Heat dissipation performance of grooved- and copper foam -type vapor chambers

Both grooved-type and copper foam-type vapor chambers are explored and investigated. The overall performance of vapor chamber depends on both axial and spread thermal resistance mutually. The copper foam-type vapor chambers achieved the lowest axial thermal resistance less than 0.2 K/W. The grooved-type sample presented the lowest spread thermal resistance, indicating better temperature uniformity. The visual experiment demonstrated that the evaporating surface of the copper-foam vapor chamber was dominated by the thin film evaporation mechanism at low charging ratio while dominated by the pulsed pool boiling mechanism at large charging ratio. For the grooved-type vapor chamber, the pool boiling mode was observed at any charging ratio.

Model Construction and Experiment Study of the Fuel Nucleus Boiling Process on Hot Surface

As for the nucleus boiling pattern of the fuel on hot surface, the nucleus boiling mechanism, evaporation process and gas-liquid balance condition have been analyzed. Based on the model of Euler multiphase flow, mathematics model of the nucleus boiling process has been constituted. Furthermore, the nucleus boiling process has been simulated by FLUENT. And then, the study provides the theoretic foundation for the forecast of the process of fuel evaporation on hot surface through the comparative analysis between the theoretic calculation conclusion and the experiment.

Numerical Study on Boiling Mechanism and Rapid Phase Transfer Phenomenon of LNG Discharging on Water

Aiming at analyzing boiling mechanism and confirming rapid phase Abstract. Aiming at analyzing boiling mechanism and confirming rapid phase transfer (RPT) taking place conditions of LNG discharging on water. The models of pool spreading, heat and mass transfer rate and LNG’s property are coupled in this paper. The conditions of RPT has been confirmed, which included LNG directly contacting with water and the water temperature should higher than LNG’s superheat limit temperature, but the RPT would not take place if the LNG boils on ice. The model of LNG discharging on water has been established in this paper, which is used to simulate Boe and Burro-9 experiments. The results showed that the models can simulate evaporation and boiling rate well, and can be used in predicting the initial time of RPT happening when the discharging process is calm and the location of discharging is near the water surface.