Fabrication and performance evaluation of the thermoelectric generation and performance measuring system

A novel thennoelectric generating and performance measuring system （TGPMS） was designed and fabricated. TGPMS can not only achieve the function of thennoelectric generation, but also measure the thennoelectric performance parameters of the bismuth-telluride-based thennoelectric device accurately. These thennoelectric performance parameters mainly include the dependence of the Seebeck coefficient of the thennoelectric device on the device＇s temperature in the low temperature range （about 40 ~ 190~C ）, and the dependence of the power output and thermoelectric conversion efficiency on the temperature dif- ference or output load. With the optimum load, the optimal value of the power output is 3.39W when the temperature difference reaches 231.2~C, and the optimal value of the conversion efficiency is 3.22% when the temperature difference reaches 208.9~C. TGPMS provides an experimental foundation for the application of the thennoelectric generators in the space field.

Nanofluidic osmotic power generation from CO_(2) with cellulose membranes

The diffusion of chemical species down concentration gradient is a ubiquitous phenomenon that releases Gibbs free energy.Nanofluidic materials have shown great promise in harvesting the energy from ionic diffusion via the reverse electrodialysis process.In principle,any chemicals that can be converted to ions can be used for nanofluidic power generation.In this work,we demonstrate the power generation from the diffusion of CO_(2) into air using nanofluidic cellulose membranes.By dissolving CO_(2) in water,a power density of 87 mW/m^(2) can be achieved.Using monoethanolamine solutions to dissolve CO_(2),the power density can be increased to 2.6 W/m^(2).We further demonstrate that the waste heat released in industrial and carbon capture processes,can be simultaneously harvested with our nanofluidic membranes,increasing the power density up to 16 W/m^(2) under a temperature difference of 30°C.Therefore,our work should expand the application scope of nanofluidic osmotic power generation and contribute to carbon utilization and capture technologies.

Thermoelectric interface materials:A perspective to the challenge of thermoelectric power generation module

The past years has observed a significantly boost of the thermoelectric materials in the scale of thermoelectric figure-of-merit,i.e.ZT,because of its promising application to harvest the widely distributed waste heat.However,the simplified thermoelectric materials'performance scale also shifted the focus of thermoelectric energy conversion technique from devices-related efforts to materials-level works.As a result,the thermoelectric devices-related works didn't get enough attention.The device-level challenges behind were kept unknown until recent years.However,besides the thermoelectric materials properties,the practical energy conversion efficiency and service life of thermoelectric device is highly determined by assembling process and the contact interface.In this perspective,we are trying to shine some light on the device-level challenge,and give a special focus on the thermoelectric interface materials(TEiM)between the thermoelectric elements and electrode,which is also known as the metallization layer or solder barrier layer.We will go through the technique concerns that determine the scope of the TEiM,including bonding strength,interfacial resistance and stability.Some general working principles are summarized before the discussion of some typical examples of searching proper TEiM for a given thermoelectric conversion material.

Progress and prospects of two-dimensional materials for membrane-based osmotic power generation

The electrical energy that can be harnessed from the salinity difference across the sea water and river water interface can be one of the sustainable and clean energy resources of the future.This energy can be harnessed via the nanofluidic channels that selectively permeate ions.The selective diffusion of cations and anions can produce electricity through reverse electrodialysis.Two-dimensional(2D)materials are a class of nanomaterials that hold great promise in this field.Several breakthrough works have been previously published which demonstrate the high electrical power densities of 2D membranes.The ion transportation can be either through the nano-sized in-plane pores or interlayer spacings of 2D materials.This review article highlights the progress in 2D materials for salinity gradient power generation.Several types of 2D membranes with various nano-architectures are discussed in this review article.These include atom-thick 2D membranes with nanopores,2D lamellar membranes,2D lamellar membranes with nanopores,2D/one-dimensional(1D),and 2D/2D hybrid membranes.The fabrication techniques,physical characteristics,ion transportation properties,and the osmotic power generation of these 2D membranes are elaborated in this review article.Finally,we overview the future research direction in this area.It is envisioned that the research on 2D materials can make practical salinity gradient power generation one step closer to reality.

Cascade utilization of full spectrum solar energy for achieving simultaneous hydrogen production and all-day thermoelectric conversion

Solar-driven photocatalytic water/seawater splitting holds great potential for green hydrogen production.However,the practical application is hindered by the relatively low conversion efficiency resulting from the inadequate utilization of solar spectrum with significant waste in the form of heat.Moreover,current equipment struggles to maintain all-day operation subjected to the lack of light during nighttime.Herein,a novel hybrid system integrating photothermal catalytic(PTC)reactor,thermoelectric generator(TEG),and phase change materials(PCM)was proposed and designed(named as PTC-TEG-PCM)to address these challenges and enable simultaneous overall seawater splitting and 24-hour power generation.The PTC system effectively maintains in an optimal temperature range to maximize photothermal-assisted photocatalytic hydrogen production.The TEG component recycles the low-grade waste heat for power generation,complementing the shortcoming of photocatalytic conversion and achieving cascade utilization of full-spectrum solar energy.Furthermore,exceptional thermal storage capability of PCM allow for the conversion of released heat into electricity during nighttime,contributing significantly to the overall power output and enabling PTC-TEG-PCM to operate for more than 12 h under the actual condition.Compared to traditional PTC system,the overall energy conversion efficiency of the PTC-TEG-PCM system can be increased by∼500%,while maintaining the solar-to-hydrogen efficiency.The advancement of this novel system demonstrated that recycling waste heat from the PTC system and utilizing heat absorption/release capability of PCM for thermoelectric application are effective strategies to improve solar energy conversion.With flexible parameter designing,PTC-TEG-PCM can be applied in various scenarios,offering high efficiency,stability,and sustainability.

Further Stabilization and Power Density Improvement of Stack-Type Thermoelectric Power Generating Module with Biphasic Medium by Using Various Flexible Metals as Electrodes

In order to realize further stability of a stack-type thermoelectric power generating module (i.e. no electrical connections inside), flexible materials of metal springs and/or rods having restoring forces were installed between lower-temperature-sides of thermoelectric elements. These flexible materials were expected to play three important roles of interpolating different thermal expansions of the module components, enlarging heat removal area and penetration of any media through themselves. Then, a low-boiling-point medium (i.e. NOVEC manufactured by 3M Japan Ltd.) was also applied for a high-speed direct heat removal via its phase change from the lower-temperature-sides of the thermoelectric elements in the proposing stack-type thermoelectric power generating module. No electrical disconnections inside the module were confirmed for more than 9 years of use, indicating further module stability. The power generating density was improved to about 120 mW·m-2 with SUS304 springs having 0.7 mm diameter. Increasing power generating density can be expected in terms of suitable selection of flexible metal with high Vickers hardness, cavities control on the spring surface, more vigorous multiphase flow with adding powders to the medium and optimization of the module configurations according to numerical simulations.

A Thermoelectric Generator Manufacture Research Based on Oscillating-Flow Heat Pipe Technology

Oscillating heat pipe is a new type of heat transfer. It not only has simple structure, non-pollution and low maintenance cost, but also has high heat transfer efficiency. Semiconductor thermoelectric generation technology is also an environmental technology. This article combines these two kinds of technology. By means of this generate electricity way, we make a set of system and the related experiment. Then we do some research on the feasibility of this system.

Study on the performance of TEG with heat transfer enhancement using graphene-water nanofluid for a TEG cooling system

Improvement of the heat transfer effect of cold side of a thermoelectric generator(TEG) is one of the approaches to enhance the performance of the TEG systems.As a new type of heat transfer media,nanofluids can enhance the heat transfer performance of working liquid significantly.In this study,the performance of a commercial TEG with graphene-water(GW) nanofluid as coolants in a minichannel heat exchanger is investigated experimentally at low temperatures.The results show that the output power of TEG increases with the flow rate under 950 mL/min.However,the fluid flow rate has no influence on the output power of TEG with higher flow rate(larger than 950 mL/min) when the heat transfer dynamic balance state of the system is reached.The optimal concentration and flow rate of nanofluid are 0.1 wt%and 950 mL/min,respectively.At the optimal conditions,the improved voltage,output power and conversion efficiency with GW nanofluid applied in the cooling system are increased by11.29%,21.55%and 3.5%in comparison with those with only water applied,respectively.

Improving the performance of a thermoelectric power system using a flat-plate heat pipe

A gravitational flat-plate heat pipe is designed and fabricated in this paper to serve as a heat spreader to diffuse the local heat source to the hot side of the thermoelectric power module.Based on this, an experimental test for the thermoelectric power generation system is conducted to study the influences of the heat spreader on the temperature uniformity and power generation performance when exposing to a local heat source.In addition,the effects of the heating power, inclination angle, and local heat source size on the power generation performance of the thermoelectric power module using a flat-plate heat pipe as a heat spreader are examined and compared with that using a metal plate.The results indicate that the gravitational flat-plate heat pipe has considerable advantages over the metal plate in the temperature uniformity.The superiority of temperature uniformity in the improvement of power generation performance for the thermoelectric power system using a heat pipe is demonstrated.Particularly, the heat pipe shows good adaptability to placement mode and the local heat source size, which is beneficial to the application in the thermoelectric power generation.

Photothermal hygroscopic hydrogel for simultaneous generation of clean water and electricity

Harvesting water from the air using adsorbents and obtaining fresh water by solar-driven desorption is considered as one of the most effective ways to solve the freshwater crisis in arid and desert regions.Based on a simple and low-cost photothermal hygroscopic hydrogel,a new strategy is proposed to boost solar energy efficiency by coupling solar-driven atmospheric water harvesting technology with thermoelectric power generation technology in this paper.Photothermal hygroscopic hydrogel ink PAM-CaCl_(2)is prepared by in situ polymerization using Acrylamide as monomer,Ammonium persulfate as thermal initiator and CaCl_(2)as hygroscopic component.During the day,the photothermal hygroscopic hydrogel absorbs solar energy and evaporates its own internal water to obtain fresh water.Simultaneously,the residual waste heat is utilized to power the thermoelectric panel,which produces electricity based on Seebeck effect.At night,the hydrogel harvests water molecules in the air to achieve regeneration.This hybrid system can achieve a water production rate of 0.33 kg m^(-2)h^(-1)and an additional electrical energy gain of 124 mW m^(-2)at 1 kW m^(-2)solar intensity.Theoretical model of the hybrid system is developed to understand the heat flow and thermoelectric generation process.The results provide new insights into energy and freshwater replenishment options in arid or desert areas with abundant solar energy.

Energy Analyses of Thermoelectric Renewable Energy Sources

The recent energy crisis and environmental burden are becoming increasingly urgent and drawing enormous attention to solar-energy utilization. Direct solar thermal power generation technologies, such as, thermoelectric, thermionic, magneto hydrodynamic, and alkali-metal thermoelectric methods, are among the most attractive ways to provide electric energy from solar heat. Direct solar thermal power generation has been an attractive electricity generation technology using a concentrator to gather solar radiation on a heat collector and then directly converting heat to electricity through a thermal electric conversion element. Compared with the traditional indirect solar thermal power technology utilizing a steam-turbine generator, the direct conversion technology can realize the thermal to electricity conversion without the conventional intermediate mechanical conversion process. The power system is, thus, easy to extend, stable to operate, reliable, and silent, making the method especially suitable for some small-scale distributed energy supply areas. Also, at some occasions that have high requirements on system stability, long service life, and noiselessness demand, such as military and deep-space exploration areas, direct solar thermal power generation has very attractive merit in practice. At present, the realistic conversion efficiency of direct solar thermal power technology is still not very high, mainly due to material restriction and inconvenient design. However, from the energy conversion aspect, there is no conventional intermediate mechanical conversion process in direct thermal power conversion, which therefore guarantees the enormous potential of thermal power efficiency when compared with traditional indirect solar thermal power technology [1].

Advances in bismuth-telluride-based thermoelectric devices: Progress and challenges

By effectively converting waste heat into electricity,thermoelectric materials and devices can provide an alternative approach to tackle the energy crisis.Amongst thermoelectric materials,bismuth telluride(Bi_(2)Te_(3))and its derivatives exhibit high figure of merit ZT values in the near-room-temperature region and show great potential for application in thermoelectric devices.Considering the rapid development of Bi_(2)Te_(3)-based thermoelectric materials and their devices in the last few years,a short and systematic review is much needed.Here,we sum-marize the novel designs,properties,and applications of Bi_(2)Te_(3)-based thermoelectric devices in different contexts,including wearable,portable,implantable,and cross-disciplinary applications.The challenges and outlook for Bi_(2)Te_(3)-based thermoelectric devices are also considered.This work will guide the future development of Bi_(2)Te_(3)-based thermoelectric devices that target broader and more practical applications.

Zn_4Sb_3高性能热电材料的制备(英文)

A "reaction-extrusion process" has been developed to prepare Zn4Sb3 bulk materials with high thermoelectric performance.The synthesis,densification,and shape-forming of Zn4Sb3 bulk materials were realized simultaneously in one hot-extrusion process,and the resulting extrudates had high density with single β-Zn4Sb3 phase.A large extrusion ratio and a small punch speed are advantageous to enhance thermoelectric performance.The extruded Zn4Sb3 materials exhibited excellent thermoelectric performance,for example,the dimensionless thermoelectric figure of merit is 1.77 at 623 K,which is 36% higher compared to conventional hot-pressed materials.On the other hand,the incorporation of 1% SiC nanosized particles into Zn4Sb3 matrix leads to improvements in both thermoelectric and mechanical properties.

Thermodynamic analyses and optimization for thermoelectric devices:The state of the arts

Thermoelectric effect is the most efficient way to convert electric energy directly from the temperature gradient. Thermoelectric effect-based power generation, cooling and heating devices are solid-stated, environmentally friendly, reliable, long-lived, easily maintainable, and easy to achieve miniaturization and integration. So they have unparalleled advantages in the aerospace, vehicle industry, waste heat recovery, electronic cooling, etc. This paper reviews the progress in thermodynamic analyses and optimizations for single- and multiple-element, single- and multiple-stage, and combined thermoelectric generators, thermoelectric refrigerators and thermoelectric heat pumps, especially in the aspects of non-equilibrium thermodynamics and finite time thermodynamics. It also discusses the developing trends of thermoelectric devices, such as the heat sources of thermoelectric generators, multi-stage thermoelectric devices, combined thermoelectric devices, and heat transfer enhancement of thermoelectric devices.