Theoretical profile for heat capacity peaks of phase-change materials

2018 ◽  
Author(s):  
Igor Medveď ◽  
Anton Trník
Keyword(s):  
Heat Capacity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Theoretical Profile

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 Preparation and characterization of phase change energy storage gypsum

2020 ◽  
pp. 217-217
Author(s):  
Yichao Zhang ◽  
Ying Wang ◽  
Jinghai Zhou ◽  
Jian Huang ◽  
Xiaoxin Wu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Compressive Strength ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Materials ◽  
Loss Rate ◽  
Thermal Conductivity Coefficient ◽  
Mass Loss Rate ◽  
Capric Acid

The thermophysical properties of binary phase change materials with different ratios of capric acid and palmitic acid were studied by step cooling curve method and differential scanning calorimetry in this paper. Furthermore, the best adsorption materials and coating materials were selected by testing their mass adsorption rate and mass loss rate. Finally, the specific heat capacity, thermal conductivity coefficient and compressive strength of phase change energy storage gypsum (PCESG) was determined respectively, and the energy-saving effect of the PCESG in the wall is evaluated. The results show that the binary phase change materials can form a eutectic system. When the mass ratio of capric acid to palmitic acid is 7:3, the low eutectic point of the binary system is formed, and the crystallization temperature of system is 26?C. The adsorption capacity of expanded perlite is much larger than that of ceramsite, and the mass loss rate of the material coated by styrene acrylic emulsion is lower than that of EVA. The specific heat capacity of PCESG is about twice that of ordinary gypsum. With the addition of phase change materials, the thermal conductivity coefficient of PCESG decreases gradually, and the compressive strength of PCESG decreases gradually at the same time. Compared with ordinary gypsum, PCESG has better energy-saving performance.

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.

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 ◽  
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.

Uncertainty Analysis of Thermal Protection by Microencapsulated Phase Change Micro/Nanoparticles during Hyperthermia

2011 ◽  
Vol 291-294 ◽  
pp. 1816-1819
Author(s):  
Yong Gang Lv ◽  
Yang Zou ◽  
Li Yang
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Protection ◽  
Treatment Protocol ◽  
Lower Phase ◽  
Phase Transition Temperatures ◽  
Protection Efficacy

Uncertainties for thermal protection efficacy caused by deviations of the values of phase change materials (PCMs) properties (including conductivity, heat capacity, thermal conductivity, latent heat and phase transition temperature) were studied based on our previous study. Our results suggested that the radius of the micro/nano PCM particle, and the upper and lower phase transition temperatures of the PCM should be carefully measured before performing thermal protection by PCMs during hyperthermia. The results will further help us to enlarge the application of clinical hyperthermia in cancer treatment and optimize the treatment protocol of thermal protection by PCMs.

Numerical Simulation of Borehole Heat Transfer with Phase Change Material as Grout

2014 ◽  
Vol 577 ◽  
pp. 44-47 ◽  
Author(s):  
Jin Long Wang ◽  
Jing De Zhao ◽  
Ni Liu
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Transfer Characteristic ◽  
Heat Pumps ◽  
Ground Source Heat Pumps ◽  
Numerical Heat Transfer ◽  
Ground Source ◽  
Key Factor

Ground source heat pumps (GSHP) have been widely used in recent years. The heat transfer between borehole heat exchanger (BHE) and earth is the key factor impacting on the performance of GSHP. However, in order to setup BHE, a large amount of area of land is necessary, since the heat capacity of earth is limited. In this paper, phase change materials (PCMs) are used as grout instead of common materials. Thus, the heat capacity of soil has been improved, but the heat transfer characteristic of BHE has also changed. To prove its feasibility, the 3-dimensional numerical heat transfer simulation has been carried for three models which grout are respectively soil, PCMs, and PCMs with heat transfer enhancement measures. The characteristics of heat transfer and the land areas used of the three models are compared. The results show that the land area can be reduced effectively with PCMs as backfilling, while heat transfer enhancements must be adopted because the conductivity of PCM is small.

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