Thermal Modeling of Unlooped and Looped Pulsating Heat Pipes

By M. Shafii, A. Faghri, Yuwen Zhang. Heat Transfer, 2001

365 citations recorded by the source corpus.

Analytical models for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs are presented in this study. The governing equations are solved using an explicit finite difference scheme to predict the behavior of vapor plugs and liquid slugs. The results show that the effect of gravity on the performance of top heat mode unlooped PHP is insignificant. The effects of diameter, charge ratio, and heating wall temperature on the performance of looped and unlooped PHPs are also investigated. The results also show that heat transfer in both looped and unlooped PHPs is due mainly to the exchange of sensible heat.

Subfields: Biomedical Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/07ddc096e5eb0bf28cf4edb61fe0e72d3c84f187

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In Biomedical Engineering

In Mechanical Engineering

Citations in the corpus

Closed loop pulsating heat pipes: Part A: parametric experimental investigations (2003, background): “It has been indicated earlier that the sensible heat transfer is the major contributor in the overall heat exchange [6–8].”
Operational limit of closed loop pulsating heat pipes (2008, background): “While quite some research has been performed on the operational behavior and physical phenomena in PHPs, including various experimental studies [5–12] and attempts of mathematical modeling [13–18], rather limited knowledge exists on the ultimate performance or performance limits of PHPs [19–22].”
HEAT PIPES: REVIEW, OPPORTUNITIES AND CHALLENGES (2014, background): “(2002) further developed their earlier numerical model (Shafii et al., 2001) by including an analysis of the evaporation and condensation heat transfer in the thin liquid film separating the liquid and vapor plugs.”
Understanding operational regimes of closed loop pulsating heat pipes: an experimental study (2003, background): “The heat transfer is primarily due to sensible heat transport by the liquid [4,7] and therefore it may be argued that a low latent heat is in fact more beneficial, aiding quick bubble generation and collapse.”
High speed flow visualization of a closed loop pulsating heat pipe (2005, methodology): “[4,5] performed the numerical modeling of PHP with multiple liquid and vapor plugs using the constant wall temperature condition.”
An insight into thermo-hydrodynamic coupling in closed loop pulsating heat pipes (2004, methodology): “If the flow patterns remains strictly slug flow in the ent system, it has been shown by experimental and simula studies that latent heat will play an insignificant role the overall heat transfer [4,7].”
A novel design of pulsating heat pipe with fewer turns applicable to all orientations (2012, background): “However, PHP with fewer turns fails to operate at horizontal orientations for lacking gravity assistance [9].”
Performance characteristics of pulsating heat pipes as integral thermal spreaders (2009, result): “rameters affecting the system dynamics [8,11–19].”
Closed loop pulsating heat pipes Part B: visualization and semi-empirical modeling (2003, methodology): “These may be summarized as: Type 1: comparing PHP action to equivalent single spring-mass-damper system [5], Type II: kinematic analysis by comparison with a multiple spring-mass-damper system [6], Type III: applying conservation equations of mass, momentum and energy to specified slug–plug control ”
Multiple quasi-steady states in a closed loop pulsating heat pipe (2009, background): “The contribution of latent heat portion, in the overall heat transfer, depends on the exiting two-phase flow pattern in the tube [17–23].”
Advances and Unsolved Issues in Pulsating Heat Pipes (2008, methodology): “[13] developed a theoretical model to simulate the behavior of liquid slugs and vapor plugs in both closed- and open-loop PHPs with two turns (see Figure 6).”