Acoustically-enhanced condensation heat recovery in heat exchangers

Two-phase heat transfer by direct-contact condensation can accommodate high heat fluxes in numerous industrial applications. However, coupling this approach to system-level heat transfer, especially for large volumetric flow rates of vapor, is commonly hindered by the development of stratified flows that decrease the contact between the subcooled liquid and vapor phases. The present investigations focus on acoustic enhancement in two-phase heat transfer at short actuation wavelengths (O[1 mm]). It is shown that the actuation enhances direct contact condensation by bulk deformations at vapor-liquid interface and the ejection of subcooled liquid droplets into the vapor volume that increase substantially the contact between phases. These effects are investigated in an adiabatic flow by visualizing droplet production and spreading in gas and separately in condensing stratified flow that demonstrate significant heat transfer enhancement between the liquid and the vapor streams.