Person: MENGÜÇ, Mustafa Pınar
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Mustafa Pınar
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MENGÜÇ
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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.Conference paperPublication Open Access An evaluation of energy efficiency measures in a Turkish campus building for thermal comfort and economic risk(International Building Performance Simulation Association, 2015) Wang, Q.; Öcal, M. Rıfat; Augenbroe, G.; Mengüç, Mustafa Pınar; Özuyar, Pınar Gökçin; Entrepreneurship; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; ÖZUYAR, PinarAs new and retrofitted Turkish buildings adopt stateof-the-art energy efficiency measures, hidden risks associated with compromised thermal comfort and disappointing returns on investment could go unnoticed unless a building is subjected to an uncertainty and risk analysis. Standard deterministic predictions are not sufficient, as they do not capture the effects of uncertainty and variability with regard to local microclimate conditions, physical parameters, and discrepancies in the model formulations, also known as “model form uncertainties”. In this paper, we analyze the impact of uncertainty on the performance of a Turkish campus building. We examine the risk that an energy efficient design that is accepted because of the positive results of a conventional energy simulation, causes unacceptable discomfort and unsatisfactory returns on investment. The results of a comprehensive uncertainty analysis shows that these risks exist in certain areas and not in others. The predicted annual output of PV panels is relatively stable with only minor variability, which justifies the investment in Istanbul. Same with shading devices, which lead to a satisfactory internal rate of return under uncertainty. However, with regard to comfort we find that risks could be substantial. We find that relying completely on occupants opening and closing windows for fresh air with fan coil units maintaining the indoor temperature may lead to an insufficient supply of outdoor air for occupants and a substantial risk of overheating. Overall, the results of the analysis demonstrate that understanding risks is in some cases crucial to make an informed design decision regarding various energy saving design strategies.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.Conference paperPublication Metadata only Polarization imaging of multiply-scattered radiation based on integral-vector Monte Carlo method(Elsevier, 2010-01) Gay, B.; Vaillon, R.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa PınarA new integral-vector Monte Carlo method (IVMCM) is developed to analyze the transfer of polarized radiation in 3D multiple scattering particle-laden media. The method is based on a “successive order of scattering series” expression of the integral formulation of the vector radiative transfer equation (VRTE) for application of efficient statistical tools to improve convergence of Monte Carlo calculations of integrals. After validation against reference results in plane-parallel layer backscattering configurations, the model is applied to a cubic container filled with uniformly distributed monodispersed particles and irradiated by a monochromatic narrow collimated beam. 2D lateral images of effective Mueller matrix elements are calculated in the case of spherical and fractal aggregate particles. Detailed analysis of multiple scattering regimes, which are very similar for unpolarized radiation transfer, allows identifying the sensitivity of polarization imaging to size and morphology.ArticlePublication Metadata only Comparison between discrete dipole approximation and other modelling methods for the plasmonic response of gold nanospheres(Springer Science+Business Media, 2014-05) Loke, Vincent L. Y.; Huda, G. M.; Donev, E. U.; Schmidt, V.; Hastings, J. T.; Mengüç, Mustafa Pınar; Wriedt, T.; Mechanical Engineering; MENGÜÇ, Mustafa PınarWe investigate the plasmonic response of gold nanospheres calculated using discrete dipole approximation validated against the results from other discretization methods, namely the finite-difference time-domain method and the finite-element methods. Comparisons are also made with calculations from analytical methods such as the Mie solution and the null-field method with discrete sources. We consider the nanoparticle interacting with the incident field both in free space and sitting on a planar substrate. In the latter case, discrete dipole approximation with surface interaction is used; this includes the interaction with the 'image dipoles' using Sommerfeld integration.CorrectionPublication Open Access Publisher correction: A biomimicry design for nanoscale radiative cooling applications inspired by Morpho didius butterfly(2019-02-26) Didari, Azadeh; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Didari, AzadehA correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper. The original PDF version of this Article contained a truncated Figure 4. This error has now been corrected in the PDF version of the Article; the HTML version was correct from the time of publication.ArticlePublication Metadata only Plasmonic responses of metallic/dielectric core-shell nanoparticles on a dielectric substrate(IOP Publishing, 2019-06) Avşar, D.; Ertürk, H.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa PınarThe effect of material selection on the plasmonic response and local absorption are evaluated for core- shell nanoparticles placed over a BK7 glass substrate. Eight different core-shell pairs are studied using the vectorized version of discrete dipole approximation with surface interactions (DDA-SI). Two classes of dielectric core-metallic shell and metallic core-dielectric shell particles are considered. It is shown that core-shell structures with dielectric materials can have absorption enhancement compared to the bare metallic nanoparticles. Moreover, it is observed that core-shell pairs yield multipeak localized surface plasmon resonance (LSPR) response due to their hybrid structure. Absorption enhancement and LSPR tuning ranges are shown with different dielectric materials that can be used in localized heating of designated core-shell NPs placed over a surface for nanomanufacturing purposes. In order to determine the optimum size configurations, a number of core-shell pairs are explored with specified volumetric filling ratio of core materials.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.Conference paperPublication Open Access Exergy efficiency for radiation heat transfer(IOP Publishing, 2020) Mohammed, Hayder Noori; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar; Mohammed, Hayder NooriOne of the evaluation criteria for the performance of thermal processes is exergy analysis. Along with energy analysis, exergy calculations provide a clear and highly effective understanding of the performance of a system. Although exergy analysis has been extensively applied to many industrial processes, there are limited works for solar energy conversion systems that include the details of radiation transfer. The use of the Carnot efficiency expressions for calculating the exergy received from the thermal radiation source is questionable because it neglects the directional and spectral aspects of radiation heat transfer. In this study, the exergy efficiency calculations for radiation heat transfer in energy conversion systems are discussed. Comparisons of different expressions for exergy efficiency are presented, and the effects of source and sink temperature variations are explored.