Understanding the self-sustained oscillating two-phase flow motion in a closed loop pulsating heat pipe

Spinato, Giulia; Borhani, Navid; Thome, John R.

doi:10.1016/j.energy.2015.07.119

Cited by 56 publications

(14 citation statements)

References 29 publications

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“…The study of the fluid oscillation frequency is crucial for understanding the PHP working principles since the thermally induced oscillations are responsible for efficient heat dissipation [27]. The core issue regarding the fluid oscillation frequency evaluation can be referred to the non-fixed oscillation frequency of the fluid between the evaporator and the condenser section due to the chaoticity of the thermofluidic system [28].…”

Section: Frequency Analysismentioning

confidence: 99%

Thermal characterization of a multi-turn pulsating heat pipe in microgravity conditions: Statistical approach to the local wall-to-fluid heat flux

Pagliarini

Cattani

Bozzoli

et al. 2021

International Journal of Heat and Mass Transfer

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Section: Frequency Analysismentioning

confidence: 99%

Thermal characterization of a multi-turn pulsating heat pipe in microgravity conditions: Statistical approach to the local wall-to-fluid heat flux

Pagliarini

Cattani

Bozzoli

et al. 2021

International Journal of Heat and Mass Transfer

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“…In the present work the expected maximum velocities are in the range 0.2-0.45 m/s making the velocity code applicable in the specific range with known and acceptable accuracy. Test conducted on a single loop pulsating heat pipe by Spinato et al [33] for power input varying between 30W and 65W, shows a velocity range of 0.07 and 0.15 m/s, graphically evaluated from a time-strips method at the evaporator. This confirms the applicability of the code in the specific range of velocity values, also from comparison with experimental data from similar geometries.…”

Section: Fluid Velocity and Acceleration Estimationmentioning

confidence: 99%

Developing flow pattern maps for accelerated two-phase capillary flows

Pietrasanta

Mameli

Mangini

et al. 2020

Experimental Thermal and Fluid Science

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The prediction of flow pattern transitions is extremely important to understand the coupling of thermal and fluid dynamic phenomena in two phase systems and it contributes to the optimum design of heat exchangers. Two phase flow regimes have been extensively studied under controlled mass flow rate and velocity. On the other hand, less effort has been spent in the literature on the cases where the flow motion is purely thermally induced and consequently the mass flow rate or the velocity of the phases are not known a priori. In the present work, flow pattern transitions and bubble break-up and coalescence events have been investigated in a passive two phase wickless capillary loop, where the mass flow rate is intrinsically not controllable. Modified Froude, Weber and Bond numbers have been introduced, considering the actual acceleration of the fluid and the length of the bubble as merit parameters for the transitions. The proposed nondimensional investigation was developed by analysing experimental data obtained with ethanol and FC-72, as working fluids, different heat input levels (from 9 to 24 W) as well as three different gravity levels (through a parabolic flight campaign). A new empirical diabatic flow pattern map for accelerated two-phase capillary flows is presented, together with quantitative criteria for the calculation of the flow regime transitions, defining the physic limits for the bubble coalescence and break-up. This kind of new regime maps will be useful to the further development of comprehensive designing tools for passive two-phase wickless heat transfer devices.

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“…Since the Single Loop PHP (SLPHP) can be considered the basic constituent of a multi-turn Pulsating Heat Pipe, its full thermo-fluidic characterization is fundamental for the complete description of the PHP working principles. At present, several studies already contribute to the understanding of SLPHP behavior (Khandekar and Groll, 2004, Khandekar et al 2009, Spinato et al 2015, Spinato et al 2016, but further work is needed to have a clearer view on the thermo-fluid dynamics of the two-phase flow. Detecting quantitatively the liquid slug temperature with a non-intrusive technique is a mandatory step for a better comprehension of the PHP heat transfer phenomena.…”

Section: Introductionmentioning

confidence: 99%

Infrared analysis of the two phase flow in a single closed loop pulsating heat pipe

Mangini

Marengo

Araneo

et al. 2018

Experimental Thermal and Fluid Science

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Research Highlights Adiabatic section made of sapphire tubes, transparent both to visible and IR spectrum.  Thermal-hydraulic characterization at different heat input levels.  Direct Fluid temperature measurement with IR camera.  Temperature gradients along a liquid slug could be measured with 1,5 K accuracy.  Liquid film wetting and de-wetting phenomena qualitatively detected by the IR.

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Understanding the self-sustained oscillating two-phase flow motion in a closed loop pulsating heat pipe

Cited by 56 publications

References 29 publications

Thermal characterization of a multi-turn pulsating heat pipe in microgravity conditions: Statistical approach to the local wall-to-fluid heat flux

Thermal characterization of a multi-turn pulsating heat pipe in microgravity conditions: Statistical approach to the local wall-to-fluid heat flux

Developing flow pattern maps for accelerated two-phase capillary flows

Infrared analysis of the two phase flow in a single closed loop pulsating heat pipe

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