CAVITATION-BOILING COUPLING PHENOMENON EXPERIMENTAL INVESTIGATION OF R134A FLOW IN MICROCHANNEL

Cavitation-boiling coupling phenomenon of R134a flow in micro-channel was experimentally investigated. The cavitation structure, a rectangular micro-orifice 0.2 mm wide and 4mm long, embedded in a micro-channel 0.8 mm wide and 1 mm deep which was engraved on an oxygen-free copper plate covered with quartz glass. Electric film heater was employed under the copper bottom corresponding cavitation structures. Flow patterns were observed by microscope. In the experiment, a phenomenon was observed that hydrodynamic cavitation occurred easier as the mass flow rate increasing. The microchannel wall temperature increased and then decreased along channel with heat power, and flow regimes were different when heat power changed. The cavitation initial position is the corner behind the cavitation structure but not the main flow region.