Visualization of pool boiling and occurring critical heat flux on coiled wire

Abstract

Pool boiling is used in various industries and play a significant role in heat transfer. So far, multiple studies have been carried out on investigating boiling and applying heat flux on the wire. In the present paper, the boiling of the coiled wire under atmospheric pressure conditions has been investigated. The fluid temperature inside the pool is considered under both constant (equal to saturation temperature) and variable temperature conditions. The value of the ring density in the coiled wire is considered to be variable. Based on the results, changing the pool liquid temperature changes bubble departure diameter and frequency. Also, increasing the density of the coil ring increases the diameter of bubbles. It has been observed that the bubbles are usually formed inside the coil, and after moving to the two ends of the coil, they leave the coil. However, by increasing the amount of heat flux and the pool liquid temperature, the size of bubbles will be larger; therefore, the bubbles must leave the coil from the empty spaces between the rings. By increasing the amount of applied heat flux, the coil was enclosed in a layer of vapor, which results in a decrease in the amount of heat transfer coefficient, and finally, a sudden increase in temperature on the wire will occur, which indicates the critical heat flux. Also, it has been observed that the critical heat flux always arises in the coil region of wire and not in the straight part of the wire.

Numerical simulation and experimental investigation of bubble behaviour during pool boiling in the coiled wire

“…Boiling and the application of heat flux on the wire have been the subject of numerous research to date [ 31 ]. DolatiAsl et al [ 32 ]examined the boiling of coiled wire at atmospheric pressure; it examined the pool boiling purely visually and noted the bubble shape; the research did not include a simulation or experimental setup. An experimental setup has been created for carrying out the experiment and validating the simulation results.…”

“…An experimental setup has been created for carrying out the experiment and validating the simulation results. In this study, using the simulation approach, we model pool boiling on the coiled wire from nucleate boiling to the film boiling regime [ 32 ].…”