8. Effective Use of Low-Enthalpy Geothermal Fields for Heating and Energy Production by Using Optimal Thermal-Transfer Fluids and Energy-Producing Systems

Coordinator: Voutetakis Spyrus, Institution: Centre for Research & Technology Hellas

This work studies efficient energy production from geothermal fields of low heat content (enthalpy) through the use of a systematic method for the design and selection of heat exchange working fluids tailored for Organic Rankine (ORC) systems.
The implementation of the proposed technological developments enables the generation of an inclusive map of heat exchange fluids representing conventional and novel molecular structures together with their performance characteristics for selected geothermal fields. The obtained heat exchange fluids result in considerably higher overall performance in applications οf heat and/or electrical power cogeneration using ORC systems, compared to conventionally utilised fluids in similar applications. The identification of heat exchange fluids with optimum characteristics is based on the use of a Computer Aided Molecular Design method (CAMD) that facilitates the systematic synthesis of such fluids.
The performance of the designed fluids is evaluated using a model of the ORC system that enables simulation and economic design optimisation. Additionally, the performed evaluation considers properties such as safety (toxicity and flammability) and environmental performance (ozone depletion potential and global warming potential). An overall performance index is developed that facilitates the systematic evaluation of the heat exchange fluids for geothermal fields with a broad range of temperature and flowrate characteristics.
Final Report

9. Efficient Algorithms for Reachability and Path-Selection Problems with Applications

Coordinator: Georgiadis Loukas, Institution: University of Western Macedonia

Graphs are mathematical structures that model many important entities such as the world-wide web, transportation, communication and social networks, databases, and biological systems.
The objective of this research project was the design of efficient algorithms for a collection of graph problems related to Reachability and Path-Selection. In Reachability and Path-Selection problems, we are given an input graph and wish to efficiently perform queries that report if two vertices are connected by a path, or compute paths connecting specified vertices so that certain requirements are satisfied. Algorithmic problems of this kind have numerous applications, including internet routing, geographical navigation, and knowledge-representation systems. Specifically, in this project the following types of problems were discussed:
Join-Reachability: This is a natural extension of the standard Reachability problem for a collection of graphs G. We wish to process G so that we can quickly report the set of vertices that reach a given vertex in all graphs of G. Computation of Disjoint Paths: The goal is to compute a pair of disjoint paths from a given source vertex to every other vertex, or to a specific target vertex.
Algorithmic techniques were developed and efficient algorithms for problems of the above types were provided. New applications were considered for the techniques and algorithms.
Final Report

10. Ash as a Material of Passive Cooling of Buildings and Open-Air Areas

Coordinator: Karamanis Dimitrios, Institution: University of Ioannina

The objective of the project was the study of ash as an application material for evaporative cooling of buildings and open spaces in order to mitigate the urban heat island effect and save energy. The study was completed in three phases.
During the first phase, several samples of fly and bottom ash materials from the major lignite power plants in Greece were collected and characterised, while a fly ash sample was converted into zeolite of type NaP1. The moisture adsorption experiments of the second phase indicated the effectiveness of the ash applications for evaporative cooling of buildings, since the fly ash reduced its surface temperature increase in simulated light. A maximum difference of 8° C was recorded between the converted zeolitic fly ash and concrete or empty space. For the unmodified fly and bottom ash samples, the temperature differences were smaller, but still appreciable.
The study was completed in the third phase, where it was found that the reduction of environmental impact can be achieved by mixing the ash either with an inert substance or with synthetic soil used in green roofs or with nanocomposite materials of high moisture adsorption capacities and multifunctional environmental applications.
Final Report

11. Structural health monitoring of glass fiber reinforced composites using embedded carbon nanotube (CNT) fibers

Coordinator: Kourkoulis Stavros, Institutions: National Technical University of Athens / University of the Aegean / Centre de Recherche Paul Pascal-CNRS, Université de Bordeaux

Polyvinyl alcohol carbon nanotube (PVA-CNT) fibers of ultra small diameter (~ 40 μm) were embedded in glass fiber reinforced plastic composites and used as strain sensors for damage monitoring of the composite. Sensing of the structural integrity of the composite was made by the in situ measurement of the electrical resistance of the embedded PVA-CNT fiber during the mechanical tests.
Currently available technologies are based on sensors attached with appropriate adhesive on the surface of the composite materials. Experimental data obtained from such sensors remain rather limited and give more or less information gathered from the outer surface and not from the inside of the composite. Instead of using sensors in the outer surface of the composites, the use of embedded sensors could provide the engineers with direct and more accurate information regarding the deformation and generally the structural health of the composite materials.
PVA-CNT fibers were produced at the National Centre for Scientific Research (CNRS) at Bordeaux, France. After preliminary tests, it was decided to pre-stretch the fibers in order to use them as a strain sensor. Glass fiber composites were manufactured with four different embedded PVA-CNT fibers; the fibers differ in the pre-stretching ratio. The multi-functionable materials were tested in monotonic tensile tests as well as progressive damage accumulation (PDA) tests. The later tests aimed to seek the electrical response of untreated and different pre-stretched PVA-CNT fibers with known level of progressively introduced damage to the composite.
The advantages and disadvantages of each PVA-CNT fiber used as a sensor are analysed; the electrical resistance readings of the PVA-CNT fibers were correlated with known parameters that express the induced damage of the composite. It was found that fibers with higher degree of pre-stretching perform better under progressive damage tolerance applications, as currently applied in aeronautics. This better performance was mainly attributed to the higher degree of alignment of the carbon nanotubes inside the polymeric PVA matrix of the macroscopic fiber.
Final Report

12. Geophysical and Mineralogical Investigations on the twin-meteorite impact craters in Thessaly (Central Greece) of Holocene age

Coordinator: Lagios Evaggelos, Institutions: National & Kapodistrian University of Athens/Institute of Mineralogy and Petrography, ETH Zürich

This is the first time that impact meteorite craters have been recognised in Greece.
Two circular permanent lakes of 150 and 250 m. in diameter and respective depths of 6 and 8 m., occur 250 m. apart from each other in the agricultural fields southwest of the town of Almyros (Thessaly). Based on their fresh morphological character, the formation of the lakes can be assumed as the Holocene age and may be bracketed between approximately 12,500 and 8,000 years BP. The working hypothesis of their origin due to meteorite impact was based on the finding of a considerable amount of angular to rounded clasts and polygenic breccias in the sandy-silty clay of their shores as well as in their suspicious halos during reconnaissance investigations. All these rocks did not resemble either any of the surrounding rock formations or any volcanic material. The petrographic, mineralogical and chemical evidence of the collected clasts and polygenic breccias lead to the interpretation of the ‘carbonatitic’ material as molten and quenched ‘impact fallback breccias and carbonatitic tectites’ due to high-temperature caused by a metamorphic shock from a meteoritic impact. According to the size of the crater lakes, the dimensions of the meteorite, which might have split into two fragments, could have been about 10-30 m. before reaching the surface.
Detailed petrographic and mineralogical studies (optical microscopy, scanning electron microscopy, Raman spectroscopy, X-ray diffraction) on a large number of samples from millimeter to decimeter rock size confirmed the previous results (spinifex carbonatites with feathery spinifex and spherulitic textures, glassy tectites, deformed and fragmented quartz crystals) and thus evidence for shockmetamorphism and melting. The most convincing evidence is the finding of partial melted zircon, for which temperatures greater than 1,400°–1,800°C are required, which do not occur in metamorphic and magmatic process in the Earth’s crust and uppermost mantle.
Final Report

13. Prototype Database of High-Quality Digital Mammography Images and its Portal-based Public Dissemination to the Scientific Community

Coordinator: Mavroforakis Michael, Institutions: University of Houston, Texas/ National & Kapodistrian University of Athens

The goal of this project was the creation of a prototype database of high-resolution digital mammographic images, as well as the development of a web portal to provide public access to the database.
This study covers an important need on several research areas, related to medical databases for breast imaging, in terms of quality and specialisation, as well as availability to the public. Similar public-access breast imaging databases include either low-quality digitized (from film) images or proprietary data formats, making their use cumbersome and limited in scope.
In this database, each image is accompanied by a full clinical evaluation record and fully annotated findings (calcifications, masses, asymmetries, etc). These images, as well as the annotation data, can be used by researchers as raw material for studies related to medical imaging and automated detection/diagnosis in mammography.
The web portal and the public access to this mammographic database constitute perhaps the first such attempt in Greece for the creation of high-quality research material for future studies in these areas.
This project is also available at www.medsip.gr
Final Report

14. Disk-shaped Graphene Liquid Crystals: Self-Organization and Dynamics

Coordinator: Floudas Georgios, Institutions: University of Ioannina / Max-Planck Institute for Polymer Research (MPI-P)

The main objective of this research was to obtain an understanding of the selfassembly and dynamics of a series of new discotic liquid crystals (DLC) based on graphene and their applications in electronics.
For this purpose, a series of new discotic liquid crystals bearing dipoles directly substituted at the graphene core has been made (collaborating research team at the Max-Planck Institute for Polymer Research, MPI-P). These DLCs were subsequently investigated with respect to the self-assembly (with X-rays scattering, Differential Scanning Calorimetry, Polarising Optical Microscopy) and the dynamics (with Dielectric Spectroscopy at the University of Ioannina and solid state Nuclear Magnetic Resonance, at the MPI-P).
The main results of the present investigation were: (i) the influence of dipole on the thermodynamic stability of the crystalline phase, (ii) the disk dynamics within the columnar phases.
Final Report