An experimental study is conducted on pulsed spray cooling heat transfer on a vertical surface under controlled nozzle pressure. Nozzle flow rate is found to be directly proportional to the duty cycle when the nozzle pressure is maintained constant and hence fixed at 2 bar throughout the investigation. The temperature fluctuates on the heated surface due to the interaction of the injection/non-injection spray cycles. The temperature fluctuation amplitude decreases with an increase in the distance from the heated surface. However, the temperature fluctuations along three measuring locations from the heated surface disappear when the spray frequency is equal to or larger than 5 Hz. It is found that the heat flux decreases as the spray frequency decreases at a fixed duty cycle. The influence of the spray frequency on the heat flux is more significant at a relatively small duty cycle. The heat flux decreases with a decrease in the duty cycle in both the single-phase and the nucleate boiling regimes. This is mainly due to the decrease in the spray mass flow rate as the duty cycle decreases. The decrease in the heat flux as the duty cycle decreases is more significant in the nucleate boiling regime than that in the single-phase regime. The specific heat flux is used to evaluate the efficiency of pulsed spray cooling heat transfer. It is found that the pulsed spray cooling has a larger specific heat flux than the continuous spray cooling. The pulsed spray cooling is therefore more efficient in fluid usage than continuous spray cooling. Experimental results in this study compare reasonably well with previous correlation in the single-phase regime. However, the comparison is poorer in the nucleate boiling regime. Therefore, a new correlation is developed for pulsed spray cooling on a vertical surface in the nucleate boiling regime. The new correlation predicted experimental data in this study with an accuracy of 10% in the nucleate boiling regime. Finally, an ANN model has been successfully developed for pulsed spray cooling heat transfer on a vertical surface. The ANN model is in excellent comparison with the experimental results. Compared with the empirical correlations, the ANN model shows much higher accuracy in predicting the pulsed spray cooling heat transfer. It is thus concluded that ANN is a promising method which can be integrated in an active spray control system for superior control accuracy.

在控制喷嘴压力的情况下，对垂直表面上的脉冲喷雾冷却传热进行了实验研究。当喷嘴压力保持恒定并因此在整个研究过程中固定为2 bar时，发现喷嘴流速与占空比成正比。由于喷射/非喷射喷雾循环的相互作用，温度在加热的表面上波动。温度波动幅度随着距加热表面距离的增加而减小。但是，当喷雾频率等于或大于5 Hz时，从被加热表面沿三个测量位置的温度波动将消失。已经发现，在固定占空比下，热流量随着喷射频率的降低而降低。喷雾频率对热通量的影响在相对较小的占空比下更为明显。在单相和成核沸腾状态下，热通量都随着占空比的减小而减小。这主要是由于占空比降低导致喷涂质量流量的降低。随着占空比的减小，热通量的减少在有核沸腾状态下比在单相状态下更显着。比热通量用于评估脉冲喷雾冷却换热的效率。发现脉冲喷雾冷却比连续喷雾冷却具有更大的比热通量。因此，与连续喷雾冷却相比，脉冲喷雾​​冷却在流体使用方面更为有效。这项研究中的实验结果与以前在单相状态下的相关性相当好。但是，在核沸腾方面，比较差。因此，开发了一种新的相关性，用于在成核沸腾状态下在垂直表面上进行脉冲喷雾冷却。新的相关性预测了这项研究中的实验数据，在核沸腾过程中的准确度为10％。最后，已经成功开发了用于在垂直表面上进行脉冲喷雾冷却传热的ANN模型。人工神经网络模型与实验结果具有很好的对比。与经验相关性相比，ANN模型在预测脉冲喷雾冷却换热方面显示出更高的准确性。