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Browsing Centros UC by browse.metadata.fuente "ORCID-mayo23"

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    Assessment of the Effect of Phase Change Material (PCM) Glazing on the Energy Consumption and Indoor Comfort of an Office in a Semiarid Climate
    (2021) Daniel Uribe; Sergio Vera; CEDEUS (Chile)
    Office buildings are usually characterized by low thermal inertia, which could cause underperformance in terms of energy consumption. Moreover, the use of large, glazed facades in office buildings can cause thermal and visual discomfort due to high solar heat gains and excessive daylight transmitted into the office space. Phase Change Materials (PCMs) integrated into glazing have arisen as an innovative strategy to increase thermal inertia and improve office buildings' energy performance and indoor comfort at a low cost. This paper aims to analyze the impact of PCM glazing on buildings' energy performance and occupants' thermal and visual comfort. The analysis is performed through a one-year real-scale experiment in two offices in Santiago, Chile, with an east-oriented facade and a window-to-wall ratio (WWR) of 56%. The results are analyzed on two timescales: seasonally and daily. Representative days in each season were selected to carry out the analysis. Regarding the energy consumption of the HVAC system, PCM glazing reduces energy consumption during summer and mid-seasons and significantly reduces the peak loads in summer. A meaningful improvement in thermal comfort is achieved due to the control of the mean radiant temperature for the whole year. Considering visual comfort, there is an improvement in the luminance distribution in winter and mid-season cold conditions.
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    Effect of particle size on the photocatalytic activity of modified rutile sand (TiO2) for the discoloration of methylene blue in water
    (2019) Claudia Retamoso; CEDEUS (Chile)
    The advanced oxidation process (AOP) has been identified as a promising technology for pollutant degradation. To maximize the performance of this process, new materials need to be found or existing materials need to be modified. In this work, the effect of the particle size of modified rutile materials on the photocatalytic discoloration of methylene blue was investigated. Rutile samples with different particle sizes were obtained by milling, and the photocatalytic reaction was carried out in a continuous magnetic stirring photoreactor under UV-vis illumination. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), laser diffraction for particle size distribution (PSD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), N-2 adsorption (S-BET) and total X-ray fluorescence (TXRF). The results showed an efficiency increase in the photocatalytic activity of the materials for the discoloration of methylene blue in water; the rutile hematite sand had an efficiency of 8%, while the sample that underwent the highest energy milling had an efficiency of 64%. The improved efficiency of the photocatalytic activity occurred as the particle size decreased and the optical band gap shifted from the visible to the UV region of the light spectrum. By eliminating the natural iron impurities (hematite, according to the DRS and XPS results) from the surface of the rutile particles through milling, enhanced behavior was achieved. This was explained because the smaller particle size promoted an increase in the surface area, leading to a higher number of active sites on the nanoparticle surface, which allowed an increase in the removal of water pollutants in the UV-vis range of the solar spectrum.
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    Public transport and urban structure
    (2021) Leonardo J. Basso; Matias Navarro; Hugo E. Silva; CEDEUS (Chile)
    Public transport is central to commuting in most cities. This paper studies the role of public transportation in shaping the urban structure. Its main contribution is to propose a tractable model as a tool to study urban regulations and transport policies in the long-run. Using the classic monocentric city framework, we model public transport as a mode that can only be accessed by walking to a set of stops. By incorporating a discrete transport mode choice and income heterogeneity, the model remains simple yet can reproduce non-monotonous urban gradients observed in cities with public transport, and well-observed spatial patterns of sorting by income and use of public transport. For example, it can reproduce an inverted U-shape of transit usage along the city. To highlight the relevance of the model, we study the effects of pricing pollution externalities together with extending the public transportation network on the urban structure.
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    Seismic performance of squat thin reinforced concrete walls for low-rise constructions
    (2020) Hube, M.A.; María, H.S.; Arroyo, O.; Vargas, A.; Almeida, J.; López, M.; CEDEUS (Chile)
    Thin reinforced concrete (RC) walls with single layer reinforcement have been used for houses and buildings in several Latin American countries. Although some design codes include recommendations for squat thin walls in low-rise constructions, its seismic performance has not been validated adequately in past earthquakes. This article presents the results of an experimental campaign of nine full-scale specimens conducted to characterize the influence of the steel type, the reinforcement ratio, and the wall thickness on the seismic behavior of squat thin RC walls with single layer reinforcement. Both welded wire and deformed bars were used as web reinforcement. Experimental results are used to develop nonlinear models to assess the seismic behavior of a prototype two-story house with welded wire reinforcement and deformed bars by means of incremental dynamic analyses. The experimental results show that the type of steel has the largest influence on wall seismic performance. The numerical results suggest that RC walls with single layer reinforcement are suitable for housing applications up to two stories in high seismicity regions, particularly walls detailed with deformed bars.