Browsing by Author "Dursunkaya, Zafer"

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Embargo
Accelerated 3D CFD modeling of multichannel flat grooved heat pipes
(Elsevier, 2024-10-01) Gökçe, Gökay; Çetin, Barbaros; Dursunkaya, Zafer
Flat grooved heat pipes (HPs) have become essential in advanced thermal management solutions across various engineering applications. Modeling these devices, especially multichannel flat grooved HPs, involves significant challenges due to complex phenomena such as phase-change heat transfer and free-surface flow, requiring substantial computational resources, time and expertise. These constraints often limit the full exploration and optimization of HPs’ potential in diverse applications. To address this gap, an accelerated 3D computational fluid dynamics (CFD) modeling approach is presented in this study. This novel method begins with a detailed 3D modeling of a single groove, developed using kinetic theory and facilitated by CFD software. The results from this model are then applied as boundary conditions to simulate the entire HP in a multichannel configuration. The importance of this methodology is further highlighted by the alignment of simulation results with experimental observations. The approach significantly enhances computational efficiency by reducing the number of iterations by 10% and computational time by 80%, resulting in a five-fold speed-up. The methodology enables accelerated, comprehensive modeling of multichannel variations and delivers critical insights for optimizing the design of multichannel flat grooved HPs for various engineering applications.
Open Access
Accelerated solution methodology for 3D hydrodynamic and thermal modeling of grooved heat pipes with complex geometries
(Springer, 2024-08-31) Gökçe, Gökay; Çetin, Barbaros; Dursunkaya, Zafer
Heat pipes play a crucial role in industrial thermal management owing to their exceptional heat-carrying capacity, minimal thermal resistance and reliable performance. However, designing and optimizing heat pipes becomes intricate especially when dealing with multi-phase heat transfer encompassing complex phenomena like phase-change processes (i.e., evaporation, condensation and free surface flow). Grooved heat pipes, characterized by complex groove shapes, introduce an additional layer of complexity necessitating physically based mathematical models and skin friction correlations that may not always be readily available or may yield inferior results. To address these limitations, an innovative computational methodology is integrated into a commercial CFD program (Fluent®) using the Python® programming language. This approach allowed for comprehensive computation of the 3D fluid flow field and heat transfer phenomena within grooved heat pipes. Notably, the methodology incorporates data fitting procedures for boundary conditions leading to a substantial acceleration of the computation process and a reduction in solution times. This investigation represents a substantial advancement in addressing the challenges of multi-phase heat transfer phenomena while providing a compelling solution to the limitations of previous modeling methodologies for grooved heat pipes. Furthermore, the proposed methodology exhibits versatility, extending beyond its initial scope to encompass complex geometries like omega-shaped grooves and various physical scenarios involving phase-change phenomena and free-surface flow. Due to its comprehensive insights and adaptable framework, developed methodology serves as a valuable tool for analyzing heat pipes with multiple grooves addressing a significant gap in the literature.
Open Access
Fast and predictive heat pipe design and analysis toolbox: H-Pat
(Journal of Thermal Science and Technology, 2022-04-30) Saygan, Samet; Akkuş, Yiğit; Dursunkaya, Zafer; Çetin, Barbaros
For the assessment of the thermal performance of heat pipes, a wide range of modeling is available in the literature, ranging from simple capillary limit analyses to comprehensive 3D models. While simplistic models may result in less accurate predictions of heat transfer and operating temperatures, comprehensive models may be computationally expensive. In this study, a universal computational framework is developed for a fast but sufficiently accurate modeling of traditional heat pipes, and an analysis tool based on this framework, named Heat Pipe Analysis Toolbox, in short H-PAT is presented. As a diagnostic tool, H-PAT can predict the fluid flow and heat transfer from a heat pipe under varying heat inputs up to the onset of dryout. During the initial estimation of phase change rates, the solutions of particular thin film phase change models are avoided by specifying an appropriate pattern for the mass flow rate of the liquid along the heat pipe rather than using finite element/volume based methods for the computational domain. With the help of a modular structure, H-PAT can simulate heat pipes with different wick structures as long as an expression for the average liquid velocity and corresponding pressure drop can be introduced. H-PAT is also capable of analyzing heat pipes with variable cross-sections, favorable/unfavorable gravity conditions and utilizes temperature dependent thermo-physical properties at evaporator, condenser and adiabatic regions together with heat input sensitive vapor pressure. In addition, H-PAT performs the computation very fast which also makes it a perfect design tool for researchers and design engineers in the field of thermal management.