HFE-7100/HFE-7300 spray quenching via a piezoelectric atomizer with a single-hole micronozzle

Abstract

The flow and thermal characteristics of spray cooling with a single-hole micronozzle via a piezoelectric (PZT) atomizer with two dielectric fluids were studied to provide a better physical insight of the flow phenomena as well as the cooling mechanism with HFE-7100 and HFE-7300 as coolants. The target/heater's surface was made of indium tin oxide (ITO)-coated glass. A microhole of dj = 35 µm was used and tested with a volumetric flow rate of 0.0838 ml/min (HFE-7100) and 0.1180 ml/min (HFE-7300), respectively, for spray heights of 10 mm, 20 mm, 30 mm, and 40 mm, with heater surface temperatures of 25 °C, 75 °C, 125 °C, 175 °C, and 225 °C. The spray velocity and droplet size were measured by microparticle image velocimetry (µPIV) and interferometric particle imaging (IPI), respectively, for the spray centerline velocity along the downstream during the spray flight and for the spray droplet impact velocity as well as the associated droplet size measurements. Quench cooling curves as well as the transient boiling curves were obtained. Boiling curve related parameters such as the onset of nucleate boiling, Leidenfrost temperature, etc. were identified. The maximum heat transfer coefficient (hmax) correlation was developed in terms of q“, Wep and Ja.