Person: MENGÜÇ, Mustafa Pınar
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Mustafa Pınar
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MENGÜÇ
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ArticlePublication Metadata only Colorization of passive radiative cooling coatings using plasmonic effects(Elsevier, 2023-05) Pirouzfam, N.; Mengüç, Mustafa Pınar; Sendur, K.; Mechanical Engineering; MENGÜÇ, Mustafa PınarPassive radiative cooling is a novel concept and is likely to be important for building and industrial energy ef-ficiency efforts, as it will significantly contribute to the reduction of thermal management costs for electronic equipment. In most studies, radiative cooling devices are not considered for their colors; although to find a large number of users, it must be attractive to designers or architects, who usually pay significant attention to aesthetic and decorative aspects of paints. Since the majority of the coatings reported in the literature are white, there is also a need to develop color-coordinated paints and coatings. Here, we propose an approach for designing a simple structure of colored radiative cooling devices assisted by a plasmonic structures. We show that they can be tuned as desired to produce different hues of colored coatings, while maintaining adequate radiative cooling power. To demonstrate the conflicting functions of color display and radiative cooling performance, we use a bowtie nanoantenna as a color-displaying structure to investigate how the structural factors affect the cooling performance and color display accordingly. We show that periodic high index-low index alternating layers (SiO2-TiO2) on top of a thin silver layer cause broadband reflection in visible and near-infrared spectrums, while to achieve narrowband absorption in the visible region, which leads to the desired colorization, the bowtie nanoantenna is utilized. We report that by changing the structural parameters of a nanoantenna, the resonance peaks are controlled to yield a narrowband absorption in the visible spectrum to create different colors. More-over, our results indicate that although adding coloration structure to a conventional radiative cooling system reduces the cooling power by around 30%, it is still reasonable high, around 60 W/m2, and is still suitable to be used for daytime radiative cooling where control over the color is needed. Acceptable cooling power while ability to control the coloration make the proposed colored radiative cooling a potential candidate to be used in various applications, both in high end buildings or for thermal management of electronic equipment.BookPublication Metadata only Handbook of thermal science and engineering(Springer Nature, 2018-07-05) Kulacki, F. A.; Acharya, S.; Chudnovsky, Y.; Cotta, R. M.; Devireddy, R.; Dhir, V. K.; Mengüç, Mustafa Pınar; Mostaghimi, J.; Vafai, K.; Mechanical Engineering; Kulacki, F. A.; MENGÜÇ, Mustafa PınarThis Handbook provides researchers, faculty, design engineers in industrial R&D, and practicing engineers in the field concise treatments of advanced and more-recently established topics in thermal science and engineering, with an important emphasis on micro- and nanosystems, not covered in earlier references on applied thermal science, heat transfer or relevant aspects of mechanical/chemical engineering. Major sections address new developments in heat transfer, transport phenomena, single- and multiphase flows with energy transfer, thermal-bioengineering, thermal radiation, combined mode heat transfer, coupled heat and mass transfer, and energy systems. Energy transport at the macro-scale and micro/nano-scales is also included. The internationally recognized team of authors adopt a consistent and systematic approach and writing style, including ample cross reference among topics, offering readers a user-friendly knowledgebase greater than the sum of its parts, perfect for frequent consultation. The Handbook of Thermal Science and Engineering is ideal for academic and professional readers in the traditional and emerging areas of mechanical engineering, chemical engineering, aerospace engineering, bioengineering, electronics fabrication, energy, and manufacturing concerned with the influence thermal phenomena.ArticlePublication Metadata only Subcooled flow boiling heat transfer of γ-Al2O3/water nanofluids in horizontal microtubes and the effect of surface characteristics and nanoparticle deposition(Elsevier, 2017) Karimzadehkhouei, M.; Sezen, M.; Şendur, K.; Mengüç, Mustafa Pınar; Koşar, A.; Mechanical Engineering; MENGÜÇ, Mustafa PınarIn this study, subcooled flow boiling heat transfer characteristics of nanofluids were investigated at micro scale. For this purpose, the effect of γ-Al2O3 (gamma-alumina) nanoparticles with an average solid diameter of 20 nm was considered. In the experiments, various mass fractions were considered in horizontal smooth stainless steel microtubes with inner and outer diameters of ∼502 µm and ∼717 µm, respectively, at mass fluxes of 1200 and 3400 kg m−2 s−1. Nanoparticles were added to distilled water (base fluid) at five mass fractions (low mass fractions 0.05 wt% and 0.2 wt%; high mass fractions 0.5 wt%, 1 wt% and 1.5 wt%). According to our results, subcooled flow boiling heat transfer coefficients for nanofluids with low mass fractions were nearly the same as those of the pure water. However, heat transfer deteriorated for nanofluids with high mass fractions. Observations of dynamic light scattering measurements for low and high mass fractions before and after the experiments revealed that agglomeration of nanoparticles is an important parameter in deterioration of heat transfer at higher concentrations. Besides, Scanning Electron Microscopy images of microtube inner surfaces showed that deposition of nanoparticles and agglomerated nanoparticles on the inner surface of the microtubes also contributed to the heat transfer deterioration at high mass fractions. Generally, the deterioration in heat transfer beyond a specific mass fraction value was linked to the disturbance in the stability of suspended nanoparticles and deposition of nanoparticles upon boiling.ArticlePublication Open Access Analysis of sustainable materials for radiative cooling potential of building surfaces(MDPI AG, 2018) Family, Roxana; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Family, RoxanaThe main goal of this paper is to explore the radiative cooling and solar heating potential of several materials for the built environment, based on their spectrally-selective properties. A material for solar heating, should have high spectral emissivity/absorptivity in the solar radiation band (within the wavelength range of 0.2-2 m), and low emissivity/absorptivity at longer wavelengths. Radiative cooling applications require high spectral emissivity/absorptivity, within the atmospheric window band (8-13 m), and a low emissivity/absorptivity in other bands. UV-Vis spectrophotometer and FTIR spectroscopy, are used to measure, the spectral absorption/emission spectra of six different types of materials. To evaluate the radiative cooling potential of the samples, the power of cooling is calculated. Heat transfer through most materials is not just a surface phenomenon, but it also needs a volumetric analysis. Therefore, a coupled radiation and conduction heat transfer analysis is used. Results are discussed for the selection of the best materials, for different applications on building surfaces.ArticlePublication Open Access On occupant behavior and innovation studies towards high performance buildings: a transdisciplinary approach(MDPI, 2018-10-06) Keskin, Cem; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Keskin, CemWith ever-increasing population and urbanization, it is crucial to decrease energy density in the built environment without sacrificing occupants’ comfort and well-being. This requires consideration of technological developments along with the human factor in order to achieve environmental and social sustainability. Two major contributors to the development of conceptualizations for human-centric technologies are behavior and innovation (B&I) studies. Behavior studies aims to explain individualistic or society-based dynamics of human behavior whereas the innovation studies focuses on social, economic, organizational, and regulatory dimensions and processes of inventive activity. If these studies are incorporated into the hardcore architecture and engineering disciplines with a transdisciplinary approach, the orchestration of occupant behavior and the innovative technologies would be possible, which in turn significantly enhance the comfort and energy efficiency in built environments. This paper aims to provide an overview of interdisciplinary dialog between B&I studies and underlines the role of their collaboration to leverage transdisciplinary research on human-building interaction for energy efficiency. The approach presented here is structured as a conceptual framework and named the ‘socio-technical core’ (STC). STC is to lead to more organic articulation of energy efficiency innovations with real life and pave the way for higher level of acceptance. In order to have a ‘big-picture’ for the well-accepted conceptualizations and the current status of interdisciplinary dialog, we provide a review of (B&I) theories and models along with network analysis of key concepts. Then we investigate the potential directions of future transdisciplinary efforts by discussing the influences of B&I studies to each other for application to energy efficiency studies. In order to put the analysis in a firm background, we provide a case study for thermostat, which can be considered as a product improved with B&I approaches during last decades. We also discuss the benefits of B&I based transdisciplinary research perspective by referring to few examples in literature and the points emerged in this study.ArticlePublication Metadata only Enhancing local absorption within a gold nano-sphere on a dielectric surface under an AFM probe(Elsevier, 2016-07) Moghaddama, S. T.; Ertürk, H.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa PınarThis study considers enhancing localized absorption by a gold nanoparticle (NP) placed over a substrate where an atomic force microscope (AFM) tip is in close proximity of the particle. The gold NP and AFM tip are interacting with a surface evanescent wave, resulting a near-field coupling between the tip and NP and consequently enhances the absorption. This concept can be used for selective heating of NPs placed over a surface that enables precise manufacturing at nanometer scales. Different tip positions are considered to identify the optimal tip location and the corresponding enhancement limits. The effects of these interactions on the absorption profiles of dielectric core/gold shell NPs are also studied. It is observed that using core–shell nanoparticles with a dielectric core leads to further enhancement of the absorption efficiency and a more uniform distribution of absorption over the shell. Discrete dipole approximation coupled with surface interactions (DDA-SI) is employed throughout the study, and it is vectorized to improve its computational efficiency.ArticlePublication Metadata only A unified Monte Carlo treatment of the transport of electromagnetic energy, electrons, and phonons in absorbing and scattering media(Elsevier, 2010-02) Wong, B. T.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa PınarThe scalar Boltzmann transport equation (BTE) is often applicable to radiative energy transfer, electron–beam propagation, as well as thermal conduction by electrons and phonons provided that the characteristic length of the system is much larger than the wavelength of energy carriers and that certain interference phenomena and the polarization nature of carriers are ignored. It is generally difficult to solve the BTE analytically unless a series of assumptions are introduced for the particle distribution function and scattering terms. Yet, the BTE can be solved using statistical approaches such as Monte Carlo (MC) methods without simplifying the underlying physics significantly. Derivations of the MC methods are relatively straightforward and their implementation can be achieved with little effort; they are also quite powerful in accounting for complicated physical situations and geometries. MC simulations in radiative transfer, electron–beam propagation, and thermal conduction by electrons and phonons have similar simulation procedures; however, there are important differences in implementing the algorithms and scattering properties between these simulations. The objective of this review article is to present these simulation procedures in detail and to show that it is possible to adapt an existing MC computer code, for instance, in radiative transfer, to account for physics in electron–beam transport or phonon (or electronic thermal) conduction by sorting out the differences and implementing the correct corresponding steps. Several simulation results are presented and some of the difficulties associated with different applications are explained.ArticlePublication Metadata only Challenges for radiative transfer 1: towards the effective solution of conjugate heat transfer problems(Elsevier, 2018-12) Howell, J. R.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa PınarThis paper lists crucial challenges in radiative transfer with the objective of gathering information on improving and choosing methods for solving conjugate heat transfer problems. Developments in computational and experimental techniques allow much deeper analysis of the complex problems that industry faces. Accurate and efficient solution of such multi-dimensional problems is important to reduce energy consumption in industry, with long-term positive impacts on climate change. In this paper, four challenging conjugate heat transfer problems are defined. These problems are presented with the hope of attracting researchers to solve them and provide information on the methods used and difficulties encountered. This ‘challenge’ is to be an on-going effort as the new solutions to these problems and the detailed comparisons are to be posted as they become available. In addition, new challenge problems will be added as needed.ArticlePublication Metadata only Heat transfer enhancement with actuation of magnetic nanoparticles suspended in a base fluid(AIP, 2012) Şeşen, M.; Tekşen, Y.; Şendur, K.; Mengüç, Mustafa Pınar; Öztürk, H.; Yağcı Acar, H. F.; Koşar, A.; Mechanical Engineering; MENGÜÇ, Mustafa PınarIn this study, we have experimentally demonstrated that heat transfer can be substantially increased by actuating magnetic nanoparticles inside a nanofluid. In order to materialize this, we have utilized a miniature heat transfer enhancement system based on the actuation of magnetic nanoparticles dispersed in a base fluid (water). This compact system consists of a pool filled with a nanofluid containing ferromagneticnanoparticles, a heater, and two magnetic stirrers. The ferromagnetic particles within the pool were actuated with the magnetic stirrers. Single-phase heat transfer characteristics of the system were investigated at various fixed heat fluxes and were compared to those of stationary nanofluid (without magnetic stirring). The heat transfer enhancement realized by the circulation of ferromagneticnanoparticles dispersed in a nanofluid was studied using the experimental setup. The temperatures were recorded from the readings of thin thermocouples, which were integrated to the heater surface. The surface temperatures were monitored against the input heat flux and data were processed to compare the heat transfer results of the configuration with magnetic stirrers to the heat transfer of the configuration without the magnetic stirrers.ArticlePublication Open Access Local density of electromagnetic states within a nanometric gap formed between two thin films supporting surface phonon polaritons(AIP Publishing, 2010) Francoeur, M.; Mengüç, Mustafa Pınar; Vaillon, R.; Mechanical Engineering; MENGÜÇ, Mustafa PınarWe present a detailed physical analysis of the near-field thermal radiation spectrum emitted by a silicon carbide (SiC) film when another nonemitting SiC layer is brought in close proximity. This is accomplished via the calculation of the local density of electromagnetic states (LDOS) within the gap formed between the two thin films. An analytical expression for the LDOS is derived, showing explicitly that (i) surface phonon polariton (SPhP) coupling between the layers leads to four resonant modes, and (ii) near-field thermal radiation emission is enhanced due to the presence of the nonemitting film. We study the impact of the interfilm separation gap, the distance where the fields are calculated, and the thickness of the nonemitting layer on the spectral distribution of the LDOS. Results show that for an interfilm gap of 10 nm, the near-field spectrum emitted around the SPhP resonance can increase more than an order of magnitude as compared to a single emitting thin layer. Interfilm SPhP coupling also induces a loss of spectral coherence of resonance, mostly affecting the low frequency modes. The effect of the nonemitting film can be observed on LDOS profiles when the distance where the fields are calculated is close to the interfilm gap. As the LDOS is calculated closer to the emitter, the near-field spectrum is dominated by SPhPs with small penetration depths that do not couple with the modes associated with the nonemitting film, such that thermal emission is similar to what is observed for a single emitting layer. Spectral distribution of LDOS is also significantly modified by varying the thickness of the nonemitting film relative to the thickness of the emitting layer, due to an increasing mismatch between the cross-coupled SPhP modes. The results presented here show clearly that the resonant modes of thermal emission by a polar crystal can be enhanced and tuned, between the transverse and longitudinal optical phonon frequencies, by simply varying the structure of the system. This analysis provides the physical grounds to tune near-field thermal radiation emission via multilayered structures, which can find application in nanoscale-gap thermophotovoltaic power generation.