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Textile-based thermoelectric (TE) devices are being investigated to power smart textiles autonomously. While previous research has focused on a solid system where the required junctions are fabricated into the device, there has been limited attention given to replacing these TE systems reliably. This work looks at a newer approach to the construction and demonstration of a wearable thermoelectric structure that employs three-dimensional knitted spacers to increase the temperature difference where the TE junctions are detachable and disposable. This system features positive and negative junctions which can be removed while maintaining its excellent voltage generation in low ΔT and good Seebeck coefficients. A mathematical model simulates the potential energy outputs and maximum power points generated, which can be used to increase the device's performance for future wearable sensing applications. [ABSTRACT FROM AUTHOR]

We propose a method for increasing power extraction from a thermoelectric generator (TEG) by switching between series/parallel circuit configurations of thermoelectric elements, which can adjust the internal impedance of the TEG. The power characteristics of the TEG can be adjusted to the load characteristics of the connected device and the relevant ambient temperature. In this paper, we analyzed the change in the TEG characteristics with the series/parallel switching function. We evaluated the power supply to the connected devices at different ambient temperatures and different series/parallel configurations and confirmed that the extracted power could be increased. By theoretically analyzing the circuit configuration of the thermoelectric devices, the switching required to improve the power extraction, and the temperature difference at which switching occurred, we devised a design method for a TEG with circuit switching in order to increase power extraction with any device. We demonstrated the configuration of switching by using a system in which a TEG supplied power to an external wireless transmitter circuit. In this system, the optimal configuration differed at temperature differences of 3.0 K and 4.0 K. At a temperature difference of 3.0 K, the 2-series/1-parallel configuration provided 10% more power to the external circuit than the 1-series/2-parallel configuration. On the other hand, at the temperature difference of 4.0 K, the 1-series/2-parallel configuration provided 23% more power than the 2-series/1-parallel configuration. [ABSTRACT FROM AUTHOR]

It's a promising way to address the global freshwater crisis and energy shortage through solar‐driven devices with evaporate, degrade, and generate electricity at the same time. Low‐efficient light‐thermal conversions for multi‐usage limit application. This paper presents a low‐cost melamine foam/TiO2/carbon black/bismuth (MF/TiO2/CB/Bi) composite with excellent activity to simultaneously process photothermal water evaporation, pollutant degradation, and thermoelectric output, namely‚ shooting three birds with one stone. Under 1 sunlight light intensity, the water evaporation rate reach 4.235 kg m−2 h−1, and the maximum electric power output of a single module is 0.733 W m−2. Meanwhile, Rhodamine B (RhB) solution with 4.0 × 10−4 mol L−1 can be almost degraded within 60 min. Excellent performance benefits from the enhanced adsorption by chemicals, 3D structure for accepting more incident light, and hydrophilic group reducing evaporation enthalpy. Combined with the simulation and experiment, the relationship between heat distribution and thicknesses is studied. When less than 1.98 cm, the lateral temperature is higher than the ambient temperature, thus additional energy cannot be obtained. This work provides a facile and novel method for the construction of photothermal conversion materials with multi‐functional, as a new and useful attempt to solve the shortage of fresh water and electric energy, as well as environmental pollution. [ABSTRACT FROM AUTHOR]

The distribution of heat at the cold and hot sides of a thermoelectric generator (TEG) is essential to its operation. Due to the inhomogeneous pattern, the TEG power-voltage (P–V) curve exhibits multiple peaks, which pose significant consequences for TEG generation. In order to increase the system conversion efficiency at this point, tracking global peak power (GPP) using a maximum power point tracker (MPPT) is crucial. The peak generation from TEG devices cannot be harvested by traditional algorithms such as hill climbing (HC) because they fall in local peaks. Therefore, the spider wasp optimizer (SWO), a new metaheristic-based tracker, is proposed in this paper to monitor the global power from TEG system operating at inhomogeneous heat distribution. In SWO, the iterative process of changing the population length aids in avoiding local solutions. The suggested SWO-based tracker is responsible for regulating the dc-dc boost converter linked to the TEG array terminals by giving its MOSFET the proper duty cycle. Seven inhomogeneous heat distributions are examined for two TEG arrays: symmetric 9 × 9 and asymmetric 10 × 15. These heat distributions are uneven row, uneven column, diagonal, outer, center, and random. The proposed approach is compared to artificial gorilla troops optimizer (GTO), gold rush optimizer (GRO), walrus optimization algorithm (WaOA), particle swarm optimizer (PSO), chef-based optimization approach (CBOA), cuckoo search (CS), Jellyfish search approach (JS), seagull optimization approach (SOA), and sine cosine approach (SCA). With regard to 9 × 9 array, the suggested SWO-tracker performed better than the published GTO method since it increased the generated power in the following scenarios: uneven row, uneven column, SN, diagonal, outer, center, and random patterns by 1.225 W, 0.4083 W, 19.5838 W, 2.4596 W, 1.394 W, and 2.4463 W, respectively. In asymmetric array, the suggested SWO performed better than all others, obtaining the least errors in relation to the Simulink GPPs of 0.016 W, 0.0822 W, 0.3615 W, 0.0603 W, 0.0569 W, 0.0081 W, and 0.0089 W. The obtained outcomes validated the proficiency and dependability of the suggested SWO-tracker in all examined cases.

Thermoelectric generation (TEG)-based waste heat recovery technology is an example of a low-grade energy recovery application. This study proposes a waste heat recovery system that can store the recovered energy and run low-power automotive car lamps. Experimental analysis was conducted to examine the output characteristics of the TEG-based waste heat recovery system, focusing on how the structural components and operational parameters influenced these characteristics. The study also explored and optimized the working strategy of the system for driving light-emitting diode (LED) car lamps. Both the dynamic output characteristics of the system and the lighting attenuation rule of the lamps were evaluated. The results revealed that increasing the heating temperature would improve the recovered energy of the system. However, when a high-power LED chip was used for heat generation instead of an electrically controlled heating plate, a slightly larger amount of energy was collected at the expense of a slightly lower thermoelectric conversion rate. Furthermore, connecting a supercapacitor to the waste heat recovery system for energy storage increased the operational time of the lamps. The supercapacitor also served as a buffer for power and voltage fluctuations caused by variations in the heating temperature. These findings demonstrate that the waste heat recovery system not only meets the requirements of the LED car lamps but can also power other low-voltage and low-power devices. [ABSTRACT FROM AUTHOR]

With the rapid development of new energy generation technology, the thermoelectric generation technology (TEG) can make good use of the waste heat generated in new energy generation. However, the change of temperature distribution will worsen the output characteristics and reduce the power generation efficiency of the TEG system. In this paper, a TEG array reconfiguration method based on the artificial bee colony (ABC) algorithm is proposed. In three different temperature distributions, ABC is used for dynamic reconfiguration of symmetric 9×9 and unsymmetric 10×15 TEG arrays. Three meta-heuristic algorithms, the genetic algorithm, the particle swarm optimization algorithm, and the bald eagle search are compared with the proposed method, and the temperature distribution of the TEG array reconfiguration by ABC is given. The results show that ABC can improve the output power of the TEG array, and the output power-voltage curves tend to show a single peak value. In addition, real-time hardware-in-the-loop (HIL) experiment based on the RTLAB platform is undertaken to verify the implementation feasibility.

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A theoretical technical feasibility investigation aiming to decrease the rate of greenhouse emissions per unit of generated power from fossil fuel plants is presented. To that end, the FGSIG/GT (fuel glycerol integrated gasifier/gas turbine) concept is applied. High-ash coal and raw glycerol—that last deriving from renewable fuel (biodiesel) production—are mixed to form a slurry, which is pumped into the gasifier. The gas stream emerging from that reactor is cleaned by cyclones and filters to decrease the concentration of suspended solids in the stream as well as its granulometry. Before combustion, the fuel gas temperature is decreased to values below the dew points of alkaline compounds in it, thus significantly reducing their concentrations in the gas stream, therefore allowing its injection into commercial gas turbines. Energy recovering is accomplished by two Rankine cycles. The exergetic efficiency is chosen as an objective function to optimize the gasification process. The results reveal a diverging aspect of the RG/solid-fuel ratio influence on the gasification efficiency when comparing with the obtained in previous works where biomasses were fed to the FGSIG/GT process. Due to that highly pressurized process, the whole power generation is optimized resulting in first law efficiencies around 45%, which is noticeable having in mind the relatively low heating values of the presently considered fuels. Additionally, it is important to stress that the objective of this investigation is not just to decrease the overall CO2 emitted per unit of power output from a station consuming fossil fuel and shift, at least part of that, to one derived from a renewable source. [ABSTRACT FROM AUTHOR]

A thermoelectric system should be designed in such a way that it harvests as large water heat as possible while using the least modules. To seek an optimal module number, the present study investigates the effect of source temperature, mass flow rate, turbulator, module number and layout on performance of a thermoelectric generator (TEG) system. The experimental results show the optimal module number isn't a fixed value and turbulator has a significant influence on the whole performance of the thermoelectric system. For compact configuration of TEG, using six modules is the best choice without a turbulator, while using eight modules has the best performance with turbulator. The study shows that module layout has a great effect on the thermoelectric system performance. Compared to compact configurations, all separate ones can harvest more power from the hot air except for 32 modules, enhancing by 10–50% whether the turbulator exists or not. In this situation, eight modules are optimal number. The net output power achieves a maximum value of 16.93W and the maximum net efficiency is 3.85% under present experimental parameters. Meanwhile, a new index called power uniformity coefficient is introduced to assess the distribution of output power among TEGs.

We propose a method for increasing power extraction from a thermoelectric generator (TEG) by switching between series/parallel circuit configurations of thermoelectric elements, which can adjust the internal impedance of the TEG. The power characteristics of the TEG can be adjusted to the load characteristics of the connected device and the relevant ambient temperature. In this paper, we analyzed the change in the TEG characteristics with the series/parallel switching function. We evaluated the power supply to the connected devices at different ambient temperatures and different series/parallel configurations and confirmed that the extracted power could be increased. By theoretically analyzing the circuit configuration of the thermoelectric devices, the switching required to improve the power extraction, and the temperature difference at which switching occurred, we devised a design method for a TEG with circuit switching in order to increase power extraction with any device. We demonstrated the configuration of switching by using a system in which a TEG supplied power to an external wireless transmitter circuit. In this system, the optimal configuration differed at temperature differences of 3.0 K and 4.0 K. At a temperature difference of 3.0 K, the 2-series/1-parallel configuration provided 10% more power to the external circuit than the 1-series/2-parallel configuration. On the other hand, at the temperature difference of 4.0 K, the 1-series/2-parallel configuration provided 23% more power than the 2-series/1-parallel configuration.

Textile-based thermoelectric (TE) devices are being investigated to power smart textiles autonomously. While previous research has focused on a solid system where the required junctions are fabricated into the device, there has been limited attention given to replacing these TE systems reliably. This work looks at a newer approach to the construction and demonstration of a wearable thermoelectric structure that employs three-dimensional knitted spacers to increase the temperature difference where the TE junctions are detachable and disposable. This system features positive and negative junctions which can be removed while maintaining its excellent voltage generation in low ΔT and good Seebeck coefficients. A mathematical model simulates the potential energy outputs and maximum power points generated, which can be used to increase the device’s performance for future wearable sensing applications.

In order to effectively control high temperatures inside coal gangue hills, gravity heat pipes with specific spacings are vertically installed in coal gangue hills. Heat extracted from these heat pipes can be utilized for power generation through energy conversion. In this study, an equivalent model of gravity heat pipes in coal gangue hills was established and, in a laboratory setting, experimental research and optimization were conducted on power generation per unit area using the temperature difference of gravity heat pipes for electricity generation. To facilitate real-time testing of different heat pipe parameters and to display the experimental results, a multi-parameter measurement system was designed and constructed. This study systematically investigated the effects of various structural parameters such as inclination angle, heating temperature, initial absolute pressure, and working fluid height. Through single-factor experiments, it was determined that the inclination angle had no significant impact. The range of values for heating temperature, initial absolute pressure, and working fluid height were confirmed based on six sets of experiments. To maximize the performance of the thermoelectric generator, a response surface analysis experiment was conducted using the Design-Expert software. The optimal conditions were determined to be a working fluid height of 200.001 mm, an initial absolute pressure of 0.002 MPa, and a heating temperature of 413.15 K. Under these conditions, the power generation per unit area of the thermoelectric generator reached 0.122981 W/(m2·K). The accuracy of the theoretical experiments was verified through on-site industrial experiments. By calculations, it was determined that the maximum temperature difference power generation capacity per gravity heat pipe was 42.39 W. This provides a new solution for the management of coal mine gangue hills and the secondary utilization of waste energy. [ABSTRACT FROM AUTHOR]

Power generation from the natural temperature difference between the soil surface and soil depth was examined by comparing four different thermoelectric generator scenarios using ANSYS software. A 40-cm stainless steel heat pipe filled with water was used to transmit heat from the soil depth to the surface to run eight thermoelectric generator modules. 30 cm of the heat pipe was buried in the soil while the remaining 10 cm was kept above the earth’s surface to which the modules were attached. In the first scenario, no fins were added. In the second, aluminium fins were attached to the cold side of the modules and copper fins were attached to the lower end of the heat pipe. The third scenario differed from the second in that the surface area of the aluminium fins was increased ten times. The fourth scenario differed from the third in that the material of the heat pipe was copper. Results showed that the generated power in the first scenario was 169.68 microwatts which were increased 2.17, 4.7, and 5.85 times in the second, third, and fourth scenarios respectively. The findings suggest that such modules can be used in indoor and outdoor low-power applications.

The internal combustion engine (ICE) exhaust gas temperature depends on fuel energy and combustion characteristics. The exhaust gas temperature of compressed natural gas fuel (CNG) is more than gasoline fuel and consequently, affect the thermoelectric generation (TEG) performance. This study evaluates how CNG and gasoline fuels affect exhaust temperatures, TEG power output and the brake specific fuel consumption (BSFC). In test setup, the engine exhaust channel is modified to support a thirty thermoelectric unit (TEM) in upper and lower of exhaust muffler; the TEM is clamped between exhaust mufflers and the cooling system to control the cold surface temperature of the TEM. The maximum power output and open circuit voltage of the TEG are described as functions of temperature difference. The electrical power output of the TEG is evaluated in terms of changing engine speed and load for both fuels. The result indicates that the CNG fuel has better temperature distribution of TEG Kit hot surface which can generate a maximum peak power output. The TEG kit can reach 178.3 W, while the gasoline fuel was 164.4 W. The average saving BSFC for a bi-fuel engine was (2.71%:3.20%) with TEG kit for both fuels.

As an efficient heat exchange component, the gravity heat pipe can effectively control the accumulated temperature inside gangue dumps and enable reuse of transferred heat. This study establishes a similar simulation experimental platform for gravity heat pipes to control gangue dumps and thermoelectric generation. The influence of wind speed on the start-up performance and isothermal performance of gravity heat pipes is analyzed, along with the impact of wind speed on their thermoelectric generation performance. Initially, the optimal working fluid height and heating height are determined, followed by a comparison and analysis of the isothermal performance, start-up performance, and thermoelectric generation performance of the gravity heat pipe under different wind speeds. The results indicate that at a wind speed of 1.0 m/s, the gravity heat pipe exhibits better start-up and isothermal performance. At a wind speed of 2.0 m/s, the thermoelectric power generation reaches its peak. In the range of 1.0~2.0 m/s wind speeds, the curve of thermoelectric generation exhibits the most fluctuations. [ABSTRACT FROM AUTHOR]

Sodium acetate trihydrate (SAT) is a solid liquid phase change material that can be used for solar energy photothermal conversion and thermal energy storage. However, the existence of its supercooling leads to the inability to release and utilize the stored latent heat in time. In this work, disodium hydrogen phosphate dodecahydrate (DSP) was used as the molecular nucleating agent. When the amount of DSP was 3%, the supercooling of SAT was reduced to 0.4 ℃. The corresponding phase transition enthalpy and thermal conductivity are 226.08 J/g and 0.63 W/ (m·K), respectively. The combination of carbon nanotubes (CNTs) with high solar absorptance and SAT/DSP heat storage unit leads to a device with solar energy photothermal conversion and thermal energy storage SAT/DSP/CNTs, which realizes solar energy thermoelectric generation. This study provides a feasible and effective method for the utilization of solar energy by sodium acetate trihydrate. [ABSTRACT FROM AUTHOR]

Nowadays, renewable energy sources are considered better choices in the field of energy generation. It is possible to replace traditional energy sources (i.e., petroleum oil and gases) with more attractive alternatives. This presents several advantages, such as low emissions of greenhouse gases and reduction of climatic change along with associated global warming. In the current paper, a comprehensive review is done introducing thermoelectric generation (TEG). These are applications of renewable energy sources that use the Seebeck effect to generate electricity. In this type of system, two different materials melt at their ends. One is on the hot side, while the other is used as a cold side. The present paper is a survey that includes applications and hybrid systems (based on renewable energy sources) that are integrated with a thermoelectric generator. Also, investigations of the effects of including thermoelectric generation in hybrid systems on the overall performance of such systems are reviewed. These systems can be viewed as an investment in recovery of waste heat from devices such as water pipes, photovoltaic panels, and vehicle exhaust to produce extra power in a hybrid system.

Coal gangue is industrial waste formed during coal production. Due to the accumulation of a large amount of heat inside, it is prone to spontaneous combustion. At present, the use of heat pipes to extract heat from coal gangue has become a relatively effective method, but the extracted heat has not been used rationally, causing damage to the natural environment. This paper proposes to use this part of thermal energy for thermoelectric conversion to realize thermoelectric generation, and on the basis of the experiment platform, and the factors that affect the maximum output power such as the arrangement mode, hierarchical structure and cold end heat dissipation mode of the thermoelectric module are studied. The paper also presents a thermoelectric conversion structure of “pipe in pipe”, which reduces heat loss, increases the contact area between the heat pipe and the thermoelectric generation sheet, and improves the energy conversion efficiency and reduces energy waste, thus the output power of thermoelectric conversion increases. The use of thermoelectric conversion to convert waste heat energy into electrical energy is of great significance to the secondary use of energy.

Abstract Solid‐state thermoelectric (TE) devices offer many interesting features compared with other methods of generation, such as no moving parts, high reliability, low maintenance, and straightforward integration with other heating equipment. In this study, a thermoelectric assembly was integrated into a residential heating boiler to convert a portion of combustion heat to electricity while meeting space and/or water heating needs. A prototype was developed, in which recently developed thermoelectric modules were incorporated into a gas‐fired boiler. The electricity generated by the thermoelectric assembly would be sufficient to power the electrical auxiliary components of the heating system. In this way, the heating system could operate entirely on fuel combustion and provide the consumer with heating system reliability and a reduction in power consumption. A model for the thermoelectric conversion system was established and the thermal resistance analysis was carried out to show the influence of heat transfer coefficients and other parameters on power output and efficiency, and thus improve the system design. In this study, the single‐module integrated assembly can produce a 22.5 W power output. However, each module of the four‐/eight‐module integrated assembly can only generate a power output of 7.85/9.175 W on average. The performance of a single module in a multimodule assembly is worse than that of a single module assembly. The number of modules placed on the furnace wall is not as many as possible but has an optimal value. In this experimental environment, the assembly of eight modules is the optimal choice. Furthermore, it is found that enhancing combustion‐side heat transfer capacity is an effective way to promote system performance. The power output of the assembly composed of four modules will increase by 70% from 7.85 to 13.5 W due to the installation of the fin on the hot end.

The improvement of the structure of the heat exchanger in the thermoelectric power generation system is an effective way to enhance the power generation efficiency. The current study proposes a segmented converging TEG (thermoelectric generator) structure on the left and right sides of the heat exchanger and establishes TEG structure models with different converging angles. Simulation analyses were conducted to analyze the effects of exhaust gas temperature and mass flow on the thermoelectric coupling effect of the system, as well as back pressure power loss and system temperature uniformity. The results have shown that in comparison with the traditional TEG structure, the proposed converging TEG structure and TEM (thermoelectric module) layout could effectively improve the output power of the system and the uniformity of the surface temperature of the heat exchanger, thereby reducing the pressure drop loss of the system. Moreover, in comparison to the traditional TEM layout in an overall converging TEG, the proposed TEM layout in this study can increase the system output power by 14.64% under low-speed working condition and when the converging angle α = 6°; the net power of the proposed bidirectional converging TEG system has increased by 36.22% and the temperature uniformity coefficient has decreased by 71.98% under the medium-speed working condition and when the converging angle α = 6°. The research may shed new light on the structural design and improvement of TEG. [ABSTRACT FROM AUTHOR]

Most industrial processes generate raw heat. To enhance the efficiency of industrial operations, this raw heat is recovered. Thermoelectric generators (TEG), as solid state devices, provide an excellent application of heat recovery in the form of most manageable electrical power. This work presents a novel MPPT controller based on the Mud Ring Optimization algorithm for a centralized Thermoelectric Generator (TEG) under dynamic thermal gradients. The existing stochastic optimization algorithm for Maximum Power Point Tracking (MPPT) control in renewable energy systems exhibits several limitations that affect its performance in MPPT control. The convergence speed, local minima trap, hyper parameters' sensitivity toward the population size, acceleration coefficients, and the stopping criterion all impact the convergence stability. In addition to these limitations, sensor noise sensitivity in measurement fluctuates the control system leading to reduced performance. Therefore, the careful design and implementation of the MRO algorithm is crucial to overcome these limitations and achieve a satisfactory performance in MPPT control. The results of this study contribute to developing more efficient MPPT control of TEG systems and implementing renewable energy technologies. The algorithm effectively tracks the maximum power point in dynamic thermal environments and increases the power output compared to conventional MPPT methods. The findings illustrate the efficacy of the proposed controller providing a higher power output (Avg. 99.95%) and faster response time (220 ms) under dynamic thermal conditions achieving 38–70% faster tracking of the GM in dynamic operating conditions. [ABSTRACT FROM AUTHOR]

Unmanned systems are increasingly adopted in various fields, becoming an indispensable technology in daily life. Power systems are the lifeblood of unmanned systems, and affect the working time and task complexity. However, traditional power systems, such as batteries and fuels have a fixed capacity. Therefore, once the power supply is exhausted and cannot be replenished in time, the unmanned systems will stop working. Hence, researchers have increasingly begun paying attention to renewable energy generation technologies. The principles, advantages, and limitations of renewable energy generation technologies are different, and their application effects in different unmanned systems are also uneven. This paper presents a comprehensive study of the application and development status of photovoltaic, thermoelectric, and magnetoelectric generation technologies in four kinds of unmanned systems, including space, aviation, ground, and water, and then summarizes the adaptability and limitations of the three technologies to different systems. Moreover, future development directions are predicted to enhance the reliability of renewable energy generation technologies in unmanned systems. This is the first study to conduct a comprehensive and detailed study of renewable energy generation technologies applied in unmanned systems. The present work is critical for the development of renewable energy generation technologies and power systems for unmanned systems. [ABSTRACT FROM AUTHOR]

Power generation from the natural temperature difference between the soil surface and soil depth was examined by comparing four different thermoelectric generator scenarios using ANSYS software. A 40 cm stainless steel heat pipe filled with water was used to transmit heat from the soil depth to the surface to run eight thermoelectric generator modules. The heat pipe part, 30 cm long, was buried in the soil. The remaining 10 cm part to which the modules were attached was kept above the earth's surface. In the first scenario, no fins were added. In the second, aluminium fins were attached to the cold side of the modules, and copper fins were attached to the lower end of the heat pipe. The third and fourth scenarios differed from the second in that the surface area of the aluminium fins was increased ten times; in the fourth scenario, the heat pipe material was copper. Results showed that the generated power in the first scenario was 169.68 microwatts, which increased 2.17, 4.7, and 5.85 times in the second, third, and fourth scenarios, respectively. The findings suggest that such modules can be used in indoor and outdoor low-power applications. [ABSTRACT FROM AUTHOR]

Small-size concentrated solar power (CSP) plants are presently not diffused due to a too-high levelized cost of electricity (LCoE), contrarily to CSP plants with capacity >100 MW, which provide LCoE < 20 cEUR/kWh. The integration of solid-state converters within CSP plants can enhance the scalability and economic competitiveness of the whole technology, especially at smaller scales, since the conversion efficiency of solid-state converters weakly depends on the size. Here a system with a high-temperature thermionic energy converter (TEC), together with an optical concentrator designed to be cheap even providing high concentration ratios, is proposed to improve the cost-effectiveness of CSP plants, thus achieving conditions for economic sustainability and market competitiveness. This is possible since TEC can act as a conversion topping cycle, directly producing electricity with a possible conversion efficiency of 24.8% estimated by applying realistic conditions and providing useful thermal flows to a secondary thermal stage. Under established technical specifications for the development of optical concentrator and TEC and according to reasonable economic assumptions, the overall plant conversion efficiency is estimated to be 35.5%, with LCoE of 6.9 cEUR/kW and considering the possibility of an 8 h storage tank for a 1 MW input solar energy system. The calculated projected value is an extremely competitive value compared with other available renewable energy technologies at small capacity scales and opens the path for accelerating the deployment of technological efforts to demonstrate the proposed solution. [ABSTRACT FROM AUTHOR]

Thermoelectric generator can directly convert thermal energy into electrical energy, and applying it to recover waste heat from automobile exhaust is conducive to energy saving. In this paper, a thermoelectric generation experimental system is built, the power output performance and channel power consumption of the flat-plate thermoelectric power generation system under different exhaust gas flow rates are experimentally studied. The results show that when the exhaust flow rate is 40 Nm3/h and the exhaust inlet temperature is 400 °C, the maximum output power of the system is 26.8 W, and the maximum net output power is about 23.3 W. In addition, the exhaust flow rate is changed from 10 Nm3/h to 40 Nm3/h, and the proportion of power consumption in the hot air channel is changed from 1.91% to 12.85%, which has increased by more than six times.

Thermoelectric generators have struggled with low efficiency, limiting their widespread use. To further improve the performance of the thermoelectric generator, this paper introduces the biconical pin structure into the segmented annular thermoelectric generator, and simultaneously incorporates exergy efficiency and economic cost to evaluate its performance. Experiments are first used to verify the accuracy of the simulation model, and then the effects of the cone angle θ , leg height H , leg length ratio δ and resistance ratio ε are discussed. Finally, correlation analysis is used to obtain the weight of the impact of research parameters on thermoelectric performance, and the optimized results are obtained. The results demonstrate that the output power of the biconical segmented annular thermoelectric generator is 20.23 % higher, the exergy efficiency is 8.55 % higher, and the economic cost is reduced by 21.36 % compared to the traditional segmented annular thermoelectric generator. As the θ and H increase, the thermoelectric performance enhances. The influence of δ on thermoelectric performance is more complicated. When ε is 1.5, the thermoelectric generator has optimal thermoelectric performance. This paper provides a reference for optimizing the segmented annular thermoelectric generator structure and is of paramount importance for enhancing the efficiency of waste heat recovery. • The biconical segmented annular thermoelectric generator is proposed. • Research is conducted using exergy analysis and economic cost analysis. • The influence weight of parameters on performance is explored. • The optimal parameters of thermoelectric generator are obtained. [ABSTRACT FROM AUTHOR]

We report enhanced longitudinal spin Seebeck coefficient in Au/polycrystalline Y 3 Fe 5 O 12 (YIG) system in polycrystalline pellets with higher density of surface magnetic moments and a good surface finish. The surface finish, with low artifacts, of the YIG pellet was achieved by using the oxide polishing suspension for a single long-duration of time (1 h) with controlled pressure, in addition to the normal practice of diamond polishing. The longitudinal spin Seebeck effect (LSSE) voltage (V ISHE) for the Au/polycrystalline YIG system is found to vary sinusoidally as a function of external magnetic field direction (θ), and increases linearly with the applied temperature difference (Δ T). The observed values of longitudinal spin Seebeck coefficient S are 0.163 and 0.181 μV/K at Δ T = 11 and 19 K, respectively. The observed LSSE coefficient in the present study is ∼ 11.1 times of the reported value of 0.016 μV/K for Au/ polycrystalline YIG system (at Δ T = 10 K). The observed enhancement in V ISHE has been ascribed to higher surface moment density and good surface quality. • Order of magnitude higher longitudinal spin Seebeck coefficient in Au/polycrystalline Y 3 Fe 5 O 12 than reported in literature. • The higher spin Seebeck signal due to higher density of surface magnetic moments and improved surface quality. • The observed higher spin Seebeck signal will be useful in flexible spin Seebeck devices and spin-caloritronics area. • The ferrimagnetic order determined using the microscopic neutron diffraction technique in polycrystalline Y 3 Fe 5 O 12 sample. [ABSTRACT FROM AUTHOR]

There are two different numerical modelling approaches of thermoelectric generation (TEG) device: separating model that is one-way coupling from CFD model to thermal-electric model and coupling model that is two-way coupling between CFD model and thermal-electric model. With the change of application conditions, the TEG device is subjected extensive changes of fluid parameters. To determine the applicable fluid range of sharing two models of TEG device, a comprehensive comparison between two models is conducted in this study. The results indicated that for the coupling numerical model, the Peltier heat has a negative effect on the temperature difference and output performance of thermoelectric module compared with the prediction results of separating numerical model. Therefore, an output error is induced between the prediction results of separating and coupling numerical models. This error can be decreased by increasing fluid mass flow rate and decreasing fluid temperature. Consequently, the applicable fluid ranges of sharing two models are divided by setting the different error bounds. It is suggested that the separating numerical model is given priority to reduce the calculation complexity when the fluid range of practical application is within a small error bound. • Separating and coupling numerical models of TEG device are comprehensively compared. • The negative influence of Peltier effect on the temperature difference is investigated. • The variation in output error between two models is examined across different fluid parameters. • The applicable fluid ranges of sharing two models are determined under different error bounds. [ABSTRACT FROM AUTHOR]

The abundant aromatic ring structure and a large number of oxygen-containing functional groups in the lignin offer the possibility of achieving excellent photothermal conversion ability and modulating the synthesis of metal nanoparticles. Herein, three kinds of the lignin with different functional group content were employed to investigate the potential influence on the particle size and the solution stability of the CuS through two reaction pathways. The result of various characterizations indicated that the higher the oxygen-containing functional group content (4.83 mmol/g) of lignin, the smaller the size of CuS nanoparticles (∼80 nm) in solution. And the smaller and homogeneously dispersed CuS offered a higher surface temperature for the solar-driven heat-generating materials. The regulation mechanism was also proposed based on the result of the molecular dynamics simulation and DFT calculation. Subsequently, the photothermal film (Route2 DTAL-PVA-30) and solar-driven aerogel evaporator (Route2 DTAL-AG3) were successfully prepared using the lignin-guided stabilization solution of CuS nanoparticles. The photothermal conversion efficiency of 49.43 % and the equilibrium voltage of 266 mV can be achieved by the Route2 DTAL-PVA-30 under 1 sun using a thermoelectric generator. The Route2 DTAL-AG3 exhibited promising salt-rejecting property and outstanding acid and alkali resistance performance, reaching an evaporation rate of up to 1.93 kg/(m2 h) in the 3.5 wt% seawater under 1sun. This work may provide a novel strategy to realize the regulatory role of lignin in the metal synthesis and achieve the high value-added applications of the lignin. [Display omitted] • The influence of the functional group in lignin on the synthesis process of CuS was investigated. • The regulation mechanism of the lignin on the synthesis process of the CuS was clarified. • The photothermal conversion efficiency of Route2 DTAL-PVA-30 can reach as high as 49.43 %. • The equilibrium voltage of 381 mV can be achieved by the Route2 DTAL-PVA-30 under 3 sun. • The Route2 DTAL-AG3 can reach an evaporation rate as high as 4.83 kg/(m2 h) under 3 sun. [ABSTRACT FROM AUTHOR]

Solid‐state thermoelectric (TE) devices offer many interesting features compared with other methods of generation, such as no moving parts, high reliability, low maintenance, and straightforward integration with other heating equipment. In this study, a thermoelectric assembly was integrated into a residential heating boiler to convert a portion of combustion heat to electricity while meeting space and/or water heating needs. A prototype was developed, in which recently developed thermoelectric modules were incorporated into a gas‐fired boiler. The electricity generated by the thermoelectric assembly would be sufficient to power the electrical auxiliary components of the heating system. In this way, the heating system could operate entirely on fuel combustion and provide the consumer with heating system reliability and a reduction in power consumption. A model for the thermoelectric conversion system was established and the thermal resistance analysis was carried out to show the influence of heat transfer coefficients and other parameters on power output and efficiency, and thus improve the system design. In this study, the single‐module integrated assembly can produce a 22.5 W power output. However, each module of the four‐/eight‐module integrated assembly can only generate a power output of 7.85/9.175 W on average. The performance of a single module in a multimodule assembly is worse than that of a single module assembly. The number of modules placed on the furnace wall is not as many as possible but has an optimal value. In this experimental environment, the assembly of eight modules is the optimal choice. Furthermore, it is found that enhancing combustion‐side heat transfer capacity is an effective way to promote system performance. The power output of the assembly composed of four modules will increase by 70% from 7.85 to 13.5 W due to the installation of the fin on the hot end. [ABSTRACT FROM AUTHOR]

This work investigated the potential for waste heat recovery from a cement factory using thermoelectric generation (TEG) technology. Several TEGs were placed on a secondary coaxial shell separated from the kiln shell by an air gap. The performance of the system was tested and evaluated experimentally. Two cooling methods, active water and forced air, were considered. A forced closed-loop water cooling system with a heat exchanger was considered for the active-water cooling method. A heat exchanger was inserted before the water tank to improve cooling efficiency by reducing the inlet temperature of the cooling water tank, in contrast to forced-air cooling, in which a heatsink was used. The obtained results indicated that the closed-loop water-cooled system equipped with a radiator, i.e., active water, has the highest conversion efficiency. The maximum absorbed heat for the forced-air and active-water cooling systems were 265.03 and 262.95 W, respectively. The active-water cooling method improves the power of TEG by 4.4% in comparison with forced-air cooling, while the payback periods for the proposed active-water and forced-air cooling systems are approximately 16 and 9 months, respectively. [ABSTRACT FROM AUTHOR]

Thermoelectric power generation is a potential technology for providing green energy. It is expected to be able to convert enormous amounts of waste heat to electrical energy. To realize this technology, further increases in conversion efficiency and durability are essential. In particular, durability is a critical issue, especially for harnessing high‐temperature heat sources. Thus, a thermoelectric module of SiGe is fabricated without electrodes at the hot side, which is the main cause of aging. Electronic conduction between p‐ and n‐type elements is alternatively introduced using a direct connection, forming a p‐n junction. Sufficiently low electrical contact resistances are achieved at the p‐n junction above 300 °C due to the dissipation of the depletion layer. The conversion efficiency is 2.0% with a hot‐side temperature of 700 °C. The power‐generation performance is constant during heat‐run tests conducted at 700 and 500 °C under vacuum and air, respectively, for more than 450 h. The results demonstrate that a stable power‐generation technology using a thermoelectric module at high temperatures is established successfully. [ABSTRACT FROM AUTHOR]

As a waste heat recovery power generation technology, the thermoelectric generation (TEG) system is popular and promising for its high reliability and environmental benefits. However, because of its low conversion efficiency, it has not been in large-scale use. To raise the efficiency of the TEG system, maximum power point tracking (MPPT) techniques are effective ways to gain the maximum power of the TEG system. But in practical engineering scene, TEG usually works under nonuniform temperature distribution (NTD) conditions; this will bring some difficulties on MPPT controlling, such as local maximum power point (LMPP) and oscillations around the maximum power point (MPP). For this reason, many intelligent MPPT algorithms have been emerged to solve aforementioned problems. In this article, the mathematical model and NTD condition will be introduced. Then, the latest research on classical and intelligent MPPT technologies will be reviewed, which includes a comparison of complexity, economy, efficiency, adaptive ability, and other aspects of these methods, in which researchers can obtain information in related fields.

The development of new materials for resource and energy recycling has emerged as a primary focus in addressing global energy and environmental sustainability challenges. Inspired by traditional Chinese architecture, a smart roof tile (SRT) is scientifically designed, which incorporates hierarchical micro-nanostructured polyethylene/silica/barium sulfate composites (IH-PSB), semiconductor power generation modules, and LED chips. Leveraging the combined effects of surface and interface functionalities, the IH-PSB demonstrates exceptional sub-ambient cooling capabilities, resulting in its surface and bottom temperature being 5.4 °C and 12.1 °C lower than the ambient temperature, respectively. Additionally, the precisely controlled heterogeneous wettability, with a contact angle of approximately 151° and a roll-off angle of around 32°, allows the IH-PSB to efficiently condense moisture and transport droplets. Benefiting from the excellent radiation cooling performance and precisely controlled heterogeneous wettability, the IH-PSB exhibits remarkable passive sub-dewpoint cooling efficiency coupled with efficient water harvesting performance. During a one-month outdoor experiment, the IH-PSB operated stably and continuously without any electrical input, maintaining a mass flux ranging from ∼23.2–50.0 g m−2 h−1. Interestingly, the SRT system efficiently harnesses waste heat generated by the LEDs while simultaneously regulating their temperature effectively. The development and utilization of the SRT offer a sustainable, energy-efficient, and forward-thinking solution that addresses global water scarcity and energy crises. [Display omitted] • A hierarchical micro-nanostructuredIH-PSB is designed with radiation cooling performance and heterogeneous wettability. • The IH-PSB demonstrates a reduction in surface and bottom temperatures by 5.4 °C and 12.1 °C respectively. • The heterogeneous wettability of the IH-PSB enhances its efficiency in moisture condensation and droplet transportation. • The smart roof tile efficiently harnesses waste heat generated by the LEDs while effectively regulating their temperature. [ABSTRACT FROM AUTHOR]

Most industrial processes generate raw heat. To enhance the efficiency of industrial operations, this raw heat is recovered. Thermoelectric generators (TEG), as solid state devices, provide an excellent application of heat recovery in the form of most manageable electrical power. This work presents a novel MPPT controller based on the Mud Ring Optimization algorithm for a centralized Thermoelectric Generator (TEG) under dynamic thermal gradients. The existing stochastic optimization algorithm for Maximum Power Point Tracking (MPPT) control in renewable energy systems exhibits several limitations that affect its performance in MPPT control. The convergence speed, local minima trap, hyper parameters’ sensitivity toward the population size, acceleration coefficients, and the stopping criterion all impact the convergence stability. In addition to these limitations, sensor noise sensitivity in measurement fluctuates the control system leading to reduced performance. Therefore, the careful design and implementation of the MRO algorithm is crucial to overcome these limitations and achieve a satisfactory performance in MPPT control. The results of this study contribute to developing more efficient MPPT control of TEG systems and implementing renewable energy technologies. The algorithm effectively tracks the maximum power point in dynamic thermal environments and increases the power output compared to conventional MPPT methods. The findings illustrate the efficacy of the proposed controller providing a higher power output (Avg. 99.95%) and faster response time (220 ms) under dynamic thermal conditions achieving 38–70% faster tracking of the GM in dynamic operating conditions.

Summary: With increase in environmental concerns, the idea of generating pollution‐free electricity like solar photovoltaic energy (SPV) is explored among researchers and industrialists. Despite the fact that photovoltaic is a direct and simple method of power production, it has lesser effectiveness in terms of quantum effect. The incident solar irradiance on the surface of the photovoltaic module heats the rear side of the module during the process of heat to electricity conversion giving rise to heating of the module and hence, rises its temperature. Nevertheless, when integration of solar PV system takes place, it suffers from the curse of being lower quantum efficient. Diverse integration of renewable sources makes the system complex, making regulating system parameters a difficult task; to avoid this, the system has been studied under incorporation of thermo electric generator (TEG) along with fuel cell technology (FCT) and in absence of TEG. This combined hybrid system generates substantial amount of electricity, which is helpful for residential application as well as to the utility. Nevertheless, the proposed system has only dc sources in order to make the system more reliable in terms of conversion, controlling, and feeding to the utility. Therefore, in this article, two systems have been studied and modeled, one is incorporated with TEG and another is without TEG. The performances of both the systems have been compared and analyzed on the basis of delivering real power and absorbing reactive power. It is evident from the study that the solar PV system with TEG has the ability of maintaining constant voltage at PCC terminals, absorbing lesser amount of reactive power and consequently delivering ample amount of real power without much complexity such as controlling of AC sources and grid activity. Around 41.0534% of higher real power has been supplied, and around 22.14% of lesser reactive power has been absorbed during the incorporation of TEG with this aforementioned hybrid system. On MATLAB‐based Simulink environment, the entire system has been studied, designed, and analyzed. [ABSTRACT FROM AUTHOR]

One of the most promising forms of energy production for at least several decades is thermoelectric power energy, which converts heat directly into electricity. In comparison with other methods of extraction of energy, Tthermoelectric power energy has such distinctive features as compactness, low weight, noiselessness in operation, high reliability, does not affect the growth of greenhouse gases and an increase in the radiation background. It can be recognized that low current conversion efficiency and high cost are some of the disadvantages. But there is a huge plus, because TEPG does not contribute to the depletion of natural resources and environmental pollution, such as climate warming, which has caused concern recently. In this paper, we report on some technological features of methods for obtaining semiconductor materials for thermoelectricity and their properties.

Small-size concentrated solar power (CSP) plants are presently not diffused due to a too-high levelized cost of electricity (LCoE), contrarily to CSP plants with capacity >100 MW, which provide LCoE < 20 cEUR/kWh. The integration of solid-state converters within CSP plants can enhance the scalability and economic competitiveness of the whole technology, especially at smaller scales, since the conversion efficiency of solid-state converters weakly depends on the size. Here a system with a high-temperature thermionic energy converter (TEC), together with an optical concentrator designed to be cheap even providing high concentration ratios, is proposed to improve the cost-effectiveness of CSP plants, thus achieving conditions for economic sustainability and market competitiveness. This is possible since TEC can act as a conversion topping cycle, directly producing electricity with a possible conversion efficiency of 24.8% estimated by applying realistic conditions and providing useful thermal flows to a secondary thermal stage. Under established technical specifications for the development of optical concentrator and TEC and according to reasonable economic assumptions, the overall plant conversion efficiency is estimated to be 35.5%, with LCoE of 6.9 cEUR/kW and considering the possibility of an 8 h storage tank for a 1 MW input solar energy system. The calculated projected value is an extremely competitive value compared with other available renewable energy technologies at small capacity scales and opens the path for accelerating the deployment of technological efforts to demonstrate the proposed solution.

To enhance the energy conversion of thermoelectric devices, graphene nanoplatelets (GNPs) nanofluids are generally utilized into heat exchangers to boost the cooling capability for thermoelectric generators (TEGs) and thermoelectric coolers (TECs). In this study, a fluid-thermal-electric multiphysics coupled model is developed to uncover the performance enhancements of both TEG and TEC systems using nanofluids, by which the thermodynamic and thermoelectric performances associated with the nanofluid flow behaviors can be taken into account simultaneously. The enhancement effects of nanofluid weight concentration on heat transfer, TEG's electricity generation, and TEC's cooling capability are comprehensively investigated for varying Reynolds numbers (Re). The numerical analysis demonstrates the validity of performance improvements by using nanofluids in TEG/TEC systems, which also shows that the enhancement effect increases with the nanoparticle concentration but reduces with Re. Specifically, with a 0.1 wt% nanofluid used instead of water cooling for Re = 100, the output power and the conversion efficiency are enhanced by 11.38% and 5.7% for the TEG system, while the cooling power and the coefficient of performance (COP) of the TEC system are improved by 12.13% and 9.1%, respectively. The enhancement ratios, however, decrease rapidly to be less than 5% with the increasing Re, and gradually reach a steady level when Re exceeds 1200. Of particular interest is that the performance enhancement of the TEC system proves much stronger than that of the TEG system with nanofluids used as coolants in various Re cases, suggesting that the application of nanofluids seems more promising for a TEC system. This work provides a multiphysics coupling modeling approach to reveal the enhancement effect of nanofluids on thermoelectric performances, which may bring new implications for the optimization design of thermoelectric systems.

In this paper, anew hybrid energy converter is designed which consists of a Thermoelectric Generator (TEG) unit and aTriboelectric Nanogenerator (TENG) unit. The device can harvest solar energy and wind energy from the environment individually or simultaneously, and utilize them as the energy source of sensors and wireless transmission equipment in the system. When working individually, the TENG unit can achieve 244 V output voltage and 35 Aoutput current from wind energy of 12m/s. The output voltage of 4.27 V and the output current of 328 mA can be obtained from the solar thermoelectric unit at the hot end temperature of 110°C. According to the experimental data of capacitor charging by hybrid energy converter, compared with TEG unit and TENG unit individually, the charging voltage of the proposed device increases by 93.3% and 28.9%, respectively, and successfully drives Bluetooth module and realizes wireless data transmission. Compared with the traditional method, the proposed unit achieves not only hybrid energy harvesting but also better output performance. It is an important exploration for the development of self-powered sensors in the future intelligent Internet of things. [ABSTRACT FROM AUTHOR]

Green energy from waste heat is one of the major areas of research in current focus for power generation. This project aims at reusing the heat energy produced from chimneys and solar panels to generate electricity for domestic applications through thermoelectric generators (TEGs). TEGs are cost‐efficient, durable, and low‐maintenance due to no moving parts. Mountings of TEGs on a chimney and a solar panel were designed and fabricated along with TEGs. The experimental results show that a typical house can generate electricity corresponding to about 20–30 % of its total power consumption. The new design is more effective and durable for environment sustainability and will lead to an alternative source to generate electricity. [ABSTRACT FROM AUTHOR]

Summary: On most dual fuel ships, the waste heat of engine exhaust gas and the cooling capacity of liquefied natural gas (LNG) in the fuel regasification process are not effectively used. In order to recover these redundant energy under the large temperature difference around 600 K, thermoelectric technology provides a feasible solution with the advantages of small size, no noise and high stability. In this article, a waste energy recovery system has been developed for LNG‐diesel dual fuel ships using multistage thermoelectric generators (TEGs) scheme. According to the thermodynamic analysis and the materials selection, the recoverable energy, recovery form and thermoelectric materials used in the large temperature range of the dual fuel ship were determined. A multistage TEGs model considering the temperature distribution, fluid properties, connection methods and contact effects has been developed to predict the thermoelectric performance under the operating condition with large temperature difference. The results show that the maximum conversion efficiency can reach up to 18.54% with appropriate thermoelectric materials in different temperature zones and suitable multistage series‐parallel schemes. Besides, the thermoelectric conversion effect makes the temperature distribution of the cold and hot fluids in the TEG quite different from that in the traditional heat exchangers. The output characteristics of TEGs are directly affected by the flow parameters of the cold and hot fluids and the connection methods of thermoelectric elements. This study provides a brand‐new inspiration for developing the waste energy recovery and corresponding power conversion system on LNG‐diesel dual fuel ships. [ABSTRACT FROM AUTHOR]

The performance of solar photovoltaic-thermoelectric generation hybrid system (PV-TGS) and solar photovoltaic-thermoelectric cooling hybrid system (PV-TCS) under different conditions were theoretically analysed and compared. To test the practicality of these two hybrid systems, the performance of stand-alone PV system was also studied. The results show that PV-TGS and PV-TCS in most cases will result in the system with a better performance than stand-alone PV system. The advantage of PV-TGS is emphasised in total output power and conversion efficiency which is even poorer in PV-TCS than that in stand-alone PV system at the ambient wind speed uw being below 3 m/s. However, PV-TCS has obvious advantage on lowering the temperature of PV cell. There is an obvious increase in tendency on the performance of PV-TGS and PV-TCS when the cooling capacity of two hybrid systems varies from around 0.06 to 0.3 W/K. And it is also proved that not just a-Si in PV-TGS can produce a better performance than the stand-alone PV system alone at most cases.

Thermoelectric generation (TEG) is one of the most effective technologies converting heat directly into electric power. In this paper, a nearly kilowatt class TEG system mainly based on radiation heat transfer was designed and built. The open circuit voltage, the output power, the power density, and the conversion efficiency of the TEG system were investigated in detail at different temperature gradients. The maximum inverter power output of the TEG system assembled with 182 TEG devices can reach 684 W at a temperature difference around 125 K, and the corresponding power density can reach 845 W/m2. The inverter output power is almost proportional to the temperature difference between the hot and the cold side of TEG system. Our results confirmed that if the waste heat resource was sufficient to provide a greater temperature difference of 200 K in practical application, the output power and the power density of this TEG system would reach 1.23 kW and 1.51 kW/m2, respectively. [ABSTRACT FROM AUTHOR]

In this study, the performance of an applied TEG for the recovery of residual heat from the low displacement engine diesel engine exhaust gases has been evaluated. Twenty thermoelectric modules located on the upper and lower surface of a rectangular duct heat exchanger have been used in a 2×5 arrangement. By means of a cooling system formed by two rectangular coolers, the temperature of the cold surface of the TEMs remains constant. The diesel engine has worked a total of nine operating conditions, in which the rotation speed has been varied in 3000, 3400, and 3800 rpm, while the torque has been modified in 3, 4.5, and 6 Nm. The experimental results have indicated that the electrical performance of the thermoelectric modules decreases for an electrical current greater than 1.6 A. In general, the maximum electrical power of the TEG has been reached when the external load resistance has approached the total internal resistance of the TEMs. The maximum value of the electric power generated by the TEG has been 72 W, achieved with an engine speed of 3800 rpm and a torque of 6 Nm. These same conditions have allowed reaching an energy conversion efficiency of 2.61%. [ABSTRACT FROM AUTHOR]