scholarly journals Metal-Formate Framework Stiffening and Its Relevance to Phase Transition Mechanism

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6150
Author(s):  
Paulina Peksa ◽  
Justyna Trzmiel ◽  
Maciej Ptak ◽  
Aneta Ciupa-Litwa ◽  
Adam Sieradzki
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Phase Transition Temperature ◽  
Temperature Dependent ◽  
Transition Mechanism ◽  
The Impact ◽  
Ir And Raman ◽  
Metal Formate

In the last decade, one of the most widely examined compounds of motel-organic frameworks was undoubtedly ((CH3)2NH2)(Zn(HCOO)3), but the problem of the importance of framework dynamics in the order–disorder phase change of the mechanism has not been fully clarified. In this study, a combination of temperature-dependent dielectric, calorimetric, IR, and Raman measurements was used to study the impact of ((CH3)2NH2)(Zn(DCOO)3) formate deuteration on the phase transition mechanism in this compound. This deuteration led to the stiffening of the metal-formate framework, which in turn caused an increase in the phase transition temperature by about 5 K. Interestingly, the energetic ordering of DMA+ cations remained unchanged compared to the non-deuterated compound.

Study on the Microstructure and Storage Heat Performance of Mg-25Al-15Zn-xCu Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1104-1108
Author(s):  
Hong Yan Wen ◽  
Xiao Ming Fan ◽  
Xiao Min Cheng
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Optical Microstructure ◽  
Solid Solution Matrix ◽  
And Storage

With the help of optical microstructure(OM), X-ray diffraction(XRD) and differential scanning calorimetry(DSC), the microstructure and storage heat performance of Mg-based phase change thermal storage alloys were investigated.The results show that the microstructure of Mg-25Al-15Zn-xCu (x=0, 2%, 8% and 14%, respectivly) alloys are mainly composed of primary crystal α (Mg) solid solution matrix, β-Mg17Al12, CuZn, MgAl2Cu and Mg32(Al,Zn)49 phases. The phase transition temperature of Mg-25Al-15Zn and Mg-25Al-15Zn-8Cu alloys ​​are 412.1 °C and 405.9 °C respectively; and phase change latent heat values of that were 175.4 J/g and 209.3 J/g. The addition of Cu led to the formation of new phase, reducing the phase transition temperature and increasing the value of phase change latent heat.

Research on Compound and the Best Proportion of Phase Change Materials Using in Clothes

2011 ◽  
Vol 399-401 ◽  
pp. 1596-1599
Author(s):  
Rou Xi Chen ◽  
Yu Chai Sun
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Phase Transition Temperature ◽  
Phase Change Materials ◽  
Eutectic Point ◽  
Eutectic System ◽  
Matlab Software ◽  
Application Fields

The desired phase-transition temperature and enthalpy of phase change materials are different in different application fields. When the composite way is reasonable, the phase-transition temperature and enthalpy of phase change can satisfy the demand of PCMs using in clothes. Based on The theory of eutectic system and the Schroeder Formula, the lowest eutectic point was computed by using MATLAB software in this paper, and then the enthalpy of phase change was also compared in order to get the best proportion of PCMs.

Analysis and Design of a Paraffin/Graphite Composite PCM Integrated in a Thermal Storage Unit

2008 ◽  
Author(s):  
R. Pokhrel ◽  
J. E. Gonza´lez ◽  
T. Hight ◽  
T. Adalsteinsson
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Transition Temperature ◽  
Phase Change ◽  
Specific Heat ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
Thermal Storage ◽  
High Energy ◽  
Melting And Solidification

The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction of storage tanks and maintaining the temperature range of the thermal storage. A Phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter (DSC) and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (i.e., CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, based on the properties obtained in DSC, a numerical simulation for a known volume of CPCM in a water tank was produced and indicated a reduction in solidification time by a factor of six.

scholarly journals Engineering thermoresponsive polyether-based nanogels for temperature dependent skin penetration

2015 ◽  
Vol 6 (32) ◽  
pp. 5827-5831 ◽  
Author(s):  
M. Asadian-Birjand ◽  
J. Bergueiro ◽  
F. Rancan ◽  
J. C. Cuggino ◽  
R.-C. Mutihac ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Human Skin ◽  
Phase Transition Temperature ◽  
Skin Penetration ◽  
Temperature Dependent

Improved skin penetration of thermoresponsive nanogels into human skin at temperatures above the phase-transition temperature.

Analysis and Design of a Paraffin/Graphite Composite PCM Integrated in a Thermal Storage Unit

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
R. Pokhrel ◽  
J. E. González ◽  
T. Hight ◽  
T. Adalsteinsson
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Transition Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Specific Heat ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
Thermal Storage ◽  
Melting And Solidification

The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction in storage tanks and maintaining the temperature range of the thermal storage. A phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature of 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, a numerical simulation and the experimental results for a known volume of CPCM indicated a reduction in solidification time by a factor of 6. The numerical analysis was further explored to indicate the optimum operating Biot number for maximum efficiency of the composite PCM thermal energy storage.

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