Development of an evaporative spray cooling system for a high-power electronic test boards

• Main Author: Chen, Wenjie.
• Other Authors: Toh Kok Chuan
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/16117
• Institution: Nanyang Technological University

The continued push of technology and electronic advancement, the amount of heat generated on electronic boards has increased over the years. It has created a tough heat management problem. The current conventional methods of heat removal are barely able to keep up with the demands of cooling such high heat fluxes. Relatively new cooling method like spray cooling is not commonly use and studies has only been made recently on it. Spray cooling has a high heat transfer coefficient as there is a high amount of latent heat involved in the phase change when the working fluid boils upon contact with the heated surface. An Evaporative Spray Cooling system was built in previous final year project to studies the effect of spray cooling. The Evaporative Spray Cooling system consist of a closed loop R134A refrigeration system and the R134A is sprayed on to a 1000W of heated plate by means of an atomizing spray nozzle where the R134A is atomize in to fine droplets. The Evaporative Spray Cooling System is modeled and using Engineering Equation Solver to find out the theoretic parameters that is required to achieve the cooling of 1000W heated plate. The Evaporative Spray Cooling System was modified allows better studies of the system at various parameter. Thermocouples, pressure transducers and flow meters were added to obtain various parameters at different points of the system. Based on the experimental results, maintaining an average of 22.83oC was achieved on the heated plate with a difference of less than 2oC was achieved. The temperatures measured shows that the points nearer to the spray circle centers are colder than those on the circumferences as those on the circumferences of the top circles only have heat removal by spray cooling, whereas the other points experience spray cooling as well as forced convection due to surface runoff. The chamber pressure also affects the cooling performance of the system. The higher the chamber pressure, the high the heat transfer coefficient was obtained.