This setup is intended to test cooling of power electronics when submerged in liquid water. The experiments are performed inside an insulated tank to minimize heat interference with the environment. Two immersion heaters are used to control the water temperature inside the tank which can be measured by the K-type thermocouple probe.
The printed circuit board used generates heat inside the EPC2034 GaN transistor through two different electric modes: conduction and switching. In order to prevent any shorting due to the immersion in tap water, the PCBs are coated with a 5 μm thick layer of Parylene C. Power generation in the transistor is varied to obtain different cooling modes in the single-phase and boiling water regimes. The temperature of the transistor is measured by an 80 μm diameter K-type thermocouple attached on its surface via a high thermal conductivity epoxy bead. The performance of water as a cooling fluid is compared against that of other fluids such as ethylene glycol – water mixtures and commercial dielectric fluids.
Electric equipment used:
- HP6633A DC power supply as the gate voltage source
- HP6031A DC power supply as the drain current source
- Yokogawa WT3000 Digital Sampling Power Analyzer to measure VDS, drain current and switching power
Imaging equipment used:
- Photron Mini AX200 high speed camera
- InfiniProbe TS-160 lens