Solar-and/or Radiative Cooling-Driven Thermoelectric Generators:A Critical Review

Thermoelectric generators(TEGs)play a critical role in collecting renewable energy fromthe sun and deep space to generate clean electricity.With their environmentally friendly,reliable,and noise-free operation,TEGs offer diverse applications,including areas with limited power infrastructure,microelectronic devices,and wearable technology.The review thoroughly analyses TEG system configurations,performance,and applications driven by solar and/or radiative cooling,covering non-concentrating,concentrating,radiative cooling-driven,and dual-mode TEGs.Materials for solar absorbers and radiative coolers,simulation techniques,energy storage management,and thermal management strategies are explored.The integration of TEGs with combined heat and power systems is identified as a promising application.Additionally,TEGs hold potential as charging sources for electronic devices.This comprehensive review provides valuable insights into this energy collection approach,facilitating improved efficiency,reduced costs,and expanded applications.It also highlights current limitations and knowledge gaps,emphasizing the importance of further research and development in unlocking the full potential of TEGs for a sustainable and efficient energy future.

Thermoelectric Stirling Engine (TEG-Stirling Engine) Based on the Analysis of Thermomechanical Dynamics (TMD)

The thermoelectric energy conversion technique by employing the Disk-Magnet Electromagnetic Induction (DM-EMI) is examined in detail, and possible applications to heat engines as one of the energy-harvesting technologies are discussed. The idea is induced by the analysis of thermomechanical dynamics (TMD) for a nonequilibrium irreversible thermodynamic system of heat engines, such as a drinking bird and a low temperature Stirling engine, resulting in thermoelectric energy generation different from conventional heat engines. The current thermoelectric energy conversion with DM-EMI can be applied to wide ranges of machines and temperature differences. The mechanism of DM-EMI energy converter is categorized as the axial flux generator (AFG), which is the reason why the technology is applicable to sensitive thermoelectric conversions. On the other hand, almost all the conventional turbines use the radius flux generator to extract huge electric power, which uses the radial flux generator (RFG). The axial flux generator is helpful for a low mechanoelectric energy conversion and activations of waste heat from macroscopic energy generators such as wind, geothermal, thermal, nuclear power plants and heat-dissipation lines. The technique of DM-EMI will contribute to solving environmental problems to maintain clean and sustainable energy as one of the energy harvesting technologies.

Waste Heat Recovery from a Drier Receiver of an A/C Unit Using Thermoelectric Generators

Thermoelectric generators(TEGs)are considered promising devices for waste heat recovery from various systems.The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer receiver(FDR)of an air conditioning(A/C)system,which would otherwise go to waste.The study aims to build a set of thermoelectric generators(TEG)to collect the waste heat of the FDR and generate low-power electricity.A novel electrical circuit with two transformers is designed and fabricated to produce a more stable voltage for operation and charging.The thermoelectric generator(TEGs)was installed on the FDR of the A/C unit.The test showed that climate conditions have a significant impact on the output power generated from the system.The results showed that the peak voltage recorded in the current study is 5.2 V per day(wet,cold,and wind weather)with an output power of 0.2 W.These values are acceptable for powering the load and charging a single battery with 3.5 V as the voltage increases battery 0.1 V/20 min charge.A case study of operating the emergency signs in a building was considered.The current heat recovery system is deemed to be easily installed and can be connected to a network of TEGs to produce more power.

Thermoelectric generators and their applications:Progress,challenges,and future prospects

Our community currently deals with issues such as rising electricity costs,pollution,and global warming.Scientists work to improve energy harvesting-based power generators in order to reduce their impacts.The Seebeck effect has been used to illustrate the capacity of thermoelectric generators(TEGs)to directly convert thermal energy to electrical energy.They are also ecologically beneficial since they do not include chemical products,function quietly because they lack mechanical structures and/or moving components,and may be built using different fabrication technologies such as three-dimentional(3D)printing,silicon technology,and screen printing,etc.TEGs are also position-independent and have a long operational lifetime.TEGs can be integrated into bulk and flexible devices.This review gives further investigation of TEGs,beginning with a full discussion of their operating principle,kinds,materials utilized,figure of merit,and improvement approaches,which include various thermoelectric material arrangements and utilised technologies.This paper also discusses the use of TEGs in a variety of disciplines such as automobile and biomedical.

The Method of Thermoelectric Energy Generations Based on the Axial and Radial Flux Electromagnetic Inductions*

The traditional thermoelectric energy conversion techniques are explained in detail in terms of the axial flux electromagnetic (AFE) and the radial flux electromagnetic (RFE) inductions, and applications to heat engines for the energy-harvesting technologies are discussed. The idea is induced by the analysis of thermomechanical dynamics (TMD) for a nonequilibrium irreversible thermodynamic system of heat engines (a drinking bird, a low temperature Stirling engine), resulting in thermoelectric energy generation different from conventional heat engines. The mechanism of thermoelectric energy conversion can be categorized as the axial flux generator (AFG) and the radial flux generator (RFG). The axial flux generator is helpful for low mechanoelectric energy conversion and activations of waste heat from macroscopic energy generators, such as wind, geothermal, thermal, nuclear power plants and heat-dissipation lines, and the device contributes to solving environmental problems to maintain clean and sustainable energy as one of the energy harvesting technologies.

The Application of Thermomechanical Dynamics (TMD) to Thermoelectric Energy Generation by Employing a Low Temperature Stirling Engine

A thermoelectric generation Stirling engine (TEG-Stirling engine) is discussed by employing a low temperature Stirling engine and the dissipative equation of motion derived from the method of thermomechanical dynamics (TMD). The results and mechanism of axial flux electromagnetic induction (AF-EMI) are applied to a low temperature Stirling engine, resulting in a TEG-Stirling engine. The method of TMD produced thermodynamically consistent and time-dependent physical quantities for the first time, such as internal energy ℰ(t), thermodynamic work Wth(t), the total entropy (heat dissipation) Qd(t)and measure or temperature of a nonequilibrium state T˜(t). The TMD analysis produced a lightweight mechanical system of TEG-Stirling engine which derives electric power from waste heat of temperature (40˚CT100˚C) by a thermoelectric conversion method. An optimal low rotational speed about 30θ′(t)/(2π)60(rpm) is found, applicable to devices for sustainable, clean energy technologies. The stability of a thermal state and angular rotations of TEG-Stirling engine are specifically shown by employing properties of nonequilibrium temperature T˜(t), which is also applied to study optimal fuel-injection and combustion timings of heat engines.

Textile-Based Thermoelectric Generators and Their Applications

With the rapid development of Internet of Things and miniaturized electronics, the demand for wearable power sources with high reliability and long duty cycle promotes the exploration of wearable thermoelectric generators(TEGs). In particular, textile-based TEGs that can perpetually convert the ubiquitous temperature gradient between human body and ambience into electrical energy have attracted intensive attention to date.These lightweight and three-dimensional deformable TEGs comprised of fibers, filaments, yarns, or fabrics offer unique merits as wearable power source in comparison with conventional TEGs. In this review, we systematically summarize the state-of-the-art strategies for textile-based TEGs, including the structure design, fabrication, device performance, and application. Existing critical issues and future research emphasis are also discussed.

State-of-the-art review of MPPT techniques for hybrid PV-TEG systems:modeling,methodologies,and perspectives

The development of alternative renewable energy technologies is crucial for alleviating climate change and promoting energy transformation.Of the currently available technologies,solar energy has promising application prospects owing to its merits of being clean,safe,and sustainable.Solar energy is converted into electricity through photovoltaic(PV)cells;however,the overall conversion efficiency of PV modules is relatively low,and most of the captured solar energy is dissipated in the form of heat.This not only reduces the power generation efficiency of solar cells but may also have a negative impact on the electrical parameters of PV modules and the service life of PV cells.To overcome the shortcomings,an efficient approach involves combining a PV cell with a thermoelectric generator(TEG)to form hybrid PV-TEG systems,which simultaneously improve the energy conversion efficiency of the PV system by reducing the operating temperature of the PV modules and increasing the power output by utilizing the waste heat generated from the PV system to generate electricity via the TEGs.Based on a thorough examination of the literature,this study comprehensively reviews 14 maximum power point tracking(MPPT)algorithms currently applied to hybrid PV-TEG systems and classifies them into five major categories for further discussion,namely conventional,mathematics-based,metaheuristic,artificial intelligence,and other algorithms.This review aims to inspire advanced ideas and research on MPPT algorithms for hybrid PV-TEG systems.

Water-resistant organic thermoelectric generator with >10μW output

Flexible p–n thermoelectric generator(TEG)technology has rapidly advanced with power enhancement and size reduction.To achieve a stable power supply and highly efficient energy conversion,absolute chemical stability of n-type materials is essential to ensuring large temperature differences between device terminals and ambient stability.With the aim of improving the long-term stability of the n-type operation of carbon nanotubes(CNTs)in air and water,this study uses cationic surfactants,such as octylene-1,8-bis(dimethyldodecylammonium bromide)(12-8-12),a gemini surfactant,to stabilize the nanotubes in a coating,which retains the n-doped state for more than 28 days after exposure to air and water in experiments.TEGs with 10 p-n units of 12-8-12/CNT(n-type)and sodium dodecylbenzene sulfonate/CNT(p-type)layers are manufactured,and their water stability is evaluated.The initial maximum output of 16.1μW(75 K temperature difference)is retained after water immersion for 40 days without using a sealant to prevent TEG module degradation.The excellent stability of these CNT-based TEGs makes them suitable for underwater applications,such as battery-free health monitoring and information gathering systems,and facilitates the development of soft electronics.

Powering a Low Power Wireless Sensor in a Harsh Industrial Environment: Energy Recovery with a Thermoelectric Generator and Storage on Supercapacitors

Wireless sensor networks are widely used for monitoring in remote areas. They mainly consist of wireless sensor nodes, which are usually powered by batteries with limited capacity, but are expected to last for long periods of time. To overcome these limitations and achieve perpetual autonomy, an energy harvesting technique using a thermoelectric generator (TEG) coupled with storage on supercapacitors is proposed. The originality of the work lies in the presentation of a maintenance-free, robust, and tested solution, well adapted to a harsh industrial context with a permanent temperature gradient. The harvesting part, which is attached to the hot spot in a few seconds using magnets, can withstand temperatures of 200°C. The storage unit, which contains the electronics and supercapacitors, operates at temperatures of up to 80°C. More specifically, this article describes the final design of a 3.3 V 60 mA battery-free power supply. An analysis of the thermal potential and the electrical power that can be recovered is presented, followed by the design of the main electronic stages: energy recovery using a BQ25504, storage on supercapacitors and finally shaping the output voltage with a boost (TPS610995) followed by an LDO (TPS71533).

基于人工蜂群算法的温差发电阵列最优重构方法

在新能源发电技术快速发展的背景下,温差发电(TEG)技术能够很好地利用新能源发电中产生的废热.然而,温度分布的变化会使得TEG阵列的输出特性恶化、发电效率降低.提出基于人工蜂群(ABC)算法的TEG阵列重构方法,在3种不同温度分布情况下,利用ABC在对称9×9和不对称10×15两种TEG阵列进行动态重构.将所提算法与遗传算法、粒子群优化算法和秃鹰搜索优化算法3种启发式算法作对比,并给出由ABC重构后的TEG阵列温度分布图.结果表明:ABC能够提高TEG阵列的输出功率,输出功率-电压曲线均趋向呈现出单个峰值.此外,利用基于RTLAB平台上的硬件在环实验验证了硬件可行性.

温差发电协同储能元件驱动LED车灯的响应特性

为实现低品位能源的高效利用,构建了基于温差发电的余热回收系统将余热转化为电能,用以驱动发光二极管(light emitting diodes,LED)车灯点亮.利用恒温加热炉模拟热源,探究了余热回收系统在不同阶段能量转化和驱动LED车灯的响应特性.在实际应用中,研究了储能元件独立驱动LED车灯时光输出特性的变化规律.结果表明:储能元件可以存储回收余热所转化的电能,并独立驱动LED车灯工作,还能缓冲温度变化引起的电压波动;锂电池的能量密度高,可储存更多电能,独立驱动LED车灯时冷启动速度快,点亮时间更长,但充满电所需时间也较长;超级电容冷启动速度慢,但充放电速度较快,有助于余热回收系统短时间工作时缓解LED车灯的驱动电压波动.

汽车尾气温差发电系统瞬态回收性能分析

为了预测温差发电(thermoelectric generator, TEG)系统的动态特性,基于COMSOL Multiphy-sics建立了用于求解温差发电系统温度场分布的瞬态计算流体力学(computational fluid dynamics, CFD)模型和用于研究温差发电模块瞬态响应特性的分析模型,提出了混合瞬态CFD-分析模型,并经过瞬态试验验证.结果表明:由于热惯性的影响,TEG系统的转化效率会出现一个瞬时的较高值;相较于尾气温度和质量流量的瞬态波动,热电半导体的热端温度和冷端温度会存在时滞;在美国环保局的高速公路燃油经济性测试(highway fuel economy test, HWFET)模式循环工况下,瞬态模型求解得到整个温差发电系统的平均输出功率、平均转化效率分别为35.63 W和3.40%,瞬态模型的输出电压平均误差为6.41%;该模型能够以较高的精度及较短的计算时间预测温差发电系统在瞬态热源激励下的瞬态响应特性.

热电发电技术回收工业余热分析

工业余热资源形式多样且总量巨大,节能潜力可观。利用热电发电技术将工业余热资源转化为电能,既能提升能源利用率又可以降低热污染,是实现双碳目标的重要技术途径。介绍了工业中不同类型余热的分布占比情况和热电发电的基本原理,重点对热电发电技术在工业领域中的应用研究进展进行了综述,并针对热电发电技术以及该技术在工业应用中存在的一些问题进行了分析、总结和展望。

应用于光纤传感网络的热电发生器设计与研究

研制并测试了用于光纤海底地震传感网络节点的热电能量收集系统。基于碲化铋热电材料,制作了用于光纤传感器的热电发生器(TEG),建立了热电模型并进行了验证。提出了一种将TEG输出的能量收集并利用的能量管理电路。详细介绍了该系统的设计思想、电路原理图和模拟水下环境实验。实验数据表明:所制作的TEG能够以2.67%的效率将热能直接转换成电能,设计的能量管理电路能够以23.09%的效率将电能收集并利用。该研究结果对延长光纤海底节点工作时间、增加系统可靠性有重要意义。

10 kW低浓铀月表反应堆电源系统概念设计与分析

针对未来月球科研站所面临的能源需求问题,提出一种采用低浓化U-Mo合金燃料和热管冷却的月球表面反应堆电源系统的新型概念设计。低浓化U-Mo合金燃料技术成熟,在RERTR项目中被作为主要燃料而得到广泛使用。采用低浓化U-Mo合金燃料,能够有效降低核扩散的风险和简化相关部门的监管流程。反应堆的额定热功率为180 kW,输出电功率≥10 kW,设计寿命为10年。反应堆为Na热管冷却的快中子反应堆,采用控制鼓对堆芯反应性进行控制,堆芯热量通过Na热管传递到半Heusler型温差发电模块,废热由Hg热管辐射器翅片辐射到太空。基于蒙特卡洛程序RMC和CFD软件对反应堆堆芯物理及热工进行了初步计算和分析,针对温差发电器件的热电转换性能进行了优化设计,对热管失效等假想事故进行了分析评价。结果表明,该反应堆设计能够满足中子物理设计和临界安全的要求,在稳态工况下温差发电器件的热电转换效率能够达到7.60%,系统能够有效输出≥10 kW电功率,热管级联失效时能够满足热工安全要求。

不同温比下自由活塞斯特林发电机的数值研究

为提高自由活塞斯特林动力系统的输出功率和热电转换效率,通过Sage软件对斯特林机的关键参数进行模拟研究,探讨关键参数在不同温比下对发电机输出功率和热电转换效率的影响。研究结果表明在不同温比下,相位角分别为80°和50°时对应输出功率和热电转换效率最高,充气压力的增大对输出功率的增大效果显著,但对热电转换效率的影响较小;同温比下,提高冷端温度对输出功率和热电转换效率的影响大于提高热端温度的影响,但当温比为2.5时,冷端温度高于430 K后,热电转换效率反而降低。

基于SKD-HH分段级联器件与GPHS的RTG输出性能计算

Pu-238放射性同位素温差发电器(RTG)在深空探测中具有广泛应用。基于先进热电材料CoSb_(3)填充方钴矿和半赫斯勒材料,设计了六π对构型分段级联器件。在此基础上,结合通用模块化热源GPHS,设计了一种面向深空应用的80 W级RTG,采用有限元软件Ansys计算了其在深空环境温度下的电性能输出和温度分布。该RTG最大输出功率80.3 W,转换效率8.36%,设计转换效率达到了美国eMMRTG的水平。

汽车温差发电系统的多物理场建模与对比

为了获取实际行驶工况下汽车温差发电系统的瞬态响应特性,提出瞬态流-热-电多物理场耦合模型、混合瞬态CFD-TE数值模型和混合瞬态CFD-分析模型3种瞬态理论模型;以瞬态工况下的尾气温度和质量流量作为边界条件,使用COMSOL软件完成模型的瞬态仿真求解,并对比分析不同模型预测的输出响应特性;搭建系统瞬态试验台架,验证模型的准确性。结果表明:输出功率的响应特性与尾气温度的变化有关,且显示出较大的热惯性,而转换效率的响应特性主要与尾气质量流量的变化有关;瞬态流-热-电多物理场耦合模型、混合瞬态CFD-TE和CFD-分析模型与试验结果之间的输出电压平均误差分别为7.99%、25.96%和21.05%。

立体平板热管强化温差发电性能的实验研究

为提升温差发电装置的发电效率,提出了一种立体平板热管强化性能方法,通过实验对比评估了2种充液率对该立体平板热管均热性能的影响,探究了不同温差下温差发电系统的最大输出功率和发电效率。结果表明:充液率为27.4%时立体平板热管启动过程为分段启动,且温度分层现象明显;充液率为31.7%时立体平板热管可在40℃左右时迅速启动,启动后温度分布均匀性和一致性较好,有利于温差发电系统持续稳定高效发电;基于立体平板热管强化的温差发电系统的最大输出功率和发电效率均随着冷热端温差的增大而增大,且温差发电效率最高可达3.99%。