This figure describes the operation of a PHP.  In this project, it aims at cooling electronic devices.

Operation of a PHP

It illustrates a closed loop PHP (which is considered here) that shows the condenser (dark blue), the adiabatic (white) and the evaporator (red) zones. The heat enters in the evaporator zone (cooling the electronics) and travels to the condenser zone, which the fluid (vapour bubbles and liquid slugs) is pulsating within the loop. The inherent features of the PHP are to make the flow passively pulsate, and thus carrying the vapour and slugs (latent and specific heat) back and forth, transporting the heat to the condenser end where it is removed.

The “hot” elements in electronic units to be cooled are typically Insulated Gate Bipolar Transistors (IGBT), Central Processing Units (CPU), Graphic Processing Units (GPU), diodes, radars and communication amplifiers, etc. These come in a wide range of sizes and shapes with flat surface areas to be cooled usually ranging in size from 5x5mm up to 40x40mm or even larger (especially if there is an array of hot elements to be cooled). The heat fluxes to be cooled typically range from about 1-50 W/cm2 but these are getting ever higher with even values over 100 and 500 W/cm2 being demanded (even higher from very small “hot spots” of 1x1mm).