TY - JOUR
T1 - Microscopic picture of heat conduction in liquid ethylene glycol by molecular dynamics simulation
T2 - Difference from the monohydric case
AU - Matsubara, Hiroki
AU - Kikugawa, Gota
AU - Ishikiriyama, Mamoru
AU - Yamashita, Seiji
AU - Ohara, Taku
N1 - Funding Information:
This work was supported by the future pioneering program “Research and Development of Thermal Management Materials and Technology” commissioned by the New Energy and Industrial Technology Development Organization (NEDO) of Japan. Numerical simulations were performed on the SGI Altix UV1000 and UV2000 at the Advanced Fluid Information Research Center, Institute of Fluid Science, Tohoku University.
Funding Information:
This work was supported by the future pioneering program “ Research and Development of Thermal Management Materials and Technology ” commissioned by the New Energy and Industrial Technology Development Organization ( NEDO ) of Japan. Numerical simulations were performed on the SGI Altix UV1000 and UV2000 at the Advanced Fluid Information Research Center, Institute of Fluid Science, Tohoku University .
Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/6
Y1 - 2018/6
N2 - The present study investigates the molecular-scale heat transfer in the liquid of ethylene glycol, which is widely used as heat transfer media. First, by combining existing molecular models, we developed a new united atom model of ethylene glycol, and showed that this model reasonably reproduces the experimental thermal conductivity. Using the non-equilibrium molecular dynamics simulations with this model, we characterized the heat transfers due to different kinds of inter- and intramolecular interactions on the basis of a picture that a single pair interaction is a path of heat transfer. These characteristics were compared with those of ethanol (Matsubara et al., 2017) to elucidate the molecular mechanism which realizes an enhanced thermal conductivity because of an additional hydroxylation on ethanol. The results indicate that the thermal conductivity enhancement occurs because the additional heat paths provided by the second hydroxyl group increases the amount of heat conduction owing to all of the van der Waals, Coulomb, and covalent interactions. In particular, the increase in the number of the paths associated with the intermolecular Coulomb interaction between the non-hydrogen bonding hydroxyl groups is prominent and consequently the Coulomb interaction, which is an efficient heat carrier, performs the largest amount of heat conduction in ethylene glycol. Although the second hydroxyl group also increases the number of hydrogen bonds, the direct heat transfer via the hydrogen bonds accounts for only a small portion of the total heat conduction. On the other hand, this augmentation of hydrogen bond, since it keeps a dense molecular packing against the increase in molecular volume, is indispensable in increasing the density of heat paths.
AB - The present study investigates the molecular-scale heat transfer in the liquid of ethylene glycol, which is widely used as heat transfer media. First, by combining existing molecular models, we developed a new united atom model of ethylene glycol, and showed that this model reasonably reproduces the experimental thermal conductivity. Using the non-equilibrium molecular dynamics simulations with this model, we characterized the heat transfers due to different kinds of inter- and intramolecular interactions on the basis of a picture that a single pair interaction is a path of heat transfer. These characteristics were compared with those of ethanol (Matsubara et al., 2017) to elucidate the molecular mechanism which realizes an enhanced thermal conductivity because of an additional hydroxylation on ethanol. The results indicate that the thermal conductivity enhancement occurs because the additional heat paths provided by the second hydroxyl group increases the amount of heat conduction owing to all of the van der Waals, Coulomb, and covalent interactions. In particular, the increase in the number of the paths associated with the intermolecular Coulomb interaction between the non-hydrogen bonding hydroxyl groups is prominent and consequently the Coulomb interaction, which is an efficient heat carrier, performs the largest amount of heat conduction in ethylene glycol. Although the second hydroxyl group also increases the number of hydrogen bonds, the direct heat transfer via the hydrogen bonds accounts for only a small portion of the total heat conduction. On the other hand, this augmentation of hydrogen bond, since it keeps a dense molecular packing against the increase in molecular volume, is indispensable in increasing the density of heat paths.
KW - Associate liquid
KW - Ethylene glycol
KW - Heat conduction
KW - Molecular simulation
KW - Thermal conductivity
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U2 - 10.1016/j.ijheatmasstransfer.2018.01.060
DO - 10.1016/j.ijheatmasstransfer.2018.01.060
M3 - Article
AN - SCOPUS:85041675191
VL - 121
SP - 1033
EP - 1038
JO - International Journal of Heat and Mass Transfer
JF - International Journal of Heat and Mass Transfer
SN - 0017-9310
ER -