Person:
ARIK, Mehmet

Profile Picture

Email Address

Birth Date

WoSScopusGoogle ScholarORCID

Name

Job Title

First Name

Mehmet

Last Name

ARIK
OrgUnit Logo
Organizational Unit

Filters

2011 - 2019492020 - 202331
Reset filters

Settings

Publication Search Results

Now showing 1 - 10 of 81
  • Placeholder
    Conference paperPublicationMetadata only
    Thermal and optical performance of eco-friendly silk fibroin proteins as a cavity encapsulation over LED systems
    (ASME, 2015) Yuruker, Sevket Umut; Arık, Mehmet; Tamdoğan, Enes; Melikov, R.; Nizamoğlu, Sedat; Press, D. A.; Durak, Ilkem; Mechanical Engineering; ARIK, Mehmet; TAMDOĞAN, Enes; Yuruker, Sevket Umut; Durak, Ilkem; Tamdoğan, Enes
    The demand for high power LEDs for illumination applications is increasing. LED package encapsulation is one of most critical materials that affect the optical path of the generated light by LEDs, and may result in lumen degradation. A typical encapsulation material is a mixture of phosphor and a polymer based binder such as silicone. After LED chips are placed at the base of a cavity, phosphor particles are mixed with silicone and carefully placed into the cavity. One of the important technical challenges is to ensure a better thermal conductivity than 0.2 W/m-K of current materials for most of the traditional polymers in SSL applications. In this study, we investigated an unconventional material of the silk fibroin proteins for LED applications, and showed that this biomaterial provides thermal advantages leading to an order of magnitude higher thermal performance than conventional silicones. Silk fibroin is a natural protein and directly extracted from silk cocoons produced by Bombyx mori silkworm. Therefore, it presents a “green” material for photonic applications with its superior properties of biocompatibility and high optical transparency with a minimal absorption. Combining these properties with high thermal performance makes this biomaterial promising for future LED applications. An experimental and computational study to understand the optical and thermal performance is performed. A computational fluid dynamics study with a commercial CFD software was performed and an experimental set-up was developed to validate the computational findings to determine the thermal conductivity of the proposed material.
  • Placeholder
    Conference paperPublicationMetadata only
    Effect of actuator deflection on heat transfer for low and high frequency synthetic jets
    (IEEE, 2014) Ikhlaq, Muhammad; Ghaffari, Omidreza; Arık, Mehmet; Mechanical Engineering; ARIK, Mehmet; Ikhlaq, Muhammad; Ghaffari, Omidreza
    Synthetic jets are being investigated over the last four decades. Researchers have been interested in its unique applications for a wide range of flow control to thermal management of electronics applications. Synthetic jets are made up of actuators such as piezoelectric, magnetic, or linear piston technology etc. In this study, we performed an experimental and numerical investigation of a piezoelectric disk deflection over a range of frequencies in order to understand the performance for low and high frequency synthetic jets. First, we performed a numerical analysis of a piezoelectric based synthetic jet and, validated computational result with experimental findings. Numerical models are performed by using commercial finite element software. To understand the size effect on the operating frequency, three jets with different sizes are manufactured and examined. Two different low frequency synthetic jets manufactured in our laboratory and a commercially available high frequency jet are included in the present study. Heat transfer performance is given as an enhancement over natural convection heat transfer. The heat transfer enhancement factor of each of these jets with respect to natural convection is measured over a 25.4×25.4 (mm) vertical heater. Finally, power consumption of the low and high frequency synthetic jets were measured and compared. It is found that disk deflection and operating frequency are directly related to heat transfer enhancement factor, if the Helmholtz frequency of a cavity has no effect on the performance of a jet. The Helmholtz frequency of each jet was calculated to ensure that it has no effect on the synthetic jet, but we found that the commercial synthetic jet took partial advantage of Helmholtz phenomena to enhance the performances at high frequencies.
  • Placeholder
    ArticlePublicationMetadata only
    On the individual droplet growth modeling and heat transfer analysis in dropwise condensation
    (IEEE, 2021-10) Azarifar, Mohammad; Budaklı, M.; Başol, Altuğ Melik; Arık, Mehmet; Mechanical Engineering; BAŞOL, Altuğ Melik; ARIK, Mehmet; Azarifar, Mohammad
    The low convective coefficient at condenser part of spreaders and vapor chambers due to film blanket blocking encourages utilizing dropwise condensation (DWC). Challenges exist in the experimental characterization of DWC, which includes dependency on numerous parameters and more importantly measurement difficulties due to low driving temperature differences. This highlights the necessity of accurate modeling of this complex process. The widely used macroscale modeling process of DWC, known as classical analytical modeling of DWC, typically combines state of the art droplet size distribution model with a simplified shape-factor based heat transfer analysis of a single droplet which contains major simplifications such as conduction-only through the bulk liquid, hemispheric droplet shape, and homogeneously distributed temperature over the entire droplet surface. Recent numerical approaches included effect of Marangoni convection and implanted realistic thermal boundary conditions on liquid-vapor interface and reported significant errors of classical modeling. Based on a novel dynamic numerical approach which incorporates surface tension, Marangoni convection, and active mass transfer at the liquid-vapor interface, droplet growth phenomenon has been modeled in this study. Notable differences of droplet growth and flow field have been observed resulted from dynamic growth modeling of the droplet as more than 70% heat transfer rate underestimation of quasi steady modeling in 1 mm droplets with contact angle of 150° is observed. Effect of shape change due to gravity on the heat and mass transfer analysis of individual droplets found to be negligible.
  • Placeholder
    Conference paperPublicationMetadata only
    An investigation into momentum and temperature fields of a meso-scale synthetic jet
    (IEEE, 2014) Ghaffari, Omidreza; Doğruöz, M. B.; Arık, Mehmet; Mechanical Engineering; ARIK, Mehmet; Ghaffari, Omidreza
    Thermal management has become a critical part of advanced micro and nano electronics systems due to high heat transfer rates. More constraints such as compactness, small footprint area, lightweight, high reliability, easy-access and low cost are exposed to thermal engineers. Advanced electronic systems such as laptops, tablets, smart phones and slim TV systems carry those challenging thermal needs. For these devices, smaller thermal real estates with higher heat fluxes than ever have created issues that current thermal technologies cannot meet those needs easily. Therefore, innovative cooling techniques are necessary to fulfill these aggressive thermal demands. Synthetic jets have been studied as a promising technology to satisfy the thermal needs of such tight electronics devices. The effect of nozzle-to-surface distance for a synthetic jet on its cooling performance has neither been studied extensively nor been well-understood. In a few available experimental studies, it was reported that synthetic jet performance is very sensitive to this distance and when the jet gets closer to the hot surface its performance degrades. Therefore, a computational study has been performed to understand the flow physics of a small-scale synthetic jet for a jet-to-surface spacing of H/Dh=5. Spatial discretization is implemented via a second order upwind scheme and a second order implicit scheme is used for temporal discretization to ensure stability. It is found that pulsating flow at the nozzle exit generates vortices and these vortices seem to have minimal effect on the target surface profiles. Local surface pressure, velocity, turbulence profiles and heat transfer coefficient distributions are determined, then the effects of jet frequency as well as near-wall vortices are discussed.
  • Placeholder
    ArticlePublicationMetadata only
    Design and development of a durable series elastic actuator with an optimized spring topology
    (Sage, 2021-12) Yıldırım, M. C.; Şendur, Polat; Kansızoğlu, Mehmet Taha; Uras, U.; Bilgin, Onur; Emre, Sinan; Yapıcı, Güney Güven; Arık, Mehmet; Uğurlu, Regaip Barkan; Mechanical Engineering; ŞENDUR, Polat; YAPICI, Güney Güven; ARIK, Mehmet; UĞURLU, Regaip Barkan; Kansızoğlu, Mehmet Taha; Bilgin, Onur; Emre, Sinan
    This paper aims to present the integrated design, development, and testing procedures for a state-of-the-art torsion-based series elastic actuator that could be reliably employed for long-term use in force-controlled robot applications. The main objective in designing the actuator was to meet weight and dimensional requirements whilst improving the long-term durability, ensuring high torque output, and containing its total weight. A four-fold design approach was implemented: (i) following recursive design-and-test procedures, an optimal torsional spring topology was unveiled with the help of SIMP (Solid Isotropic Material with Penalization) topology optimization method, (ii) the proposed spring was manufactured and multiple specimens were experimentally tested via a torsional test machine to validate linearity, loading rate response, and mechanical limits, (iii) the actuator’s thermal response was experimentally scrutinized to ensure that the generated heat was dissipated for long-term use, and (iv) the fatigue life of the spring was computed with the help of real-life experiment data. Having concluded the development and verification procedures, two different versions of the actuator were built, and preliminary torque control experiments were conducted. In conclusion, favorable torque tracking with a bandwidth of 19 Hz was achieved while peak-to-peak torque input was 20 Nm.
  • Placeholder
    ArticlePublicationMetadata only
    An investigation into flow and heat transfer for a slot impinging synthetic jet
    (Elsevier, 2016-09) Ghaffari, Omidreza; Solovitz, S. A.; Arık, Mehmet; Mechanical Engineering; ARIK, Mehmet; Ghaffari, Omidreza
    According to the latest trends in miniature consumer and military electronics, there is a need for compact cooling solutions to meet performance requirements at compact volumes. Successful technology must feature a thin profile and a small footprint area, while still removing a significant amount of heat dissipation. Impinging synthetic jets driven by a piezoelectric membrane are a promising method for cooling small-scale electronics. In this paper, we explore the thermal response of a miniature synthetic jet impinging upon a vertical heater. In addition, we study the local flow field using the particle image velocimetry (PIV) technique to couple heat transfer with fluid dynamics. Heat transfer results show that the maximum cooling performance occurs with a jet-to-surface spacing of 5 ⩽ H/Dh ⩽ 10, which is associated with the flow consisting of coherent vortex structures. There is a degradation of heat transfer for closer jet-to-surface spacings, such as H/Dh = 2. This was due to the incomplete growth of the vortices, along with re-entrainment of warm air from the impinging plate back into the jet flow. There was also some warm air sucked back into the jet during the suction phase of the synthetic jet. For a fixed value of Reynolds number, cooling was improved at high Stokes numbers, but with a reduced coefficient of performance.
  • Placeholder
    Conference paperPublicationMetadata only
    An investigation into momentum and temperature fields of a meso-scale slot synthetic jet for a small jet-to-surface spacing
    (Begell House Inc., 2014) Ghaffari, Omidreza; Doğruöz, M. B.; Arık, Mehmet; Mechanical Engineering; ARIK, Mehmet; Ghaffari, Omidreza
    Impinging synthetic jets have been identified as a promising technology for cooling miniature structures. Recognizing their thermal performance on the target surface requires a fundamental understanding of the momentum field produced by the pulsating coolant flow which is dependent on the distance between the nozzle exit and the wall. It was earlier reported that the cooling performance of a synthetic jet is highly sensitive to this distance, i.e. as the nozzle-to-plate distance is reduced the jet performance degrades, however the fundamental mechanism for this behavior has not been well-understood. Therefore, a computational study is performed to investigate the flow and thermal fields of a meso-scale slot synthetic jet for a small jet-to-surface spacing of H/Dh = 2. Spatial discretization is implemented via a second order upwind scheme and a second-order implicit scheme is used for temporal discretization to ensure stability. The results show that the pulsating flow at the nozzle exit generates vortices and these vortices seem to have effect on the target surface profiles before they get dissipated. Mean surface profiles are also determined and their applicability at various frequencies is discussed.
  • Placeholder
    Conference paperPublicationMetadata only
    Effect of direct liquid cooling on light emitting diode local hot spots: Natural convection immersion cooling
    (Begell House Inc., 2014) Tamdoğan, Enes; Arık, Mehmet; Mechanical Engineering; ARIK, Mehmet; TAMDOĞAN, Enes; Tamdoğan, Enes
    The increased popularity of solid state systems with the technological developments have led them to be a favorable choice for many lighting applications besides electronics. However, the development of denser high lumen packages has been accompanied by increasing heat fluxes at the LED chip and package levels. Especially, the chips driven at high currents may experience local hot spots, which may cause thermal degradation or even catastrophic failures. As the air cooling has been widely used over the years and significant advances have been made to manage increased heat fluxes. It has been recognized as very difficult to rely solely on it to have an efficient cooling in higher heat fluxes. Moreover, active cooling methods may provide necessary thermal performance but at the expense of high cost and energy consumption. Hence, an efficient cooling capability in high heat fluxes (100 W/cm2) can be accommodated through the use of immersion liquid cooling. Immersion cooling has been studied for electronics circuits since last several decades where the thermal capability of such cooling systems have proved several orders of magnitude higher heat fluxes capability due to phase change heat transfer. Thus, direct liquid cooling with the usage of fluorocarbon liquids, generally considered as the most suitable liquids, has been applied in the current study. The thermal and optical performances of a multi chip LED light engine has been investigated with a series of computational fluid dynamics models and experimental validation studies. Heat transfer mode has been kept at the single phase in dielectric fluids. Effect on the local temperatures, peak and dominant wavelength shifts with respect to temperatures, and impact on total lumen extraction has been presented. Finally, a close form first order correlation has been developed for total lumen extraction depending on driving current and chip temperature.
  • Placeholder
    Conference paperPublicationMetadata only
    Direct liquid cooling of high flux LED systems: hot spot abatement
    (ASME, 2013) Tamdoğan, Enes; Arık, Mehmet; Doğruöz, M. B.; Mechanical Engineering; ARIK, Mehmet; TAMDOĞAN, Enes; Tamdoğan, Enes
    With the recent advances in wide band gap device technology, solid-state lighting (SSL) has become favorable for many lighting applications due to energy savings, long life, green nature for environment, and exceptional color performance. Light emitting diodes (LED) as SSL devices have recently offered unique advantages for a wide range of commercial and residential applications. However, LED operation is strictly limited by temperature as its preferred chip junction temperature is below 100 °C. This is very similar to advanced electronics components with continuously increasing heat fluxes due to the expanding microprocessor power dissipation coupled with reduction in feature sizes. While in some of the applications standard cooling techniques cannot achieve an effective cooling performance due to physical limitations or poor heat transfer capabilities, development of novel cooling techniques is necessary. The emergence of LED hot spots has also turned attention to the cooling with dielectric liquids intimately in contact with the heat and photon dissipating surfaces, where elevated LED temperatures will adversely affect light extraction and reliability. In the interest of highly effective heat removal from LEDs with direct liquid cooling, the current paper starts with explaining the increasing thermal problems in electronics and also in lighting technologies followed by a brief overview of the state of the art for liquid cooling technologies. Then, attention will be turned into thermal consideration of approximately a 60W replacement LED light engine. A conjugate CFD model is deployed to determine local hot spots and to optimize the thermal resistance by varying multiple design parameters, boundary conditions, and the type of fluid. Detailed system level simulations also point out possible abatement techniques for local hot spots while keeping light extraction at maximum.
  • Placeholder
    Conference paperPublicationMetadata only
    Effect of optical design on the thermal management for the smart tv led backlight systems
    (IEEE, 2014) Karslı, K.; Arık, Mehmet; Mechanical Engineering; ARIK, Mehmet
    Due to recent advances in electronics, lighting and communication technologies, SMART Televisions (TV) have become more affordable, and are rapidly eplacing old-fashioned LCD (liquid crystal display) TV technologies. These TVs are nearly ten times thinner; they include much brighter displays, true-color ualities, at least two times faster refresh rates and smart communication features. While providing such advanced features, lighting has become a critical part of technology advancement. While the backlight unit consumes over 50% of total energy in TVs, light emitting diodes (LEDs) have rapidly replaced the conventional CCFL (Cold Cathode Fluorescent Lamp) based LCD backlight units due to their low energy consumption. The present study identifies the impact of optical solutions with high-power LEDs located at the corner of the backlight unit on the optical efficiency for an advanced TV system. Various optical designs are created and impacting metrics for novel LED backlight units are determined. A computational and experimental study has been performed to identify the optical-thermal interactions in a tight-space LED packaging for a slim TV. Optical modeling has been performed via Light Tools optical simulation software, while thermal modeling was performed via Icepak CFD software. Smart optical packaging resulted in an effective light distribution of minimum 75% brightness uniformity, with no MURA effect problem on the panel The thermal challenge was found to be immense; so a smart thermal packaging was vital. An experimental validation of computational models was also performed. While the target is obtaining a uniform light distribution generated by HB (high brightness) LEDs and reduction of cost by having fewer LEDs, optical structure is found to be very critical in terms of both optical efficiency and pattern design of the light guide plate (LGP), which is an essential part of slim LED TVs. The study is concluded with a detailed discussion of the impact on lum- nance uniformity and cost for advanced SMART TVs.