to improve the efficiency such as the ejector, multiple compressor arrangements, mechanical subcooler, etc., add complexity and increase the cost of the refrigeration facility, which is not ideal for small units. In this low-medium power range, two technologies stand out to increase the performance of a carbon dioxide transcritical cycle: the internal heat exchanger and the thermoelectric subcooler. This study brings a complete research in which both solutions have been tested in the same experimental transcritical carbon dioxide refrigeration facility under the same working conditions. It focuses on the real performance of both systems and discusses the strengths and weaknesses of using an internal heat exchanger or a thermoelectric subcooler. The results show that the thermoelectric subcooler outperforms the internal heat exchanger in both the coefficient of performance and the cooling capacity while also being a more controllable and flexible solution.
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Experimental investigation of the applicability of a thermoelectric generator to recover waste heat from a combustion chamber
(Elsevier, 2015) Aranguren Garacochea, Patricia; Astrain Ulibarrena, David; Rodríguez García, Antonio; Martínez Echeverri, Álvaro; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
A thermoelectric generator prototype has been built; it produces 21.56 W of net power, the produced thermoelectric power minus the consumption of the auxiliary equipment, using an area of 0.25 m2 (approximately 100 W/m2). The prototype is located at the exhaust of a combustion chamber and it is provided with 48 thermoelectric modules and two different kinds of heat exchangers, finned heat sinks and heat pipes. Globally, the 40 % of the primary energy used is thrown to the ambient as waste heat; one of the many different applications in which thermoelectricity can be applied is to harvest waste heat to produce electrical power. Besides, the influence on the thermoelectric and on the net power generation of key parameters such as the temperature and mass flow of the exhaust gases, the heat dissipation systems in charge of dispatching the heat into the ambient and the consumption of the auxiliary equipment has been studied. In terms of heat dissipation, the heat pipes outperform the finned dissipators, a 43 % more net power is obtained.
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Initiative to increment the number of women in STEM degrees: women, science and technology chair of the Public University of Navarre
(IEEE, 2020) Aranguren Garacochea, Patricia; San Martín Biurrun, Idoia; Catalán Ros, Leyre; Martínez Ramírez, Alicia; Jurío Munárriz, Aránzazu; Díaz Lucas, Silvia; Pérez Artieda, Miren Gurutze; Gómez Fernández, Marisol; Barrenechea Tartas, Edurne; Estadística, Informática y Matemáticas; Ingeniería; Ingeniería Eléctrica, Electrónica y de Comunicación; Estatistika, Informatika eta Matematika; Ingeniaritza; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The Public University of Navarre joined with Navarre Government has created the Women, Science and Technology Chair. This chair arises due to the plummeting tendency of the percentage of women in STEM degrees with the aim of reversing this trend. The programme of activities is defined throughout this contribution by six activities: a Theatre Play, a Poster Award on Final Degree/Masters Project, The 1st Week of Women, Science and Technology, the Promotion of Technical Degrees in schools and high-schools, a Workshop about Gender Stereotypes and the Fostering of Women among Science and Environment. Each activity gained great success and the preset goals were highly accomplished, especially, the 1st Week of Women, Science and Technology activity. The latter achieved a great success both in participation and in repercussion, contributing to visualize the role of women in science and technology.
Open Access
Thermoelectric generators for waste heat harvesting: a computational and experimental approach
(Elsevier, 2017) Aranguren Garacochea, Patricia; Araiz Vega, Miguel; Astrain Ulibarrena, David; Martínez Echeverri, Álvaro; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
Waste heat generation has a widespread presence into daily applications, however, due to the low-temperature grade which presents, its exploitation with the most common technologies is complicated. Thermoelectricity presents the possibility of harvesting any temperature grade heat; besides it also includes many other advantages which make thermoelectric generators perfect for generating electric power from waste heat. A prototype divided into two levels along the chimney which uses the waste heat of a combustion has been built. The experimentation has been used to determine the parameters that influence the generation and to validate a generic computational model able to predict the thermoelectric generation of any application, but specially applications where waste heat is harvested. The temperature and mass flow of the flue gases and the load resistance determine the generation, and consequently, these parameters have been included into the model, among many others. This computational model incorporates all the elements included into the generators (heat exchangers, ceramics, unions) and all the thermoelectric phenomena and moreover, it takes into account the temperature loss of the flue gases while circulating along the thermoelectric generator. The built prototype presents a 65 % reduction in the generation of the two levels of the thermoelectric generator due to the temperature loss of the flue gases. The general computational model predicts the thermoelectric generation with an accuracy of the ±12 %.
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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.