Enhanced cooling in a sealed cabinet using an evaporating-condensing dielectric mist

Abstract

Many factors, such as acoustic noise limits and fan reliability considerations, limit the heat dissipation capacity of air-cooled cabinets housing telecommunications or computing hardware. The present work examines the potential of enhanced cooling in a sealed telecommunications cabinet using an evaporating- condensing dielectric mist introduced upstream of heat sinks attached to high-power components in a circuit pack, or at the inlet to the circuit packs. The conceptualized system is of a two-component (air and dielectric fluid) and two-phase nature, wherein droplets of mist are dispersed within the air circulating through a sealed cabinet. The evaporated mist is condensed at the outlet of the circuit packs in a cabinet and recycled back to their inlets. First-order models of the mist flow through a heat sink are developed to estimate its influence on flow and heat transfer. The optimum droplet diameter and the optimum mist concentration are obtained from these models for representative conditions. Moreover, the models are used to obtain a first-order estimate of the heat dissipation capacity and the pressure drop required for sustaining the mist flow. The results show that the proposed mist cooling approach offers significant promise for providing high-flux heat removal solutions for sealed cabinets in telecommunications central offices and data centers.