Browsing by Author "Üstüner, MA"

Now showing 1 - 6 of 6
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    Enhancing Bi2Te2.70Se0.30 Thermoelectric Module Performance through COMSOL Simulations
    Hasan, MK; Üstüner, MA; Mamur, H; Bhuiyan, MRA
    This research employs the COMSOL Multiphysics software (COMSOL 6.2) to conduct rigorous simulations and assess the performance of a thermoelectric module (TEM) meticulously crafted with alumina (Al2O3), copper (Cu), and Bi2Te2.70Se0.30 thermoelectric (TE) materials. The specific focus is on evaluating diverse aspects of the Bi2Te2.70Se0.30 thermoelectric generator (TEG). The TEM design incorporates Bi2Te2.70Se0.30 for TE legs of the p- and n-type positioned among the Cu layers, Cu as the electrical conductor, and Al2O3 serving as an electrical insulator between the top and bottom layers. A thorough investigation is conducted into critical parameters within the TEM, which include arc length, electric potential, normalized current density, temperature gradient, total heat source, and total net energy rate. The geometric configuration of the square-shaped Bi2Te2.70Se0.30 TEM, measuring 1 mm x 1 mm x 2.5 mm with a 0.25 mm Al2O3 thickness and a 0.125 mm Cu thickness, is scrutinized. This study delves into the transport phenomena of TE devices, exploring the impacts of the Seebeck coefficient (S), thermal conductivity (k), and electrical conductivity (sigma) on the temperature differential across the leg geometry. Modeling studies underscore the substantial influence of S = +/- 2.41 x 10(-3) V/K, revealing improved thermal conductivity and decreased electrical conductivity at lower temperatures. The findings highlight the Bi2Te2.70Se0.30 TEM's high potential for TEG applications, offering valuable insights into design and performance considerations crucial for advancing TE technology.
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    Future perspective and current situation of maximum power point tracking methods in thermoelectric generators
    Mamur, H; Üstüner, MA; Bhuiyan, MRA
    One of the green technologies that can be used to increase energy efficiency by recovering a part of waste heat as electrical energy is thermoelectric generators (TEG) by using the Seebeck phenomenon. Conventional and modern maximum power point tracking (MPPT) methods used to deliver maximum power from energy sources. Conventional MPPT algorithms have disabilities such as a delay in reaching the maximum power point (MPP), certain oscillations around the MPP, being stuck at local MPP (LMPP), and not being able to find global MPP (GMPP). In order to overcome the drawbacks of conventional MPPT methods, methods using metaheuristic MPPT algorithms have come to the fore in recent years. However, the issue of determining the appropriate method among the increasing number and complexity of MPPT methods causes confusion. The aim of this study is to review more than sixty-two MPPT methods that have been used in TEGs in the last six years and have the potential to be adapted for TEGs and provide a reference for researchers. Eventually, this review will be a resource that introduces the next generation MPPT methods, presents MPPT methods with the potential to be adapted to TEGs, and will be a good reference for future studies.
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    INVERTED DECOUPLING PID CONTROLLER DESIGN FOR A MIMO SYSTEM
    Üstüner, MA; Taskin, S
    Eliminating loop interaction is a critical issue in the control of Multi Input Multi Output (MIMO) systems. In this study, an experimental setup, Festo Didactic MPS-PA, is used as MIMO system. Inverted decoupling PID method is applied to the system to eliminate the loop interactions of MIMO system. For this purpose, firstly, the system is modelled. Then, decoupler blocks are designed to eliminate the loop interactions. Finally, the modelled system is simulated, and experiments are performed on the real system. The effect of inverted decoupling PID control on the system performance and the effect of classical PID control on the system performance are compared.
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    Modeling and validation of the thermoelectric generator with considering the change of the Seebeck effect and internal resistance
    Üstüner, MA; Mamur, H; Taskin, S
    Thermoelectric generators (TEGs) produce power in direct proportion to the temperature difference between their surfaces. The Seebeck coefficient and internal resistance of the thermoelements (TEs) that make up the TEGs change depending on the temperature change. In simulation studies, it is seen that these two values are kept constant. However, this situation prevents approaching the data of TEG in real applications. In this study, a TEG Simulink/MATLAB (R) model has been developed to capture real TEG module data, which considers changing of both the Seebeck coefficient and the internal resistance depending on the temperature difference change. To achieve this aim, a commercially available TEG data used in also academic studies has been used. A boost converter with a perturb and observe (P & O) maximum power point tracker (MPPT) algorithm has been designed to maximize the TEG power. The TEG Simulink/MATLAB (R) model data are compared with commercially available TEG data at different temperatures. The error between the actual values and the simulation results, and the mean absolute percent errors (MAPEs) are calculated. The open circuit voltage and short circuit current error rates of the designed TEG module are 0.125% and 0.256%, respectively. The MAPE values of the designed model are 0.5104%, 0.7837%, and 2.0952% for 30 degrees C, 50 degrees C, and 80 degrees C cold surface temperatures, respectively. In addition, simulations are made in order to see the effect of temperature-dependent parameters in a TEG system built using the designed model. While the simulations made with the designed model give realistic results, with the simulations made with constant coefficients, up to 2.63% more power is obtained than the capacity of the system, contrary to reality. Simulation and validated results show that this new TEG Simulink/MATLAB (R) model gives more realistic results.
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    Selection of Load Resistance for Boost Converters with Maximum Power Point Tracking Algorithm in Thermoelectric Generators
    Üstüner, MA; Mamur, H; Taskin, S; Nil, M; Bhuiyan, MRA; Kherkhar, A; Chiba, Y
    Thermoelectric generators (TEGs) face challenges in efficiently converting waste heat into electrical energy. To enhance their performance, converters are employed, with the crucial feature being the implementation of the maximum power point tracking (MPPT) algorithm. However, the efficiency of the MPPT software in tracking the maximum power point (MPP) is influenced by the load connected to the converter's output, necessitating the determination of an appropriate load range. The primary objective of this study is to identify an acceptable load range for an isolated DC-DC boost converter used in MPPT within an installed TEG system. The methodology includes building a Simulink/MATLAB model based on TEG manufacturer data, designing a DC-DC boost converter with embedded MPPT algorithms, and conducting simulations and experiments at various load range values. Simulations and experimental studies reveal that the effectiveness of algorithms in tracking the MPP is optimized when the load resistance is between the TEG's internal resistance and three times this value. Below the internal resistance, the MPP cannot be tracked, while at high load values, the MPP significantly decreases. This underscores the critical role of load resistance selection in optimizing TEG system performance during MPPT applications.
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    Opportunities for thermoelectric generators in supporting a low carbon economy
    Bhuiyan, MRA; Mamur, H; Dilmaç, ÖF; Üstüner, MA
    Environmental pollution, global warming and increasing energy demands are urgent challenges facing society. Governments all over the world have set a national policy target for the transition to a zero or low carbon dioxide economy. As a result, scientists and engineers in industry and academia are working to develop cleaner, alternative and sustainable energy production technologies. One technology that has potential in this green technology transition is thermoelectric generators (TEGs), traditionally used off-grid and isolated from things such as stand-alone solar-thermal cells for military and aerospace applications such as missile-testing systems and space telescope cameras. However, future applications based on home entertainment, security systems and smart metering applications are imminent. Key limitations to this are low efficiency, high costs and self-heating with low thermal conductivity. Hence, this study aims to examine the current state of the art of TEGs and identify future research directions to achieve support for the green technology transition. The key findings of this study show that present successes will fulfill the future advancement of thermoelectric technology by supporting a low carbon dioxide economy.