Abstract

Leidenfrost (LF) and rewetting (RWT) phenomenon are both closely related and involved for the cooling of a very hot object utilizing a suitable cooling agent. The present study focusses on the influence of different parameters on both LF and RWT phenomenon of vertical tubes by bottom flooding. The various parameters primarily include the quantity or injection rate of the coolant (CLNT), type of CLNT and initial temperature of the heated substrate. For both the phenomena, a critical comparison of the findings between nanofluids (NFs) and water has been presented. In case of the LF phenomenon, as a small mass of liquid comes into contact with a heated solid, the dynamics of the vapor layer formed in between the solid and the liquid governs the rate of evaporation of the liquid. The vapor layer vibration leads to the formation of different shapes which are orderly random in occurrence and has been investigated in details. In another event, during the RWT phenomenon, as the CLNT enters the heated solid, different flow regimes are observed to form which has been investigated in details. The temperature responses of the vertical tubes have been utilized to construct the boiling curves from which the surface heat flux can be easily estimated.

摘要

Leidenfrost (LF) 和再润湿 (RWT) 现象都与使用合适的冷却剂冷却非常热的物体密切相关并涉及。目前的研究重点是不同参数对底部溢流垂直管的 LF 和 RWT 现象的影响。各种参数主要包括冷却剂 (CLNT) 的数量或注入速率、CLNT 的类型和加热基板的初始温度。对于这两种现象，我们对纳米流体 (NFs) 和水之间的发现进行了批判性比较。在 LF 现象的情况下，当少量液体与加热的固体接触时，固体和液体之间形成的蒸汽层的动力学控制着液体的蒸发速率。蒸汽层振动导致不同形状的形成，这些形状是有序随机发生的，已被详细研究。在另一种情况下，在 RWT 现象期间，当 CLNT 进入加热的固体时，观察到形成了不同的流态，这已被详细研究。垂直管的温度响应已被用来构建沸腾曲线，从中可以很容易地估计表面热通量。