SOLAR ENERGY

Author: ZARZALEJO TIRADO LUIS FERNANDO.
Year: 2004.
University: COMPLUTENSE DE MADRID.
Place of defense: FACULTAD DE CIENCIAS FÍSICAS.
Place of preparation: FACULTAD DE CC. FÍSICAS.

Summary: The main objective of this thesis is focused on the development and application of new models to estimate the global irradiance time from satellite imagery for the geographic area of peninsular Spain. Until very few years, the only source of data for solar radiation applicable in a particular location came from the use of measures from the nearest station radiometric or, in the best case, the interpolation of radiometric data from several stations measure circundantes.Aún when radiometric station network has experienced considerable improvement over the last años.la information can be obtained from measures piranométricas remains insufficient (temporal and spatial) for a proper understanding of the solar radiation received at a site concrete. To fill this gap, the estimated solar radiation from images from satellites geosestacionarios is a useful tool, mainly in terms of spatial distribution and disponibiliidad Series representative is refiere.Esta methodology is unquestionably accepted by the scientific community-related item as useful for estimating the spatial distribution of solar radiation. The achievement of that objective is addressed from the perspective of the proposal and validation of a set of models to estimate the global irradiance time from images satélite.Estos new models are adjusted and validated data piranométricos, correspondeentes to 30 stations radiometric Spanish and satellite simltáneos (period 1994-2003). Adjustment and validation of new models has been made after a thorough analysis of available data quality, which has developed and implemented a protocol for quality, both for data piranométricos to satellite imagery. In this thesis is proved the validity of the proposed new models, as well as the significant improvement compared with existing considarados of models universal application.

Author: VERA MELLA NELSON.
Year: 2004.
University: POLITÉCNICA DE CATALUÑA.
Place of defense: ETSEIB.
Place of preparation: ETSEIB, EDIFICI H PLANTA 10 Campus SUD.

Summary: The study of solar radiation is a key process for the utilization of solar energy. In most cases, however, the availability of information is inadequate and outdated. In addition, the interpolation surface obtained from measuring stations on the surface does not allow observation of the microclimatic aspects of solar radiation (Zelenka et al., 1999). Therefore, we have chosen a statistical model and images from the NOAA-AVHRR satellite maps for the determination of solar radiation for the entire Iberian Peninsula. The statistical method based on Diabaté et al. (1989) and Flowers (2002) ensures the accuracy of the process NOAA-AVHRR imagery and high spatial resolution of about 1 km2, which is necessary given the complexity of the study area. The period of study is 5 years (1998-2002), which allows to study the variation of solar radiation. The statistical model was calibrated with 21 stations distributed across the surface area of Spain. The data from the measuring stations are acuciosamente filtered with the aim of eliminating all records errors, crucial aspect of the method. The images are calibrated and geometrically corrected, besides being an in-cloud detection for the purpose of obtaining surface albedo (Laine et al., 1999). The evaluation of the results with data from 7 stations in separate surface, it produces an MBE of 3.8% and RMSE of 24.2% for daily data and an MBE for 1.1% and RMSE of 15.9% for hourly data . Get maps radiaci ¾ No plot point and daily schedules for all a ± os of perà odo study ademÃs determining the average trend of the same. The results show that Penà nsula IbÚrica receives more nimo of 4.2 MJm2 d1 and a maximum of 26 MJm2 d1, with a solar radiation average 15.1 MJm2 d1. The interannual variability of solar radiation is expressed with values ranging from 14.9 MJm2 d1 for the year 2002 to 17.3 MJm2 d1 for the year 2000. The results clearly demonstrate the usefulness of the work in obtaining maps of solar radiation and daily schedules with a high spatial resolution (1 km2).

Author: VARO MARTINEZ MARTA MARIA.
Year: 2005.
University: CÓRDOBA.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: The research into the solar ultraviolet radiation has undergone a major breakthrough in the last few decades, because of the importance of their biological effects and potential technological applications. In this sense, this Doctoral Thesis aims to contribute to the characterization of solar ultraviolet radiation on the Iberian peninsula. Specifically, from long series of experimental data recorded in Cordoba, have been analyzed statistically distributions of solar ultraviolet radiation as both hourly and daily has been modeled their relationship to the solar radiation daily and hourly respectively, as well as other radiometric and atmospheric variables. Also, in the case of radiation time, then compared the results with those derived from experimental measures to another locality of the Iberian peninsula and, more specifically, the Mediterranean area (Valencia). Moreover, data córdoba again, but for different intervals optics on air, has been studied and modeled distributions relative frequency of ultraviolet index clarity, comparing the results with those of the distributions index total clarity. Lastly, from pilot registered in Hobart (Australia), a model that helps determine the total column ozone from the measures commonly recorded in the radiometric stations, such as solar radiation and its total component ultraviolet eritemática. This will contribute to the progress of this line of research, with the decline of the ozone layer and the resulting increase in solar ultraviolet radiation reaching the earth's surface, it tries to meet the demands on the part of the information society and research on this issue, as well as preventive measures based on the results of these studies.

Author: FAGGEMBAUU TUMAC DEBORA FABIANA.
Year: 2006.
University: POLITÉCNICA DE CATALUÑA.
Place of defense: SALA DE CONFERÈNCIES ETSEIAT.
Place of preparation: ETSEIB, Edifici H LAB. TERMODINAMICA, PLANTA 8 SD.

Summary: A significant proportion of the total national energy budget of european countries goes toward energy consumption in buildings, therefore the efforts addressed to optimize building's thermal behaviour are of vital importance. In this sense, facades play a fundamental role. Not only do they act as barriers between external and internal conditions, but they can also help to reduce the consumption of energy for heating, ventilation and air conditioning. Moreover, they can help to produce healthy and comfortable indoor conditions. The use of large, transparent areas in facades is a common current practice. Despite the architectural interest of these glazed areas, in Mediterranean climatic conditions they are responsible for building overheating. In these zones, double-skin envelopes made up of two layers of glass separated by an air channel -to collect or evacuate the solar energy absorbed by the facade- are considered to be a design option that could resolve this issue. In other climatic conditions, large heat losses may constitute the most determinant factor. Anyway, the comfort parameters are influenced by the large transparent areas, also in this design aspect, double skin facades may contribute to obtain more comfortable and pleasant living spaces. The objectives of this thesis are to give a step forward in the study and numerical analysis of passive systems in general, and advanced facades in particular. A one-dimensional and transient numerical code for the simulation of double and single skin facades including advanced technological elements, like phase change materials, transparent insulation and facade integrated collectors-accumulators has been developed. The features of the physic and mathematical models implemented are described and instantaneous or integratedperformance parameters describing thermal behaviour of the facades are defined. The numerical models implemented within the numerical tool have been subjected to a verification and validation process in different forms: by comparing the numerical results with those obtained for simplified situations with analytical solutions, with tabulated global performance coefficients of simple façade configurations and with the results of other building simulation codes. Experimental research has been carried out in test cells situated at different geographical locations, thus they were subjected to different climatic conditions. The main objective of the developed numerical code is to simulate advanced facades in order to assess the long term performance, and to account with a virtual tool to test passive designs, including challenging innovations. The applications of the numerical tool described in this thesis, for the optimisation of facades of real buildings are presented. As future actions, the link of the one-dimensional simulations produced by this numerical tool with a multi-dimensional simulation of specific zones of the facades is foreseen.

Author: RODRIGUEZ PEREZ IVETTE MARIA.
Year: 2006.
University: POLITÉCNICA DE CATALUÑA.
Place of defense: SALA DE CONFERÈNCIES ETSEIAT.
Place of preparation: ETSEIB, Edifici H LAB. TERMODINAMICA, PLANTA 8 SD.

Summary: Thermal storage devices are widely used in many thermal systems and applications that are characterised by the delay between energy production and consumption, such as thermal solar systems. The improvement in their design and optimisation is a key aspect in the thermal optimisation of the system, where a good preformance of the storage tank can represent a considerable increase in the overall efficiency of the installation. In the subject of optimisation of thermal equipment, Computational Fluid Dynamics have been consolidated as an indispensable tool providing researchers and engineers with a method to test virtually their prototypes with low effort in time, personnel and resources. This thesis is focused in the numerical simulation of unsteady laminar convection in cylindrical domains and its application to the study of the heat transfer and fluid flow that take place in stratified storage tanks. The first part of this document is devoted to present the methodology followed for the numerical resolution of the governing equation of heat and fluid flow in cylindrical coordinates. The main particularities of the discretisation of the equations in these geometries, as well as the solution procedure for incompressible and transient flow problems are also presented. Special emphasis is given to the verification of the code, the ppropriateness of the discretisation adopted and the verification of the numerical solution obtained. The second part of this thesis is focused on the study of the heat transfer and fluid flow phenomena that take place in stratified storage tanks, including the performance measures and modeling efforts of these devices. The quality of the energy stored is determined by the degree of the thermal stratification of the storage tank, which is affected by several factors such as the mixing due to the inlet streams during load and unload, the heat losses to the environment, among others. In this sense, thermal stratification analysis is carried out by means of the virtual prototyping of the tanks for different working conditions and configurations. In order to measure the performance of the tanks, different parameters are considered. The analysis led to the proposition of a new exergy-based parameter as a tool for assessing and comparing storage tanks. The usefulness of this parameter for quantifying the quality of the energy stored is also shown. Furthermore, the thermal behaviour of storage tanks during the static mode of operation considering the heat losses to the environment is also analysed. The study is addressed to characterise the cool down of the fluid inside storage tanks for solar thermal systems in the low-to-medium temperature range. The methodology followed, from the identification of the significant non-dimensional parameters that define the problem, the formulation of a zonal prediction model, a parametric numerical study by means of detailed multidimensional CFD computations and the post-processing of the results in order to feed the global model are exposed in detail. Zonal model presented, together with the correlations given are in good agreement with the numerical results and constitute an alternative for the prediction of the long-term performance of the storage tanks during the cooling process.