Development of cavitation in refrigerant (R-123) flow inside rudimentary microfluidic systems

The existence of hydrodynamic cavitation in the flow of refrigerant (R-123) through micro-Venturis has been viewed in the form of a bubbly cavitating regime. Flow visualization discloses inchoate cavitation bubbles/bubble clouds emerging from the inside of the micro-Venturi throat egress. The bubble density decreases when the flow passes through the diffuser section and further downstream into the microchannel owing to the collapse of the vapor filled bubbles caused by a rise in the static pressure. An increase in the flow rate beyond cavitation inception results in the formation of twin cavities. The elongated cavities emerge from inside the Venturi boundaries and amalgamate further downstream sending out thick and dense vapor/bubble clouds. The discharge is affected by the aggressive cavitation and flow rate choking has been observed at different backpressures. The physical properties of the liquid (wettability, small contact angle, etc.) assist in the inhibition of cavitation by modifying the surface nuclei population. The liquid is able to endure significant tension and remains in a metastable state before sudden rupture. Flow visualization reveals considerable differences between cavitating flow patterns observed in refrigerant (R-123) and water flows through a micro-Venturi system.