Heat transfer correlation models for electrospray evaporative cooling chambers of different geometry types

Development of future electronics for high speed computing requires a silent thermal management method capable of dissipating a broad range of heat generated from application-specific integrated circuits, while keeping the skin temperature below 45 °C. Electrospray evaporative cooling (ESEC) chambers show promise because of their ability to dissipate a broad range of heat within a relatively small size. However, the development and the optimization of ESEC chambers are currently restricted, in part due to the lack of sufficient empirical heat transfer correlations. This paper investigates empirical heat transfer correlations for ESEC chambers with three different geometry types. Since the unstable multi-jet behavior of an ESEC chamber is similar to that of a free-surface traditional impinging liquid jet, these correlations are based on the traditional impinging liquid jet’s empirical correlations, yet are modified to factor in the electric field effect. The results show that the heat transfer enhancement ratio correlations and the Nusselt number correlations for different ESEC chambers cover more than 83% of the experimental data, within ±10% deviation. The sensitivity analysis results and experimental data prove that the variation in the enhancement ratio is sensitive to that of the potential and the flow rate. It is not sensitive to the geometric factor of the same ESEC type. This paper presents a natural convection correlation for chip-scale, heated, flat surfaces when the Rayleigh number is below 3000. Further investigation is necessary to extend these heat transfer correlations to cover additional parameters for different thermal management applications.

► We develop empirical heat transfer correlations for electrospray evaporative cooling chambers. ► The developed heat transfer enhancement correlations fit more than 83% experimental data. ► The developed Nusselt number correlations fit more than 89% experimental data. ► We present a new natural convection correlation for a Rayleigh number below 3000.