A closed hybrid electronics cooling device using liquid synthetic jet and phase change material

The continuous miniaturisation of electronic components demands advances in thermal management systems capable of mitigating high-flux transient thermal spikes. While Phase Change Materials (PCMs) offer excellent latent heat of storage, the low conductivity in the liquid phase inevitably leads to severe buoyancy induced thermal layering and degraded thermal management. This study presents a numerical investigation of a novel closed hybrid cooling strategy that integrates a paraffin-based PCM with a dual-cavity synthetic jet actuator within a confined 2-dimensional domain. The system utilizes a moving orifice configuration, where the orifice is centrally located on an oscillating diaphragm for synthetic jet cycles with a 180 ° phase difference between two domains. This jet induced forced convection suppresses thermal layering by periodically ejecting counter rotating vortex pairs that impinge upon the bottom heated surface. Parametric analyses reveal a non-monotonic dependence of thermal performance on excitation frequency, attaining a maximum Nusselt number ( Nu ) at an optimal Strouhal number of Sr = 0.15 ( Nu max ≈ 42 ) . Conversely, heat transfer scales monotonically with Reynolds number, showing significant improvements as the Reynolds number is increased from 500 to 1000. The system maintains high cooling efficiency post melting regime by utilizing jet induced mixing to overcome the thermal resistance of the liquid PCM. This active intervention not only enhances heat dissipation after phase change completion but also accelerates the re-solidification process. This study demonstrates that the proposed configuration enables control of PCM melting and solidification behaviour while preserving the benefits of passive latent heat storage. Due to its enhanced cooling effectiveness in the post melting phase, this device is highly applicable in advanced electronics cooling and compact thermal management systems.