The Superheat Limit of Liquids- A Review and Discussion

Predictions of the superheat limit of a liquid can be made using the equation of state or classical nucleation theory or bubble formation model based on molecular interactions. The spinodal lines predicted by the Redlich-Kwong equation of state accurately predict the superheat limit for hydrocarbons such as pentane, hexane, and heptane. The classical bubble nucleation theory assuming a nucleation rate of 1012 bubles/m3⋅s and the molecular interaction-based bubble nucleation model with a nucleation rate of 1028 nuclei/cm3⋅s effectively predict the superheat limit of hydrocarbons, alcohols and halocarbons very well. However, bubble nucleation models based on molecular interactions predict vaporization of the liquid at the superheat limit as indicated by the nucleation rates estimated by Lienhard. The superheat limit of liquids, as measured by various experimental techniques and methods, is close to the spinodal limit of liquids. The superheat limit of liquids measured by various experimental techniques and methods is close to the spinodal of liquid. This study reviews various experimental methods for measuring the superheat limit of liquids, including the droplet explosion technique and pulse heating methods, recent experimental findings on the superheat limit of liquids on microscale surfaces, and the role of nucleation rate in bubble nucleation. Various experiments have shown that the superheat limit occurs close to the spinodal point of a liquid at a given pressure as predicted by Lienhard.