Effect of the Tesla Valve on the heat transfer performance and the suppression of pressure drop oscillation in a liquid cooling loop

Abstract

The suppression of pressure drop oscillation within a liquid cooling loop is necessary to maintain the system stability and develop a steady heat transfer performance. The Tesla Valve is proposed as a means of eliminating this instability by suppressing the backward flow, which in turn facilitates a stable heat transfer process. The steady-state analysis is performed to identify the conditions that would induce flow instability. The calculated results indicate that the flow instability will appear when the heat flux (q) reaches a threshold value of 28 W/cm2. Furthermore, the impact of the Tesla Valve on the suppression of instability and the heat transfer coefficient is revealed by comparison with the dynamic features observed in a common liquid cooling loop. Two flow instability regimes, with and without backflow, are observed in the common liquid cooling loop. In the case of the former instability, a violent fluctuation in both the inlet temperature and the heat transfer coefficient is captured. This phenomenon can be effectively eradicated by the Tesla Valve. In the latter instability regime, the hydrodynamic characteristics of pressure drop remain significantly oscillatory, while the heat transfer performance returns stable. Furthermore, this specific form of instability cannot be eliminated by the prototype I of Tesla Valve when q ≥ 30.4 W/cm2. In addition, the liquid cooling loop with prototype III displays a superior heat transfer performance, yet results in an additional pressure drop of 8.1 kPa in comparison to prototype II. To assess the suppression mechanism and efficiency, the Suppression Factor (Fs) and Coefficient of Suppression Performance (Fc) are proposed. It can be found that the pressure drop oscillation instability can be thoroughly suppressed by the Tesla Valve when Fs > 1. Meanwhile, the greater the Fc, the more effective the suppression performance. However, the incorporation of the Tesla Valve shows a negligible effect on the heat transfer performance in the two-phase region.