20 results on '"Miguel Araiz"'
Search Results
2. Enhanced behaviour of a passive thermoelectric generator with phase change heat exchangers and radiative cooling
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David Astrain, Juliana Jaramillo-Fernandez, Miguel Araiz, Achille Francone, Leyre Catalán, Alejandra Jacobo-Martín, Patricia Alegría, Clivia M. Sotomayor-Torres, Universidad Pública de Navarra. Departamento de Ingeniería, Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. Institute of Smart Cities - ISC, and Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa more...
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Heat-pipe ,Energy Engineering and Power Technology ,Thermal resistance ,Radiative cooling ,Industrial and Manufacturing Engineering ,Thermoelectric generator - Abstract
Heat exchangers are essential to optimize the efficiency of Thermoelectric Generators (TEGs), and heat pipes without fans have proven to be an advantageous design as it maintains the characteristic robustness of thermoelectricity, low maintenance and lack of moving parts. However, the efficiency of these heat exchangers decreases under natural convection conditions, reducing their heat transfer capacity and thus thermoelectric power production. This work reports on a novel heat exchanger that combines for the first time, phase change and radiative cooling in a thermoelectric generator to improve its efficiency and increase the production of electrical energy, specially under natural convection. For this, two thermoelectric generators with heat-pipes on their cold sides have been tested: one with the radiative coating and the other without it. Their thermal resistances have been determined and the electric power output was compared under different working conditions, namely, natural convection and forced convection indoors and outdoors. The experimental tests show a clear reduction of the heat exchanger thermal resistance thanks to the radiative coating and consequently, an increase of electric production 8.3 % with outdoor wind velocities of 1 m/s, and up to 54.8 % under free convection conditions. The application of the radiative surface treatment is shown to result in a more stable electrical energy production, suppressing the drastic decrease in the generated electric power that occurs in thermoelectric generators when they work under free convection. The authors acknowledge the support of the Spanish Ministry of Science, Innovation and Universities, and the European Regional Development Fund , under grants PID2021-124014OB-I00 (VIVOTEG), TED2021-129359B-I00 (GEOTEG), PGC2018-101743-B-I00 (SIP) and RTI2018-093921-A-C44 (SMOOTH). Open access funding provided by Universidad Pública de Navarra. more...
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- 2023
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3. Field test of a geothermal thermoelectric generator without moving parts on the Hot Dry Rock field of Timanfaya National Park
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Leyre Catalan, Patricia Alegria, Miguel Araiz, David Astrain, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. Institute of Smart Cities - ISC, and Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa more...
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Energy Engineering and Power Technology ,HDR ,Biphasic thermosyphon ,Heat pipe ,Phase change ,Geothermal energy ,Industrial and Manufacturing Engineering ,Thermoelectric generator - Abstract
Although in the last years thermoelectric generators have arisen as a solution to boost geothermal power generation, tests on field are still scarce. The vast majority of the available studies focus on computational simulations or laboratory experiments, mainly with active heat exchangers that require pumps or fans, and, consequently, present moving parts and auxiliary consumption. The present paper demonstrates for the first time the suitability of a geothermal thermoelectric generator (GTEG) with passive phase change heat exchangers, and therefore, without moving parts nor auxiliary consumption, on the shallow Hot Dry Rock (HDR) field of Timanfaya National Park (Canary Islands, Spain), where 173 °C air anomalies can be found. The device has been in operation without maintenance for 2 years now, producing more than 520 kWh of energy. In terms of power generation, since the installed device is in turn composed of two prototypes with 10 and 6 thermoelectric modules, it has been confirmed that installing more modules leads to a lower generation per module, although total generation can be higher. In fact, the prototype with 10 thermoelectric modules generated a maximum of 20.9 W (2.09 W per module) with a temperature difference between sources of 158 °C, while the prototype with 6 thermoelectric modules obtained 16.67 W (2.78 W per module) under the same conditions. These results open the door for a large-scale exploitation thanks to the intrinsic advantages of modularity, reliability, robustness, and minimal environmental impact of the developed device. The authors would like to acknowledge the support of the Spanish State Research Agency and FEDER-UE under the grants PID2021-124014OB-I00 and TED2021-129359B-I00. Open access funding provided by Universidad Pública de Navarra more...
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- 2023
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4. Impact of a thermoelectric subcooler heat exchanger on a carbon dioxide transcritical refrigeration facility
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Álvaro Casi, Patricia Aranguren, Miguel Araiz, Patricia Alegría, David Astrain, Universidad Pública de Navarra. Departamento de Ingeniería, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila, Gobierno de Navarra / Nafarroako Gobernua, and Universidad Pública de Navarra / Nafarroako Unibertsita more...
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Heat exchangers ,R744 ,Energy Engineering and Power Technology ,CO2 ,Thermoelectric subcooler ,Industrial and Manufacturing Engineering ,COP - Abstract
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. The authors would like to acknowledge the support of the Spanish Ministry of Science, Innovation and Universities, and European Regional Development Fund, for the funding under the RTI2018-093501-B-C21 and RTI2018-093501-B-C22 research projects. We would also like to acknowledge the support from the Education Department of the Government of Navarra with the Predoctoral Grants for Phd programmes of Interest to Navarra and the Official School of Industrial Engineers of Navarre with the scholarship Fuentes Dutor. Open access funding provided by Universidad Pública de Navarra. more...
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- 2022
5. Introductory Chapter: Heat Transfer
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Miguel Araiz
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Materials science ,Heat transfer ,Mechanics - Published
- 2021
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6. Heat Transfer - Design, Experimentation and Applications
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Miguel Araiz Vega
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Materials science ,Heat transfer ,Mechanical engineering - Published
- 2021
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7. Improvements in the cooling capacity and the COP of a transcritical CO2 refrigeration plant operating with a thermoelectric subcooling system
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Miguel Araiz, Ramón Cabello, Leyre Catalan, David Astrain, A. Merino, Daniel Sánchez, Rodrigo Llopis, P. Aranguren, Universidad Pública de Navarra. Departamento de Ingeniería, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, and Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila more...
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020209 energy ,Energy Engineering and Power Technology ,02 engineering and technology ,Cooling capacity ,Transcritical cycle ,Industrial and Manufacturing Engineering ,020401 chemical engineering ,R744 ,Heat exchanger ,Thermoelectric effect ,0202 electrical engineering, electronic engineering, information engineering ,Transcritical ,0204 chemical engineering ,Process engineering ,COP ,Subcooling ,business.industry ,Computational model ,Refrigeration ,Thermoelectricity ,Thermoelectric generator ,Working fluid ,Environmental science ,CO2 ,business - Abstract
Restrictive environmental regulations are driving the use of CO 2 as working fluid in commercial vapour compression plants due to its ultra-low global warming potential (GWP 100 = 1) and its natural condition. However, at high ambient temperatures transcritical operating conditions are commonly achieved causing low energy efficiencies in refrigeration facilities. To solve this issue, several improvements have been implemented, especially in large centralized plants where ejectors, parallel compressors or subcooler systems, among others, are frequently used. Despite their good results, these measures are not suitable for small-capacity systems due mainly to the cost and the complexity of the system. Accordingly, this work presents a new subcooling system equipped with thermoelectric modules (TESC), which thanks to its simplicity, low cost and easy control, results very suitable for medium and small capacity plants. The developed methodology finds the gas-cooler pressure and the electric voltage supplied to the TESC system that maximizes the overall COP of the plant taking into account the ambient temperature, the number of thermoelectric modules used and the thermal resistance of the heat exchangers included in the TESC. The obtained results reveal that, with 20 thermoelectric modules, an improvement of 20% in terms of COP and of 25.6% regarding the cooling capacity can be obtained compared to the base cycle of CO 2 of a small cooling plant refrigerated by air. Compared to a cycle that uses an internal heat exchanger IHX, the improvements reach 12.2% and 19.5% respectively. The authors would like to acknowledge the support of the Spanish Ministry of Science, Innovation and Universities for the funding under the FPU Program (FPU16/05203). more...
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- 2019
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8. Performance assessment of an experimental CO2 transcritical refrigeration plant working with a thermoelectric subcooler in combination with an internal heat exchanger
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Álvaro Casi, Patricia Aranguren, Miguel Araiz, Daniel Sanchez, Ramon Cabello, and David Astrain
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Fuel Technology ,Nuclear Energy and Engineering ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology - Published
- 2022
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9. Experimental development of a novel thermoelectric generator without moving parts to harness shallow hot dry rock fields
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Leyre Catalan, David Astrain, A. Rodríguez, Miguel Araiz, Patricia Alegria, Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila, Universidad Pública de Navarra. Departamento de Ingeniería, and Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities more...
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Fins dissipator ,Work (thermodynamics) ,Materials science ,business.industry ,Geothermal energy ,Nuclear engineering ,Energy Engineering and Power Technology ,Thermoelectricity ,Industrial and Manufacturing Engineering ,Generator (circuit theory) ,Electricity generation ,Thermoelectric generator ,Thermoelectric effect ,Heat exchanger ,Heat pipe ,business ,Thermosiphon ,Geothermal gradient - Abstract
Nowadays, geothermal energy in shallow hot dry rock fields is not exploited enough due to the high economic and environmental impact as well as the lack of scalability of the existing technologies. Here, thermoelectricity has a great future potential due to its robustness, absence of moving parts and modularity. However, the efficiency of a thermoelectric generator depends highly on the heat exchangers. In this work, a novel geothermal thermoelectric generator is experimentally developed, characterizing different configurations of biphasic heat exchangers to obtain low thermal resistances that allow the maximum efficiency in the thermoelectric modules. As a result, robust and passive heat exchangers were obtained with thermal resistances of 0.07 K/W and 0.4 K/W in the hot and cold sides, respectively. The geothermal thermoelectric generator was built with the most effective heat exchangers and was experimented under different temperature and convection conditions, generating 36 W (17 W by a prototype with 10 modules and 19 W by a prototype with 6 modules) for a temperature difference of 160 °C between the heat source and the environment. Furthermore, the experimental development showed that it is possible to increase electricity generation with a more compact generator, since a decrease in the number of modules from 10 to 6 increases the efficiency from 3.72% to 4.06%. With this research, the feasibility of a novel and robust geothermal thermoelectric generator whose working principle is phase change has been experimentally demonstrated, as well as the importance of compactness to maximize its efficiency and thus, power generation. more...
- Published
- 2021
10. Thermoelectric Generator with Passive Biphasic Thermosyphon Heat Exchanger for Waste Heat Recovery: Design and Experimentation
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Miguel Araiz, P. Aranguren, David Astrain, Leyre Catalan, Álvaro Casi, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, Universidad Pública de Navarra. Departamento de Ingeniería Eléctrica, Electrónica y de Comunicación, Nafarroako Unibertsitate Publikoa. Ingeniaritza Elektriko, Elektroniko eta Telekomunikazio Saila, and Gobierno de Navarra / Nafarroako Gobernua more...
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Technology ,Control and Optimization ,Renewable Energy, Sustainability and the Environment ,Computer science ,MathematicsofComputing_GENERAL ,Energy Engineering and Power Technology ,Mechanical engineering ,Energy consumption ,Waste heat recovery unit ,thermoelectric generator ,waste heat recovery ,experimental setup ,power generation ,passive heat-exchanger ,Electricity generation ,Thermoelectric generator ,Waste heat ,Heat exchanger ,Thermosiphon ,Electric power ,Electrical and Electronic Engineering ,Waste heat recovery ,Engineering (miscellaneous) ,Experimental setup ,Passive heat-exchanger ,Power generation ,Energy (miscellaneous) - Abstract
One of the measures to fight against the current energy situation and reduce the energy consumption at an industrial process is to recover waste heat and transform it into electric power. Thermoelectric generators can be used for that purpose but there is a lack of experimental studies that can bring this technology closer to reality. This work presents the design, optimizations and development of two devices that are experimented and compared under the same working conditions. The hot side heat exchanger of both generators has been designed using a computational fluid dynamics software and for the cold side of the generators two technologies have been analysed: a finned dissipater that uses a fan and free convection biphasic thermosyphon. The results obtained show a maximum net generation of 6.9W in the thermoelectric generator with the finned dissipater; and 10.6W of power output in the generator with the biphasic thermosyphon. These results remark the importance of a proper design of the heat exchangers, trying to get low thermal resistances at both sides of the thermoelectric modules, as well as, the necessity of considering the auxiliary consumption of the equipment employed. more...
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- 2021
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11. Simulation of thermoelectric heat pumps in nearly zero energy buildings: Why do all models seem to be right?
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Sergio Díaz de Garayo, Alvaro Martinez, Leyre Catalán, Miguel Araiz, and Patricia Aranguren
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Renewable Energy, Sustainability and the Environment ,business.industry ,020209 energy ,Thermal resistance ,Energy Engineering and Power Technology ,02 engineering and technology ,Mechanics ,Coefficient of performance ,Thermoelectric materials ,Fuel Technology ,Thermoelectric generator ,020401 chemical engineering ,Nuclear Energy and Engineering ,Air conditioning ,Heat exchanger ,Thermoelectric effect ,0202 electrical engineering, electronic engineering, information engineering ,0204 chemical engineering ,business ,Uncertainty analysis ,Mathematics - Abstract
The use of thermoelectric heat pumps for heat, ventilation, and air conditioning in nearly-zero-energy buildings is one of the most promising applications of thermoelectrics. However, simulation works in the literature are predominately based on the simple model, which was proven to exhibit significant deviations from experimental results. Nine modelling techniques have been compared in this work, according to statistical methods based on uncertainty analysis, in terms of predicted coefficient of performance and cooling power. These techniques come from the combination of three simulation models for thermoelectric modules (simple model, improved model, electric analogy) and five methods for implementing the thermoelectric properties. The main conclusion is that there is no statistical difference in the mean values of coefficient of performance and cooling power provided by these modelling techniques under all the scenarios, at 95% level of confidence. However, differences appear in the precision of these results in terms of uncertainty of the confidence intervals. Minimum values of uncertainty are obtained when the thermal resistance ratio approaches 0.1, being ±8% when using temperature-dependent expressions for the thermoelectric properties, ±18% when using Lineykin’s method, and ± 25% when using Chen’s method. The best combination is that composed of the simple model and temperature-dependent expressions for the thermoelectric properties. Additionally, if low values of resistance ratio are anticipated, empirical expressions from the literature can be used for the thermal resistance of the heat exchangers; for high values, though, experimental tests should be deployed, especially for the heat exchanger on the hot side. more...
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- 2021
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12. Thermoelectric heat recovery in a real industry: From laboratory optimization to reality
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Miguel Araiz, David Astrain, Leyre Catalan, Álvaro Casi, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, Universidad Pública de Navarra. Departamento de Ingeniería, Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila, and Gobierno de Navarra / Nafarroako Gobernua, 0011-1365-2018-000101 more...
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Computer science ,business.industry ,Computational model ,020209 energy ,Energy Engineering and Power Technology ,02 engineering and technology ,Industrial and Manufacturing Engineering ,On-site experimentation ,Waste heat recovery unit ,Waste-heat ,Heat pipe ,Thermoelectric generator ,020401 chemical engineering ,Waste heat ,Heat recovery ventilation ,Heat exchanger ,Thermoelectric effect ,0202 electrical engineering, electronic engineering, information engineering ,Passive heat-exchangers ,Electric power ,0204 chemical engineering ,Process engineering ,business - Abstract
Thermoelectricity, in the form of thermoelectric generators, holds a great potential in waste heat recovery, this potential has been studied and proved in several laboratory and theoretical works. By the means of a thermoelectric generator, part of the energy that normally is wasted in a manufacturing process, can be transformed into electricity, however, implementing this technology in real industries still remains a challenge and on-site tests need to be performed in order to prove the real capabilities of this technology. In this work, a computational model to simulate the behaviour of a thermoelectric generator that harvest waste heat from hot fumes is developed. Using the computational model an optimal configuration for a thermoelectric generator is obtained, also an experimental study of the performance of different heat pipes working as cold side heat exchangers is carried out in order to optimize the performance of the whole thermoelectric generator, thermal resistances of under 0,25 K/W are obtained. The optimized configuration of the thermoelectric generator has been built, installed and tested under real conditions at a rockwool manufacturing plant and experimental data has been obtained during the 30 days field test period. Results show that 4.6 W of average electrical power are produced during the testing period with an efficiency of 2.38%. Moreover, the computational model is validated using this experimental data. Furthermore, the full harvesting potential of an optimized designed that takes advantage of the whole pipe is calculated using the validated computational model, resulting in 30.8 MWh of energy harvested during a sample year which could meet the demand of 8.34 Spanish average households. The authors are indebted to the Navarra Government for economic support of this work, included in the 0011-1365-2018-000101 Research Project, also to the State Research Agency of Spain for economic support, included in the RTI2018-093501-B-C22 Project from the Research Challenges Program. We would also like to acknowledge the support from the FPU Program of the Spanish Ministry of Science, Innovation and Universities (FPU16/05203). more...
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- 2021
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13. Experimental Evidence of the Viability of Thermoelectric Generators to Power Volcanic Monitoring Stations
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P. Aranguren, Amaia Garacochea, Miguel Araiz, Álvaro Casi, David Astrain, Leyre Catalan, Universidad Pública de Navarra. Departamento de Ingeniería, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, and Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila more...
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Power supply ,Volcano surveillance ,Geothermal ,020209 energy ,heat pipe ,thermoelectric generator ,02 engineering and technology ,lcsh:Chemical technology ,LoRa ,Biochemistry ,Article ,Automotive engineering ,autonomous ,Analytical Chemistry ,Generator (circuit theory) ,Autonomous ,geothermal ,Thermoelectric effect ,Heat exchanger ,0202 electrical engineering, electronic engineering, information engineering ,lcsh:TP1-1185 ,Electronics ,Energy supply ,Electrical and Electronic Engineering ,Instrumentation ,Thermoelectric generator ,business.industry ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Heat pipe ,power supply ,Environmental science ,Electricity ,volcano surveillance ,0210 nano-technology ,business - Abstract
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 0.49 W and a continuous emission over more than 14 km. more...
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- 2020
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14. Prospects of Autonomous Volcanic Monitoring Stations: Experimental Investigation on Thermoelectric Generation from Fumaroles
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Pedro A. Hernández, Jose Francisco Albert, Leyre Catalan, P. Aranguren, David Astrain, Nemesio M. Pérez, Celestino Garcia de la Noceda, Germán D. Padilla, Miguel Araiz, Universidad Pública de Navarra. Departamento de Ingeniería, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, and Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila more...
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Geothermal ,020209 energy ,Nuclear engineering ,heat pipe ,thermoelectric generator ,02 engineering and technology ,lcsh:Chemical technology ,Biochemistry ,Article ,thermoelectricity ,autonomous ,Analytical Chemistry ,Volcanic Gases ,Autonomous ,geothermal ,Heat exchanger ,Thermoelectric effect ,0202 electrical engineering, electronic engineering, information engineering ,lcsh:TP1-1185 ,event ,Electrical and Electronic Engineering ,Volcano ,Instrumentation ,Thermoelectric generator ,event.disaster_type ,geography ,geography.geographical_feature_category ,power generation ,Thermoelectricity ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Fumarole ,Heat pipe ,volcano ,Electricity generation ,0210 nano-technology ,Power generation - Abstract
Fumaroles represent evidence of volcanic activity, emitting steam and volcanic gases at temperatures between 70 and 100 ∘ C . Due to the well-known advantages of thermoelectricity, such as reliability, reduced maintenance and scalability, the present paper studies the possibilities of thermoelectric generators, devices based on solid-state physics, to directly convert fumaroles heat into electricity due to the Seebeck effect. For this purpose, a thermoelectric generator composed of two bismuth-telluride thermoelectric modules and heat pipes as heat exchangers was installed, for the first time, at Teide volcano (Canary Islands, Spain), where fumaroles arise in the surface at 82 ∘ C . The installed thermoelectric generator has demonstrated the feasibility of the proposed solution, leading to a compact generator with no moving parts that produces a net generation between 0.32 and 0 . 33 W per module given a temperature difference between the heat reservoirs encompassed in the 69&ndash, 86 ∘ C range. These results become interesting due to the possibilities of supplying power to the volcanic monitoring stations that measure the precursors of volcanic eruptions, making them completely autonomous. Nonetheless, in order to achieve this objective, corrosion prevention measures must be taken because the hydrogen sulfide contained in the fumaroles reacts with steam, forming sulfuric acid. more...
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- 2020
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15. New opportunities for electricity generation in shallow hot dry rock fields: a study of thermoelectric generators with different heat exchangers
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Gurutze Perez, P. Aranguren, Miguel Araiz, Leyre Catalan, David Astrain, and Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities
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Geothermal ,020209 energy ,Thermal resistance ,Nuclear engineering ,Energy Engineering and Power Technology ,02 engineering and technology ,020401 chemical engineering ,Heat exchanger ,0202 electrical engineering, electronic engineering, information engineering ,0204 chemical engineering ,Geothermal gradient ,Thermoelectric generator ,Hot dry rock ,Renewable Energy, Sustainability and the Environment ,business.industry ,Geothermal energy ,Thermosyphon ,Renewable energy ,Fuel Technology ,Electricity generation ,Nuclear Energy and Engineering ,Environmental science ,Thermosiphon ,Fin dissipator ,business - Abstract
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. The authors would like to acknowledge the support of the Spanish State Research Agency and FEDER-UE under the grants DPI2014-53158-R and RTC-2017-6628-3 ; as well as the FPU Program of the Spanish Ministry of Science, Innovation and Universities (FPU16/05203 ). more...
- Published
- 2019
16. Prospects of waste-heat recovery from a real industry using thermoelectric generators: Economic and power output analysis
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Miguel Araiz, David Astrain, A. Martínez, Leyre Catalan, Álvaro Casi, Universidad Pública de Navarra. Departamento de Ingeniería, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila, and Gobierno de Navarra / Nafarroako Gobernua, 0011-1365-2018-000101 more...
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Government ,LCOE ,Renewable Energy, Sustainability and the Environment ,Computational model ,020209 energy ,Waste-heat recovery ,Economic analysis ,Energy Engineering and Power Technology ,02 engineering and technology ,Economic support ,Environmental economics ,Waste heat recovery unit ,Fuel Technology ,Thermoelectric generator ,020401 chemical engineering ,Nuclear Energy and Engineering ,Work (electrical) ,0202 electrical engineering, electronic engineering, information engineering ,Christian ministry ,Business ,Power output ,0204 chemical engineering ,Cost of electricity by source - Abstract
One of the options to reduce industrial energy costs and the environmental impact is to recover the waste-heat produce in some processes. This paper proposes the use of thermoelectric generators at a stone wool manufacturing plant to transform waste-heat from a hot gas flow into useful electricity. A combination of two computational models, previously developed and validated, has been used to perform the optimization from a double point of view: power output and economic cost. The proposed thermoelectric generator includes fin dissipaters and biphasic thermosyphons as the hot and cold side heat exchangers respectively. The model takes into account the temperature drop along the duct where the gases flow, the electric consumption of the auxiliary equipment, and the configuration and geometry of the heat exchangers. After the simulations a maximum net power production of 45 838 W is achieved considering an occupancy ratio of 0.40 and a fin spacing of 10 mm. The installation cost is minimized to 10.6 €/W with an occupancy ratio of 0.24. Besides, the Levelised Cost of Electricity, LCOE, is estimated for a thermoelectric generator for the first time. It is necessary to use standar methodologies to compare this technology to others. The LCOE estimated for the proposed design is around 15 c€/kWh within the ranges of current energy sources, proving, in this way, the capabilities of waste-heat recovery from industrial processes at reasonable prices with thermoelectric generators. The authors are indebted to the Government of Navarre funds for economic support of this work, included in the 0011-1365-2018-000101 Research Project; and the Spanish Ministry of Economy and Competitiveness for the economic support thanks to the DPI2014-53158-R project. more...
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- 2020
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17. The importance of the assembly in thermoelectric generators
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A. Rodríguez, Gurutze Perez, Miguel Araiz, Leyre Catalan, Oscar Herrero, Universidad Pública de Navarra. Departamento de Ingeniería, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities, and Nafarroako Unibertsitate Publikoa. Ingeniaritza Saila more...
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Engineering ,business.industry ,020209 energy ,Assembly ,Clamping pressure ,02 engineering and technology ,Economic support ,Pressure distribution ,021001 nanoscience & nanotechnology ,Manufacturing engineering ,Thermoelectric generator ,Thermal bridge ,Work (electrical) ,Contact ,0202 electrical engineering, electronic engineering, information engineering ,Christian ministry ,Thermal resistance ,0210 nano-technology ,business - Abstract
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. The authors are indebted to the Ministry of Economy, Industry and CompetitivenessGovernment of Spain and FEDER Funds for economic support of this work, included in the DPI2014-53158-R Research Project, as well as to the FPU Program of the Spanish Ministry of Education, Culture and Sport (FPU16/05203). more...
- Published
- 2018
18. Auxiliary consumption: a necessary energy that affects thermoelectric generation
- Author
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P. Aranguren, David Astrain, Miguel Araiz, Universidad Pública de Navarra. Departamento de Ingeniería Mecánica, Energética y de Materiales, and Nafarroako Unibertsitate Publikoa. Mekanika, Energetika eta Materialen Ingeniaritza Saila more...
- Subjects
Consumption (economics) ,Optimization ,020209 energy ,Energy (esotericism) ,Thermoelectric generation ,Energy Engineering and Power Technology ,02 engineering and technology ,Economic support ,Environmental economics ,021001 nanoscience & nanotechnology ,Industrial and Manufacturing Engineering ,Thermoelectric generator ,Work (electrical) ,0202 electrical engineering, electronic engineering, information engineering ,Economics ,Water cooling ,Auxiliary consumption ,Christian ministry ,0210 nano-technology ,Waste heat harvesting - Abstract
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. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the economic support to this work, included in the DPI2014-53158-R research project. more...
- Published
- 2018
19. Experimental and computational study on thermoelectric generators using thermosyphons with phase change as heat exchangers
- Author
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P. Aranguren, Miguel Araiz, A. Martínez, David Astrain, Universidad Pública de Navarra. Departamento de Ingeniería Mecánica, Energética y de Materiales, Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. InaMat - Institute for Advanced Materials, and Nafarroako Unibertsitate Publikoa. Mekanika, Energetika eta Materialen Ingeniaritza Saila more...
- Subjects
Engineering ,Work (thermodynamics) ,Renewable Energy, Sustainability and the Environment ,business.industry ,020209 energy ,Computational model ,Waste-heat recovery ,Energy Engineering and Power Technology ,Mechanical engineering ,02 engineering and technology ,Economic support ,Waste heat recovery unit ,Phase change ,Fuel Technology ,Thermoelectric generator ,020401 chemical engineering ,Nuclear Energy and Engineering ,Thermosyphon with phase change ,Heat exchanger ,0202 electrical engineering, electronic engineering, information engineering ,Christian ministry ,Thermosiphon ,0204 chemical engineering ,business - Abstract
An important issue in thermoelectric generators is the thermal design of the heat exchangers since it can improve their performance by increasing the heat absorbed or dissipated by the thermoelectric modules. Due to its several advantages, compared to conventional dissipation systems, a thermosyphon heat exchanger with phase change is proposed to be placed on the cold side of thermoelectric generators. Some of these advantages are: high heat-transfer rates; absence of moving parts and lack of auxiliary con- sumption (because fans or pumps are not required); and the fact that these systems are wickless. A com- putational model is developed to design and predict the behaviour of this heat exchangers. Furthermore, a prototype has been built and tested in order to demonstrate its performance and validate the compu- tational model. The model predicts the thermal resistance of the heat exchanger with a relative error in the interval [?8.09;7.83] in the 95% of the cases. Finally, the use of thermosyphons with phase change in thermoelectric generators has been studied in a waste-heat recovery application, stating that including them on the cold side of the generators improves the net thermoelectric production by 36% compared to that obtained with finned dissipators under forced convection. The authors are indebted to the Ministry of Economy, Industry and Competitiveness-Government of Spain and FEDER Funds for economic support of this work, included in the DPI2014-53158-R Research Project. more...
- Published
- 2017
20. Thermoelectric generators for waste heat harvesting: a computational and experimental approach
- Author
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P. Aranguren, David Astrain, Miguel Araiz, A. Martínez, Universidad Pública de Navarra. Departamento de Ingeniería Mecánica, Energética y de Materiales, and Nafarroako Unibertsitate Publikoa. Mekanika, Energetika eta Materialen Ingeniaritza Saila more...
- Subjects
Engineering ,Flue gas ,020209 energy ,Thermoelectric generation ,Energy Engineering and Power Technology ,Mechanical engineering ,02 engineering and technology ,Combustion ,Waste heat recovery unit ,Waste heat ,Thermoelectric effect ,Heat exchanger ,0202 electrical engineering, electronic engineering, information engineering ,Process engineering ,Waste heat recovery ,Renewable Energy, Sustainability and the Environment ,business.industry ,Computational model ,021001 nanoscience & nanotechnology ,Prototype ,Fuel Technology ,Thermoelectric generator ,Nuclear Energy and Engineering ,Electric power ,0210 nano-technology ,business - Abstract
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 %. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the economic support to this work, included in the DPI2014-53158-R research project. more...
- Published
- 2017
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