Hybrid fluid enhanced pool boiling in the absence of buoyancy assisted bubble departure

Buoyancy induced bubble departure is key to efficient heat transfer during pool boiling. In the absence of bubble departure, such as in microgravity condition, pool boiling heat transfer significantly worsens due to the formation of large dry patch on the heater caused by the coalescence of non-departing bubbles. In this work, we investigate the unexplored potential of hybrid fluids (aqueous alcohol solutions), to enhance pool boiling in the absence of buoyancy assisted bubble departure on a downward-facing heater setup (generally used to mimic boiling in microgravity). Boiling with pure water and aqueous SDS solution was also performed for comparison. Coalescence of non-departing bubbles formed a large dry area on the heater, resulting in substantial deterioration in heat transfer with water. In contrast, aqueous alcohols solutions not only exhibited a large number of non-coalescing bubbles on the heater, due to their foamability, but also resulted in bubble departure in downward direction even against the buoyancy. Consequently, significant enhancement in HTC ( ∼ 3 × ) and CHF ( ∼ 4 × ) is observed as compared to water. We believe, the physical insights presented in this work highlights the untapped potential of aqueous alcohol solutions as working fluid for the design of boiling-based energy systems for earth and microgravity conditions.