scholarly journals Specification of Glazings for Façades Based on Spectrophotometric Characterization of Transmittance

2021 ◽  
Vol 13 (10) ◽  
pp. 5437
Author(s):  
Helenice Maria Sacht ◽  
Luís Bragança ◽  
Manuela Almeida ◽  
Rosana Caram
Keyword(s):  
Heat Transfer ◽  
Optical Properties ◽  
Energy Consumption ◽  
Heat Exchange ◽  
Thermal Performance ◽  
Near Infrared ◽  
Temperate Climate ◽  
Solar Control ◽  
Indoor Spaces

The correct specification of glazings for façades can reduce the energy consumption in buildings. The heat exchange occurs through transparent surfaces and radiation reaches the building as light and heat. Therefore, glazings significantly contribute to the heat transfer between outdoor and indoor spaces and act directly on daylighting and thermal comfort. This paper reports on the spectrophotometric characterization of glazings transmittance for the study of components of a modular façade system and its suitability for the climate of Portugal (temperate climate). The study focused on results of spectrophotometric measurements of optical properties, specifically the transmittance of some types of glazings (solar control, self-cleaning, low-e, float, and extra-clear) and two types of double glazings. The results show the percentage of transmission to ultraviolet, visible, and near-infrared regions and its importance, which enabled the analysis of the glazing efficiency regarding daylighting and the correlation to thermal performance. Subsidies and indications for the specification and adequate uses of transparent surfaces have been presented and complemented the datasheets available from the manufactures.

scholarly journals Synthesis, Mesomorphism and the Optical Properties of Alkyl-deuterated Nematogenic 4-[(2,6-difluorophenyl)ethynyl]biphenyls

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4653
Author(s):  
Jakub Herman ◽  
Piotr Harmata ◽  
Michał Czerwiński ◽  
Olga Strzeżysz ◽  
Marta Pytlarczyk ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Optical Properties ◽  
Liquid Crystalline ◽  
Near Infrared ◽  
Synthesis And Characterization ◽  
Molecular Approach ◽  
Scanning Calorimetry

The synthesis and characterization of new deuterated liquid crystal (LC) compounds based on phenyl tolane core is described in this paper. The work presents an alternative molecular approach to the conventional LC design. Correlations between molecular structure and mesomorphic and optical properties for compounds which are alkyl-hydrogen terminated and alkyl-deuterium, have been drawn. The compounds are characterized by mass spectrometry (electron ionization) analysis and infrared spectroscopy. They show enantiotropic nematic behavior in a broad temperature range, confirmed by a polarizing thermomicroscopy and differential scanning calorimetry. Detailed synthetic procedures are attached. Synthesized compounds show a significantly reduced absorption in the near-infrared (NIR) and medium-wavelength infrared (MWIR) radiation range, and stand as promising components of medium to highly birefringent liquid crystalline mixtures.

Optical properties of traditional clay tiles for ventilated roofs and implication on roof thermal performance

2018 ◽  
Vol 42 (4) ◽  
pp. 484-505 ◽  
Author(s):  
Elisa Di Giuseppe ◽  
Simona Sabbatini ◽  
Nikita Cozzolino ◽  
Pierluigi Stipa ◽  
Marco D’Orazio
Keyword(s):  
Optical Properties ◽  
Thermal Performance ◽  
Temperate Climate ◽  
Second Phase ◽  
Analysis Tool ◽  
Urban Heat ◽  
Indoor Comfort ◽  
The Impact ◽  
Clay Tiles ◽  
Warm Temperate

A remarkable advantage of clay tiles roof coverings in hot climates is the realization of a ventilated air layer between them and the roofing underlay that allows a natural and forced convection through the tiles joints and the channel from eaves to ridge, thus cooling the roof materials. However recently, in many countries, regulatory developments on buildings energy efficiency or buildings sustainability certification protocols are increasingly encouraging the use of alternative strategies, with the aim of reducing the urban heat island (UHI) effect and the buildings’ cooling consumptions. Among them, the use of ‘cool’ materials for roof covering. These mandatory or voluntary measures de facto push the construction products market towards specific directions, risking penalizing traditional components such as clay tiles. This article reports the results of experimental and numerical activities carried out in order to extensively characterize the optical properties of clay tile materials and investigate their impact, also coupled with above sheathing ventilation, on the thermal performance of a ventilated roof under warm-temperate climate. In the first phase of the research, the main optical properties of over 30 different clay products have been experimentally characterized in order to get a clear and extensive picture of such properties for the materials spread in the market. In a second phase, starting from the thermal data collected on an experimental real-scale building, a dynamic energy analysis tool was calibrated and used to perform simulations by varying the optical properties of the roof covering thus assessing the impact on the roof temperatures, also in comparison to a clay tiles roof. The results underline that the use of the above sheathing ventilation obtained through clay tiles is an effective strategy to reduce roof temperatures, even if covering materials are not qualified as ‘cool’, thus impacting on both UHI and indoor comfort.

scholarly journals Fluorine-Doped Tin Oxide Colloidal Nanocrystals

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 863 ◽  
Author(s):  
Owen Kendall ◽  
Pierce Wainer ◽  
Steven Barrow ◽  
Joel van Embden ◽  
Enrico Della Gaspera
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Tin Oxide ◽  
Near Infrared ◽  
Transparent Electrode ◽  
High Quality ◽  
Detailed Characterization

Fluorine-doped tin oxide (FTO) is one of the most studied and established materials for transparent electrode applications. However, the syntheses for FTO nanocrystals are currently very limited, especially for stable and well-dispersed colloids. Here, we present the synthesis and detailed characterization of FTO nanocrystals using a colloidal heat-up reaction. High-quality SnO2 quantum dots are synthesized with a tuneable fluorine amount up to ~10% atomic, and their structural, morphological and optical properties are fully characterized. These colloids show composition-dependent optical properties, including the rise of a dopant-induced surface plasmon resonance in the near infrared.

Novel Turbulators to Enhance Turbine Blade Internal Heat Transfer Rates

2015 ◽  
Author(s):  
Venkata Naga Ramakumar Bommisetty ◽  
Sridhar Murari ◽  
Jong S. Liu ◽  
Malak F. Malak
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Turbine Blade ◽  
Thermal Performance ◽  
Thermal Load ◽  
Turbine Blades ◽  
Internal Heat ◽  
Current Paper ◽  
Transfer Rates ◽  
Internal Heat Transfer

Turbine blades are driven by hot gases from the combustor. The heat transfer from the hot gases produces substantial thermal load and can affect the performance of the turbine blades. In previous designs, cavities inside the blades were created to pass the coolant. Such cooling designs helped to increase the thermal performance of the blades by taking away the turbine blades’ heat. The cooling effect was further enhanced by increasing the turbulence in the flow of coolant. To increase the turbulence in the cavities, various turbulator designs were proposed. However, most of the designs have also introduced wake area while increasing the turbulence. This reduces the heat exchange between the coolant and the blade. The current paper discusses new designs of tabulators for turbine blades that increase the heat transfer rates of the cooling surface by increasing the turbulence of the coolant flow while minimizing the wake area.

scholarly journals Thermal Performance of a Low-Temperature Heat Exchanger Using a Micro Heat Pipe Array

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 675 ◽  
Author(s):  
Jingang Yang ◽  
Yaohua Zhao ◽  
Aoxue Chen ◽  
Zhenhua Quan
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Low Temperature ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Flue Gas ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Micro Heat Pipe

Domestic heat exchangers, even though widely used in industry, are not adequate for studies on low-temperature flue-gas use technologies. Despite spite their limitations, very few theoretical models have been investigated based on practical applications. Moreover, most of the existing studies on heat exchangers have focused particularly on one-dimensional and two-dimensional heat transfer models, while limited studies focus on three-dimensional ones. Therefore, this study aims at investigating the thermal performance of a low-temperature flue-gas heat recovery unit in the cold regions. Specifically, this study was conducted in the context of Changchun of Jilin Province, China, a city with the mean ambient temperature of −14 °C and mean diurnal temperature of −10 °C during winter. Experimental results showed that the thermal efficiency of the heat exchanger was higher than 60%. Through assessing the heat exchange coefficient and heat exchange efficiency of the heat exchanger, it is found that the thermal efficiency had been improved up to 0.77–0.83. Furthermore, the ICEPAK software and the standard k-ε RNG turbulence model were used to carry out simulations. The velocity and outlet temperature of fresh airflow and polluted airflow were simulated through setting different inlet temperatures of fresh air and polluted air inlet. Numerical results further indicated that the flow state was laminar flow. The micro heat pipe array side had small eddies and the heat transfer was significantly improved due to the flow of air along the surface of the micro heat pipe.

Impacts of Courtyard Geometrical Configurations on Energy Performance of Buildings

2019 ◽  
Vol 4 (10) ◽  
pp. 29
Author(s):  
Abdulbasit Almhafdy ◽  
Norhati Ibrahim ◽  
Sabarinah Sh Ahmad
Keyword(s):  
Energy Consumption ◽  
Thermal Performance ◽  
Architectural Design ◽  
Publishing House ◽  
Energy Performance ◽  
Design Element ◽  
Humid Climate ◽  
Simulation Tools ◽  
International Publishing ◽  
Indoor Spaces

The courtyard is an architectural design element often regarded as microclimate modifiers. It has the potential of improving comfort conditions within the outdoor courtyard space and the enclosing indoor spaces. Harnessing the optimum benefits of courtyards depends on several conditions namely the orientation and configurations of the courtyards, as well as the treatment of the external surfaces of the enclosing building envelopes. As three variables of orientation, number of floors and wall envelope have not been investigated in a single study, therefore, this parametric study was performed to investigate the microclimatic influence of varying courtyard geometric configurations and its enclosing facades in hot and humid climate using IES<VE> simulation tools. The study observed the environmental impact regarding thermal performance and energy consumption of the enclosing indoor spaces. The results suggest optimum conditions to harness the potential of courtyards to lower energy consumption of buildings in the tropics.Keywords: courtyard; thermal performance; energy consumption; simulationeISSN: 2398-4287 © 2019. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.DOI: https://doi.org/10.21834/e-bpj.v4i10.1637

Experimental Characterization of Heat Transfer and Thermal Energy Storage Capability Using Swirling Two-Phase Flow in the Package Integrated Cyclone COoler (PICCO)

2020 ◽  
Author(s):  
Peter deBock ◽  
Rinaldo Miorini ◽  
Cathleen Hoel ◽  
Darin Sharar ◽  
Bryan Whalen
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Resistance ◽  
Power Electronics ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Two Phase ◽  
Thermal Capacitance

Abstract The increasing demand for high power density wide-bandgap power electronics has propelled heat transfer research leading to a constant increase in the thermal performance of cold plates and heat sinks. Most of this research has focused on reducing thermal resistance of the package which can have a detrimental effect on transient thermal performance if thermal capacitance is reduced. In order to provide both a low thermal resistance and a higher thermal capacitance integrated into the package and near the thermal junction, a new cold plate called the Package Integrated Cyclone COoler (PICCO) was developed. GE Research and the US Army Research Lab collaborated to explore and validate the potential of this concept. The PICCO coldplate, which is enabled by 3D printing, establishes a swirling coolant flow field to remove heat. The swirling flow is anticipated to significantly aid in vapor removal from the surface and hence allow for the fluid to provide thermal capacitance through two-phase heat transfer efficiently. This paper describes the experiment design and development for thermal storage and cooling performance characterization of PICCO. The test rig includes a high-pressure capability gear pump moving fluid first through a Coriolis flowmeter and then through PICCO, where the fluid is accelerated in the cyclone and heated by miniaturized ceramic heaters, simulating SiC power electronics. The coolant releases the accumulated enthalpy to a plate-fin heat exchanger that is connected to a chiller. Several absolute and differential pressure transducers and thermocouples monitor the state of FC-72. The experiments will provide empirical transfer functions characterizing the PICCO pressure drop, heat transfer coefficient, critical heat flux and thermal energy storage capability.

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