Lifespan and efficiency gain for outdoor electronic systems from radiative cooling: A case study on distribution transformers

We investigate the impact of radiative cooling (RC) on pole-type distribution transformers which are utilized daily around the world, as a case study for broad range of outdoor electrical systems that feature high internal heating and require unique cooling strategies. A majority outdoor electrical equipment, including distribution transformers, rely on passive thermal management techniques via natural convection and radiation to dissipate the internal heat generated by electrical inefficiencies. Utilizing RC paint on the exterior of the case would allow further dissipation of heat to deep-space, an infinite heat sink at 3 K, as well as increase the solar reflectance to lessen the external heat load on the equipment. A single 25 kVA pole-type transformer is modeled via CFD. Two different exterior case coatings, the standard gray coatings commonly utilized and an RC coating, BaSO4 paint, are analyzed under different operating loads and ambient temperatures. The RC coating makes a 25 kVA distribution transformer’s windings more than 9 K cooler than the standard case with an ambient air temperature of 321 K and demonstrates below ambient cooling of the case at low heat generations. The lifetime of the distribution transformers is increased by greater than 50% when comparing the standard paint case to the RC paint case based on the Aging Acceleration Factor.