Thermal Simulation for Outdoor Optical Network Unit

An Optical Network Unit (ONU) used in Fiber-to-the-Curb (FTTC) system is one of the last mile equipment in telecommunications industry. The ONU usually operates in an outdoor environment like many other telecommunications cabinets. The ONU, in this study, is placed inside a CAT12 pedestal. The pedestal provides the housing for the termination block, the cable harness, the gas tube protection, etc. besides the ONU. Due to the proximity to residential areas and the reliability requirement for the operation, most of ONUs uses the passive cooling instead of the active cooling. It is very critical to ensure that all electronics including the optics operate within their thermal specifications. From the thermal perspective, most of the outdoor equipment for telecommunications industry follows the guidelines of GR-487-CORE, Issue 2. The CFD model analysis as well as engineering mockup tests provide the effective tools to meet the thermal requirements in this study. With the baseline model working, it is found that it would be very efficient to predict the thermal trends in different design conditions performing CFD simulations using readily available analysis tool Icepak.