scholarly journals Microencapsulated Phase Change Material Suspension for Cold Start of PEMFC

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1514
Author(s):  
Sitong Chen ◽  
Shubo Wang ◽  
Xueke Wang ◽  
Weiwei Li ◽  
Baorui Liang ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Phase Change ◽  
Specific Heat ◽  
Latent Heat ◽  
Specific Heat Capacity ◽  
Proton Exchange Membrane ◽  
Phase Change Materials ◽  
Chemical Properties ◽  
Cold Start ◽  
Proton Exchange

We added microencapsulated phase change materials (MPCMs) into the homemade antifreeze fluid to take advantage of the latent heat of phase change materials, and explored the possibility of solving the cold start problem of proton exchange membrane fuel cells (PEMFC) with variable specific heat capacity antifreeze. The physical and chemical properties of the MPCMs and their suspensions were tested, and a PEMFC platform for cold start with a thermal management system was established to compare the exothermic performance of MPCS and commercial antifreeze fluid. According to the output voltage, temperature and polarization curves before and after cold start, the MPCMs has a stronger heat transfer capacity than the commercial antifreeze fluid, and the addition of MPCMs can transform the latent heat generated during the phase transition into apparent specific heat capacity, leading to a better solution to the problem of PEMFC cold start.

Thermal Analysis of Phase Change Material Based Heat Transfer Fluid in Solar Thermal Collector

2020 ◽  
Author(s):  
Tyler J. E. O’Neil ◽  
Celine S. L. Lim ◽  
Sarvenaz Sobhansarbandi
Keyword(s):  
Heat Capacity ◽  
Phase Change ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Phase Change Materials ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Liquid Form ◽  
High Specific Heat ◽  
Multi Walled Carbon Nanotubes

Abstract Phase change materials (PCMs) are commonly used as energy storage mediums in solar thermal systems. This paper investigates the mixture of PCM doped with nanoparticles to be used as HTFs directly integrated in a U-pipe ETC to be applied in solar thermal collectors. The selected type of PCM-HTF in this study is erythritol (C4H10O4), with high specific heat capacity in liquid form, as well as its unique sub-cooling behavior. In order to overcome the low thermal conductivity of erythritol and further enhance specific heat capacity, a weight concentration of 1% multi-walled carbon nanotubes (MWCNT) is added. Additionally, to insure even distribution of MWCNT and consistent properties of the HTF, triethanolamine (TEA) is proposed to be incorporated as a dispersant. The samples were each tested in a Thermogravimetric Analyzer (TGA) and Differential Scanning Calorimeter (DSC) to analyze their thermal properties. The results from the DSC tests show 12.4% enhancement of specific heat capacity of the proposed HTF mixture as well as nearly 5° C depression of freezing onset temperature. This study allows for the optimization of the operating temperature range of the collector when integrated with these materials, where direct heat gain can be obtained in the collector.

scholarly journals Determination of effective specific heat capacity of interior plaster containing phase change materials

2019 ◽  
Vol 282 ◽  
pp. 02052
Author(s):  
Václav Kočí ◽  
Jiří Maděra ◽  
Robert Černý
Keyword(s):  
Heat Capacity ◽  
Phase Change ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Building Materials ◽  
Phase Change Materials ◽  
Calorimetric Data ◽  
Thermal Oscillation ◽  
Effective Specific Heat

A precise technique for determination of effective specific heat capacity of building materials is presented within this paper. The applicability of the technique is demonstrated on a PCM-enhanced plaster, being characterized by a phase change between 15 and 30 °C. The effective specific heat capacity is determined by means of inverse analysis of calorimetric data using computational model of the device. The identified effective specific heat capacity values reached up to 1890 J·kg-1·K-1 when cooled and 1580 J·kg-1·K-1 when heated. Using this quantity in simulation of thermal performance, the PCM-enhanced plaster showed to have a promising potential to be used in buildings’ interiors as a thermal regulator to stabilize inner environment as it contributed to a thermal oscillation decrease by up to 2.5 °C

Synthesis and Characterization of Solid State Phase Change Material Microcapsules for Thermal Management Applications

2013 ◽  
Author(s):  
Fangyu Cao ◽  
Jing Ye ◽  
Bao Yang
Keyword(s):  
Heat Capacity ◽  
Solid State ◽  
Phase Change ◽  
Thermal Management ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Silica Shell ◽  
Heat Transfer Fluid ◽  
Change Behavior

Polyalcohols such as neopentyl glycol (NPG) undergo solid-state crystal transformations that absorb/release sufficient latent heat. These solid-solid phase change materials (PCM) can be used in practical thermal management applications without concerns about liquid leakage and thermal expansion during phase transition. In this paper, microcapsules of NPG encapsulated in silica shell were successfully synthesized with the use of the emulsion technique. The size of the microcapsules was in the range of 0.2–4 μm, and the thickness of the silica shell was about 30 nm. It was found that the endothermic event of the phase change behavior of these NPG-silica microcapsules was initiated at around 39 °C and the latent heat was about 96.0 J/g. A large supercooling of about 43.3 °C was observed in the pure NPG particles without shell. The supercooling of the NPG microcapsules can be reduced to about 14 °C due to the heterogeneous nucleation sites provided by the silica shell. These NPG microcapsules were added into heat transfer fluid PAO to enhance its heat capacity. The effective heat capacity of the fluids can be increased by 56% by adding 20 wt. % NPG-silica microcapsules.

Synthesis and Characterization of Solid-State Phase Change Material Microcapsules for Thermal Management Applications

2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Fangyu Cao ◽  
Jing Ye ◽  
Bao Yang
Keyword(s):  
Heat Capacity ◽  
Solid State ◽  
Phase Change ◽  
Thermal Management ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Silica Shell ◽  
Heat Transfer Fluid ◽  
Nucleation Sites

Polyalcohols such as neopentyl glycol (NPG) undergo solid-state crystal transformations that absorb/release significant latent heat. These solid–solid phase change materials (PCM) can be used in practical thermal management applications without concerns about liquid leakage and thermal expansion during phase transitions. In this paper, microcapsules of NPG encapsulated in silica shells were successfully synthesized with the use of emulsion techniques. The size of the microcapsules range from 0.2 to 4 μm, and the thickness of the silica shell is about 30 nm. It was found that the endothermic phase transition of these NPG-silica microcapsules was initiated at around 39 °C and the latent heat was about 96.0 J/g. A large supercooling of about 43.3 °C was observed in the pure NPG particles without shells, while the supercooling of the NPG microcapsules was reduced to about 14 °C due to the heterogeneous nucleation sites provided by the silica shell. These NPG microcapsules were added to the heat transfer fluid PAO to enhance its heat capacity and the effective heat capacity of the fluid was increased by 56% with the addition of 20 wt. % NPG-silica microcapsules.

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