Diego Andrés Vasco

University of Santiago, Chile | USACH · Departamento de Ingeniería Mecánica

The main results of an experimental study of the effect of temperature and nanoparticle concentration on thermal conductivity and viscosity of a nanofluid are shown. The nanofluid was prepared with Octadecane, an alkane hydrocarbon with the chemical formula CH3(CH2)16CH3, as a base fluid and 75-nm CuO spherical nanoparticles. Since the base fluid i...

Domestic refrigerators are among the most energy-consuming appliances. In many countries, efforts have been undertaken to enhance the thermal efficiency of domestic refrigerators, and such improvements have been focused mainly on compressor operation and electronic control. The use of phase change materials (PCMs) in domestic refrigerators decrease...

This paper reports on the properties of Pinus radiata wood impregnated with an organic phase change material (O-PCM). The tests are aimed at characterizing the kinetics of impregnation (rates, flows, and fronts) and the thermophysical properties (thermal conductivity and specific heat). In particular, a paraffin type O-PCM (octadecane) is used to i...

The inadequate use of passive thermal conditioning alternatives, such as phase change materials (PCM), in Chile, despite the climatological advantages in various regions of the country and the need to improve thermal comfort indexes in many houses and buildings, is mainly due to cultural and economic reasons. Passive thermal conditioning measures e...

In the present work, we have studied the laminar (200 ⩽ Re ⩽ 1200) three-dimensional flow of a water-based nanofluid in rectangular microchannels of constant wide cross section (283 μm) and three different heights (800 μm, 600 μm, and 400 μm). Moreover, we analyse the concentration of dispersed TiO2 nanoparticles (<6 nm) on the thermal and hydrauli...

Com mais de 1 bi de pessoas vivendo em favelas, estima-se que o objetivo de erradicar a pobreza não será alcançado até 2030 (meta ODS#1). Tendo políticas públicas habitacionais como foco, este trabalho objetiva discutir a importância de implementações no produto, de modo a transformar HIS em habitações acessíveis sustentáveis (HAS) e, ainda, aprese...

Cellulose and paper produce significant waste such as ash, activated sludge, and sludge from the pulp and paper industry. Depending on the raw material, legislation, and subprocesses, these sludges contain around 30–50% organic matter, mainly composed of less than 0.02 mm cellulose fibers and hemicellulose and lignin. This work used sludge from the...

The design, construction, operation, and maintenance of urban infrastructure are permanent activities that shape the built environment and impact the sustainability of cities as these are typically large projects and require a high degree of intervention. In recent times, infrastructure projects have been developed in an environment in which there...

Nowadays, there are many studies with a significant focus on affordable housing. The relevance of this theme, which is usually the central object of public housing policies, requires an updated review of the problems and challenges to be overcome, especially in terms of sustainability, in favor of an improvement in the quality of products delivered...

Over the past two decades, the field of Robotics in Construction has evolved into an interdisciplinary research domain that combines a multitude of pressing technologies. This work introduces an innovative review framework that assesses the interconnection between robotics in construction and automation, while also examining advancements in technol...

Renewable energy has become a relevant alternative to solve energy and environmental problems worldwide. The characterisation of the geothermal resource is fundamental for an efficient and sustainable extraction of heat. In this study, thermal conductivity λ , volumetric heat capacity C and thermal diffusivity α of two soils from Chile, namely Bío...

In recent years, wood has gained great popularity among engineers, builders, and architects, particularly in the construction sector. This is due to the physical and mechanical properties of wood along with its sustainable nature, which make it an excellent building material. However, understanding wood properties requires first the comprehension o...

Introduction: The construction sector plays a pivotal role in global natural resource consumption, underscoring the urgency of promoting energy efficiency in buildings. With the escalating demand for renewable energy, solar power has gained significant traction. This study focuses on conducting a comprehensive cost-benefit analysis of solar energy...

This article presents an improved mathematical model and numerical simulation for weathering of large areas with complex topography. It uses the equations of momentum, temperature, and humidity in turbulent air and for heat and water infiltration into soils. A mathematical model is also presented to calculate the soil porosity fraction produced by...

The thermal properties of Octadecane vary due to the addition of copper oxide (CuO) nanoparticles. The synthesis of two nano‐enhanced phase change material (NEPCM) required the implementation of the two‐step method, using Octadecane as the base phase change material and CuO nanoparticles at 2.5 and 5.0 wt%. The experimental characterization determi...

Project management has incorporated sustainability concepts, but their relationship is still widely discussed. In this article, we research key practices for incorporating sustainability in project management from the perspective of 919 Brazilian professionals with experience in the field. We used factor analysis to explore the relationship between...

This work analyzed the thermal behavior of an existing building, considering different retrofitting strategies. The methodology starts with an in-situ survey that allowed for obtaining information about occupation, work schedules, envelope materials, lighting, and equipment, which was vital to develop an energy model of the building. Then, the ther...

We numerically evaluated the thermal performance of microchannel heat sinks, considering rectangular, hexagonal, and circular cross-sections. Moreover, as a passive heat transfer augmentation technique, dimples were added to improve the rectangular microchannel heat sinks. These simulations use nanofluids based on TiO2 nanoparticles or nanotubes di...

Due to its anatomical properties, wood is an anisotropic, porous, and heterogeneous material with constituent cells of varying types and shapes. The time-dependent mechanical response of wood is of notable interest in structural applications, especially the viscoelastic response. This work characterized the viscoelastic response of Pinus radiata im...

Numerical simulations of a geothermal reservoir often assume that the primary heat source is a magmatic system; however, heat from the host rock and the coupled complex transport phenomena between magma chamber and host rock also need to be considered. This research numerically simulated the cooling history of an enclosed magma chamber and the ther...

Nanofluids have become of interest in recent years thanks to their improved thermal properties, which make them especially interesting for microchannel heat sink applications. In this study, we prepared two aqueous nanofluids based on reduced graphene oxide (rGO) decorated with manganese dioxide (MnO2) at a concentration of 0.1 wt.%. The difference...

he encapsulation of phase change materials (PCMs) is a convenient alternative for latent heat thermal energy storage systems (LHTESSs) because of the excellent relationship between their storage volume and the heat transfer surface. The goal is to establish a unified heat transfer behavior of encapsulated PCM. Computational fluid dynamics (CFD) num...

This article focuses on agar biopolymer films that offer promise for developing biodegradable packaging, an important solution for reducing plastics pollution. At present there is a lack of data on the mechanical performance of agar biopolymer films using a simple plasticizer. This study takes a Design of Experiments approach to analyze how agar-gl...

Carbon-based nanomaterials have a high thermal conductivity, which can be exploited to prepare nanofluids. Graphene is a hydrophobic substance, and consequently, graphene-based nanofluid stability is improved by adding surfactants. An attractive alternative is the decoration of reduced graphene oxide (rGO) with metallic materials to improve the the...

Hybrid materials based on ionic liquids (ILs) known as Ionanofluids (INFs) have shown exciting improvements in their thermophysical properties compared to their base fluids (BF). Within this group, INFs obtained using mixtures of ionic liquids as BFs have been virtually ignored until now. In this work, INFs composed of two equimolar mixtures of ILs...

The social, economic, and environmental impacts associated with fuels used to power cities cause the sustainability of energy produced and consumed in our urban environment to be constantly challenged. In order to address the issue of urban energy sustainability, we propose a Framework for Assessing Urban Energy Sustainability (FAUES), whose main a...

The present study examines the development of a push-pull ventilation system with localized extraction located for use in wastewater treatment. The proposed approach aims to minimize the concentration of H2S in the settling stage of a wastewater treatment plant located in Santiago de Chile. Computational fluid dynamic simulations were implemented,...

Water-based nanofluids prepared with ZnO nanoparticles (⩽17 nm) were characterized. The thermal conductivity and viscosity were measured as a function of temperature (278-303 K), for two ZnO concentration (1wt% and 3wt%) establishing that, whereas the nanofluid prepared with a concentration of 1wt% registered an average improvement of the thermal c...

This article presents the mechanical responses of Pinus radiata wood that was impregnated with octadecane to obtain a shape-stabilized phase change material (PCM). PCMs are used as heat storage materials to reduce the temperature peaks and displace the thermal loads in an enclosed space. It is important to study the effect of PCMs on the mechanical...

The development of long-time stable nanofluids for practical use in heat transfer processes is a tremendous scientific challenge because nanoparticles tend to precipitate and agglomerate when in a solution, affecting both their thermophysical properties and their stability. This work experimentally investigates the role of the electro-repulse force...

Adding Phase Change Materials (PCM) in construction elements and materials increase their thermal mass, which may reduce temperature variation of indoor environment and improve thermal comfort of occupants. The present paper aims to study the thermal and mechanical impacts of embedding microencapsulated PCM in the adhesive of plywood boards. Mechan...

The incorporation of phase change materials (PCM) in construction components has become an alternative to reduce the effect of thermal loads in buildings with low thermal inertia. This study put together the effective heat storage capacity of an organic phase change material (O-PCM, octadecane) with the construction and production potential of Pinu...

The application of phase change materials (PCM) in the thermal envelope of buildings has proven to be an alternative to reduce energy consumption and to improve thermal comfort conditions. The present work evaluates the thermal behavior of gypsum boards modified with a microencapsulated PCM (mPCM) in a cubic test enclosure, considering the climatic...

The present work in nanofluids is focusing into using the electro-kinetic phenomenal occurring around nanoparticles immersed in a base fluid as a method to stabilize a nanofluid and enhance its thermal conductivity. The electro-kinetic physic establishes, that when an electrolyte solution is in contact with a solid, an electric double layer (EDL) i...

In this work, a computational homogenization-based multiscale modeling strategy is adopted to compute the thermal conductivity of wood and to study the thermal performance of cross-laminated timber. In order to determine the thermal conductivity of wood within a multiscale modeling framework, the behavior of its microscopic constituents is investig...

Energy consumption of commercial buildings has increasingly gained attention worldwide, because of its significant electricity consumption and peak power demand. Chiller plants are mostly used in commercial buildings to generate cold water for air conditioning. However, because the chiller plants and the refrigeration systems tend to be oversized w...

Reversible Heat pumps is one of the most important key solutions to reduce energy consumption and carbon dioxide emission in residential and service buildings since they have a high energy efficiency compared to combustion-based systems. Although the refrigeration cycle is a mature technology with a high coefficient of performance, it is necessary...

Variable rates on electricity costs are used by utilities to reflect the high cost of providing electricity during peak periods of the day. The higher prices during peak hours are because the system needs a higher offer than the rest of the day to supply only these periods, which requires the entry of other rapid response systems, increasing the ma...

Nanofluids based on spherical gold, silver, and copper nanoparticles, nonspherical silver nanoparticles, layered graphene oxides (GO), and GO/silver hybrid structures, were synthesized to analyze their effect on the thermal behavior of direct absorption solar collectors. The thermal conductivities at room temperature of all the nanofluids were simi...

Laboratory scale experiments are performed in order to characterize the artificial wood drying of Pinus radiata at conventional temperatures and accelerated temperatures. The experimental data allow determining the wood thermal conductivity through inverse methodology. The comparative analysis shows that the implementation of the developed inverse...

Steam treatment was used in this work to correct the observed warp in dried core-wood radiata pine (Pinus radiata) lumber that appears during the industrial drying process at high temperatures. The experimental design considered seven tests and three process variables: temperature, overload, and treatment time. The warp and moisture content before...

Chile exhibits a continuous growth of energy demand, and for this reason energy saving approaches in the commercial, public, and residential sectors, which share 21% of the final energy consumption in Chile, have been encouraged. One of the solutions to increase energy savings in buildings and dwellings is to increase the thermal performance of the...

Numerical prediction of heat transfer by natural convection of a Herschel-Bulkley non-Newtonian fluid inside a square cavity has been computationally analyzed. Unsteady 2D fluid mechanics and heat transfer were described in terms of the non-linear coupled continuity, momentum and heat equations. These equations were solved by the control volume fin...

The present work studied the numerical modelling of heat transfer in a pile of Pinus radiata samples of a square cross-section by using radio frequency heating. More precisely, the study focused on the effects of the energy transferred to a dielectric material (wood) from an electromagnetic field, which required the calculation of the dielectric lo...

Nanofluids are a type of composite material with a demonstrated potential for improving heat transfer processes present in industries such as computers, electronics, and automobile. However, they have a limitation, which is that the suspended nanoparticles tend to agglomerate and in that way decrease their thermophysical properties. The present wor...

The present work was originally carried out as a project by HVAC-R engineering students of a heat transfer undergraduate course. The main goal was to introduce to the students to the implementation of a commercial simulation tool, ANSYS/Transient thermal, to analyze a transient heat transfer process of their professional interest. Behind this goal...

ExaStencils aims at providing intuitive interfaces for the specification of numerical problems and resulting solvers, particularly those from the class of (geometric) multigrid methods. It envisions a multi-layered domain-specific language and a sophisticated code generation framework ultimately emitting source code in a chosen target language. We...

A numerical and experimental analysis of the mechanical response of asphalt felt paper is presented. This material is widely used as a moisture barrier in buildings made of light materials. To ensure such function, it is necessary for this material not to be torn during its installation and operation and, for this reason, it is important to know it...

As in most countries, Chile exhibits a continuous growth of energy demand, although nowadays the country does not have enough conventional energy sources to supply it. For this reason, energy saving approaches in the residential sector have been encouraged. One of the solutions to improve the energy performance of the buildings is to decrease wasti...

This paper presents the results of a numerical study on the unsteady three-dimensional natural convection of a power-law fluid in a thick walled vessel being driven by natural heat convection in the surrounding air inside a cubical cavity. Continuity, linear momentum and energy equations for the internal Otswald the Waele shear thinning fluid, with...

Nanofluids are colloidal suspensions of nanometer-sized particles (metals, metallic oxides or carbon nanotubes) in a base fluid (polar or non-polar). Nanofluids have interesting properties that make them useful especially in the design of compact heat transfer equipment. Laminar convective heat transfer of nanofluids (water, Al2O3) in a square and...

RESUMEN Este trabajo presenta el análisis numérico y experimental del ensayo de tracción uniaxial del papel fieltro. Se caracteriza la respuesta mecánica del material la cual es de tipo elastoplástica con dependencia de las direcciones de fibras de celulosa presentes en el plano del papel. Esta estructura deriva del proceso de fabricación del papel...

RESUMEN El Decreto Supremo N • 47 de vivienda y urbanismo, plantea una serie de exigencias de acondi-cionamiento térmico que debe cumplir la envolvente de una vivienda respecto a los muros pe-rimetrales. El decreto establece un valor del coeficiente global de transferencia para cada zona térmica de Chile. Bajo este contexto, se plantea el estudio c...

RESUMEN Los materiales de cambio de fase (PCM), tienen la capacidad de almacenar energía térmica como calor latente, que puede ser liberada, absorbida y utilizado en aplicaciones de sistemas HVAC-R. Una propiedad desfavorable de los PCM orgánicos es su baja conductividad térmica, la cual no permite un proceso de carga y descarga eficiente de energí...

RESUMEN Una aplicación derivada de la capacidad de almacenamiento térmico de los PCM, es la regula-ción de temperatura que realizan, manteniéndola estable en un recinto por un periodo de tiempo. Mediante la implementación de PCM, es posible prescindir del uso de equipos HVAC, ya que las variaciones de la temperatura pueden ser reguladas mediante la...

Unsteady natural convection process of a fluid inside an inner walled vessel caused by an external forced turbulent convective flow of air in a rectangular duct has been analyzed numerically for Re = 5000; Re = 22,000. Fluid mechanics and conjugate convective heat transfer, for both inner fluid (water) and outer fluid (air), described in terms of c...

Resumen Nanofluids are colloidal suspensions of nanometer-sized particles (metals, metallic oxides or carbon nanotubes) in a base fluids such as water, ethylene glycol and paraffins. Nanofluids have novel properties that make them potentially useful in heat transfer equipment design. Laminar convective heat transfer of a nanofluid (water, Al2O3) in...

Three-dimensional fluid mechanics and heat transfer for viscoplastic flows are described by finite volume method, FVM. The open multi-processing approach has been implemented to parallelize the numerical code. Results for the elapsed times, speed-ups and efficiencies are presented. The code was used to describe the natural convection (Ra = 10(4); 1...