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Controllable thermal rectification realized in binary phase change composites.

Chen R, Cui Y, Tian H, Yao R, Liu Z, Shu Y, Li C, Yang Y, Ren T, Zhang G, Zou R - Sci Rep (2015)

Bottom Line: Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points.It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic.Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.

ABSTRACT
Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management.

No MeSH data available.


Related in: MedlinePlus

Thermal properties of PCM@rGO aerogel composites.(a) DSC curves of PEG4000 and composite with PEG4000 weight percentage of 97.8%. (b) DSC curves of eicosane and composite with eicosane weight percentage of 97.5%. (c) Thermal conductivities of pure PCMs, recorded across a temperature range of 20 to 64°C. (d) Thermal conductivities of two composites, recorded across a temperature range of 20 to 64°C.
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f2: Thermal properties of PCM@rGO aerogel composites.(a) DSC curves of PEG4000 and composite with PEG4000 weight percentage of 97.8%. (b) DSC curves of eicosane and composite with eicosane weight percentage of 97.5%. (c) Thermal conductivities of pure PCMs, recorded across a temperature range of 20 to 64°C. (d) Thermal conductivities of two composites, recorded across a temperature range of 20 to 64°C.

Mentions: Thermal properties were investigated by Differential Scanning Calorimetry (DSC) and thermal conductivity measurements. Interestingly, the solid-liquid phase transition point of PEG4000@rGO is 6.7°C lower than that of pure PEG4000 (Figure 2a and Table 1), which should be attributed to the fact that the porous rGO aerogel partly interrupts the inherent intermolecular hydrogen bonds and eventuates in a lower crystallinity of PEG4000, while the weak polarity of rGO leads to a weak binding interaction with PEG molecules, and therefore a remarkable phase transition and an enthalpy depression happen36. On the contrary, the eicosane@rGO composite displays a slightly higher phase transition temperature and lower enthalpy depression than those of pure eicosane (Figure 2b and Table 1). It indicates that the crystallinity of eicosane molecules within rGO aerogel has no significant change and the intermolecular interactions between rGO layer and highly dispersed eicosane film have compensated enthalpy depression of eicosane29.


Controllable thermal rectification realized in binary phase change composites.

Chen R, Cui Y, Tian H, Yao R, Liu Z, Shu Y, Li C, Yang Y, Ren T, Zhang G, Zou R - Sci Rep (2015)

Thermal properties of PCM@rGO aerogel composites.(a) DSC curves of PEG4000 and composite with PEG4000 weight percentage of 97.8%. (b) DSC curves of eicosane and composite with eicosane weight percentage of 97.5%. (c) Thermal conductivities of pure PCMs, recorded across a temperature range of 20 to 64°C. (d) Thermal conductivities of two composites, recorded across a temperature range of 20 to 64°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352864&req=5

f2: Thermal properties of PCM@rGO aerogel composites.(a) DSC curves of PEG4000 and composite with PEG4000 weight percentage of 97.8%. (b) DSC curves of eicosane and composite with eicosane weight percentage of 97.5%. (c) Thermal conductivities of pure PCMs, recorded across a temperature range of 20 to 64°C. (d) Thermal conductivities of two composites, recorded across a temperature range of 20 to 64°C.
Mentions: Thermal properties were investigated by Differential Scanning Calorimetry (DSC) and thermal conductivity measurements. Interestingly, the solid-liquid phase transition point of PEG4000@rGO is 6.7°C lower than that of pure PEG4000 (Figure 2a and Table 1), which should be attributed to the fact that the porous rGO aerogel partly interrupts the inherent intermolecular hydrogen bonds and eventuates in a lower crystallinity of PEG4000, while the weak polarity of rGO leads to a weak binding interaction with PEG molecules, and therefore a remarkable phase transition and an enthalpy depression happen36. On the contrary, the eicosane@rGO composite displays a slightly higher phase transition temperature and lower enthalpy depression than those of pure eicosane (Figure 2b and Table 1). It indicates that the crystallinity of eicosane molecules within rGO aerogel has no significant change and the intermolecular interactions between rGO layer and highly dispersed eicosane film have compensated enthalpy depression of eicosane29.

Bottom Line: Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points.It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic.Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.

ABSTRACT
Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management.

No MeSH data available.


Related in: MedlinePlus