The Superheat Limit of Liquids–A Review and Discussion

Abstract

Abstract. The superheat limit of a liquid can be predicted using the equation of state, classical nucleation theory, or bubble formation model based on molecular interactions. The spinodal point calculated by the Redlich-Kwong equation of state reasonably predicted the superheat limit for hydrocarbons such as pentane, hexane, and heptane. Both classical bubble nucleation theory, assuming a nucleation rate of 1012bubbles/m3s and the molecular interaction-based bubble nucleation model with a nucleation rate of 1028nuclei/m3s, effectively predict the superheat limits of hydrocarbons, alcohols, and halocarbons. The model based on molecular interactions further suggests that vaporization occurs at the superheat limit, as supported by the nucleation rate estimates from Lienhard. Experimentally, the superheat limit has been measured using various techniques—such as droplet explosion and pulse heating methods—and is typically found within 3∼10 K, which is close to the spinodal point of the liquid. This study reviews these experimental approaches, explores recent findings on microscale surface effects, and emphasizes the critical role of nucleation rates in determining the superheat limit. Numerous experiments confirm that the superheat limit closely approaches the spinodal point at a given pressure, aligning with Lienhard's predictions. Applications related to the superheat limit phenomena are also discussed.