Thermophysical properties analysis of graphene-added phase change materials and evaluation of enhanced heat transfer effect in underwater thermal vehicles

2021 ◽  
pp. 118048
Author(s):  
Guohui Wang ◽  
Yanan Yang ◽  
Shuxin Wang
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Transfer Effect ◽  
Enhanced Heat Transfer

Experimental study on enhanced heat transfer of nanocomposite phase change materials

2019 ◽  
Vol 92 (3) ◽  
pp. 285-301 ◽  
Author(s):  
Wei Li ◽  
Yan Dong ◽  
Jun Wang ◽  
Yong Zhang ◽  
Xu Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Phase Change ◽  
Phase Change Materials ◽  
Enhanced Heat Transfer

Phase-Change Nanofluids With Enhanced Thermophysical Properties

2009 ◽  
Author(s):  
Zenghu Han ◽  
Bao Yang ◽  
Yung Y. Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Phase Change ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Effective Heat Capacity ◽  
Heat Transfer Fluids ◽  
Effective Heat ◽  
Indium Nanoparticles

The colloidal dispersion of solid nanoparticles (1–100nm) has been shown experimentally to be an effective way to enhance the thermal conductivity of heat transfer fluids. Moreover, large particles (micrometers to tens of micrometers) of phase-change materials have long been used to make slurries with improved thermal storage capacity. Here, a hybrid concept that uses nanoparticles made of phase-change materials is proposed to simultaneously enhance the effective thermal conductivity and the effective heat capacity of fluids. Water-in-perfluorohexane nanoemulsion fluids and indium-in-polyalphaolefin nanofluids are examples of fluids that have been successfully synthesized for experimental studies of their thermophysical properties (i.e., thermal conductivity, viscosity, and heat capacity) as functions of particle loading and temperature. The thermal conductivity of perfluorohexane was found to increase by up to 52% for nanoemulsion fluids containing 12 vol. % water nanodroplets with a hydrodynamic radius of ∼10 nm. Also observed in water-in-perfluorohexane nanoemulsion fluids was a remarkable improvement in effective heat capacity, about 126% for 12 vol. % water loading, due to the melting-freezing transitions of water nanodroplets to ice nanoparticles and vice versa. The increases in the thermal conductivity and dynamic viscosity of these nanoemulsion fluids were found to be highly nonlinear against water loading, indicating the important roles of the hydrodynamic interaction and the aggregation of nanodroplets. For indium-in-polyalphaolefin nanofluids, the thermal conductivity enhancement increases slightly with increasing temperature (i.e., about 10.7% at 30°C to 12.9% at 90°C) with a nanoparticle loading of 8 vol. %. The effective volumetric heat capacity can be increased by about 20% for the nanofluids containing 8 vol. % indium nanoparticles with an average diameter of 20 nm. Such types of phase-change nanoemulsions and nanofluids possess long-term stability and can be mass produced without using as-prepared nanoparticles. The observed melting-freezing phase transitions of nanoparticles of phase-change materials (i.e., water nanodroplets and indium nanoparticles) considerably augmented the effective heat capacity of the base fluids. The use of phase-change nanoparticles would thus provide a way to substantially enhance the thermal transport properties of conventional heat transfer fluids. Future development of these phase-change nanofluids is expected to open new opportunities for studies of thermal fluids.

scholarly journals Experimental Characterization of Phase Change Materials for Refrigeration Processes

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3033
Author(s):  
Anastasia Stamatiou ◽  
Lukas Müller ◽  
Roger Zimmermann ◽  
Jamie Hillis ◽  
David Oliver ◽  
...  
Keyword(s):  
Energy Density ◽  
Phase Change ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Cost Effective ◽  
Latent Heat Storage ◽  
Lower Energy Density ◽  
Change Material ◽  
Storage Units

Latent heat storage units for refrigeration processes are promising as alternatives to water/glycol-based storage due to their significantly higher energy densities, which would lead to more compact and potentially more cost-effective storages. In this study, important thermophysical properties of five phase change material (PCM) candidates are determined in the temperature range between −22 and −35 °C and their compatibility with relevant metals and polymers is investigated. The goal is to complement existing scattered information in literature and to apply a consistent testing methodology to all PCMs, to enable a more reliable comparison between them. More specifically, the enthalpy of fusion, melting point, density, compatibility with aluminum, copper, polyethylene (PE), polypropylene (PP), neoprene and butyl rubber, are experimentally determined for 1-heptanol, n-decane, propionic acid, NaCl/water mixtures, and Al(NO3)3/water mixtures. The results of the investigations reveal individual strengths and weaknesses of the five candidates. Further, 23.3 wt.% NaCl in water stands out for its very high volumetric energy density and n-decane follows with a lower energy density but better compatibility with surrounding materials and supercooling performance. The importance of using consistent methodologies to determine thermophysical properties when the goal is to compare PCM performance is highlighted.

Natural Convection in an Enclosure With Blend of Micro Encapsulated Phase Change Materials

2013 ◽  
Author(s):  
Yasmin Khakpour ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Thermal Expansion ◽  
Natural Convection ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Pure Water ◽  
Operating Conditions ◽  
Effective Density

This numerical study investigates the effect of using a blend of micro-encapsulated phase change materials (MEPCMs) on the heat transfer characteristics of a liquid in a rectangular enclosure driven by natural convection. A comparison has been made between the cases of using single component MEPCM slurry and a blend of two-component MEPCM slurry. The natural convection is generated by the temperature difference between two vertical walls of the enclosure maintained at constant temperatures. Each of the two phase change materials store latent heat at a specific range of temperatures. During phase change of the PCM, the effective density of the slurry varies. This results in thermal expansion and hence a buoyancy driven flow. The effects of MEPCM concentration in the slurry and changes in the operating conditions such as the wall temperatures compared to that of pure water have been studied. The MEPCM latent heat and the increased volumetric thermal expansion coefficient during phase change of the MEPCM play a major role in this heat transfer augmentation.

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