Thermal hysteresis in phase-change materials: Encapsulated metal alloy core-shell microparticles. (September 2018)

• Record Type: Journal Article
• Authors: Hsu, Ting-Heng; Chung, Chieh-Hsuan; Chung, Feng-Ju; Chang, Chun-Che; Lu, Ming-Chang; Chueh, Yu-Lun
• Is Part Of: Nano energy. Volume 51(2018)
• Page Start: 563
• Page End: 570
• Publication Date: 2018-09
• Subjects: Thermal hysteresis -- Core-shell microparticles -- Viscosity -- Phase-change materials; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2018.06.021
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Thermal hysteresis (TH) is defined as the temperature difference between the melting points and crystallization temperatures of phase-change materials (PCMs). The magnitude of the TH is proportional to the energy loss in a system. In addition, the latent heats of the PCMs cannot be exploited if the TH is beyond the operation temperature range of a system. In this study, Zn/TiO2, Zn/Al2 O3, and Zn/SiO2 core-shell microparticles were synthesized and the TH values of the microparticles were examined. The TH for the microparticles was mainly affected by the ramping rate in differential scanning calorimetry, the shell thermal resistance and the required temperature for heterogeneous nucleation. Given that Al2 O3 possesses a superior thermal conductivity than that of TiO2 and SiO2, the Zn/Al2 O3 core-shell microparticles provided the smallest TH among the three types of microparticles. The heat capacity of the salt can be enhanced by 6.7% by doping with 10 wt% Zn/Al2 O3 microparticles while the viscosity increased from 1.3 to 3 cp. The study provided guidelines to modulate the TH of PCMs, and the concept learned from this study can be applied to enhancing the thermal energy storage in various thermal systems. Graphical abstract: Thermal Hysteresis in Phase-Change Materials was investigated based on alloy core-shell microparticles. The TH was found to be affected by the ramping rate in differential scanning calorimetry, the shell thermal resistance and the required temperature for heterogeneous nucleation. The study provided guidelines to modulate the TH of PCMs, and the concept learned from this study can be applied to enhancing the thermal energy storage in various thermal systems. fx1 Highlights: Zn microparticles were successfully encapsulated through sol-gel methods to form Zn/TiO2 and Al2 O3 core-shell microparticles. Thermal Hysteresis (TH) which defined as the difference between the melting and the crystallization temperatures of the microparticles increased with increasing shell thickness and ramping rate. The effective heat capacity of the salt can be increased by 6.7 % by doping with 10 wt. % Zn/Al2 O3 core-shell microparticles while the viscosity of the salt increased from 1.3 to 3 cp. The developed technique was also applied to encapsulate an Al2 O3 shell on the ZnSn alloy microparticles. The TH of the ZnSn/Al2 O3 was substantially reduced compared to the TH of theZnSn/SiO­2 alloy microparticles.