Evaluation of Phase Change Materials for Personal Cooling Applications

Copper foam is widely used in industrial catalysis, flow boiling, and latent heat storage systems. It is expected that a multi-level topology copper foam with micro/nanostructures can further enhance performance. In this study, an electrochemically patterned copper foam with micro/nanostructures was fabricated and used to reduce supercooling in water-based cool storage phase-change materials. By controlling the reaction time (e.g., 195 s, 255 s, and 300 s), the pattern on the copper foam skeleton appeared as granular, dendritic, and coral-like structures, respectively. Compared with a blank group with supercooling of 11 °C during the solidification process, the unmodified copper foam (CF#0s) can reduce it to 7.7 °C. Electrodeposition-patterned copper foam with micro/nanostructures can further reduce supercooling. The average supercooling degree for CF#195s, CF#255s, and CF#300s was further reduced to 5.6 °C, 4.8 °C, and 4.6 °C, respectively. Among them, CF#300s reduced the supercooling and delay time by 60%. This occurred because the micro-nanostructure on the skeleton of copper foam provides abundant nucleation sites for the solidification of water, and surface roughness increases the nucleation rate.

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Experimental Study on the Efficacy of a Novel Personal Cooling Vest Incorporated with Phase Change Materials and Fans

Materials ◽

10.3390/ma13081801 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1801 ◽

Cited By ~ 1

Author(s):

Xiaoyang Ni ◽

Tianyu Yao ◽

Ying Zhang ◽

Yijie Zhao ◽

Qin Hu ◽

...

Keyword(s):

Phase Change ◽

Phase Change Materials ◽

Energy Savings ◽

Thermal Sensation ◽

Humid Climate ◽

Physiological Strain ◽

Human Trials ◽

High Level ◽

Hot Humid Climate ◽

Personal Cooling

In recent years, personal cooling has aroused much attention because it can achieve both localized high-level thermal comfort and build energy savings. In this study, a novel hybrid personal cooling vest (PCV) incorporated with phase change materials (PCMs) and ventilation fans was developed, and its efficacy was investigated by human trials in a hot-humid climate chamber. Three generally accepted indices (thermal load, Q; thermal sensation, TS; and physiological strain index, PSI) and a new proposed index (cumulative heat storage, CHS) during human trials were comparatively studied between the two human trial groups, i.e., the PCV group (wearing the PCV) and the CON group (without PCV). Results found that TS, PSI, and CHS were significantly reduced by the PCV, which suggests that the PCV can significantly improve both the perceptual and physiological strain. In addition, a strong linear relationship (r2 = 0.8407) was found between the proposed index of CHS with PSI, which indicates the applicability and reliability of CHS for assessing physiological heat strain.

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Cooling Capacity Figure of Merit for Phase Change Materials

Journal of Heat Transfer ◽

10.1115/1.4031252 ◽

2015 ◽

Vol 138 (2) ◽

Cited By ~ 29

Author(s):

Patrick J. Shamberger

Keyword(s):

Phase Change ◽

Figure Of Merit ◽

Phase Change Materials ◽

Surrounding Medium ◽

High Heat ◽

Cooling Capacity ◽

High Heat Flux ◽

Two Phase ◽

Fixed Temperature ◽

Design And Optimization

In this paper, a figure of merit for the cooling capacity (FOMq) of phase change materials (PCMs) is defined from the analytical solution of the two-phase Neumann–Stefan problem of melting of a semi-infinite material with a fixed temperature boundary condition (BC). This figure of merit is a function of the thermophysical properties of a PCM and is proportional to the heat transfer across the interface with the surrounding medium in this general case. Thus, it has important implications for design and optimization of PCMs for high heat-flux thermal management applications. FOMq of example low melting point metals are presented which exceed those in common nonmetallic PCMs over the same temperature range by over an order of magnitude.

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