Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
Browse
5 results
Search Results
Article Citation - WoS: 83Citation - Scopus: 95Canopy-To Liquid Cooling for the Thermal Management of Lithium-Ion Batteries, a Constructal Approach(Elsevier Ltd., 2022) Güngör, Şahin; Çetkin, Erdal; Lorente, SylvieWith the growing interest on electric vehicles comes the question of the thermal management of their battery pack. In this work, we propose a thermally efficient solution consisting in inserting between the cells a liquid cooling system based on constructal canopy-to-canopy architectures. In such systems, the cooling fluid is driven from a trunk channel to perpendicular branches that make the tree canopy. An opposite tree collects the liquid in such a way that the two trees match canopy-to-canopy. The configuration of the cooling solution is predicted following the constructal methodology, leading to the choice of the hydraulic diameter ratios. We show that such configurations allow extracting most of the non-uniformly generated heat by the battery cell during the discharging phase, while using a small mass flow rate.Article Citation - WoS: 9Citation - Scopus: 13Local Heat Transfer Control Using Liquid Dielectrophoresis at Graphene/Water Interfaces(Elsevier Ltd., 2021) Yenigün, Onur; Barışık, MuratGraphene-based materials are considered for the solution of the thermal management problem of current and next generation micro/nano-electronics with high heat generation densities. However, the hydrophobic nature of few-layer graphene makes passing heat to a fluid very challenging. We introduced an active and local manipulation of heat transfer between graphene and water using an applied, non-uniform electric field. When water undergoes electric field induced orientation polarization and liquid dielectrophoresis, a substantial increase in heat transfer develops due to a decrease in interfacial thermal resistance and increase in thermal conductivity. By using two locally embedded pin and plate electrodes of different sizes, we demonstrated a two-dimensional heat transfer control between two parallel few-layer graphene slabs. We obtained local heat transfer increase up to nine times at pin electrode region with an ultra-low Kapitza resistance through the studied non-uniform electric field strength range creating highly-ordered compressed water in the experimentally measured density limits. With this technique, heat can be (i) distributed from a smaller location to a larger section and/or (ii) collected to a smaller section from a larger region. Current results are important for hot spot cooling and/or heat focusing applications. © 2020Article Citation - WoS: 23Citation - Scopus: 24Determination of the Material Model and Damage Parameters of a Carbon Fiber Reinforced Laminated Epoxy Composite for High Strain Rate Planar Compression(Elsevier Ltd., 2021) Shi, C.; Guo, B.; Sarıkaya, Mustafa; Çelik, Muhammet; Chen, P.; Güden, MustafaThe progressive failure of a 0°/90° laminated carbon fiber reinforced epoxy composite was modeled in LS-DYNA using the MAT_162 material model, including the strain rate, damage progression and anisotropy effects. In addition to conventional standard and non-standard tests, double-shear and Brazilian tests were applied to determine the through-thickness shear modulus and the through-thickness tensile strength of the composite, respectively. The modulus reduction and strain softening for shear and delamination parameters were calibrated by low velocity drop-weight impact tests. The rate sensitivities of the modulus and strength of in-plane and through-thickness direction were determined by the compression tests at quasi-static and high strain rates. The fidelity of the determined model parameters was finally verified in the in-plane and through-thickness direction by the 3D numerical models of the Split Hopkinson Pressure Bar compression tests. The numerical bar stresses and damage progressions modes showed acceptable correlations with those of the experiments in both directions. The composite failed both numerically and experimentally by the fiber buckling induced fiber-matrix axial splitting in the in-plane and the matrix shear fracture in the through-thickness direction. © 2020Article Citation - WoS: 31Citation - Scopus: 37Kinematic Design of a Non-Parasitic 2r1t Parallel Mechanism With Remote Center of Motion To Be Used in Minimally Invasive Surgery Applications(Elsevier Ltd., 2020) Yaşır, Abdullah; Kiper, Gökhan; Dede, Mehmet İsmet CanIn minimally invasive surgery applications, the use of robotic manipulators is becoming more and more common to enhance the precision of the operations and post-operative processes. Such operations are often performed through an incision port (a pivot point) on the patient's body. Since the end-effector (the handled surgical tool) move about the pivot point, the manipulator has to move about a remote center of motion. In this study, a 3-degrees-of-freedom parallel mechanism with 2R1T (R: rotation, T: translation) remote center of motion capability is presented for minimally invasive surgery applications. First, its kinematic structure is introduced. Then, its kinematic analysis is carried out by using a simplified kinematic model which consists of three intersecting planes. Then the dimensional design is done for the desired workspace and a simulation test is carried out to verify the kinematic formulations. Finally, the prototype of the final design is presented.Article Citation - WoS: 9Citation - Scopus: 10Microstructural Investigation of the Effect of Electrospraying Parameters on Lscf Films(Elsevier Ltd., 2020) Sındıraç, Can; Akkurt, SedatIntermediate temperature solid oxide fuel cells (IT-SOFC) require an effectively functioning cathode layer whose performance depends largely on their microstructures. Improved electrochemical performance of the cathode layer can be possible by tailoring the microstructure to ensure that both the oxygen reduction reaction (ORR) occurs fast along the triple-phase boundaries (TPB) and the diffusion pathway is short enough for fast ion diffusion through the cathode layer. Electro spray deposition (ESD) method is a low-cost deposition method which allows the optimization of microstructure by changing the spraying parameters. In this study, gadolinium doped ceria (GDC) electrolyte layer is deposited with La1-xSrxCo1-yFeyO3-? (LSCF) derived from polymeric precursor salts, symmetrically. As a solvent couple, 2-butoxyethanol and ethylene glycol are used instead of the conventional solvent couples frequently employed in the literature. The use of the new type of solvents in the precursor solution leads to promising results on modifying the microstructure of the deposited layer. The effect of electrospraying parameters on the cell performance was also studied. Promising results were obtained as measured by impedance spectroscopy when this new solvent couple was employed. © 2020 Hydrogen Energy Publications LLC