Evaluation of Cooling Solutions for Outdoor Electronics

摘要

The thermal management of an outdoor electronic enclosure can be quitechallenging due to the additional thermal load from the sun and the requirementof having an air-sealed enclosure. It is essential to consider the effect ofsolar heating loads in the design process; otherwise, it can shorten the lifeexpectancy of the electronic product or lead to catastrophic failure. In thispaper we analyze and compare the effectiveness of different cooling techniquesused for outdoor electronics. Various cooling techniques were compared likespecial coatings and paints on the outer surface, radiation shields,double-walled vented enclosures, fans for internal air circulation andair-to-air heat exchangers. A highly simplified, typical outdoor system wasselected for this study measuring approximately 300x300x400 mm (WxLxH). Solarradiation was incident on 3 sides of the enclosure. There were 8 equally spacedPCBs inside the enclosure dissipating 12.5W each uniformly (100 watts total). Acomputational fluid dynamics (CFD) model of the system was built and analyzed.This was followed by building a mock-up of the system and conductingexperiments to validate the CFD model. It was found that some of the simplestcooling techniques like white oil paint on the outer surface can significantlyreduce the impact of solar loads. Adding internal circulation fans can also bevery effective. Using air-to-air heat exchangers was found to be the mosteffective solution although it is more complex and costly.