Output Conversion Efficiency Research Articles

Synergistically enhanced PVDF-based nanofiber membranes randomly embedded with ZnWO4@PDA nanorods for self-powered sensors with multi-mode free switching

In spite of the high level of attention paid to multifunctional sensors, the flexible and multifunctionality are still intractable challenges to be tackled. Herein, we design a flexible, hydrophobic and stable multifunctional sensing material by electrostatic spinning of PVDF/ZnWO4@PDA (PZP). The incorporation of ZnWO4@PDA into PVDF nanofibers can act as an effective nucleating agent and photosensitizer, which increases the polar crystalline phase and photovoltaic properties of PVDF. With the synergy of PVDF and ZnWO4@PDA, PZP based piezoelectric sensors offer significantly superior electrical output (28.4 V, 600 nA) and high sensitivity (1.04 V/kPa). Moreover, it is particularly surprising that photoelectric sensor based on PZP textiles has excellent optical properties, as confirmed by the response/recovery time (0.6 s/0.66 s) of simulated sunlight detection. Piezoelectric photoelectric effect exists in PZP textiles, as evidenced by the significant increase in the strain output current of photoelectric sensor when irradiated with sunlight. Furthermore, based on the coupling of piezoelectric effect and triboelectric effect of PZP composite, the contact out nano-triboelectric generator has enhanced the electrical output and electromechanical conversion efficiency. Therefore, this work has successfully prepared multifunctional sensing materials that integrate pressure sensing, audio recognition, underwater communication, optoelectronic detection and triboelectric energy collection, paving a new way for the flexible multifunctional sensors.

Defying Gravity to Enhance Power Output and Conversion Efficiency in a Vertically Oriented Four-Electrode Microfluidic Microbial Fuel Cell.

High power output and high conversion efficiency are crucial parameters for microbial fuel cells (MFCs). In our previous work, we worked with microfluidic MFCs to study fundamentals related to the power density of the MFCs, but nutrient consumption was limited to one side of the microchannel (the electrode layer) due to diffusion limitations. In this work, long-term experiments were conducted on a new four-electrode microfluidic MFC design, which grew Geobacter sulfurreducens biofilms on upward- and downward-facing electrodes in the microchannel. To our knowledge, this is the first study comparing electroactive biofilm (EAB) growth experiencing the influence of opposing gravitational fields. It was discovered that inoculation and growth of the EAB did not proceed as fast at the downward-facing anode, which we hypothesize to be due to gravity effects that negatively impacted bacterial settling on that surface. Rotating the device during the growth phase resulted in uniform and strong outputs from both sides, yielding individual power densities of 4.03 and 4.13 W m-2, which increased to nearly double when the top- and bottom-side electrodes were operated in parallel as a single four-electrode MFC. Similarly, acetate consumption could be doubled with the four electrodes operated in parallel.

Performance analysis and optimization of an annular thermoelectric generator integrated with vapor chambers

To overcome the structural barriers of conventional annular thermoelectric generators (ATEGs), a new ATEG integrated with vapor chambers (VCs) is proposed in this paper, where the use of VCs enables a large hot-end contact area and a high temperature uniformity for traditional planar thermoelectric modules. Besides, a numerical model for the ATEG is built to conduct performance analysis and optimization under different parameters. Results suggest that the heat absorption of the ATEG increases with the increase of the number of VCs, thereby boosting the output power of the system. When the flow rate is lower than 35 g/s, the optimal number of VCs for the ATEG is 12, with the highest output power, conversion efficiency, net power, and net efficiency of 287.3 W, 5.36 %, 214.1 W, and 3.99 %, respectively, at the exhaust temperature of 800 K. Besides, the exhaust temperature does not affect the optimal result, while the ATEG should be designed with fewer VCs when applied to the waste heat recovery with a larger flow rate. The increase in the VC thermal conductivity is not related to heat absorption but can improve temperature uniformity, and the thermal conductivity of 4000 W m−1 K−1 already meets performance requirements. This study provides new perspectives on the structure design of ATEGs.

Thermodynamic performance evaluation and optimization of a hybrid system integrating vacuum graphene-anode thermionic converters with direct carbon fuel cells

An efficient hybrid system integrating a direct carbon fuel cell (DCFC) with a vacuum graphene-anode thermionic converter (VGTC) is proposed for cogeneration. The VGTC efficiently recycles waste heat released from the DCFC and generate additional electricity, significantly improving energy utilization efficiency and economic performance. A comprehensive mathematical model is developed to quantitatively assess the thermodynamic performance of the hybrid system, taking into account the overpotential losses of the DCFC and the irreversible energy losses occurring within the system. The results show that at an operating temperature of 923 K, the hybrid system can achieve a maximum power density of 466 W/m2, which is approximately 1.34 times that of a single DCFC, indicating a significant improvement in output performance. Besides, the optimal operating region and parameter selection criteria for the hybrid system are determined using finite-time thermodynamic optimization theory. Furthermore, the effects of essential parameters on the output performance of the hybrid system, such as the operating temperature of the DCFC, the heat transfer coefficient, the Fermi level of graphene, the work function of the cathode, the thermal emissivity, and the reflectivity of the back mirror, are investigated. Finally, the comparative study shows that the proposed hybrid system outperforms other previously reported hybrid systems regarding output electric power and conversion efficiency due to the efficient high-grade waste heat recovery and energy conversion by the VGTC.

Hybridization of heat recovery from exhaust gas of boilers using thermoelectric generators

This study investigates the possibilities for energy recovery and environmental effect reduction of waste heat, a consequence of industrial activities. The main objective of the work is to integrate thermoelectric generators (TEGs) into industrial hybrid waste heat recovery system. The study consists of combining TEGs modules with a boiler waste heat recovery system with Rockwool insulation, taking into consideration variables like thermal resistance, power output, water temperature, and energy conversion efficiency. The results show that TEG placement has a major impact on system performance. One of the promising configuration is TEGs placed close to heat source, especially outside exhaust pipe outer walls, where electrical power up to 27 W can be generated and heat of 4215 W can be recovered from the exhaust gas.

Research on the power generation performance and optimization of thermoelectric generators for recycling remaining cold energy

Compared with extensive research on the power generation of thermoelectric generators (TEGs) under medium-high temperatures, research on power generation for cold energy utilization is still limited. To study the performance and feasibility of low-temperature power generation, this paper combines simulation and experiments for research. Firstly, a simulation model based on actual material parameters is established. Then, a thermoelectric low-temperature power generation experimental platform is established to conduct experimental research on TEG in different temperature zones and temperature differences and compared with simulation results. Finally, optimization research is conducted by changing thermoelectric materials and structures. The research results indicate that the maximum errors between the dates of simulation and experiment in terms of output voltage, conversion efficiency, and exergy efficiency are 11.3 %, 10.57 %, and 10.57 %, respectively. Compared with Bi2Te3, the output voltage, conversion efficiency, and exergy efficiency of CsBi4Te6 are improved by 21.95 %, 34.64 %, and 34.64 %, respectively. The maximum output power and conversion efficiency are linearly related to the output current. The performance is optimal when the thermoelectric unit height is 1.0 mm and the side length is 1.6 mm. This proves the feasibility of TEG application at low temperatures and lays the foundation for low-temperature power generation.

Optimization of a unileg thermoelectric generator by the combination of Taguchi method and evolutionary neural network for green power generation

The performance optimization of thermoelectric generators (TEGs) is crucial for efficiently converting waste heat to green energy. This study analyzes the performance and thermal stress of a unileg thermoelectric module by combining the Taguchi method, analysis of variance (ANOVA), and artificial neural network. The results of the Taguchi method indicate that the leg geometry exerts a negligible effect on output power (OP) and conversion efficiency but significantly affects the thermal stress (TS). The analysis of the objective function (maximum OP-to-maximum TS ratio, denoted by P/S) reveals the optimal configuration results in a P/S value of 0.01255 W‧MPa−1, accompanied by a maximum output power (2.9 W) and thermal stress (232.32 MPa). The maximum thermal stress of the rectangle TE leg (182.29 MPa) is less than that of the triangle (279.85 MPa) by 34.86 %. The Taguchi method, analysis of variance, and artificial neural network have the same sensitivity order on P/S with leg height > leg geometry > copper thickness > ceramic thickness. Furthermore, an evolutionary neural network (ENN) method with five-step optimization from 4000 datasets has been developed to improve machine learning prediction. The average error of P/S value and conversion efficiency from ENN is 1.61 % and 0.35 %, respectively. However, for the ENN predictions, the relative errors of P/S value and efficiency between predictions and simulations are 1.28 % and 0.19 %, respectively. In conclusion, this work has demonstrated the numerical optimization of the performance of unileg TEM for the first time. The use of ENN can predict the performance of TEM precisely, saving running time and markedly reducing computational costs. Moreover, the results are conducive to designing high-performance TEGs with long lifespans.

Effect of length and attack angle of the splitter plates on circular cylinder piezoelectric water energy harvester

With the micro-miniaturization of offshore wireless sensors, signal lights, and other devices and the emergence of the problem of self-powering in the distant sea, how to harvest energy from low-speed currents has become a hot spot of research nowadays. To improve the energy output power and conversion efficiency of low-speed water flow, we propose a vertical cantilever beam circular cylinders fitted with a rigid splitter plate piezoelectric energy harvester (CSPPEH). In this paper, the influence of the length and the attack angle of the splitter plate on CSPPEH has been experimentally investigated. The vibration response mechanism involving the mutual transition between vortex-induced vibration and galloping was analyzed through particle image velocimetry flow field visualization. The experimental results indicate that the vibration and piezoelectric characteristics of the CSPPEH increase initially and then decrease with the length of the splitter plates (L/D = 0–2.4) at the attack angle of 0°, which can be explained by the theoretical model of the energy harvester. It is found that the optimal vibration and piezoelectric characteristics occur at a rigid splitter plate length of 1.40D with an attack angle of 90°. The maximum values for amplitude, vibration swing angle, voltage, power, and power density are 4.96D, 21.7°, 42.68 V, 910.81 μW, and 1.94 mW/cm3, respectively. Efficiency was up to 2.2% at 0.4D length and 90° attack angle of the splitter plate. Compared to the bare circular cylinder energy harvester, the output power and efficiency are significantly improved. The demonstration of continuous charging and discharging of capacitors and light emitting diode lights is performed to show the practicability of the designed CSPPEH. Overall, the present study enables the applications of CSPPEH for realizing self-powered wireless sensing and signal lights under low-water-speed environments.

Al2O3/graphene/PVDF‐HFP radiative cooling coating reinforced heat dissipation of BIPV modules

AbstractBuilding integrated photovoltaic modules, applied to industrial and commercial buildings, generally used metal as the backsheet. In summer, the operating temperature of modules is as high as 70°C, resulting in instability of output power and service life. Therefore, it is very important to reduce the operating temperature of photovoltaic modules. In this work, Al2O3/graphene/poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) composite radiative cooling coatings were prepared and utilized for reinforcing heat dissipation of photovoltaic modules. The results indicate that 0.75 wt%Al2O3/1wt%graphene/PVDF‐HFP composite coating exhibited a thermal diffusivity of 3.24 μm2/s and an average emissivity of 0.94. The maximum temperature drop of the coating in the outer door reached 5.8°C. In addition, a mini photovoltaic module coated with the composite coating achieved the cooling effect of 2.4°C, and the output power and conversion efficiency were increased by 5.8% and 7%, respectively. This demonstrates that the heat conduction radiative cooling coating possesses potential applications for improving the reliability of photovoltaic modules.

Numerical investigations on the performance enhancement of a hydrogen-fueled micro planar combustor with finned bluff body for thermophotovoltaic applications

To achieve higher power output and energy conversion efficiency for micro-thermophotovoltaic (MTPV) systems, a hydrogen-fueled micro planar combustor with finned bluff body is proposed and compared to the micro planar combustor with/without bluff body. Numerical results indicate that among micro planar combustors without bluff body, with bluff body, and with finned bluff body, the micro planar combustor with finned bluff body obtains a higher and more uniform wall temperature, but the pressure loss is higher. This is due to that the Peclet number near the inner walls is significantly higher compared to those without bluff body, and the Peclet number in the center of the axis is significantly lower, which reveals a stronger convection effect in the non-recirculation region and diffusion effect in the recirculation region. Then, effects of finned bluff body position, fin length/bluff body radius ratio and fin angle on the performance of micro planar combustor are investigated. It is found that the micro planar combustor with a larger finned bluff body position, smaller fin length/bluff body radius ratio and larger fin angle is more practical for MTPV system.

Enhanced average power factor and ZT value in PbSe thermoelectric material with dual interstitial doping

High PFave of 24.18 μW cm−1 K−2 and ZTave of 1.01 at 300–773 K have been achieved in n-type Pb1.02Se–0.2%Cu thermoelectric through dual Pb and Cu interstitial doping, and it exceeds other Se/S-based (Te free) n-type thermoelectric materials.

Efficient continuous-wave Nd:YVO4/KGW intracavity Raman laser

We demonstrate an efficient Nd:YVO4/KGW intracavity Raman laser in continuous-wave (CW) scheme. With a V-shaped fundamental laser cavity and a short Stokes cavity in it, the oscillating beam sizes are designed to alleviate the thermal effect and to enhance the Raman gain for efficient CW operation. The output power of CW Stokes wave at 1177 nm reached 9.33 W under an incident laser diode pump power of 36.65 W, with corresponding optical efficiency being 25.5%. To the best of our knowledge, these are the highest Stokes output power and conversion efficiency of CW intracavity Raman lasers.

Energy and exergy analysis with cost-efficiency comparison of modified phase change material (PCM) integrated with solar panel thermal system

This study investigates the efficiency and cost-effectiveness of integrating Phase Change Materials (PCMs) into solar panels to optimize power output and power conversion efficiency under varying temperature conditions. By applying PCMs, temperature fluctuations can be reduced, maintaining solar panels at an optimal temperature for power generation. The research employs modeling and simulation techniques, focusing on energy and exergy analysis of solar energy storage systems based on pure and modified PCMs such as Paraffin wax, Sodium acetate trihydrate, Sodium sulfate decahydrate, etc. Temperature and light intensity data are collected in the Wangchan district, Rayong province, using a light intensity sensor and a thermocouple. The study analyzes each layer of the solar panel, employing numerical methods and matrix solutions to solve the system of non-algebraic equations, yielding temperature values for each component layer. The thermodynamic properties of the modified PCMs are calculated theoretically, and their cost-efficiency is analyzed by comparing the solar panel’s increased power area density generation after applying specific PCMs to the cost of the PCM. The simulation results demonstrate that the solar panel integrated with PCM generates up to 11.1% more power than a regular solar panel, assuming negligible heat loss from the sides of the solar panel and an average temperature during the melting and solidification processes for the PCMs. Moreover, the best cost-efficiency of the modified PCM is achieved, with an increase of up to 637.7%, using a combination of paraffin wax and polyethylene glycol.

Power and efficiency optimizations for an open cycle two-shaft gas turbine power plant

In finite-time thermodynamic analyses for various gas turbine cycles, there are two common models: one is closed-cycle model with thermal conductance optimization of heat exchangers, and another is open-cycle model with optimization of pressure drop (PD) distributions. Both of optimization also with searching optimal compressor pressure ratio (PR). This paper focuses on an open-cycle model. A two-shaft open-cycle gas turbine power plant (OCGTPP) is modeled in this paper. Expressions of power output (PP) and thermal conversion efficiency (TCE) are deduced, and these performances are optimized by varying the relative PD and compressor PR. The results show that there exist the optimal values (0.32 and 14.0) of PD and PR which lead to double maximum dimensionless PP (1.75). There also exists an optimal value (0.38) of area allocation ratio which leads to maximum TCE (0.37). Moreover, the performances of three types of gas turbine cycles, such as one-shaft and two-shaft ones, are compared. When the relative pressure drop at the compressor inlet is small, the TCE of third cycle is the biggest one; when this pressure drop is large, the PP of second cycle is the biggest one. The results herein can be applied to guide the preliminary designs of OCGTPPs.

Global sensitivity analysis and optimization of a multistage thermoelectric generator based on failure probability

Thermoelectric generator (TEG) is a thermoelectric conversion device that mainly utilizes the Seebeck effect, and the electrical energy generated is usually directly converted from thermal energy. However, research on the global sensitivity analysis and optimization of three-stage TEG systems is currently lacking. In this study, a multistage semiconductor TEG system model based on functional failure probability and a global sensitivity analysis model were established. These models are first used to compare the performance of TEG configurations with different stages. Then, based on the double random uncertainties of design variables, a series of studies were conducted. The results showed that the performance parameters of the all TEG configurations exhibited similar performance variation trends. An first-best working current was identified to obtain the first-best output power and conversion efficiency. Next, as the sample size used to determine the variable uncertainty for a three-stage TEG increased, it increased to 4 × 106, the sensitivity indicators of the output response (P and η) tended to constant values of 0.02322 and 0.02039. Among the 11 considered design parameters, the uncertainties of the heat and cold source temperatures had the most significant influence on the functional failure probability of the three-stage TEG system, followed by the working current, Zeebek coefficient, number of temperature difference components in each stage, and heat transfer coefficient of the cold source. The remaining variables had negligible influence. Finally, small changes in the mean heat and cold source temperatures changed the sensitivity of the output response of the three-stage TEG to each critical design variable, but did not affect the relative ranking of the sensitivity indicators corresponding to each. The results of this study can provide some basis for the further development of TEG systems.

Enhancing heat-driven acoustic characteristics of standing wave thermoacoustic engines by using corrugated stack

The present work considers the heat-driven acoustic characteristics and dynamic thermal-fluid flow fields of a standing-wave thermoacoustic engine (SWTAE) by using sinusoidally shaped corrugated stack surfaces. 3-D numerical SWTAE models are developed and validated, aiming to examine the heat-driven acoustic effects caused by different corrugation amplitudes and wave-lengths of the sinusoidal stack surface. The results demonstrate that corrugated-shaped stack channels increase the contact area of the working gas in the stack area, and the thermos-acoustic conversion is more amplified. Compared to the SWTAE with uniform-shaped stack, the corrugated-shaped stack exhibit enhanced acoustic power output while maintaining a constant acoustic oscillation frequency. With the corrugation peak and wave-length of the sinusoidal stack are 2 and 0.2 mm, respectively, the amplitude and acoustic power of the acoustic pressure oscillations increase by 10.12% and 17.31%, respectively, in comparison with that of the conventional SWTAE. However, when the corrugation peak exceeds 0.4 mm, stronger nonlinear acoustics and flow effects are observed in the stack channels, leading to a reduction in the heat-driven acoustic power output, and thermo-acoustics energy conversion efficiency. The developed model highlights the effects of the corrugated-shaped stack on enhancing acoustic power output and thermo-acoustic conversion efficiency.

Selective enrichment strategy induces ultra-broadband NIR emission in Cr3+-doped multi-phase glass-ceramics for NIR spectroscopy applications

Near-infrared (NIR) spectroscopy has gained widespread application in food analysis, disease diagnosis, fingerprint analysis, and security monitoring. However, the lack of efficient, broadband NIR luminescent materials hinders the full potential of this technology. Here, an ultra-broadband and high-efficiency Cr3+-doped multi-phase glass-ceramics containing MgAl2O4, Al2SiO5, and SiO2 nanocrystals was discovered, which exhibited an ultra-broadband NIR emission (λem ∼ 900 nm) with a full width at half maximum more than 300 nm and a high internal quantum yield of 50.9% under the excitation of 465 nm blue light. Moreover, the integrated emission intensity at 100 °C and 150 °C can keep 88% and 77% of that at room temperature. The ultra-broadband, high efficiency, and thermally robust luminescence of this Cr3+-doped multi-phase glass-ceramics can be attributed to the selective enrichment of Cr3+ ions into different nanocrystals with octahedral sites, and medium electron-photon coupling effect. The NIR glass-ceramics-converted light-emitting diode constructed by the glass-ceramics combined with 465 blue LED chip produced an excellent NIR output and photoelectric conversion efficiency of 274 mW/1007 mW and 3.43%/2.79% at 100 mA/320 mA drive current, which demonstrated superior overall performance to the NIR device built by using the well-known NIR phosphors. Additionally, the NIR camera can capture the image of license plate and nectarine, as well as identify the residual drug content in the bottle under the irradiation of the NIR device constructed by the glass-ceramics. This work not only presented an ultra-broadband and high-efficiency NIR material but also highlights a design strategy to effectively enhance the efficiency and broadband characteristics of NIR glass-ceramics.

Broadband ultrafast ultraviolet laser output by using β-BaB2O4 crystal

In this paper, a broadband ultrafast ultraviolet (UV) laser was generated through sum-frequency method with β-BaB2O4 (BBO) crystal by using a femtosecond (fs) Ti:sapphire laser as the fundamental laser source. We studied the influence of the power ratio between the fundamental frequency and second harmonic laser beams on output power and conversion efficiency of UV laser. The time delay method was used to change the optical path difference in the sum-frequency generation (SFG). At the same time, the cutting angle of the crystal was optimized and the effect of different focal lengths of lenses on the experimental results was studied. Finally, we obtained a tunable UV laser beam with a tuning range from 226.7 nm to 360 nm generated by the BBO crystal. The laser had high conversion efficiency, and the maximum output power was 540 mW at 270 nm.

A skutterudite thermoelectric module with high aspect ratio applied to milliwatt radioisotope thermoelectric generator

This study focuses on the design and optimization of a high aspect ratio skutterudite (SKD) thermoelectric module (TEM) for a milliwatt Radioisotope Thermoelectric Generator (RTG). The RTG is a solid-state energy conversion device that utilizes the heat generated by radioactive isotope decay to generate electrical energy through the Seebeck effect. The aim of this work is to enhance the output performance of the RTG by investigating the influence of TEM structure on temperature distribution and overall performance using thermal resistance network and finite element analysis (FEA) methods. In this work, the RTG's Radioisotope Heater Unit (RHU) and diameter are kept constant as 4 W and 70 mm, while the effects of leg length (L), number of legs (n), and cross-sectional area (A) on voltage, output power, and conversion efficiency are studied. It is observed that increasing L, selecting an appropriate A, and reducing n result in a larger temperature gradient within the TEM, ultimately improving the output power and conversion efficiency of the milliwatt RTG. For A = 0.64 mm2, L = 25 mm, and n = 36, the milliwatt RTG generates maximum output power (Pmax) of 86.95 mW and maximum conversion efficiency (ηrmax) of 2.17%. To optimize the output power and conversion efficiency of the milliwatt RTG while simultaneously assuring the large voltage and manufacturability, a SKD TEM with 64 legs, each with dimensions of 0.8 × 0.8 × 25 mm3, is chosen. The milliwatt RTG installed with this SKD TEM will provide a voltage output (Vout) of 1.13 V, maximum output power (Pmax) of 63.30 mW, and maximum conversion efficiency (ηrmax) of 1.58%. Furthermore, it exhibits excellent environmental adaptability, capable of operating in ambient temperatures (T∞) up to 538 K. The thermal stress distribution in the high aspect ratio SKD TEM is also analyzed. Due to the varying coefficients of thermal expansion (CTE) between the SKD material and the adhesive, the maximum stress within the SKD TEM occurs inside and around the p-SKD legs. Finally, a SKD TEM of 9.9 × 9.9 × 25 mm3 containing 64 legs with each leg's dimension of 0.8 × 0.8 × 25 mm3 is fabricated. It shows an open circuit voltage (Voc) of 3.51 V, a maximum output power (Pmax) of 194.45 mW, and a maximum conversion efficiency (ηtmax) of 3.4% at the hot side temperature (Th) of 723 K and cold side temperature (Tc) of 296 K.

Effects of material doping on the performance of thermoelectric generator with/without equal segments

Thermoelectricity is a clean energy source that has garnered attention worldwide. Improving the performance of thermoelectric devices to convert waste heat into electricity efficiently is currently a priority for many researchers. One way to do this is by improving the thermoelectric performance of the materials used in thermoelectric generators (TEGs). In recent years, doping different materials into thermoelectric materials to enhance TEG's performance has attracted attention. This study analyzes the improvement of TEGs by performing 3D numerical simulations of thermoelectric devices using a series of SnTe with different doping levels. The results show that the undoped SnTe-AgSbSe2 composite has the highest output power compared with the doped case. In terms of conversion efficiency, the composite AgSbSe2 doped with 3% SnTe achieves the highest conversion efficiency. Furthermore, the performance comparison with conventional TEG shows that the equal segmented thermoelectric generator (STEG) has higher output power and conversion efficiency at all doping ratios. In addition, the SnTe-AgSbSe2 composite with 3% doping concentration has the best thermoelectric performance with an output power of 64.49 mW and an efficiency of 14.17% at a temperature difference of 500 K (a hot side temperature of 800 K and a cold side temperature of 300 K). Accordingly, it is summarized that the combination of doped SnTe thermoelectric material and equal-STEG design can efficiently enhance the thermoelectric module's (TEM) performance.