The simulation and analysis of wood fuel low-grade heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

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Efficient Co-Harvesting of Solar Energy and Low-Grade Heat by Molecular Photoswitches for High Energy Density, Long-Term Stable Solar Thermal Battery

10.26434/chemrxiv.9730694 ◽

2019 ◽

Author(s):

Zhao-Yang Zhang ◽

Tao LI

Keyword(s):

Energy Density ◽

Solar Energy ◽

High Performance ◽

High Energy ◽

Solar Thermal ◽

High Energy Density ◽

Low Grade ◽

Thermal Battery ◽

Low Grade Heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

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Thermally regenerative electrochemical cycle for low-grade heat harnessing

Chemical Physics Reviews ◽

10.1063/5.0044616 ◽

2021 ◽

Vol 2 (2) ◽

pp. 021304

Author(s):

Hang Zhang ◽

Qing Wang

Keyword(s):

Low Grade ◽

Low Grade Heat

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Low‐Grade Heat Harvesting: Efficient Low‐Grade Heat Harvesting Enabled by Tuning the Hydration Entropy in an Electrochemical System (Adv. Mater. 13/2021)

Advanced Materials ◽

10.1002/adma.202170096 ◽

2021 ◽

Vol 33 (13) ◽

pp. 2170096

Author(s):

Caitian Gao ◽

Yezhou Liu ◽

Bingbing Chen ◽

Jeonghun Yun ◽

Erxi Feng ◽

...

Keyword(s):

Low Grade ◽

Electrochemical System ◽

Low Grade Heat

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Enhanced Thermoelectric Performance of n-Type Bi2Se3 Nanosheets through Sn Doping

Nanomaterials ◽

10.3390/nano11071827 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1827

Author(s):

Mengyao Li ◽

Yu Zhang ◽

Ting Zhang ◽

Yong Zuo ◽

Ke Xiao ◽

...

Keyword(s):

Figure Of Merit ◽

Cost Effective ◽

Low Grade ◽

Hot Press ◽

Processing Technologies ◽

Sn Doping ◽

Practical Applications ◽

Alternative Materials ◽

The Cost ◽

Low Grade Heat

The cost-effective conversion of low-grade heat into electricity using thermoelectric devices requires developing alternative materials and material processing technologies able to reduce the currently high device manufacturing costs. In this direction, thermoelectric materials that do not rely on rare or toxic elements such as tellurium or lead need to be produced using high-throughput technologies not involving high temperatures and long processes. Bi2Se3 is an obvious possible Te-free alternative to Bi2Te3 for ambient temperature thermoelectric applications, but its performance is still low for practical applications, and additional efforts toward finding proper dopants are required. Here, we report a scalable method to produce Bi2Se3 nanosheets at low synthesis temperatures. We studied the influence of different dopants on the thermoelectric properties of this material. Among the elements tested, we demonstrated that Sn doping resulted in the best performance. Sn incorporation resulted in a significant improvement to the Bi2Se3 Seebeck coefficient and a reduction in the thermal conductivity in the direction of the hot-press axis, resulting in an overall 60% improvement in the thermoelectric figure of merit of Bi2Se3.

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Rolling membrane powered by low-temperature steam as a new approach to generate mechanical energy

Scientific Reports ◽

10.1038/s41598-020-73732-7 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Chongshan Yin ◽

Qicheng Liu ◽

Qing Liu

Keyword(s):

Water Vapor ◽

Low Temperature ◽

Combustion Engine ◽

Mechanical Energy ◽

Heat Energy ◽

Steam Engine ◽

Low Grade ◽

Human Society ◽

New Approach ◽

Low Grade Heat

Abstract How to convert heat energy into other forms of usable energy more efficiently is always crucial for our human society. In traditional heat engines, such as the steam engine and the internal combustion engine, high-grade heat energy can be easily converted into mechanical energy, while a large amount of low-grade heat energy is usually wasted owing to its disadvantage in the temperature level. In this work, for the first time, the generation of mechanical energy from both high- and low-temperature steam is implemented by a hydrophilic polymer membrane. When exposed to water vapor with a temperature ranging from 50 to 100 °C, the membrane repeats rolling from one side to another. In nature, this continuously rolling of membrane is powered by the steam, like a miniaturized “steam engine”. The differential concentration of water vapor (steam) on the two sides of the membrane generates the asymmetric swelling, the curve, and the rolling of the membrane. In particular, results suggest that this membrane based “steam engine” can be powered by the steam with a relatively very low temperature of 50 °C, which indicates a new approach to make use of both the high- and low-temperature heat energy.

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