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In this study, the impact of nanofluid use in solar-thermoelectric generators (Solar-TEG) on thermal performance is investigated through analysis and simulation methodology. For conventional cooling analysis, we use air as a coolant and graphene nanoplatelet aqueous nanofluids (GNAN) for nanofluid cooling. We make a comparison between traditional and nanofluid cooling to find the best performance. GNAN at a dispersion of 0.025, 0.05, 0.075, and 0.1-wt% are added to the cooling system. GNAN has been used in the technological development of energy conversion. It has been proposed as a material to achieve better efficiency in Solar-TEG. Five different geometries are developed to analyze the efficiency in a Solar-TEG to find the optimal design. The impact of the thermal concentration relationship, substrate area, and convective transfer coefficient on Solar-TEG performance is investigated. To simplify and speed up simulations, we use equivalent models based on FEM. We are considering the properties of temperature-dependent semiconductors. For thermoelement materials, we use lead-tellurium. Lead-tellurium is an excellent material for thermoelectric study and supports large temperature ranges (up to 750 K). The thermal concentration relationship depends on the substrate area, which affects the efficiency of Solar-TEG. The maximum efficiency between the five geometry types is 5.53%, with a substrate of 110 × 100 mm2. The efficiency and output power using 0.1% wt GNAN as the refrigerant is enhanced by 14.74% and 26.39%. GNAN cooling improves compared to conventional fluid cooling in a Solar-TEG. Different convection coefficients are used to verify this fact.
Cristian Ramos-Castañeda; Miguel Olivares-Robles; Juan Méndez-Méndez. Analysis of the Performance of a Solar Thermoelectric Generator for Variable Leg Geometry with Nanofluid Cooling. Processes 2021, 9, 1352 .
AMA StyleCristian Ramos-Castañeda, Miguel Olivares-Robles, Juan Méndez-Méndez. Analysis of the Performance of a Solar Thermoelectric Generator for Variable Leg Geometry with Nanofluid Cooling. Processes. 2021; 9 (8):1352.
Chicago/Turabian StyleCristian Ramos-Castañeda; Miguel Olivares-Robles; Juan Méndez-Méndez. 2021. "Analysis of the Performance of a Solar Thermoelectric Generator for Variable Leg Geometry with Nanofluid Cooling." Processes 9, no. 8: 1352.
In this work, a simulation model based on finite element analysis for a one-dimensional p-type segmented semiconductor element with different cross-sectional areas is analyzed to predict transient thermal behavior for thermoelectric coolers (TECs). The proposed model considers all thermoelectric effects, including the Peltier effect, Thomson effect, Joule heating, and Fourier's heat conduction. The supercooling occurs when a pulse current higher than the steady-state optimum current is applied to a TEC. Dynamic characteristics, such as minimum cold side temperature and holding time of transient state, which arise in transient supercooling are very important to be considered for the design and operation of TECs. In this study, we present a new approach of transient performance based on leg geometry shape, considering variable cross-sectional areas, as well as individual element lengths of two different thermoelectric materials using a segmentation model proposed. A variety of model designs are analyzed, considering rectangular, trapezoidal, and inverse trapezoidal legs, where also optimum pulse current is found as a function of the element lengths. It is demonstrated that an improvement of 4.75% in the cooling is possible when using trapezoidal legs compared with conventional rectangular systems. Our presented model is mainly a new alternative in characterizing Peltier supercooling as a function of both pulse current ratio as well as the leg shape.
Pablo Eduardo Ruiz‐Ortega; Miguel Angel Olivares‐Robles; Carlos Alberto Badillo‐Ruiz. Transient thermal behavior of a segmented thermoelectric cooler with variable cross‐sectional areas. International Journal of Energy Research 2021, 1 .
AMA StylePablo Eduardo Ruiz‐Ortega, Miguel Angel Olivares‐Robles, Carlos Alberto Badillo‐Ruiz. Transient thermal behavior of a segmented thermoelectric cooler with variable cross‐sectional areas. International Journal of Energy Research. 2021; ():1.
Chicago/Turabian StylePablo Eduardo Ruiz‐Ortega; Miguel Angel Olivares‐Robles; Carlos Alberto Badillo‐Ruiz. 2021. "Transient thermal behavior of a segmented thermoelectric cooler with variable cross‐sectional areas." International Journal of Energy Research , no. : 1.
A novel physical model of a two-stage thermoelectric cooler (TEC) is developed, based on geometry factor (γ) analysis between stages under pulsed current conditions and with phase change material (PCM), to improve performance. A detailed investigation of a two-stage Peltier cooler based on a general thermodynamic formulation considering the Thomson effect is presented. The minimum cold side temperature, coefficient of performance (COP), and further the thermoelement’s characteristic temperature profiles are discussed. The numerical analysis was carried out considering square pulse current, hot side heat transfer, metal strips, ceramic plates, and a PCM material volume in the heat sink. The investigation results proved that the geometry relation between both stages and the Thomson effect directly impacts supercooling, and a higher reduction in the cold side temperature can be achieved compared with conventional thermoelectric coolers. A reduction of 25.2 K in a two-stage over a single-stage TEC with PCM is achieved considering a large cross-sectional area in the first stage. It has been found that the holding time and the characteristic temperature profiles during and after pulse operation depends strongly on Thomson heat and geometry. A shorter holding time and maximum temperature drop are found for γ>1 values due to the PCM’s melting temperature and the higher pulse current. The characteristic cooling length reveals the part of the semiconductor element that is cooled during pulse operation. Results will guide the design or selection of a heat sink crucial to a solid-state cooling device’s overall performance.
Pablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles; Olao Yair Enciso-Montes de Oca. Supercooling in a new two-stage thermoelectric cooler design with phase change material and Thomson effect. Energy Conversion and Management 2021, 243, 114355 .
AMA StylePablo Eduardo Ruiz-Ortega, Miguel Angel Olivares-Robles, Olao Yair Enciso-Montes de Oca. Supercooling in a new two-stage thermoelectric cooler design with phase change material and Thomson effect. Energy Conversion and Management. 2021; 243 ():114355.
Chicago/Turabian StylePablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles; Olao Yair Enciso-Montes de Oca. 2021. "Supercooling in a new two-stage thermoelectric cooler design with phase change material and Thomson effect." Energy Conversion and Management 243, no. : 114355.
The electric behavior in semiconductor devices is the result of the electric carriers’ injection and evacuation in the low doping region, N-. The carrier’s dynamic is determined by the ambipolar diffusion equation (ADE), which involves the main physical phenomena in the low doping region. The ADE does not have a direct analytic solution since it is a spatio-temporal second-order differential equation. The numerical solution is the most used, but is inadequate to be integrated into commercial electric circuit simulators. In this paper, an empiric approximation is proposed as the solution of the ADE. The proposed solution was validated using the final equations that were implemented in a simulator; the results were compared with the experimental results in each phase, obtaining a similarity in the current waveforms. Finally, an advantage of the proposed methodology is that the final expressions obtained can be easily implemented in commercial simulators.
Leobardo Hernandez-Gonzalez; Jazmin Ramirez-Hernandez; Oswaldo Ulises Juarez-Sandoval; Miguel Olivares-Robles; Ramon Sanchez; Rosario Gibert Delgado. A New Approach for Approximate Solution of ADE: Physical-Based Modeling of Carriers in Doping Region. Mathematics 2021, 9, 458 .
AMA StyleLeobardo Hernandez-Gonzalez, Jazmin Ramirez-Hernandez, Oswaldo Ulises Juarez-Sandoval, Miguel Olivares-Robles, Ramon Sanchez, Rosario Gibert Delgado. A New Approach for Approximate Solution of ADE: Physical-Based Modeling of Carriers in Doping Region. Mathematics. 2021; 9 (5):458.
Chicago/Turabian StyleLeobardo Hernandez-Gonzalez; Jazmin Ramirez-Hernandez; Oswaldo Ulises Juarez-Sandoval; Miguel Olivares-Robles; Ramon Sanchez; Rosario Gibert Delgado. 2021. "A New Approach for Approximate Solution of ADE: Physical-Based Modeling of Carriers in Doping Region." Mathematics 9, no. 5: 458.
In this study, we report the novel energy behavior of high-performance nanostructured materials in a segmented thermoelectric micro-generator (TEG). Several physical elements of the materials must be considered to determine their behavior in the thermoelectric energy conversion: temperature dependence of material properties, geometric structure, segmentation, and the symmetry of each or both p-type and n-type nanostructure semiconductor thermoelements. Recently, many efforts have reported effects independent on the thermoelectric performance of semiconductor materials. In this work, exhaustive research on the performance of high-performance nanostructured materials in a segmented thermoelectric micro-generator (TEG) was carried out. Our results show the efficiency and output power of the TEG using the temperature-dependent model, i.e., a variable internal resistance for a load resistance of the system. Our approach allows us to analyze symmetrical and asymmetric geometries, showing maximum and minimum peaks values in the performance of the TEG for specific $$\gamma $$ γ values. The performance of the TEG is improved by about $$6\%$$ 6 % and $$7\%$$ 7 % , for efficiency, and output power, respectively, considering a trapezoidal geometric shape in the 2p-3n segmented system, compared with the conventional rectangular shape.
Miguel Angel Olivares-Robles; Carlos Alberto Badillo-Ruiz; Pablo Eduardo Ruiz-Ortega. A comprehensive analysis on nanostructured materials in a thermoelectric micro-system based on geometric shape, segmentation structure and load resistance. Scientific Reports 2020, 10, 1 -13.
AMA StyleMiguel Angel Olivares-Robles, Carlos Alberto Badillo-Ruiz, Pablo Eduardo Ruiz-Ortega. A comprehensive analysis on nanostructured materials in a thermoelectric micro-system based on geometric shape, segmentation structure and load resistance. Scientific Reports. 2020; 10 (1):1-13.
Chicago/Turabian StyleMiguel Angel Olivares-Robles; Carlos Alberto Badillo-Ruiz; Pablo Eduardo Ruiz-Ortega. 2020. "A comprehensive analysis on nanostructured materials in a thermoelectric micro-system based on geometric shape, segmentation structure and load resistance." Scientific Reports 10, no. 1: 1-13.
In this paper, we consider the transient state behavior of a segmented thermoelectric generator (STEG) exposed to a variable heat input power on the hot side while the transfer of heat on the cold side is by natural convection. Numerical analysis is used to calculate the power generation of the system. A one-dimensional STEG model, which includes Joule heating, the Peltier effect with constant properties of materials, is considered and governing equations are solved using the finite differences method. The transient analysis of this model is typical for energy harvesting applications. A novel design methodology, formulated on the ratio of the figure of merit of the thermoelectric materials, is developed including segmentation on the legs of the thermoelectric generator, which does not consider previous studies. In our approach, the figure of merit is an advantageous parameter to analyze its impact on thermal and electrical efficiency. The transient state of the thermoelectric generator is analyzed, considering two and three heat input sources. We obtain the temperature profiles, voltage generation, and efficiency of the STEG under pulsed heat input power. The results showed that the temperature drop along the semiconductor elements was more considerable when three pulses were applied, and when the thermal conductivity in the first segment was higher than that of the second segment. Furthermore, we show that the generated voltage and the maximum efficiency in the system occur when the value of the figure of merit in the first segment, which is in contact with the temperature source, is lower than the figure of merit for the second thermoelectric segment of the leg. The model investigated in this paper offers an essential guide on the thermal and electrical performance behavior of the system under transient conditions, which are present in many variable thermal phenomena such as solar radiation and the normalized driving cycles of an automotive thermoelectric generator.
Pablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles; Olao Yair Enciso-Montes De Oca. Segmented Thermoelectric Generator under Variable Pulsed Heat Input Power. Entropy 2019, 21, 929 .
AMA StylePablo Eduardo Ruiz-Ortega, Miguel Angel Olivares-Robles, Olao Yair Enciso-Montes De Oca. Segmented Thermoelectric Generator under Variable Pulsed Heat Input Power. Entropy. 2019; 21 (10):929.
Chicago/Turabian StylePablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles; Olao Yair Enciso-Montes De Oca. 2019. "Segmented Thermoelectric Generator under Variable Pulsed Heat Input Power." Entropy 21, no. 10: 929.
Thermoelectric coolers (TECs) can reach temperatures below that obtained with a steady-state current by applying an electrical current pulse which enables a transitory state in a Peltier device. This effect is known as supercooling. In this paper, we study characteristics parameters, such as the minimum cooling temperature and spatial temperature profile, in a TEC operated under current pulses and a cooling load ( Q c ) . Numerical analysis for a one-dimensional thermoelectric model of the cooling system is developed, and a novel MATLAB programming code is proposed for the transient state based on finite element analysis. We also investigate the influence of the thermoelement’s length upon the cooling mechanism. A new parameter called the “characteristic cooling length” is proposed to describe the length in which the minimum cooling temperature occurs along the elements of a TEM. Results show the transient temperature profiles along the elements of the semiconductor P-type element, and a “characteristic cooling length” is characterized. We also propose a general principle, and the lowest cooling temperature values are obtained for a semiconductor’s small length and variable pulse cooling load under current pulse operation. The present study will serve as guidance for the geometric design of TECs under current pulse operations.
Pablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles. Peltier Supercooling in Transient Thermoelectrics: Spatial Temperature Profile and Characteristic Cooling Length. Entropy 2019, 21, 226 .
AMA StylePablo Eduardo Ruiz-Ortega, Miguel Angel Olivares-Robles. Peltier Supercooling in Transient Thermoelectrics: Spatial Temperature Profile and Characteristic Cooling Length. Entropy. 2019; 21 (3):226.
Chicago/Turabian StylePablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles. 2019. "Peltier Supercooling in Transient Thermoelectrics: Spatial Temperature Profile and Characteristic Cooling Length." Entropy 21, no. 3: 226.
In recent years the interest for the harvest of energy with micro thermoelectric generators ( μ TEG) has increased, due to its advantages compared to technologies that use fossil fuels. There are three ways to improve the performance of the device, by modifying its structure, type of material and operation control. In this study, the role of the load resistance R L on the performance of a μ TEG with nanostructured materials is investigated. The interaction of the load resistance with the thermoelements exhibits interesting features, arising from the coupling of the temperature-dependent electrical and thermal transport properties at different temperature ranges and the architecture of nanostructured thermoelectric materials. This coupling results in inflections on the efficiency, i.e., maximum and minimum values of the efficiency at higher temperatures, 600–900 K. We show the explicit dependence of the performance of the μ TEG in terms of the load resistance and discuss the underlying physics. The unusual features of the efficiency of nanostructured thermoelectric materials are a result of the behavior of the power factor and the nonequilibrium properties of the system. We also analyze the effect of the geometric shape of the thermoelements on the device. We determine the performance of the μ TEG, evaluating the generation power and its efficiency. The results show that the efficiency of the device can decrease or increase depending on the value of R L , while the power decreases with an increase of the load resistance.
Carlos Alberto Badillo Ruiz; Miguel Angel Olivares-Robles; Jose Jorge Chanona-Perez. Design of Nano-Structured Micro-Thermoelectric Generator: Load Resistance and Inflections in the Efficiency. Entropy 2019, 21, 224 .
AMA StyleCarlos Alberto Badillo Ruiz, Miguel Angel Olivares-Robles, Jose Jorge Chanona-Perez. Design of Nano-Structured Micro-Thermoelectric Generator: Load Resistance and Inflections in the Efficiency. Entropy. 2019; 21 (3):224.
Chicago/Turabian StyleCarlos Alberto Badillo Ruiz; Miguel Angel Olivares-Robles; Jose Jorge Chanona-Perez. 2019. "Design of Nano-Structured Micro-Thermoelectric Generator: Load Resistance and Inflections in the Efficiency." Entropy 21, no. 3: 224.
Pablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles; Amado F. Garcia Ruiz. Thermoelectric Cooling: The Thomson Effect in Hybrid Two- Stage Thermoelectric Cooler Systems with Different Leg Geometric Shapes. Bringing Thermoelectricity into Reality 2018, 1 .
AMA StylePablo Eduardo Ruiz-Ortega, Miguel Angel Olivares-Robles, Amado F. Garcia Ruiz. Thermoelectric Cooling: The Thomson Effect in Hybrid Two- Stage Thermoelectric Cooler Systems with Different Leg Geometric Shapes. Bringing Thermoelectricity into Reality. 2018; ():1.
Chicago/Turabian StylePablo Eduardo Ruiz-Ortega; Miguel Angel Olivares-Robles; Amado F. Garcia Ruiz. 2018. "Thermoelectric Cooling: The Thomson Effect in Hybrid Two- Stage Thermoelectric Cooler Systems with Different Leg Geometric Shapes." Bringing Thermoelectricity into Reality , no. : 1.
Arturo Monedero Khouri; Miguel Angel Olivares Robles. Feasibility and Numerical Analysis of Hybrid Photovoltaic (PV) Panels with Thermoelectric Cooling (TEC) Systems. Bringing Thermoelectricity into Reality 2018, 1 .
AMA StyleArturo Monedero Khouri, Miguel Angel Olivares Robles. Feasibility and Numerical Analysis of Hybrid Photovoltaic (PV) Panels with Thermoelectric Cooling (TEC) Systems. Bringing Thermoelectricity into Reality. 2018; ():1.
Chicago/Turabian StyleArturo Monedero Khouri; Miguel Angel Olivares Robles. 2018. "Feasibility and Numerical Analysis of Hybrid Photovoltaic (PV) Panels with Thermoelectric Cooling (TEC) Systems." Bringing Thermoelectricity into Reality , no. : 1.
We follow the conventional two-channels resistor model to describe the spin transport through a F|N (ferromagnetic metal|normal metal) interface in the field of spin-caloritronics and its relationship with the interfacial thermal conductance. We show that the interfacial thermal conductance does not only depend on terms of Fourier conduction transport, but also on interfacial parameters just like the electrical resistance, Seebeck coefficient and the temperature gradient. The new term, which includes these parameters, is called spin-thermoelectric term of the interfacial thermal conductance and shows that when the system is excited by small fluctuations of temperature at the interface, permanent-induced currents are produced, resulting in values different to zero as a first insight of the total thermal conductance magnitude order. Moreover, the relationship between this spin-thermoelectric term and the applied charge current can be linearly approximated in the range from zero to the applied compensation current Ip under effect of Peltier cooling. In general, the thermal conductance capacity can be drastically improved at nanoscale.
Isaac Juarez-Acosta; Miguel Angel Olivares-Robles; José Jorge Chanona-Pérez. On the interfacial thermal conductance of a ferromagnetic metal junction. Journal of Physics D: Applied Physics 2018, 51, 294002 .
AMA StyleIsaac Juarez-Acosta, Miguel Angel Olivares-Robles, José Jorge Chanona-Pérez. On the interfacial thermal conductance of a ferromagnetic metal junction. Journal of Physics D: Applied Physics. 2018; 51 (29):294002.
Chicago/Turabian StyleIsaac Juarez-Acosta; Miguel Angel Olivares-Robles; José Jorge Chanona-Pérez. 2018. "On the interfacial thermal conductance of a ferromagnetic metal junction." Journal of Physics D: Applied Physics 51, no. 29: 294002.
In this work, the influences of the Thomson effect and the geometry of the p-type segmented leg on the performance of a segmented thermoelectric microcooler (STEMC) were examined. The effects of geometry and the material configuration of the p-type segmented leg on the cooling power (Qc) and coefficient of performance (COP) were investigated. The influence of the cross-sectional area ratio of the two joined segments on the device performance was also evaluated. We analyzed a one-dimensional p-type segmented leg model composed of two different semiconductor materials, Bi2Te3 and (Bi0.5Sb0.5)2Te3. Considering the three most common p-type leg geometries, we studied both single-material systems (using the same material for both segments) and segmented systems (using different materials for each segment). The COP, Qc and temperature profile were evaluated for each of the modeled geometric configurations under a fixed temperature gradient of ΔT = 30 K. The performances of the STEMC were evaluated using two models, namely the constant-properties material (CPM) and temperature-dependent properties material (TDPM) models, considering the thermal conductivity (κ(T)), electrical conductivity (σ(T)) and Seebeck coefficient (α(T)). We considered the influence of the Thomson effect on COP and Qc using the TDPM model. The results revealed the optimal material configurations for use in each segment of the p-type leg. According to the proposed geometric models, the optimal leg geometry and electrical current for maximum performance were determined. After consideration of the Thomson effect, the STEMC system was found to deliver a maximum cooling power that was 5.10% higher than that of the single-material system. The results showed that the inverse system (where the material with a higher Seebeck coefficient is used for the first segment) delivered a higher performance than the direct system, with improvements in the COP and Qc of 6.67% and 29.25%, respectively. Finally, analysis of the relationship between the areas of the STEMC segments demonstrated that increasing the cross-sectional area in the second segment led to improvements in the COP and Qc of 16.67% and 8.03%, respectively.
Carlos Alberto Badillo-Ruiz; Miguel Angel Olivares-Robles; Pablo Eduardo Ruiz-Ortega. Performance of Segmented Thermoelectric Cooler Micro-Elements with Different Geometric Shapes and Temperature-Dependent Properties. Entropy 2018, 20, 118 .
AMA StyleCarlos Alberto Badillo-Ruiz, Miguel Angel Olivares-Robles, Pablo Eduardo Ruiz-Ortega. Performance of Segmented Thermoelectric Cooler Micro-Elements with Different Geometric Shapes and Temperature-Dependent Properties. Entropy. 2018; 20 (2):118.
Chicago/Turabian StyleCarlos Alberto Badillo-Ruiz; Miguel Angel Olivares-Robles; Pablo Eduardo Ruiz-Ortega. 2018. "Performance of Segmented Thermoelectric Cooler Micro-Elements with Different Geometric Shapes and Temperature-Dependent Properties." Entropy 20, no. 2: 118.
In this work, we analyze the thermodynamics and geometric optimization of thermoelectric elements in a hybrid two-stage thermoelectric micro cooler (TEMC). We propose a novel procedure to improve the performance of the micro cooler based on optimum geometric parameters, cross sectional area (A) and length (L), of the semiconductor elements. Our analysis takes into account the Thomson effect to show its role on the performance of the system. We obtain dimensionless temperature spatial distributions, coefficient of performance (COP) and cooling power (Qc) in terms of the electric current for different values of the geometric ratio ω=A/L. In our analysis we consider two cases: (a) the same materials in both stages (homogeneous system); and (b) different materials in each stage (hybrid system). We introduce the geometric parameter, W=ω1/ω2, to optimize the micro device considering the geometric parameters of both stages, w1 and w2. Our results show the optimal configuration of materials that must be used in each stage. The Thomson effect leads to a slight improvement on the performance of the micro cooler. We determine the optimal electrical current to obtain the best performance of the TEMC. Geometric parameters have been optimized and results show that the hybrid system reaches a maximum cooling power 15.9% greater than the one-stage system (with the same electric current I=0.49 A), and 11% greater than a homogeneous system, when ω=0.78. The optimization of the ratio in the number of thermocouples in each stage shows that (COP) and (Qc) increase as the number of thermocouples in the second stage increase too, but with W=0.94. We show that when two materials with different performances are placed in each stage, the optimal configuration of materials in the stages of the system must be determined to obtain a better performance of the hybrid two-stage TEMC system. These results are important because we offer a novel procedure to optimize a thermoelectric micro cooler considering the geometry of materials at a micro level.
Pablo Eduardo Ruiz Ortega; Miguel Angel Olivares-Robles. Analysis of a Hybrid Thermoelectric Microcooler: Thomson Heat and Geometric Optimization. Entropy 2017, 19, 312 .
AMA StylePablo Eduardo Ruiz Ortega, Miguel Angel Olivares-Robles. Analysis of a Hybrid Thermoelectric Microcooler: Thomson Heat and Geometric Optimization. Entropy. 2017; 19 (7):312.
Chicago/Turabian StylePablo Eduardo Ruiz Ortega; Miguel Angel Olivares-Robles. 2017. "Analysis of a Hybrid Thermoelectric Microcooler: Thomson Heat and Geometric Optimization." Entropy 19, no. 7: 312.
We model the charge, spin, and heat currents in ferromagnetic metal|normal metal|normal metal trilayerstructures in the two current model, taking into account bulk and interfacethermoelectric properties as well as Joule heating. The results include the temperature distribution as well as resistance-current curves that reproduce the observed shifted parabolic characteristics. Thin tunneling barriers can enhance the apparent Peltier cooling. The model agrees with the experimental results for wide multilayer pillars, but the giant effects observed for diameters ≲100 nm are still under discussion.
Isaac Juarez-Acosta; Subrojati Bosu; Yuya Sakuraba; Takahide Kubota; Saburo Takahashi; Koki Takanashi; Gerrit E. W. Bauer; Miguel Angel Olivares-Robles. Modelling of the Peltier effect in magnetic multilayers. Journal of Applied Physics 2016, 119, 073906 .
AMA StyleIsaac Juarez-Acosta, Subrojati Bosu, Yuya Sakuraba, Takahide Kubota, Saburo Takahashi, Koki Takanashi, Gerrit E. W. Bauer, Miguel Angel Olivares-Robles. Modelling of the Peltier effect in magnetic multilayers. Journal of Applied Physics. 2016; 119 (7):073906.
Chicago/Turabian StyleIsaac Juarez-Acosta; Subrojati Bosu; Yuya Sakuraba; Takahide Kubota; Saburo Takahashi; Koki Takanashi; Gerrit E. W. Bauer; Miguel Angel Olivares-Robles. 2016. "Modelling of the Peltier effect in magnetic multilayers." Journal of Applied Physics 119, no. 7: 073906.
In this study, we analyze the role of the thermoelectric (TE) properties, namely Seebeck coefficient α, thermal conductivity κ and electrical resistivity ρ, of three different materials in a composite thermoelectric generator (CTEG) under different configurations. The CTEG is composed of three thermoelectric modules (TEMs): (1) two TEMs thermally and electrically connected in series (SC); (2) two branches of TEMs thermally and electrically connected in parallel (PSC); and (3) three TEMs thermally and electrically connected in parallel (TEP). In general, each of the TEMs have different thermoelectric parameters, namely a Seebeck coefficient α, a thermal conductance K and an electrical resistance R. Following the framework proposed recently, we show the effect of: (1) the configuration; and (2) the arrangements of TE materials on the corresponding equivalent figure of merit Zeq and consequently on the maximum power Pmax and efficiency η of the CTEG. Firstly, we consider that the whole system is formed of the same thermoelectric material (α1,K1,R1 = α2,K2,R2 = α3,K3,R3) and, secondly, that the whole system is constituted by only two different thermoelectric materials Entropy 2015, 17 7388 (αi,Ki,Ri ≠ αj ,Kj ,Rj 6= αl,Kl,Rl, where i, j, l can be 1, 2 or 3). In this work, we propose arrangements of TEMs, which clearly have the advantage of a higher thermoelectric figure of merit value compared to a conventional thermoelectric module. A corollary about the Zeq-max for CTEG is obtained as a result of these considerations. We suggest an optimum configuration.
Alexander Vargas-Almeida; Miguel Ángel Olivares-Robles; Federico Méndez Lavielle. Performance of a Composite Thermoelectric Generator with Different Arrangements of SiGe, BiTe and PbTe under Different Configurations. Entropy 2015, 17, 7387 -7405.
AMA StyleAlexander Vargas-Almeida, Miguel Ángel Olivares-Robles, Federico Méndez Lavielle. Performance of a Composite Thermoelectric Generator with Different Arrangements of SiGe, BiTe and PbTe under Different Configurations. Entropy. 2015; 17 (12):7387-7405.
Chicago/Turabian StyleAlexander Vargas-Almeida; Miguel Ángel Olivares-Robles; Federico Méndez Lavielle. 2015. "Performance of a Composite Thermoelectric Generator with Different Arrangements of SiGe, BiTe and PbTe under Different Configurations." Entropy 17, no. 12: 7387-7405.
In this work, we show a general approach for inhomogeneous composite thermoelectric systems, and as an illustrative case, we consider a dual thermoelectric cooler. This composite cooler consists of two thermoelectric modules (TEMs) connected thermally in parallel and electrically in series. Each TEM has different thermoelectric (TE) properties, namely thermal conductance, electrical resistance and the Seebeck coefficient. The system is coupled by thermal conductances to heat reservoirs. The proposed approach consists of derivation of the dimensionless thermoelectric properties for the whole system. Thus, we obtain an equivalent figure of merit whose impact and meaning is discussed. We make use of dimensionless equations to study the impact of the thermal conductance matching on the cooling capacity and the coefficient of the performance of the system. The equivalent thermoelectric properties derived with our formalism include the external conductances and all intrinsic thermoelectric properties of each component of the system. Our proposed approach permits us changing the thermoelectric parameters of the TEMs and the working conditions of the composite system. Furthermore, our analysis shows the effect of the number of thermocouples on the system. These considerations are very useful for the design of thermoelectric composite systems. We reproduce the qualitative behavior of a commercial composite TEM connected electrically in series.
Cuautli Yanehowi Flores-Niño; Miguel Angel Olivares-Robles; Igor Loboda. General Approach for Composite Thermoelectric Systems with Thermal Coupling: The Case of a Dual Thermoelectric Cooler. Entropy 2015, 17, 3787 -3805.
AMA StyleCuautli Yanehowi Flores-Niño, Miguel Angel Olivares-Robles, Igor Loboda. General Approach for Composite Thermoelectric Systems with Thermal Coupling: The Case of a Dual Thermoelectric Cooler. Entropy. 2015; 17 (6):3787-3805.
Chicago/Turabian StyleCuautli Yanehowi Flores-Niño; Miguel Angel Olivares-Robles; Igor Loboda. 2015. "General Approach for Composite Thermoelectric Systems with Thermal Coupling: The Case of a Dual Thermoelectric Cooler." Entropy 17, no. 6: 3787-3805.
Efficiency of gas turbine monitoring systems primarily depends on the accuracy of employed algorithms, in particular, pattern classification techniques for diagnosing gas path faults. In recent investigations many techniques have been applied to classify gas path faults, but recommendations for selecting the best technique for real monitoring systems are still insufficient and often contradictory. In our previous work, three classification techniques were compared under different conditions of gas turbine diagnosis. The comparative analysis has shown that all these techniques yield practically the same accuracy for each comparison case. The present contribution considers a new classification technique, Probabilistic Neural Network (PNN), and we compare it with the techniques previously examined. The results for all comparison cases show that the PNN is not inferior to the other techniques. We recommend choosing the PNN for real monitoring systems because it has an important advantage of providing confidence estimation for every diagnostic decision made.
Igor Loboda; Miguel Angel Olivares Robles. Gas Turbine Fault Diagnosis Using Probabilistic Neural Networks. International Journal of Turbo & Jet-Engines 2015, 32, 1 .
AMA StyleIgor Loboda, Miguel Angel Olivares Robles. Gas Turbine Fault Diagnosis Using Probabilistic Neural Networks. International Journal of Turbo & Jet-Engines. 2015; 32 (2):1.
Chicago/Turabian StyleIgor Loboda; Miguel Angel Olivares Robles. 2015. "Gas Turbine Fault Diagnosis Using Probabilistic Neural Networks." International Journal of Turbo & Jet-Engines 32, no. 2: 1.
In a recent work, we have reported a study on the figure of merit of a thermoelectric system composed by thermoelectric generators connected electrically and thermally in different configurations. In this work, we are interested in analyzing the output power delivered by a thermoelectric system for different arrays of thermoelectric materials in each configuration. Our study shows the impact of the array of thermoelectric materials in the output power of the composite system. We evaluate numerically the corresponding maximum output power for each configuration and determine the optimum array and configuration for maximum power. We compare our results with other recently reported studies.
Pablo Camacho-Medina; Miguel Angel Olivares-Robles; Alexander Vargas-Almeida; Francisco Solorio-Ordaz. Maximum Power of Thermally and Electrically Coupled Thermoelectric Generators. Entropy 2014, 16, 2890 -2903.
AMA StylePablo Camacho-Medina, Miguel Angel Olivares-Robles, Alexander Vargas-Almeida, Francisco Solorio-Ordaz. Maximum Power of Thermally and Electrically Coupled Thermoelectric Generators. Entropy. 2014; 16 (5):2890-2903.
Chicago/Turabian StylePablo Camacho-Medina; Miguel Angel Olivares-Robles; Alexander Vargas-Almeida; Francisco Solorio-Ordaz. 2014. "Maximum Power of Thermally and Electrically Coupled Thermoelectric Generators." Entropy 16, no. 5: 2890-2903.
In this work, we analyze different configurations of a thermoelectric system (TES) composed of three thermoelectric generators (TEGs). We present the following considerations: (a) TES thermally and electrically connected in series (SC); (b) TES thermally and electrically connected in parallel (PSC); and (c) parallel thermally and series electrical connection (SSC). We assume that the parameters of the TEGs are temperature-independent. The systems are characterized by three parameters, as it has been showed in recent investigations, namely, its internal electrical resistance, R, thermal conductance under open electrical circuit condition, K, and Seebeck coefficient α. We derive the equivalent parameters for each of the configurations considered here and calculate the Figure of Merit Z for the equivalent system. We show the impact of the configuration of the system on Z, and we suggest optimum configuration. In order to justify the effectiveness of the equivalent Figure of Merit, the corresponding efficiency has been calculated for each configuration.
Alexander Vargas-Almeida; Miguel Angel Olivares-Robles; Pablo Camacho-Medina. Thermoelectric System in Different Thermal and Electrical Configurations: Its Impact in the Figure of Merit. Entropy 2013, 15, 2162 -2180.
AMA StyleAlexander Vargas-Almeida, Miguel Angel Olivares-Robles, Pablo Camacho-Medina. Thermoelectric System in Different Thermal and Electrical Configurations: Its Impact in the Figure of Merit. Entropy. 2013; 15 (12):2162-2180.
Chicago/Turabian StyleAlexander Vargas-Almeida; Miguel Angel Olivares-Robles; Pablo Camacho-Medina. 2013. "Thermoelectric System in Different Thermal and Electrical Configurations: Its Impact in the Figure of Merit." Entropy 15, no. 12: 2162-2180.
In this paper we undertake the theoretical analysis of a two-stage semiconductor thermoelectric module (TEM) which contains an arbitrary and different number of thermocouples, n1 and n2, in each stage (pyramid-styled TEM). The analysis is based on a dimensionless entropy balance set of equations. We study the effects of n1 and n2, the flowing electric currents through each stage, the applied temperatures and the thermoelectric properties of the semiconductor materials on the exergetic efficiency. Our main result implies that the electric currents flowing in each stage must necessarily be different with a ratio about 4.3 if the best thermal performance and the highest temperature difference possible between the cold and hot side of the device are pursued. This fact had not been pointed out before for pyramid-styled two stage TEM. The ratio n1/n2should be about 8.
Miguel Angel Olivares-Robles; Federico Vázquez; Cesar Ramirez-Lopez. Optimization of Two-Stage Peltier Modules: Structure and Exergetic Efficiency. Entropy 2012, 14, 1539 -1552.
AMA StyleMiguel Angel Olivares-Robles, Federico Vázquez, Cesar Ramirez-Lopez. Optimization of Two-Stage Peltier Modules: Structure and Exergetic Efficiency. Entropy. 2012; 14 (8):1539-1552.
Chicago/Turabian StyleMiguel Angel Olivares-Robles; Federico Vázquez; Cesar Ramirez-Lopez. 2012. "Optimization of Two-Stage Peltier Modules: Structure and Exergetic Efficiency." Entropy 14, no. 8: 1539-1552.