Analytic framework for analysis of forced air cooling of electronic equipment.

This memorandum presents a method of analysis of heat dissipation in carriers cooled with forced air. The method uses the Reynolds analogy(which allows heat dissipation to be related to the flow resistance properties of air) and the acoustic noise properties of fans to estimate the thermal dissipation limits of circuit packs in a carrier. Functional dependences are obtained, showing that dissipation varies as fan noise power to the 1/5 power, and inversely as external air flow impedance to the 2/5 power. Application of this analysis is made to power units configured as circuit packs. It is shown that power unit rating should be proportional to the product of the top area of the carrier occupied by the power unit and the square root of the air pressure drop across the carrier.