Search Results (1,003)

Hydrogen-enriched compressed natural gas (HCNG) is a promising transitional fuel for residential-scale distributed power, yet its impacts on direct-combustion thermoelectric generator (TEG) systems remain insufficiently quantified. In this study, a micro-scale TEG integrated with a commercially available self-aspirating household burner was experimentally investigated under thermal inputs of 700–2500 W and hydrogen blending ratios of 0–20 vol%, using open-loop water cooling to maximize heat rejection. The hot- and cold-side temperatures exhibited negligible variation with a hydrogen addition, and the maximum electrical output was essentially preserved across all blending ratios; at 2500 W the system delivered 75.8 W with a system efficiency of 3.03%. In contrast, hydrogen blending substantially reduced pollutant emissions: at 2500 W, CO decreased from 52.7 to 1 mg/m³ and CO₂ from 6.73% to 5.36% as the hydrogen fraction increased from 0 to 20 vol%. Meanwhile, combustion stability improved, indicated by a reduced coefficient of variation (0.77% → 0.49%). These results demonstrate that up to 20 vol% hydrogen blending can achieve significant emissions mitigation without compromising TEG power performance, supporting HCNG-fueled TEGs as a practical option for residential backup power. Full article

The effects of Fe non-stoichiometry on crystal structure, microstructural evolution, and thermoelectric transport properties were systematically investigated in bornite (Cu₅Fe_1+yS₄; −0.06 ≤ y ≤ 0.06) synthesized by mechanical alloying followed by hot pressing. X-ray diffraction analysis confirmed the formation of a single-phase orthorhombic bornite structure over the entire composition range. Anisotropic lattice distortion was observed with increasing Fe non-stoichiometry, manifested as contraction along the a-axis and expansion along the b- and c-axes, with a non-linear dependence on composition. Crystallite sizes estimated from Lorentzian peak fitting increased from 64.1 nm for the stoichiometric composition to 70.6–76.3 nm for Fe-deficient samples and 73.2–90.9 nm for Fe-excess samples. Hall-effect measurements revealed p-type semiconducting behavior for the stoichiometric composition, degenerate p-type transport with increased hole concentration under Fe-deficient conditions, and a transition to n-type behavior with reduced carrier mobility under Fe-excess conditions. While Fe-deficient samples retained high electrical conductivity and positive Seebeck coefficients, Fe-excess samples exhibited negative Seebeck coefficients at low temperatures with sign reversal at elevated temperatures. As a consequence, the power factor of Fe-deficient samples was enhanced by approximately 20–30% relative to the stoichiometric composition. In addition, the total thermal conductivity remained below 0.8 W·m⁻¹·K⁻¹ for all samples, and Fe non-stoichiometry effectively suppressed lattice thermal conductivity. Consequently, the Cu₅Fe_0.94S₄ composition achieved a maximum dimensionless figure of merit of ZT = 0.61 at 673 K, representing a performance enhancement of approximately 30–70% compared with the stoichiometric composition (ZT = 0.36 at 673 K and 0.47 at 723 K). Full article

Conventional thermoelectric generators (TEGs) suffer from thermal resistance introduced by ceramic substrates and thermal interface materials, which limits the achievable temperature gradient across the junctions and reduces conversion efficiency. To overcome this limitation, a pin-fin integrated thermoelectric device (iTED) is proposed, in which the hot-side heat exchanger is incorporated directly into the hot-side interconnector, eliminating the ceramic and associated greases. An explicitly coupled thermal-fluid-electric finite-volume model is developed in ANSYS Fluent’s user-defined scalar (UDS) environment to quantify the simultaneous thermal-fluid-electric behavior of the iTED for inlet temperatures of 350 $\le T_{\mathrm{in}}\mathrm{K}\le$ 650, Reynolds numbers of 3000 $\le \mathrm{Re}\le$ 15,000, and load resistances ranging from 0.01 to ${10}^6$% of the internal device resistance ($R_{\mathrm{int}}$), for a fixed cold-side temperature of 300 K. The model is validated against established tube-bank correlations (2.2% agreement in pumping power) and a one-dimensional Explicit Thomson Model (1.2–6.9% agreement across all electrical system response quantities). Compared with an equivalently sized conventional TEG, the iTED achieves a 4.6-fold higher maximum power output (23.9 [W] vs. 5.2 [W] at Re = 15,000), a 2.8-fold higher thermal conversion efficiency (8.1% vs. 2.9%), and a 4.8-fold higher performance index (7.8 [-] vs. 1.6 [-] at Re = 3000), all at $T_{\mathrm{in}}$ = 650 K. A performance index analysis reveals that lower Reynolds numbers and higher inlet temperatures maximize the net power benefit, delineating the operational envelope in which the iTED produces more electrical power than is needed for fluid pumping. These findings demonstrate that device-level restructuring—specifically, the elimination of interfacial thermal resistance via integrated pin-fin heat exchangers—can yield performance improvements comparable to or exceeding those achievable through material advances alone. Full article

This study aims to develop high-performance hybrid nanocomposites for solid-state energy conversion. We achieved this by improving charge transport and thermoelectric efficiency through the interaction of polymers, nanoparticles, and ionic liquids. Nickel oxide nanoparticles (NiO NPs) were synthesized via a sonochemical route using a novel ionic liquid, 1,2-(propan). In our recent work, this approach enabled the formation of a hybrid [NiO NPs + IL] system, which was subsequently incorporated at different loadings (8, 15, and 30 wt.%) and coated with polyethylene glycol (PEG). The resulting nanocomposites were investigated to elucidate charge-transport mechanisms and assess the influence of the polymer coating on their optical, electrical, and thermal transport properties. Optical measurements showed a shift in the band gap due to π–π* electronic transitions. This effect indicates strong interface interactions. The PEG-coated [NiO NPs + IL] nanocomposites exhibited significantly enhanced charge-carrier mobility, resulting in improved electrical conductivity. Remarkably, a high Seebeck coefficient of 720 μV/K and an electrical conductivity of 0.35 S/cm were achieved, resulting in a maximum power factor of 24.74 μW/m·K², surpassing many recently reported polymer-based nanocomposites. PEG-coated [NiO NPs + IL] systems offer tunable optical properties and superior thermoelectric performance. Consequently, they are a promising alternative to conventional nanocomposites for sustainable energy conversion. Full article

The integration of thermoelectric modules (TEMs) into renewable energy systems represents a critical technological frontier for global energy efficiency. This review systematically analyzes the scientific output in the field, which has experienced accelerated growth over the last decade, reaching a historical peak in publications between 2023 and 2024. Geographically, research is led by China, Iran, Turkey, and India. Regarding sectoral distribution, the analysis reveals that solar energy dominates applications, divided into solar thermal (25.53%) and photovoltaics (23.40%), followed by biomass (21.28%) and geothermal energy (17.02%), while ocean energy (12.77%) remains the least developed area. Despite the surge in scientific interest, the results confirm a significant methodological gap: 72.34% of the literature relies exclusively on pure simulations and numerical modeling, whereas only 27.66% incorporates experimental validation. This theoretical dependence translates into a lack of data regarding long-term operational reliability; consequently, mechanical analysis indicates that performance degradation becomes critical after the first 4000 cycles of operation, resulting in an 18% power loss. It is concluded that closing the gap toward commercial scale requires a transition from idealized modeling toward polygeneration schemes and thermal coupling designs that mitigate cyclic mechanical stress. This work provides a synthesis that serves as a roadmap for future engineering implementations at the energy-thermal management nexus. Full article

Thermoelectric generators (TEGs) enable compact waste-heat energy harvesting but require high-gain DC–DC conversion due to their low-output voltage for DC microgrid interfacing. This work proposes a novel TEG-supplied two-stage architecture consisting of a perturb-and-observe (P&O)-based MPPT boost converter followed by a modified Z-source converter regulated through an advanced model predictive control (MPC) framework. The modified Z-source topology enables high-voltage gain without extreme duty ratios and mitigates switching losses by eliminating diode reverse-recovery effects via synchronous operation. To enhance dynamic performance, the advanced MPC strategy incorporating an adaptive ripple-based weighting mechanism is applied to the modified Z-source converter and benchmarked against MPC and sliding mode control (SMC). Simulation results under multiple disturbance scenarios, including hot-side and cold-side temperature variations, multi-condition disturbances, coupling-factor variation, and measurement noise, demonstrate that the proposed system maintains stable 400 V regulation at a 100 W output level. In contrast, MPC exhibits switching frequency deviations that increase switching losses during transient operation, while SMC suffers from significant voltage deviations under source variations. The proposed strategy maintains tight voltage regulation with nearly fixed-frequency operation around 50 kHz, providing a new perspective for TEG researchers while supporting sustainable waste-heat energy utilization. Full article

Buildings account for approximately 40% of global energy consumption, with heating, ventilation and air conditioning systems being the primary contributor. Building management systems offer a promising solution for enhancing energy efficiency, particularly in retrofitting older or protected buildings. However, powering numerous wireless sensors required by BMS remains a logistical challenge. This study investigates the feasibility of harvesting thermal energy lost through windowpanes to power ultra-low-power IoT sensors, a concept that was not previously explored in the literature. A thermoelectric energy harvester was developed using a TEC1-12710 thermoelectric module and an EM8900 ultra-low-voltage DC-DC boost converter. Laboratory and field experiments were conducted to evaluate the system’s performance under various thermal conditions, with electrical energy accumulated in a 0.01 mF capacitive energy storage. In laboratory conditions, a temperature difference of ~1 °C enabled the system to generate up to 3.24 V with a power density of 3 mW/m². Field tests during winter yielded lower performance (1.43 V, 1.9 mW/m²), which was attributed to suboptimal thermal gradients and operating points. It was thus experimentally shown that windowpane heat losses can be effectively harnessed for indoor energy harvesting. While the current efficiency is limited, the approach shows promise for powering battery-free IoT devices. Full article

This study presents the design, implementation, and validation of a thermoelectric energy harvesting system that exploits waste heat from an industrial electric motor to power an autonomous wireless sensor device. The proposed prototype integrates a single thermoelectric generator directly onto the motor housing and leverages the built-in cooling fan to maintain a stable thermal gradient of approximately 4–5 °C. Under real factory conditions, the system harvested 6.17 J of energy over 9612 s, sustaining continuous operation and 41 successful Long Range (LoRa) data transmissions with a positive energy balance. Compared with related works, the prototype achieved competitive or superior performance while operating at a lower motor rating of 0.25 kW, highlighting its efficiency relative to system scale. Key innovations include a hybrid DC/DC conversion chain bridging ultra-low input voltages to modern microcontrollers, and an adaptive transmission strategy that ensures predictable energy management and reliable wireless communication. These results demonstrate the feasibility of battery-free sensing in industrial environments and underline the potential of thermoelectric harvesting as a cost-effective, maintenance-free, and environmentally responsible solution for predictive maintenance and Industry 4.0 applications. Full article

Photovoltaic double-skin façades (PV-DSFs) can block solar radiation heat, mitigate air heat transfer, facilitate ventilation cooling, and generate electricity, making them a high-performance building envelope suitable for hot southern regions in summer. The thermal performance of DSFs is relatively well understood; however, with the addition of photovoltaic glass panels, the influence of design parameters is altered due to thermoelectric coupling effects. Then, the influence of design parameters on their thermoelectric performance remains unclear, hindering their design optimization. This paper establishes a mathematical model for DSFs with MATLAB (R2023a) to analyze their thermoelectric performance and the impact of design parameters. The results indicate that the daily power generation of PV-DSFs is primarily influenced by the solar radiation on the west-facing vertical surface. The wall exterior surface gains heat via longwave radiation during the day and loses heat at night, while convective heat dissipation occurs throughout the entire day, with radiative heat flux being the dominant mechanism. The power generation of photovoltaic cells is significantly influenced by their coverage ratio, while the impact of other factors can be neglected. The temperature of the wall’s exterior surface is significantly influenced by the heat storage of the outer cladding panel, the solar absorptivity of the exterior surface, and the emissivity of the interior surface. Among these factors, the heat storage of the outer cladding panel primarily affects the attenuation and delay of peak values and temperature fluctuations on the exterior surface. Meanwhile, the solar absorptivity of the exterior surface and the emissivity of the interior surface mainly influence the peak temperature of the wall’s exterior surface, with the effect becoming more pronounced when the interior surface emissivity is lower. Full article

To boost the power and conversion efficiency of a polygonal automobile exhaust thermoelectric generator (AETEG), an innovative protrusion-type disturbance is introduced to the original sickle-shaped fins in this work. A coupled multiphysics field model integrating fluid, thermal, and electrical fields was constructed, a net power framework was formulated, and the protrusion structure parameters of protrusion radius and spacing were optimized. At a flow velocity of 40 m/s and an inlet temperature of 600 K, simulation results reveal that increasing the protrusion radius and protrusion spacing effectively improves the heat capture capability and the overall performance of the AETEG system. Simultaneously, the backpressure inside the heat exchanger increases, accompanied by a decline in temperature uniformity at the hot side of the thermoelectric modules (TEMs). Based on the designed multiple performance metrics, the optimal protrusion configuration is finally set as R = 8 mm, D_tg = 8 mm, and D_hf = 5.5 mm. Compared with the original AETEG system with sickle-shaped fins, the optimized protrusion design enhances the TEMs’ average hot-side temperatures by 5.11%, increases the output power by 42.22%, and improves the net power by 76.48%. Additionally, this optimization results in a 13.44% improvement in conversion efficiency and a 40.65% enhancement in net efficiency. Full article

The independent application of conventional electrical or thermal models is, generally, not adequate to model the interdependence between temperature distribution, heat transfer mechanisms, and the electrical performance of Photovoltaic (PV) generators. In this context, coupled thermal–electrical modeling approaches have recently gained increasing importance to accurately simulate the PV performance. This work presents a comprehensive and systematic analysis of electrical, thermal, and coupled thermal–electrical models developed for PV modules. Electrical models are classified into analytical/physical, semi-empirical, and empirical classes, highlighting their assumptions, parameter requirements, computational complexity, and applicability at cell, module, and system levels. Thermal modeling approaches are reviewed by distinguishing lumped parameter and thermal network models from spatially distributed numerical methods. Particular emphasis is placed on the ability of these models to represent non-uniform temperature distributions and transient operating conditions. Furthermore, this review critically examines state-of-the-art coupled thermo-electrical models, focusing on different coupling strategies, feedback mechanisms, and levels of spatial resolution. The advantages and limitations of each modeling approach are discussed in relation to accuracy, computational cost, and suitability for performance prediction, fault analysis, and reliability assessment. Finally, current research gaps and future directions are identified, providing a structured framework to guide the selection of the most appropriate model and the development of more accurate and physically consistent PV modeling strategies under complex and realistic operating conditions. Full article

At present, the advancement of thermoelectric technology remains largely focused on developing high-performance thermoelectric materials, while comparatively little attention is directed towards its fundamental principles. To address this gap, this study introduces a new physical quantity, the “thermoelectric diffusion potential”, which clarifies the physical interpretations of various thermoelectric coefficients. Analyses reveal that, within a thermoelectric element, the Seebeck coefficient represents a balance between the thermoelectric diffusion field and electrostatic field, rather than between temperature and voltage differences. Using the thermoelectric diffusion potential, the relationship between the Seebeck and Peltier coefficients can be derived directly. Building on this framework, two additional physical quantities, namely the “thermoelectric energy” and “thermoelectric energy flow”, associated with the thermoelectric diffusion potential, are introduced. The formulation of thermoelectric energy flow helps derive the energy conversion relationship at the interface on a macroscopic level. Specifically, energy conversion at the interface occurs between thermoelectric and thermal energy flows, while within the element, it takes place between thermoelectric and electrical energy flows. Owing to the dual nature of internal energy in thermoelectric materials, manifesting as both thermal and electrical energy, the conversion within the element can also be regarded as one between thermal and electrical energy flows. The proposed quantities constitute an important complementary interpretation for the existing thermoelectric framework. Full article

Energy harvesting is an emerging approach that supports the generation of renewable and clean energy, while also augmenting the durability and stability of infrastructure. The paper aims to review applicable energy harvesting systems deployed in various types of infrastructure, including roads and bridges, for applications such as photovoltaic noise barriers, photovoltaic cells, piezoelectric devices, and thermoelectric units. The harvested energy can be utilized to generate electricity, power wireless sensors, melt ice, and provide heating or cooling, while also assisting in monitoring structural conditions. Each energy harvesting technology is described in detail, covering operational principles, application scenarios, prototype development, and key findings from the literature. Economic feasibility studies are also examined to allow for a comparative assessment of energy output, production costs, and cost-effectiveness. This review provides a comparative feasibility framework integrating energy performance, levelized cost of electricity, payback period, and technology readiness levels for infrastructure-based energy harvesting systems. Full article

This review provides a comprehensive overview of molecular doping in organic semiconductors (OSCs), with particular emphasis on the mechanistic understanding of doping processes, rational material design strategies, and processing approaches for achieving high doping efficiency and stability. We discuss fundamental doping mechanisms, including integer charge transfer and orbital hybridization models, and highlight how molecular structure, polymer design, and dopant–host interactions influence electrical performance. Recent advances in processing strategies—such as sequential, vapor-phase, and hybrid doping methods—are also summarized in relation to microstructural control and charge transport optimization. In addition, the implications of molecular doping for emerging organic thermoelectric applications are addressed, emphasizing the interplay between dopant distribution, morphology, and device performance. By integrating mechanistic insights, material design principles, and application perspectives, this review aims to provide a unified framework for researchers in organic electronics, materials science, and thermoelectric device engineering seeking to develop highly efficient and stable molecularly doped organic conductors. Full article

Ag-Sn-S/Se semiconductors, particularly Ag₈SnS₆ and Ag₈SnSe₆, have emerged as promising thermoelectric (TE) materials due to their intrinsically low lattice thermal conductivity and favorable electronic transport properties. Owing to their direct and super-narrow bandgaps, these semiconductors also hold significant potential for photovoltaic (PV) applications, especially in near-infrared (NIR) energy harvesting and tandem architecture. This review provides a detailed analysis of the synthesis strategies, crystallographic evolution, phase transition mechanisms, and bandgap modulation in Ag-Sn-S/Se semiconductors. Particular focus is given to the structural adaptability of argyrodite-type compounds, where intrinsic cationic disorder and halogen-assisted anion substitution collectively enable the fine-tuning of electronic transport and lattice dynamics. TE performance is evaluated in terms of carrier mobility and thermal conductivity, highlighting a significant improvement in figure of merit. The review further explores the potential of Ag-Sn-S/Se semiconductors in energy conversion PVs, particularly as photoabsorber layers and counter electrode materials. Despite initial demonstrations, systematic studies on device integration remain limited, highlighting substantial opportunities for future research aimed at optimizing their optoelectronic interfaces and overall PV performance. This review ultimately discusses the potential of Ag-Sn-S/Se semiconductors, emphasizing their tunable properties as being key to next-generation PV and thermoelectric technologies. It highlights the current achievements and unresolved challenges, outlining strategic pathways for future research and device integration. Full article