Belen Zalba

University of Zaragoza | UNIZAR · Department of Mechanical Engineering

Advances towards smart ecosystems showcase Internet of Things (IoT) as a transversal strategy to improve energy efficiency in buildings, enhance their comfort and environmental conditions, and increase knowledge about building behavior, its relationships with users and the interconnections among themselves and the environmental and ecological conte...

Advances towards smart ecosystems showcases Internet of Things (IoT) as a transversal strategy to improve energy efficiency in buildings, to enhance their comfort and environmental conditions, and to grow knowledge about building behavior, its relationships with the users and the interconnections among themselves and with the environmental and ecol...

La memoria a largo plazo es fundamental para tener una base de conocimiento sólida sobre la que construir nuevos modelos mentales. Sin embargo, los estudiantes a menudo estudian de forma masiva e inmediata, centrándose únicamente en superar las pruebas de evaluación. La "curva de olvido" (Herman Ebbinghaus, 1885) muestra que la pérdida de retención...

Proper use of multimedia resources in higher education can actively involve students and lead them to deep learning. In the context of Thermal Engineering, and more specifically in the subject of Thermodynamics, the use of instructional videos is an essential tool to help overcome the students' usual difficulties with this subject. Thermodynamics i...

The teaching experience on the subject of Engineering Thermodynamics and Fundamentals of Heat Transfer is presented for three Bachelor studies taught at the School of Engineering and Architecture of the University of Zaragoza (EINA): Degree in Industrial Technology Engineering (S3), Degree in Electrical Engineering (S3) and Degree in Electronic and...

Non-residential buildings contribute to around 20% of the total energy consumed in Europe. This consumption continues to increase globally. Smart building proposals (focused on Nearly Zero Energy Building (NZEB), air quality monitoring, energy saving with thermal comfort, etc.) were already necessary before 2020, and the pandemic has made this rese...

El creciente uso de las aplicaciones de la Web 2.0 (blogs, YouTube, wikis, etc.) en la enseñanza superior está favoreciendo la adopción de nuevas metodologías docentes complementarias a la docencia tradicional que permiten una mayor interacción con los estudiantes y una mejora del proceso de enseñanza-aprendizaje. Este artículo presenta las princip...

The present research has analysed the complementarity of different measuring methodologies when characterizing the phase changing behaviour of a granular PCM composite (GPCC) through a comparison of their results. Specifically, the enthalpy variation of the GR31 product manufactured by Rubitherm has been measured by using: 1) An energy balance calc...

This article presents the results of heat transfer coefficient and volumetric energy density measurements in an agitated tank containing a low-cost phase change material emulsion, heated by water flowing in a coil. For the stirring a three-stage impeller is placed in the central axis of a 46 l commercial tank. By measuring the temperature dependenc...

A 46 l commercial tank with a helical coil heat exchanger and containing a low cost phase change material emulsion has been experimentally analyzed as a thermal energy storage system in terms of volumetric energy density and heat transfer rate, for its subsequent comparison with other thermal energy storage systems. This phase change material emuls...

The present work analyses the effect of radial thermal gradients inside T-history samples on the enthalpy temperature curve measurement. A conduction heat transfer model has been utilized for this purpose. Some expressions have been obtained that relate the main dimensionless numbers of the experiments with the deviations in specific heat capacity,...

In this work uncertainty propagation and sensitivity analyses have been applied to a case study of an application where PCM is integrated into the envelope of a test cell. The aim of the study is to quantify the influence of the uncertainties associated with the measurements of the thermo-physical properties of PCM on the results of the annual ener...

A novel technique of design of experiments applied to numerical simulations is proposed in this paper as a methodology for the sizing and design of thermal storage equipment integrated in any specific application. The technique is carried out through the response surfaces in order to limit the number of simulation runs required to achieve an approp...

El almacenamiento termoquímico por adsorción ha demostrado poseer una serie de ventajas que le confieren un gran potencial comparado con el almacenamiento térmico sensible o latente. El grupo GITSE de la Universidad de Zaragoza, basándose en los trabajos de [HONGOIS S., Kuznik F., STEVENS P., RADULESCX M., ROUR J.J. Development and characterisation...

Poster - An experimental setup has been adapted in order to estimate the enthalpy variation of granular PCM composites (GPCC). The measuring principle is the energy balance calculation of the air stream that flows throughout a GPCC packed bed. Although this method cannot be applied for the determination of the enthalpy temperature curve, a good acc...

2-pages-pdf summarizing GITSE research group capabilities with a special focus on Thermal Energy Storage. Last update: October 2015

The present work focuses on the reaction to fire of a cement mortar containing phase change material (PCM), which is embedded in a lightweight aggregate, for buildings. Several samples containing different PCM mass fractions have been prepared and tested in order to study the influence of the quantity of PCM on fire behaviour. The enthalpy–temperat...

A microencapsulated PCM (Phase Change Material) slurry with three different PCM mass fractions (14, 20 and 30%) has been analyzed. The present study investigates the influence of the PCM microcapsule mass fraction on the thermal and rheological characterization. Specifically, the Enthalpy–Temperature curves, the Thermal Conductivity–Temperature cur...

For the correct design of thermal storage systems using phase change materials (PCMs) in any application, as well as for their simulation, it is essential to characterise the materials from thermophysical and rheological standpoints (phase change enthalpy, thermal conductivity in solid and liquid phases, viscosity and density in function of tempera...

Microencapsulated phase change material slurry (mPCM slurry) is a latent heat storage fluid in which the PCM microparticles have been dispersed in water. One of the main issues to be tackled is its lack of physical stability, since stratification problems tend to occur. Generally, an unstabilization process in PCM slurries can take weeks or even mo...

This paper describes how to design a PCM-air heat exchanger once an application is specified. Free-cooling and temperature maintenance in rooms with special requirements possess high potential for PCM application in different countries according to their climate. Until now, the low thermal conductivity of PCM and air hindered the development of sui...

Phase change materials (PCM) are capable of storing thermal energy within a small temperature range due to their high latent heat. In simulations of thermal energy storage (TES) systems with PCMs, natural convection is often not considered, possibly resulting in differences between numerical and experimental results. Since natural convection depend...

This paper studies the design and integration of PCM-Air heat exchangers as Thermal Energy Storage units for temperature maintenance in rooms. The methodology proposed is the use of design of experiments applied to numerical simulations on a theoretical model previously developed and experimentally validated. Although a theoretical model could be a...

Mots Clés : Changement de phase, stockage latent, calorimétrie, polymères semi-cristallins. Résumé – Les propriétés thermocinétiques de polymères semi-cristallins de type polytétrahydrofurane (pTHF) de différentes masses moléculaires ont été étudiées afin d’envisager leur possibilité d’utilisation comme matériau à changement de phase (MCP) pour d...

This work describes a model developed to simulate a radiant floor system with PCM in simple building types. The building simulation model has been validated by comparing its behavior with Energy Plus. The PCM radiant floor model is based on a one-dimensional finite difference scheme where the effective capacity method is used for PCM simulation. So...

A microencapsulated PCM (Phase Change Material) slurry is a dispersion where the PCM, microencapsulated by a polymeric capsule, is dispersed in water. Compared to water, these new fluids have a higher heat capacity during the phase change and a possible enhancement, as a result of this phase change, in the heat transfer phenomenon. From the literat...

Phase change materials (PCM) in the form of slurries have had an increasingly important role as heat transfer fluids and as thermal energy storage media. Although it is a recent technology in the field of thermal energy storage with phase change materials, the volume of literature begins to be significant. This investigation carries out a compilati...

This paper analyzes the uncertainties propagation of the theoretical model developed to simulate the thermal performance of PCM-air heat exchanger. Numerical results are compared with experimental results obtained with a full-scale heat exchanger prototype. In the model, the energy equation is considered in terms of enthalpy, as the governing equat...

This paper describes the experimental studies carried out to test thermal cycling of a real-scale PCM–air heat exchanger at ambient temperatures. To achieve this goal an experimental setup previously designed and used for testing real-scale prototypes of PCM–air heat exchangers is modified. The PCM used is commercially available, organic, and paraf...

This paper describes the models developed to simulate the performance of a thermal energy storage (TES) unit in a real scale PCM-air heat exchanger, analyzing the heat transfer between the air and a commercially available and slab macroencapsulated phase change material (PCM). The models are based on one-dimensional conduction analysis, utilizing f...

Sandwich panels are a good option as building materials, as they offer excellent characteristics in a modular system. The goal of this study was to demonstrate the feasibility of using the microencapsulated PCM (Micronal BASF) in sandwich panels to increase their thermal inertia and to reduce the energy demand of the final buildings. In this paper,...

Concentrated solar thermal power generation is becoming a very attractive renewable energy production system among all the different renewable options, as it has have a better potential for dispatchability. This dispatchability is inevitably linked with an efficient and cost-effective thermal storage system. Thus, of all components, thermal storage...

Latent heat storage using phase change materials (PCM) can be used for free-cooling. In this application low air temperature is used to solidify the PCM during the night and then during the next day, the inside air of a building can be cooled down by exchanging heat with PCM. Short times for charging and discharging the PCM are required. PCM have i...

This paper presents novel design conclusions based on the experimental results and on an empirical model for a real-scale prototype of a PCM-air heat exchanger. From experimental results, an empirical model was built aimed at simulating the thermal behavior in the tested heat exchanger in different cases. These simulations were used to evaluate the...

The use of phase change materials (PCM) in construction materials have been studied during the last decades. In the literature, development and testing were conducted for prototypes of PCM wallboard and PCM concrete systems to enhance the thermal energy storage (TES) capacity of standard gypsum wallboard and concrete blocks, with particular interes...

Building applications of phase change materials (PCM) and its contribution to energy efficiency are being studied. One of the most promising applications of thermal energy storage with phase change is the inclusion of microencapsulated phase change materials into building materials. It could be for external enclosure (increasing thermal inertia) or...

Phase change materials (PCM) are able to store thermal energy in small temperature intervals very efficiently due to their high latent heat. Accurate knowledge of the enthalpy as a function of temperature, or the storage capacity at each temperature, is the key to design any application. Conventional methods for thermal analysis however often lack...

Energy storage is a useful tool to increase energy efficiency and energy savings. Solid-Liquid phase change materials (PCMs) are used in latent heat thermal energy storage systems. Plastics are currently used as encapsulate materials with PCM, but previously a compatibility test should be made to ensure long term stability. It is not possible to fi...

The use of phase change materials (PCMs) for thermal storage in buildings was one of the first applications studied, together with typical storage tanks. An interesting possibility in building application is the impregnation of PCMs into porous construction materials, such as plasterboard or concrete, to increase thermal mass. The thermal improveme...

This work aims at designing a thermal energy storage (TES) using air as heat transfer medium, efficient mainly for free-cooling but also for other applications, improving the low heat transfer rates dues to the thermal conductivity of the materials usually employed in these systems, phase change materials (PCM). In this paper, free-cooling means th...

Accurate theoretical modelling and simulation of thermal energy storage (TES) by means of phase change materials (PCM) is very complex and its results are not close enough to experimental values. This paper presents the empirical study of a thermal storage unit operating with a commercial PCM called RT25. The study is carried out by means of the st...

In this paper, the application of phase change materials (PCM) in free-cooling systems is studied. Free-cooling is understood as a means to store outdoors coolness during the night, to supply indoors cooling during the day. The use of PCMs is suitable because of the small temperature difference between day indoors and night outdoors. An installatio...

Thermal energy storage in general, and phase change materials (PCMs) in particular, have been a main topic in research for the last 20 years, but although the information is quantitatively enormous, it is also spread widely in the literature, and difficult to find. In this work, a review has been carried out of the history of thermal energy storage...

The temperature-history method, proposed by Yinping et al, is a simple and economic way to determine the main thermophysical properties of materials used in thermal energy storage based on solid–liquid phase change. It is based on comparing the temperature history of a phase-change material sample and a sample of a well known material upon cooling...

An experimental setup was designed to test heat exchangers between air and the PCM contained in slabs, in which air flows are parallel to the slabs. The evolution of the heat exchanger cooling power is evaluated by applying an energy balance to the airflow in a closed loop. The experimental results of the proposed geometry were used to build an emp...

Thermal energy storage can shift peak load of electricity, eliminate part of the heating or air conditioning loads, and enhance the performance of alternatives to fossil fuel combustion heating. The application of phase change materials (PCM) in air conditioning systems can smooth daily fluctuations in room temperature by lowering the peak temperat...

Microencapsulated Phase Change Materials suspensions and PCM emulsions have been developed during the last 10 years to be utilized as heat transfer fluids. The prime interest in these fluids is the rise of the heat capacity associated to the phase change, with a consequent pumping power reduction as well as a higher heat transfer versus pressure dr...

Este trabajo se centra en el almacenamiento de energía térmica mediante cambio de fasesólido‐líquido y sólido‐sólido. Los trabajos realizados hasta ahora respecto al almacenamientotérmico de energía mediante materiales de cambio de fase (PCM), demuestran que es viabletécnicamente para algunas aplicaciones. Sin embargo, el alto precio de los materia...