Browsing by Author "De Simone, Marilena"

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Crossed analysis by T-history and Turbiscan for the characterization of PCM with Glauber salt
(2016-12-20) De Paola, Maria Gabriela; De Simone, Marilena; Arcuri, Natale; Calabrò, Vincenza
The Glauber salt (sodium sulfate decahydrate) is a low-cost Phase Change Material (PCM) with promising characteristics. It offers economic and environmental advantages since it can be recovered as a waste product from the lead battery disposal. However, sub-cooling and phase segregation problems [1] require the addition of appropriate additives capable to reduce the melting temperatures as well as the latent heat [2]. These mixtures are dispersions, heterogeneous systems, for which the T-history method [3] seems to be more suitable respect to the traditional DSC, due to the major and more significant sampling. On the other hand, these systems are not thermodynamically stable and need more detailed information on the kinetics of destabilization. With this aim, the authors propose the analysis by using Turbiscan, an instrument commonly used in the pharmaceutical and cosmetic sector since it allows identification of slow and not visible phenomena that precede the dispersion destabilization [4]. Also the integration of the characterization by this method could provide further information on the effectiveness of the additives addition and on the method of samples preparation.
Light scattering methods to test inorganic PCMs for application in buildings
(IOP, 2017) De Paola, Maria Gabriela; Calabrò, Vincenza; De Simone, Marilena
Thermal performance and stability over time are key parameters for the characterization and application of PCMs in the building sector. Generally, inorganic PCMs are dispersions of hydrated salts and additives in water that counteract phase segregation phenomena and subcooling. Traditional methods or in “house” methods can be used for evaluating thermal properties, while stability can be estimated over time by using optical techniques. By considering this double approach, in this work thermal and structural analyses of Glauber salt based composite PCMs are conducted by means of non-conventional equipment: T-history method (thermal analysis) and Turbiscan (stability analysis). Three samples with the same composition (Glauber salt with additives) were prepared by using different sonication times and their thermal performances were compared by testing both the thermal cycling and the thermal properties. The stability of the mixtures was verified by the identification of destabilization phenomena, the evaluation of the migration velocities of particles and the estimation of variation of particle size.
Occupants behavior influence on buildings energy performance. Investigations in residential and office buildings
(2017-10-27) Mora Guerra, Dafni Yeniveth; Furgiuele, Franco; De Simone, Marilena
The general objective of the research was to evaluate the main factors affecting the energy performance of buildings by considering both physical and occupancy variables. The research had two different approaches, one of them was regarding occupant behavior related to energy consumption in residential buildings and the other focused on the office buildings. The investigations were conducted by means of data collection and statistical analyses in existing residential buildings. Furthermore, different procedures for obtaining occupancy profiles were applied. Finally, a case of design and modeling of Nearly Zero Energy Buildings was developed in order to study the influence of occupancy in high efficient energy buildings. The results showed that different approaches of modeling occupancy can lead to considerable variations in building energy performance. In office buildings, the detection of occupancy was obtained by an experimental approach. First of all, the state of the art regarding the sensors and devices used for measuring and monitoring indoor parameters was defined. Successively, an experimental setup was created in an office of the University of Calabria in order to collect data on occupancy and energy consumption by means of sensors and manual observations. The criterion of sensor fusion was adopted. Data were processed by using different statistical techniques: clustering analysis, descriptive and stochastic elaborations. The results were models that can be used either to describe or predict occupancy profiles. Structure of this work The thesis is divided into six chapters. The first chapter is a general introduction titled Occupant behavior in buildings, regarding occupant behavior and its relationship to the energy consumption in residential buildings, office buildings, and low energy buildings. At the end of this chapter a brief description of occupant behavior and energy simulation in buildings is presented. In the second chapter, Building occupancy is presented with a description concerning the occupancy sensing techniques used and general classification following different approaches. Residential buildings is the title of the third chapter in which we attempt to describe the objectives and main findings of three investigations regarding residential buildings and occupancy profiles definition by means of the development of cases of study. The title of the fourth chapter is Office buildings: the experimental study. It consists of the description of the experimental study realized at the University of Calabria in an office building. A description of the sensors and the monitored data were presented. The Office buildings: data analysis is the fifth chapter of the thesis, with the different approaches used to analyze experimental data. It begins with the statistical analysis and ends with the results of the modeling based on indoor environment measurements. The General conclusions is the last chapter of the thesis, with a review and discussion of the key contributions of this research work
Preparation and characterization of PCM from Glauber salt recoverable from the disposal of lead batteries
(2016-12-20) De Paola, Maria Gabriela; Arcuri, Natale; Calabrò, Vincenza; De Simone, Marilena
Glauber salt (sodium sulfate decahydrate) is a promising phase change material (PCM) to use in the building sector, thanks to the high enthalpy of fusion associated with a proper phase transition temperature. Also it offers economic and environmental advantages because it can be obtained as by product from the disposal process of lead batteries. However the Glauber salt, due to phenomena of phase segregation and subcooling, cannot be used in the pure state but requires the addition of rheological modifiers and nucleating agents. In this work the thermal performances of mixtures based on Glauber salt with different compositions are compared by using T-history method, by adopting sonication for mixing, and following the same preparation procedure for all the samples. Fixed the composition, also the effects of the sequence of addition of the reagents is examined. The analysis carried out by Turbiscan allowed to identify the kinetic of destabilization of each sample and revealed the need to specify in detail the preparation stages of PCM in order to make the composition reproducible in laboratory and on a wider scale.