Effect of graphene coating on flow boiling in a minichannel at sub-atmospheric pressures

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Ebrahimpour Ahmadi, Vahid and Güler, Tayfun and Amin, Saifa and Apak, Ahmet Muhtar and Apak, Alper and Parlak, Murat and Tastan, Umur and Kaya, İsmet İnönü and Sadaghiani, Abdolali Khalili and Koşar, Ali (2024) Effect of graphene coating on flow boiling in a minichannel at sub-atmospheric pressures. International Journal of Heat and Mass Transfer, 229 . ISSN 0017-9310

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Abstract

Flow boiling in a mini-channel with graphene-coated sintered porous copper surface was investigated at sub-atmospheric pressures by analyzing bubble motion and flow patterns. A method of surface modification based on graphene coating was presented for thermal management systems operating at lower temperatures. The experiments were carried out at mass fluxes of 60 kg.m–2.s–1 and 120 kg.m–2.s–1 and sub-atmospheric pressures of 48 kPa and 68 kPa in a mini-channel with dimensions of 50 mm × 15 mm × 2 mm using HFE-7100 coolant as the working fluid. At sub-atmospheric pressures, the bubble nucleation site density decreases, and the bubble diameter increases while the bubble release frequency decreases. The existence of porous surfaces and HFE-7100 coolant with lower surface tension leads to the inception of boiling at lower wall superheats. The graphene coating promotes microlayer evaporation and consequently increases the nucleation site density by enhancing the thermal conductivity and wicking rate. Additionally, it provides stable annular flow at high heat fluxes, whereas intermittent-annular flow is observed for the untreated surface under the same condition. This enhancement results in a more pronounced increase in the boiling heat transfer for the graphene-coated surface. As a result, this study provides the high potential of graphene coatings for phase change heat transfer enhancement at sub-atmospheric pressures.
Item Type: Article
Uncontrolled Keywords: Flow boiling; Graphene coatings; Heat transfer enhancement; Minichannels; Sub-atmospheric pressures
Divisions: Faculty of Engineering and Natural Sciences
Sabancı University Nanotechnology Research and Application Center
Depositing User: Ali Koşar
Date Deposited: 06 Jun 2024 23:40
Last Modified: 06 Jun 2024 23:40
URI: https://research.sabanciuniv.edu/id/eprint/49476

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