Gabriela del Socorro Álvarez-García

• Physicist, M.S. in M. E. , PhD in Engineering
• Professor (Full) at Centro Nacional de Investigación y Desarrollo Tecnológico

A study of the experimental thermal performance of a green roof in a semi-warm climate of Mexico, which considers the irrigation effect, is presented. The experiment was performed in two stages. The first stage consisted of selecting from among five types of plants, commonly used in green roofs, the one that tolerates the greatest number of days wi...

A reflective roof is an ordinary roof with a reflective coating on its outer surface, it is characterized for its high solar reflectance and thermal emittance. In spite of its benefits, this technology is not well known in Mexico and there exist little information about the solar reflectance and thermal emittance for the coatings available in the c...

The thermal evaluation of a Room (R) coupled with a Double Glazing Window (DGW) with/without solar control film (SCF) under warm and cold climate conditions of an extreme weather of Mexico is presented. The right vertical wall of the room is partially adiabatic and contains the DGW. The DGW consists of two vertical semitransparent walls: glazing-1...

The pseudo-transient thermal performance (each 5 seconds) of a double pane window without and with a solar control coating was determined numerically. The study considers warm climatic conditions (Mexico) and a period from 8:00 to 18:00 hrs. The effect of varying the indoor air temperature (15 – 30°C); and the incident solar radiation and the outdo...

A numerical analysis of the effect of heat conduction of different building materials on conjugate heat and mass transfer in a square cavity is presented. The air fluid inside the cavity is contaminated with Carbon Dioxide (CO2). The governing equations of mass, momentum, energy and concentration with a turbulent k-ε model were solved by the finite...

Laminar and turbulent convective heat transfer in a ventilated and nonventilated cavity was analyzed by heatlines. Heatlines show that in non-ventilated cavities it is possible to estimate the energy path using the streamlines for turbulent flow regime. In ventilated cavities, heatlines allow to observe that thermal energy travels along the top, by...

This study reports the modeling of the turbulent natural convection in a double air-channel solar chimney (SC-DC) and its comparison with a single air-channel solar chimney (SC-C). Prediction of the mass flow and the thermal behavior of the SC-DC were obtained under three different climates of Mexico during one summer day. The climates correspond t...

This work quantifies the effect of the tree shading and the effect of neighboring buildings shading on the thermal performance of a non-air-conditioned house in a warm sub-humid climate. Experimental measurements and simulations using EnergyPlus of the unoccupied house were conducted from April to December 2011 with tree shading and from January to...

Opuntia ficus-indica, also known as nopal, is a cactus which grows on arid and semiarid lands of America. Dehydrated nopal is an alternative for food preservation, but drying times of cladodes are very long. The objective of this study was to evaluate dry kinetics of nopal thin slices, of 4 mm thick, 140 mm long and 17 mm wide. We conducted the dry...

A numerical study of a double pane window (DPW) with three types of commercial glass available in Mexican market is presented. The DPW consist of two vertical semitransparent walls separated by an air gap. The effect of varying the gap width (b) between glasses, the room temperature and the incident solar radiation is analyzed. Simulations were con...

A numerical study of a double pane window (DPW) with three types of commercial glass available in Mexican market is presented. The DPW consist of two vertical semitransparent walls separated by an air gap. The effect of varying the gap width (b) between glasses, the room temperature and the incident solar radiation is analyzed. Simulations were con...

The numerical study of double-diffusive natural convection in an inclined rectangular cavity, that simulates a solar still, is carried out. Surface thermal radiation and heat conduction in a glass cover are considered. The study analyzes the effect of the glass cover, the aspect ratio (5 ≤ A ≤ 20) and the tilt angle (15° ≤ θ ≤ 35°). The value of A...

This paper presents the design of a semi-automatic device for measuring the variables to calculate the thermal resistance of wall systems of buildings. The device is inspired in the hot plate technique from ASTM C-177. It consists of two units: a heating plate and cold plate. The hot plate was designed inserting a coiled electric resistance in para...

A cool roof is an ordinary roof with a reflective coating on the exterior surface which has a high solar reflectance and high thermal emittance. These properties let the roof keep a lower temperature than a standard roof under the same conditions. In this work, the thermal performance of a concrete roof with and without insulation and with two colo...

A numerical study was conducted for prediction of the thermal performance of an Earth-to-Air Heat Exchanger (EAHE) for three cities in México. The climatic conditions correspond to a temperate climate (México City), a humid-hot climate (Mérida, Yucatán) and an extreme weather (Cd. Juárez, Chihuahua). The effect of thermal insulation at the outlet s...

A transient numerical study of heat and mass transfer by turbulent natural convection of an Air–Carbon Dioxide mixture (CO2) inside a ventilated cavity is presented. The working fluid is initially considered to be at rest at an initial temperature and concentration. The inlet air velocity is a function of the Reynolds number (5 × 102 ⩽ Re ⩽ 2 × 104...

Reflective materials applied to opaque building components are becoming increasingly important because of their benefits in terms of thermal comfort and energy savings. Because of their optical properties, reflective materials stay cooler than standard materials under the same conditions; therefore, they are also known as cool materials. This paper...

A theoretical study to determine an optimal configuration for removal a CO2 contaminant from inside a room is presented. The geometry considered was a 2D ventilated cavity in turbulent flow regime and solving the governing equations of mass, momentum and chemical species by the finite volume method. The interval of Reynolds number under study was 0...

A numerical study of the heat transfer in a room with a laminated glazing wall with solar control films is presented. The thermal evaluation was performed on three different configurations of the laminated glazing, with films of CuS–Cu2−xSe or CuS using polyvinyl butyral (PVB) and/or polyethylene terephthalate (PET). For a reference case, a single...

A theoretical study to determine an optimal configuration for removal a CO2 contaminant from inside a room is presented. The geometry considered was a 2D ventilated cavity in turbulent flow regime and solving the governing equations of mass, momentum and chemical species by the finite volume method. The interval of Reynolds number under study was 0...

A numerical study was conducted for prediction the thermal behavior of an Earth-to-Air Heat Exchanger (EAHE) for three cities in México. The climate conditions correspond to an extreme heat in summer and low temperature in winter (Cd. Juárez, Chihuahua), mild weather (México city) and hot weather (Mérida, Yucatán). A Computational Fluid Dynamics co...

Dynamic simulation modeling was used to assess the impacts of cool roofs on energy consumption for non-residential and residential buildings in Mexico. Seven cities, selected from Mexico’s six climatic zones, were identified to simulate the energy loads of residential and non-residential buildings. The climates and cities were: humid hot (Villaherm...

A theoretical study of a room on top of a building with three different glazed configurations in Mexico City is presented. The research aims to show the advantages of using coupling models (CFD-BES) instead stand-alone solutions. The CFD model was simulated as a 2D cavity considering conjugate heat transfer and solving the governing equations by th...

Double-diffusive natural convection and surface thermal radiation in an inclined cavity that simulates a solar still device is studied numerically. The parameters considered were 103 ≤ RaT (RaM) ≤ 106, 8 ≤ A ≤ 16 and 15° ≤ θ ≤ 35°. The steady state 2-D governing equations have been solved by the finite volume method. Streamlines, isotherms, isoline...

Heat and mass transfer by natural convection in a square cavity filled with a mixture of air and carbon dioxide (CO2), as well as temperature and concentration gradients are numerically investigated. The study was conducted through laminar and turbulent regimes in order to analyze the influence of the buoyancy ratio changes (0 ⩽ N ⩽ 2.0) on heat tr...

Numerical results obtained from the analysis of the conjugated heat and mass transfer of an Air-Carbon Dioxide mixture (CO2) inside a ventilated cavity in turbulent flow regime are presented. Different configurations of the cavity were analyzed regarding the location of the mixture outlet gap in order to study the thermal behavior and the air quali...

In this paper we present a theoretical study of a small solar chimney. The dimensions of the solar chimney channel are 1.95 m high, 1.70 m wide, and 0.24 m deep. The channel of the solar chimney has in its backside a metallic plate as a solar heat absorber, and it is attached to a concrete wall, which acts as storage and thermal insulation. On the...

This paper presents the effect of the shade of a tree on the indoor temperature and thermal loads of a house (test house) located in the State of Morelos, Mexico, 18° 50′ 43″ north latitude and 99° 10′ 44″ west longitude. Energy Plus was used to simulate different geometries of the shadow of a tree and the simulation results were compared with expe...

In this paper a theoretical study on conjugated heat transfer (natural convection, radiation and conduction) in a square room (cavity) with turbulent flow is presented, taking into account variation on the opaque wall emissivity. The room is formed by an isothermal vertical wall, two adiabatic horizontal walls and a semitransparent wall with and wi...

In this paper, the results obtained from the analysis of the heat and mass transfer of an Air–Carbon Dioxide mixture (CO2) inside a ventilated cavity in laminar flow regime are presented. A ventilated cavity is usually the way to model a ventilated room as a first approximation. Different configurations of the cavity were analyzed regarding the loc...

The use of solar passive strategies such as new solar control coatings on windows for buildings with large glazed areas, have recently become important and helpful tools, mainly because these developments help to reduce heat gains and/or losses through transparent materials, diminishing energy loads, and improving the environment inside buildings....

In this paper the thermal analysis by natural convection of a double glazing unit (DGU) is presented. One of the sheet glasses may or may not have a solar control film (SnS–CuxS) on its surface. Solar radiation falls on the outside surface of the DGU at 32°C, the opposite sheet glass interacts with the inside environment at 24°C. The governing equa...

A theoretical study on conjugated heat transfer (natural convection, radiation and conduction) in a square cavity with turbulent flow is presented. The cavity is a representation of a room, where the left wall is isothermal, the right wall is semitransparent (glass), the lower wall is considered as insulated and on the upper opaque wall heat conduc...

This paper describes a TRNSYS simulation of a space of an office building in dessert climate. The space simulated by TRNSYS represents a meeting room which is placed in one of the high mass buildings of the Plataforma Solar of Almeria located in the desert of Tabernas, Spain. The meeting room was selected because hygrothermal variables are being me...

In this paper we present the theoretical and experimental study of a small solar chimney. The dimensions of the solar Chimney channel are 1.95 m high, 1.70 m width and 0.24 m depth. The channel of the solar chimney has in its backside a metallic plate as a solar heat absorber, and it is attached to a concrete wall, which acts as a storage and therm...

Natural ventilation in buildings using solar passive systems, such as solar chimneys, has emerged in the last years. Several theoretical and experimental studies in the literature show that their design parameters strongly depend on the ambient conditions, in which they are installed. In order to increase the knowledge of this kind of systems, this...

A steady state numerical study of combined laminar mixed convection and conduction heat transfer in a ventilated square cavity is presented. The air inlet gap is located at the bottom of a vertical glazing wall and air exits the cavity via a gap located at the top surface. Three locations for the opening at the top surface: left (case a), center (c...

Thermal performance of a solar chimney for natural ventilation was experimentally investigated. The experimental model was implemented on full scale and real meteorological conditions, so that experimental results will be compared with the simulation results. The results show that for a maximum irradiance of 604W/m2, occurring around 13:00h on Sept...

A numerical study of conjugated heat transfer in a ventilated cavity was carried out in order to analyze temperature distribution effectiveness inside it, and to determine a good ventilation configuration. The space was represented by a ventilated cavity under turbulent flow regime. All the walls were considered adiabatic, except the vertical wall...

Recently, new buildings are being designed considering natural sources such as natural ventilation as a passive technique. Solar chimneys are among those techniques of passive ventilation systems in buildings, to enhance the air quality and some times the thermal comfort. In this work, a numerical study of a solar chimney for forced ventilation is...

This paper presents a numerical study of the conjugate heat transfer (natural convection, surface thermal radiation and conduction) in a square cavity with turbulent flow. The cavity has one vertical isothermal wall, two horizontal adiabatic walls and one vertical semitransparent wall with a selective coating applied to the inner side to control th...

A two-dimensional numerical study of combined heat transfer (laminar and turbulent natural convection, surface thermal radiation and conduction) in a square cavity with a glass wall is presented. The cavity is modeled as one vertical isothermal wall, two horizontal adiabatic walls and one vertical glass wall. Numerical results in the cavity are obt...

We present a theoretical and experimental study of combined heat transfer in a cubic cavity containing non-participating air. The cubic cavity has a vertical semitransparent wall (glazing) with a solar control coating (SCC); an opaque black isothermal wall forms its opposite side. The top, bottom and side walls are opaque, gray and adiabatic. In th...

In this paper a numerical investigation of the interaction between two modes of heat transfer, natural convection and surface thermal radiation, in a tilted slender cavity is studied. The bottom and top surfaces of the cavity are heated and cooled at constant temperatures, while its sidewalls remain thermally insulated. The studied parameters are:...

This paper presents a climate characterization methodology for comfort purposes. The climate characterization is based on the measured climatic variables collected by a meteorological automatic station for 7 municipalities of the State of Morelos, Mexico. Then, a typical building in the State of Morelos is selected to calculate energy loads by two...

In this paper, a numerical investigation of the two modes of heat transfer, natural convection and surface thermal radiation, in a tilted slender cavity such a collector is presented. The 2-D conservation of mass, momentum and energy are coupled with a radiative model through the boundaries and solved by the finite volume method. The studied parame...

Conjugate mixed convection and conduction heat transfer in a ventilated square cavity is studied numerically using the 2-D steady state Navier-Stokes equations. All the walls were considered adiabatic except for the right vertical wall which is an opaque wall, which has a small air opening at the bottom side. Constant heat flux is assumed to be sup...

Interaction effects of semitransparent glazing with SnS-Cu x S solar control coating on the turbulent natural convection in a square cavity containing air is analyzed numerically. The size of the cavity covers a range from 0.70 to 6.98 m (Ra = 109–1012). One vertical wall of the cavity is isothermal, and the opposite one is the semitransparent glaz...

En este articulo se presentan los resultados numéricos de transferencia de calor por convección natural en una cavidad cúbica abierta. En la formulación matemática las suposiciones más importantes son dos: el flujo es laminar y la aproximación de Boussinesq es valida. Las ecuaciones de conservación son presentadas en variables primitivas y son resu...

Se presenta el estudio numérico de la transferencia de calor en una cavidad alargada e inclinada calentada diferencialmente desde la parte inferior. Se consideró a la cavidad alargada en dos dimensiones conteniendo en el interior aire. Se consideró que la placa absorbente y la cubierta de vidrio fueran superficies isotérmicas a una temperatura cali...

In this communication, the numeric results of the heat transfer by natural convection and surface thermal radiation in a tilted 2D open cavity are presented. This study has importance in the thermal design of receivers for solar concentrators. The opposite wall to the aperture in the cavity holds a constant temperature of 500 K, while the temperatu...

Laminar and turbulent natural convection flow in a two-dimensional tall rectangular cavity heated from the vertical side has been investigated numerically for aspect ratios of 20, 40 and 80. The finite volume method was used to solve the conservation equations of mass, momentum and energy for Rayleigh numbers from 102 to 108, the flow was considere...

This article reports a numerical study of the transient and steady-state heat transfer and air flow in a horizontal square open cavity. This study has importance in several thermal engineering problems, for example, in the design of electronic devices and thermal receivers for solar concentrators. The most important assumptions in the mathematical...

In this study, solar control coatings were prepared by sequential depositions of thin films of ZnS (40 nm)–CuS (150 nm) and ZnS (40 nm)–Bi2S3 (75 nm)–CuS (150 nm) from chemical baths on 3 mm thick commercial sheet glass. These were laminated to 3 mm thick clear glass or commercially available SnO2 based heat mirror coating of sheet resistance 15 Ω...

The present paper describes the development and testing of an efficient single-glass air solar collector with an absorber plate made of recyclable aluminum cans (RAC). This collector was designed as a proposal to use recycle recyclable materials to build absorber plates of air solar collectors at an acceptable cost. The absorber plate of the collec...

This paper presents an experimental heat transfer study of the exterior side of a semitransparent wall (window) with film coating of a enclosure. The absorptance of the semitransparent wall with film coating was simulated using a film resistance on the glazing. A technique of infrared imagining thermography and a traversing system developed in Lawr...

Influence of thermal emittance on the performance of laminated solar control glazing is presented. A transient one-dimensional mathematical model allowing the prediction of conductive heat transfer within the glazing and convective and radiative heat transfer from the glazing towards the interior and exterior are considered separately. A constant n...

In this paper an analytical solution is implemented as developed by Liu y Cheng (1991) for solving the complete partial differential equations of Luikov. A parametric study is carried out, varying the coefficient of conductivity for humidity and the thermogradient coefficient in wood, ceramic, plaster, and brick. The results demonstrate that the co...

This chapter deals with the thermal power performance of an indirect solar dryer. This chapter presents a procedure to evaluate the thermal performance of an indirect solar drier of small Capacity. The main components of the indirect solar drying system are the solar air collector, the drying chamber, where the drying takes place, and the air-handl...

A transient two-dimensional computational model of combined natural convection, conduction, and radiation in a cavity with an aspect ratio of one, containing air as a laminar and non-participating fluid, is presented. The cavity has two opaque adiabatic horizontal walls, one opaque isothermal vertical wall, and an opposite semitransparent wall, whi...

An apparatus and a methodology to evaluate the thermal performance of window glazing are presented. Single glazings commercially available in Mexico are currently tested. During the test sequence, the glass samples are mounted in a specially designed calorimeter apparatus. The test is conducted in controlled laboratory conditions at the National Ce...

Theoretical efficiencies of an evacuated-tube solar collector using a chemically deposited SnS-CuxS absorber thin film ( alpha =0.91) in contact with the working fluid are presented. A mathematical model is developed and solved numerically to yield photothermal conversion efficiencies eta of the collector for the heat transfer coefficient hb of 0.0...

A transient one-dimensional mathematical model allowing the prediction of the thermal performance of laminated glazing with and without chemically deposited solar control coating and its experimental verification are presented. A normal laminated glass is composed of two 3 mm glass sheets with a thin polymer layer between them. For the experimental...

The experimental validation of a mathematical model that predicts the shading coefficient (SC) and the solar rejection factor (SRF) of various types of solar control coatings is presented. The model allows us to input the solar absorptance and predict the temperature of the solar control glazing as a function of the thermal emittance and exterior t...

A mathematical model to predict the shading coefficients (SC) and solar rejection factor (SRF) of various types of chemically deposited solar control coatings is presented. The values of SC and SRF are presented for coatings with soar absorptance in the 50-75% range and solar reflectance in the 10-25% range for typical exterior temperature of 10-50...

The transient thermal performance of a chemically deposited thin film on a glass substrate is presented. Differential energy balances for the glass are set up assuming a one-dimensional transient state for normal incidence of the air mass to solar radiation. Using the reported properties of a SnS-CuxS thin film as a specific example, the net energy...

A mathematical model enabling the prediction of the thermal performance of solar control glazings employing chemically deposited solar control coatings with or without a transparent protective polymer coating is presented. Differential energy balance for the glazing is set up assuming one-dimensional steady state case for normal incidence of air ma...

Solar control characteristics are described for chemically deposited thin film coatings consisting of an initial layer of Bi[sub 2]S[sub 3] film of [approximately] 0.05 [mu]m thickness deposited at room temperature (25 C) for 45-76 min from baths containing bismuth nitrate, triethanolamine (TEA) and thioacetamide and a Cu[sub x]S thin film of 0.1-0...

Theoretical efficiencies (η) and thermal behaviour of all-glass Evacuated Tube solar Collectors with an Internal Absorber Film (ETCIAF), i.e. the absorber film deposited in the inner surface of the inner tube, are compared and contrasted with the traditional design of all-glass Evacuated Tube solar Collectors with an External Absorber Film (ETCEAF)...

Two analytical solutions of thermal problems connected with the disposal of nuclear waste are presented. Non-linear diffusion problems are analysed. The use of the Kirchhoff transformation and the transformation of coordinates are made along with a numerical solution. Also comparison is made for the exact and numerical solutions for temperature his...

RESUMEN Se realizó un estudio numérico de la transferencia de calor conjugada en una cavidad ventilada en régimen de flujo turbulento para analizar la eficiencia de distribución de temperaturas al interior y determinar una configuración optima de ventilación. Se consideraron todas las paredes de la cavidad adiabáticas, excepto la pared vertical der...