Design, fabrication, and investigations of prototype supersonic micro-ejector for innovative cooling system of electronic components

Innovative approach for electronics cooling was proposed, i.e. heat generated by a part of electronic equipment, e.g. CPU, is absorbed by heat driven micro-ejector refrigeration system that can provide cooling of other elec-tronic components, e.g. GPU. It was demonstrated the procedure of design, fabrication, and experimentation on the supersonic micro-ejectors for the case of isobutane as a working fluid for such system. It was demonstrated that it possible to design and fabricate the micro-ejector of cooling capacity in the range 3 W suitable for cooling of electronic equipment. For the discussed micro-ejector entrainment ratio obtained was app. 0.20 under con-ditions of the motive heat source temperature app. 60 degrees C and evaporation temperature app. 22 degrees C. There were demonstrated difficulties in fabrication of the supersonic ejector due to small dimensions of the motive nozzle as well as mixing chamber. Required throat diameter of the motive nozzle was less than 200 mu m and the diameter of the mixing chamber was 260 mu m. For reported tests conditions the boundary temperature of the on-design operation condition was between 21 - 25 degrees C. However, the operation of the micro-ejector under off-design operation regime was stable and repeatable. Micro-ejector tests required an indirect method of measurement of critical motive mass flow rate to be applied. The performance line of tested ejector fits to ejectors theory and meet the basic assumptions in terms of thermal capacity and operating temperature. CFD technique used for numerical predictions of the ejector performance fits to experimental measured values with acceptable accuracy.