Advanced numerical method for a thermally induced slug flow: application to a capillary closed loop pulsating heat pipe

Abstract

Summary An advanced hybrid lumped parameter code for the simulation of Pulsating Heat Pipes is developed. Being able to simulate transient operative conditions and removing common physical simplified assumptions, it represents a step forward with respect to the present models of passive two‐phase systems. Mass, momentum and energy balances account for the thermal and fluid‐dynamics phenomena. Heterogeneous and homogeneous phase changes are directly integrated. In addition, a fitting correlation for the wall/vapour heat transfer coefficient is implemented and tuned against experimental data in order to evaluate the influence of the liquid film on conjugate heat transfer. The resulting numerical tool have been validated against experimental data achieved testing a copper pulsating heat pipe during the 58th ESA Parabolic Flight Campaign in several operative conditions and transient gravity levels. The predicted results show very good matching with the actual thermo‐physical behaviour of the system. Copyright © 2016 John Wiley & Sons, Ltd.

Hybrid Pulsating Heat Pipe for space applications with non-uniform heating patterns: Ground and microgravity experiments

“…Furthermore, the microgravity tests in horizontal position confirmed a previous numerical analysis [17], suggesting that the PHP performance in zero gravity condition was not different from the horizontal operation on ground in case of planar geometries. Later on, Manzoni et al [18] proposed an advanced lumped numerical code and the predicted results showed a very good agreement with the experimental thermo-physical behavior during the gravity field transition obtained in [16]. Another test of a PHP in microgravity conditions was performed by Taft et al [19] ) are milled and the device is partially filled up with acetone.…”

Non equilibrium lumped parameter model for Pulsating Heat Pipes: validation in normal and hyper-gravity conditions

“…However, if the control volume is adiabatic, it cannot be assumed that the phase changes are both isothermal and isobaric, thus only the assumption of has been maintained (assumption 7). As shown in [30], evaporated and condensed mass, , as well as the final length of the vapor elements,…”

“…are computed. For more details one should refer to the annex A reported in [30]. Note that the 1 st Adams-Bashforth integration scheme [31] has been adopted to integrate mass and energy balances if not differently indicated.…”

“…Thus, the heterogeneous evaporation will occur, eventually, in each liquid slice. Accounting for the assumptions listed in the previous section (from 5 to 8), the integration of the mass and the energy balances written on CV and on each LS or VP (see the annex A in [30]) leads to the definition of the evaporated or condensed mass, :…”

A Low Cost, Flexible Pulsating Heat Pipe Technology

“…Pulsating heat pipes (PHPs) are becoming a popular technology to address passive thermal management of nuclear, defence and space applications [5][6][7]. The PHP design variants proposed and studied to date, have the potential to meet many of the present and future specific requirements from electronics cooling [8,10], heat recovery [2,15] and passive cooling of reactor containments, to name a few.…”