This work focuses on nucleate boiling performance improvement in high heat flux regions on structured surfaces. For this purpose, we present the development of a structured surface featuring poorly and highly wettable areas on copper substrates and capillary structured surfaces on copper and aluminum substrates. Surface engineering is achieved through the employment of chemical etching, laser texturing, and hydrophobization process. Boiling performance on engineered surfaces was evaluated using double distilled water under saturated conditions at atmospheric pressure. Capillary-engineered surfaces exhibited critical heat flux (CHF) values of up to 2609 kW m-2 (> 130 % enhancement over the reference surface) and heat transfer coefficients (HTC) of up to 242 kW m-2 K-1 (> 550 % enhancement). We also demonstrated that the appropriate surface pattern of poorly wettable regions for achieving exceptional boiling performance on superbiphilic surfaces (> 400% enhancement) may also depend on the heat flux at which the surface will operate. Moreover, this work also presents the evaluation of CHF scatter's origin performing 125 experimental runs on 25 nominally identical bare copper surfaces. We established an average boiling curve and mean CHF value, where despite consistent experimental conditions significant scattering in CHF was observed.
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