Flow pattern, pressure drop and heat transfer coefficient during two-phase flow boiling of R134a in pump-assisted separate heat pipe

The pump-assisted separate heat pipe (PASHP) has a broad application prospect in the field of saving energy. Two-phase flow boiling in PASHP is a multifarious physical process and the study of the characteristic of the flow boiling in PASHP is significant. The experimental investigation of two-phase flow boiling of R134a in PASHP was conducted. The results indicate that the flow patterns agree with the Wojtan-Ursenbacher-Thome map. The pressure drop has been compared with Muller-Steinhagen-Heck correlation, and the compared results indicate that the experimental data are inside the 10% confidence interval predictions. The heat transfer coefficients were compared with correlation given by Mohseni. It indicates that all the experimental data are inside the 10% confidence interval predictions at x > 0.1. However, part of error is beyond 30% at x ≤ 0.1. A new heat transfer coefficient correlation was developed, and most of the estimated values are within an error band of ±10% of the experimental data.