ENHANCED CONDUCTION AND POOL BOILING HEAT TRANSFER ON SINGLE-LAYER GRAPHENE-COATED SUBSTRATES

R Diaz and ZX Guo, JOURNAL OF ENHANCED HEAT TRANSFER, 26, 127-143 (2019).

DOI: 10.1615/JEnhHeatTransf.2018028488

Molecular dynamics simulations were employed to understand the improved thermal conductivity and water boiling heat transfer characteristics of adding single-layer graphene (SLG) to substrates. The 100, 110, and 111 planes of Cu, Ni, Pt, and Si were selected for study based on common heat transfer and graphene-compatible materials. Vibrational density of states data were analyzed in order to view heat flux trends. After equilibration at 300 K the temperature was increased to 400 K for 3 ns to induce nucleate boiling (similar to 27 K wall superheat). It was found that the addition of SLG greatly improved the overall thermal conductivity of the composite substrate, with increases in the one to two orders of magnitude range. The temperature gradients for SLG-coated substrates were found to be much lower than bare substrates. Nanoscale boiling curves were produced. The CuG100 case shows a 14% increase in critical heat flux (CHF) (similar to 0.36 GW/m(2)) over the Cu100 case, and the PtG100 shows a 9% increase (similar to 0.48 GW / m(2) ) over the Pt100 case. The SLG-coated substrates also required less superheat to achieve the CHF condition.

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