Analysis of chaotic flow in a 2D multi-turn closed-loop pulsating heat pipe

TL;DR

This study numerically investigates chaotic flow behavior in a 2D multi-turn pulsating heat pipe, revealing how operational parameters influence chaos and thermal performance.

Contribution

It introduces a detailed numerical analysis of chaos in a multi-turn PHP using VOF and nonlinear time series methods, identifying optimal conditions for thermal efficiency.

Findings

Chaos confirmed by power spectrum analysis.

Optimal filling ratio of 60% for best performance.

Minimum thermal resistance achieved at optimal conditions.

Abstract

Numerical study has been conducted for the chaotic flow in a multi-turn closed-loop pulsating heat pipe (PHP). Heat flux and constant temperature boundary conditions have been applied for heating and cooling sections respectively. Water was used as working fluid. Volume of Fluid (VOF) method has been employed for two-phase flow simulation. Volume fraction results showed formation of perfect vapor and liquid plugs in the fluid flow of PHP. Non-linear time series analysis, power spectrum density, correlation dimension and autocorrelation function were used to investigate the chaos. Absence of dominating peaks in the power spectrum density was a signature of chaos in the pulsating heat pipe. It was found that by increasing the filling ratio and evaporator heating power the correlation dimension increases. Decreasing of the autocorrelation function with respect to time showed the prediction ability is finite as a result of chaotic state. An optimal filling ratio of 60% and minimum thermal resistance of 1.62 K/W were found for better thermal performance of the pulsating heat pipe.