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An essential element for the integration of a semisolid process in the production of complex commercial components is the availability of accurate mathematical and computational tools that could describe both the rheological behavior and the material characteristics of the suspension, which are strongly affected from its internal structure and its evolution during deformation. In this study we considered the squeeze flow experiment, which is a standard method used to determine material properties of semisolid slurries, where a fixed amount of material is compressed from its topside either under constant load or constant velocity, while the bottom side remains fixed. Through high fidelity computational modeling we simulated the classical compression experiment by including the effects of thixotropy in order to demonstrate its role in determining material constants. More specifically a structural viscoplastic model based on the Bingham plastic constitutive equation is proposed. The yield stress is assumed to vary linearly with the structural parameter which follows a first-order rate equation accounting for the material structure break-down and build-up. The development of the yielded/unyielded regions in relation to material structural changes is analyzed. Furthermore, we performed also simulations, where the compression is interrupted for a short time, in order to study the material internal structure after a short relaxation time. © (2015) Trans Tech Publications, Switzerland. 217-218 121 129 Sponsors: Conference code: 107639

Energy use in buildings represents 40% of the total primary energy used in EU and therefore developing effective energy alternatives is imperative. Solar Energy Systems (STS) will have a main role to play as they they contribute directly to heating and cooling of buildings and the provision of domestic hot water. STS are typically mounted on building roofs with no attempt to incorporate them into the building envelope, creating aesthetic challenges and space availability problems. The actions will foster and accellerate long-term development in STS through critical review, experimentation, simulation and demonstration of viable systems for full incorporation and integration into the traditional building envelope. Viable solutions will also consider economic constraints, resulting in cost effective Building Integrated STS. Additionally factors like structural integrity, weather impact protection, fire and noise protection will be considered. The most important benefit of this Action is the increased adoption of RES in buildings. Three generic European regions are considered; Southern Mediterranean; Central Continental and Northern Maritime Europe, to fully explore the Pan-European nature of STS integration. The Action consortium presents a critical mass of European knowledge, expertise, resources, skills and R&D in the area of STS, supporting innovation and conceptual thinking.

Renewable energy is important nowadays, not only as an environmental scientific issue, but as an obligation with regard to the European regulations. As a result, scientific interest has increased towards the improvement of the different renewable energy technologies and their optimum utilization in different applications. Initially the paper reviews previous studies regarding the optimum utilization and control of the renewable energy generation installed in buildings and in general in building energy management. The final section of the paper is a novel application related to the studies reviewed; however, this application uses a new and simple way to minimize the energy consumption levels through linear programming optimization.

A standard method used to determine material properties of semi-solid slurries is the squeeze flow experiment a fixed amount of material is squeezed under constant force or velocity and the relation between the force and the displacement of the sample provides information about the rheology of the slurry. The objective of this work is to contribute to the further development of the squeeze flow methodology in order to accurately determine material properties. This is achieved by a model that accounts for the finite yield stress and the thixotropy of the slurry. More specifically a structural viscoplastic model based on the Bingham plastic constitutive equation is proposed. The yield stress is assumed to vary linearly with the structural parameter which follows a first-order rate equation accounting for the material structure break-down and build-up. Numerical experiments of squeeze flow under either constant load or constant velocity are presented and discussed. Comparisons with their non-thixotropic counterparts are made in the case of compression under constant load. The development of the yielded/unyielded regions in relation to material structural changes is analyzed. The numerical results show that initially thixotropy does not affect the flow. However, once the structure is destroyed, the unyielded regions grow slower than the non-thixotropic case allowing for longer compression of the sample. Under constant force the structure may be destroyed at the early stages of the compression but at a later time it re-builds steadily till the cessation of the flow experiment. Under constant velocity, however, the structure is destroyed steadily. Depending then on the case, the final internal structure of the squeezed material can vary significantly. This is an important issue that needs to be taken into consideration in the evaluation of the material parameters. © 2012 Elsevier B.V. 193 103 115 Cited By :13

The significance of the residential building sector in terms of energy consumption is well acknowledged. In this view the knowledge of the way the residential building stock of Cyprus behaves in terms of energy consumption is quite valuable since it will assist policy makers to formulate targeted measures aiming the improvement of energy efficiency and setting current legal standards and benchmarks in the energy performance certificate, a requirement of the 2002/91/EC Directive. Unfortunately, the existing knowledge on this subject is quite poor. As a remedy a research project supported by a national research grant is in operation since December 2008. This paper presents the outline, goals and methodology of this research project and the findings regarding the energy behaviour and other characteristics of the residential building stock of Cyprus. From the analysis of the results for 500 residential buildings, it seems that the energy demand and primary energy required is lower than that of other European countries. Moreover, it seems that the age of residential buildings has low correlation with the energy demand while in contrast with other Northern and Central European countries, it is clear that the contribution of cooling energy requirements to the overall energy demand is quite significant.

The flow and shape evolution during the compression of a finite amount of a Bingham plastic is investigated by means of numerical simulations. The problem relates to the popular compression test used for the rheological characterization of non-Newtonian fluids. The flow is modelled in Lagrangian coordinates using the Papanastasiou regularization for the Bingham plastic and a mixed-Galerkin finite element method. Simulations have been performed for compression under both constant load and constant velocity. Results for various Reynolds and Bingham numbers are presented and discussed. © 2007 Elsevier B.V. All rights reserved. 143 1 38 47 Cited By :15

During the last few years photovoltaic (PV) materials are increasingly incorporated (or integrated) into the construction of buildings for generating electrical power. This integration is done either on the facade or roof of the building. This integration creates also heat which if not removed can create cooling requirements in buildings, especially in summertime, whereas during winter this heat can be used effectively to cover part of the building heating load. Additionally, if this heat is not removed it will also lower the efficiency of the PV panels. Consequently there is a challenge to find solutions to remove this heat resulting from the building integrated PV (BIPV) panels. The aim of this study is to examine the effect of air flow in the air gap between the integrated PV panel and the building’s wall on the temperature of the PV panel. The examination of the effect of the air gap of a BIPV system is very important as it can lead to better understanding of the conditions that allow the higher efficiency of the PV panel and accordingly the increase of the efficiency of the BIPV system. Two different PV modules are examined; the one has a flat surface as the conventional PV panels and the other one has a repeated pi-section surface with different air gap widths through its length and thus different air velocity in the two types of sections. To formulate the heat exchange process for a fluid flowing between the PV panel and the building wall, time-dependent, partial heat transfer differential equations (PDEs) are used and solved with the COMSOL Multiphysics simulations program. Initially, the air-gap width is varied keeping a steady velocity, and subsequently the air velocity is varied keeping constant the air gap and the effect were studied in respect to the temperature of the PV-panel. The runs were carried out for three orientations for the panel facing east, south and west. For the PV module with the flat surface the simulations showed that for an air gap width of 0.02 m, an air velocity of 0.5 m/s can lower the mean temperature of the panel from 77°C to 39°C. For the PV module with non-flat surface (repeated pi-section) that has various air gap widths, the air velocity in the air-gap between the PV-panel and the building wall lowers the mean temperature of the panel by about 35°C allowing for a significant increase in its efficiency.

In order to fulfil article 4 of the 2002/91/EC Directive (EPBD) a national methodology for the energy performance of buildings was drafted and approved by the Government of Cyprus in 2009. This methodology is in line with the European standards prepared to facilitate EPBD implementation and follows the asset rating approach that is, it represents the intrinsic annual energy use of a building under standardised conditions. CEN standards leave an option, quite suitable for existing and complex buildings, for operational rating, which is an energy rating based on measured amounts of delivered and exported energy. The calculated and measured rating exhibit advantages and disadvantages and as expected the results of the two approaches vary, since the measured rating approach takes into account the effect of user behaviour, the actual weather conditions and the realized (actual) thermal comfort conditions inside the building. This paper presents the Cyprus legal framework for adopting the EPBD and exhibits the Cyprus methodology for the energy performance of buildings. Moreover the advantages and disadvantages of the asset and operational rating approaches are discussed and a comparison of the results of these two approaches for a selected number of dwellings is presented. One of these cases is also examined with respect to the climatic conditions, by changing the climatic zone in which the building is erected. The latter reveals the effect of climate on the calculated energy requirements of the building for both heating and cooling.

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Presented at 4th International Conference on Sustainable Devlopment and Planning, 2009, 13 - 15 May, Cyprus This paper describes the work that will be done in a research project, which will facilitate the implementation of the EPBD through the calculation of the existing Cyprus Building Stock energy behaviour. This will be achieved through the selection of a representative sample of 500 housing units and the collection of data through questionnaires, followed by statistical analysis of the data and the interpretation of the results. The key parameters that will form the different clusters are climatological zone, type, age and size of each housing unit. The statistical interpretation of the collected dataset will provide insights with regards to the energy behaviour of the building stock for each class. The ultimate goal is to suggest the number of classes for the Energy Performance Certificate and the upper and lower energy consumption limits for each class. Moreover, the formulation of an energy behaviour map, the consideration of the historical development of the buildings behaviour and the improvement of the insulating materials and solutions, will lead to the readjustment of the values, particularly for the best two classes, so as not only to reflect today’s reality, but also to show the intent of the state to improve the level of the construction industry. In this study, the various types and quantities of thermal insulating materials utilized in Cyprus, for the time interval 01/01/08–30/09/08, are also reported. The data were extracted from applications made by individuals who claimed financial subsidy. A random specimen of 400 applications was evaluated: 55% refer to existing housing, and 45% to new buildings. The different kinds of materials used for insulating floorings, walls and roofs, in different regions of the island were evaluated. The principal observation made is the extensive use of double glazing for doors and windows.

An essential element for the integration of the semisolid metal (SSM) process in the production of complex commercial components is the availability of accurate mathematical and computational tools that could describe both the material characteristics and the dynamics of semisolid slurries during die filling. Computational simulation and modeling is also a powerful and an effective tool that can be used to understand complex physical phenomena, such as those observed with semisolid slurries, and to support theoretical models describing them. We show how important physics can be revealed using experiments combined with numerical simulations. More specifically, we investigate the flow details and the shape evolution during the compression of a finite amount of a Herschel-Bulkley fluid, and the flow of such a material in a rotational viscometer. These two flows relate to popular experiments that are commonly used to determine rheological constants of semisolid slurries. The goal is to use mathematical and computational tools to test postulates for physical and theoretical models used to describe semisolid slurry behavior. The ultimate objective of this work is to contribute to the development of a methodology, which relates simulations to actual experimental results in order to determine the material constants of semisolid slurries. 359 361 Sponsors: American Foundry Society (AFS) American Society for Metals International (ASM) The Institute of Materials, Minerals and Mining (IOM3) North American Die Casting Association (NADCA) Conference code: 66060 Cited By :1 Centre Technique des Industries de la Fonderie (CTIF)

The significance of the residential building sector in terms of energy consumption is well acknowledged. Several studies have shown that the potential of energy savings in this sector is quite significant. In this view the knowledge of the way the residential building stock of Cyprus behaves in terms of energy consumption is quite valuable. This knowledge will assist policy makers to formulate targeted measures aiming the improvement of energy efficiency and will provide valuable information for setting current legal standards and benchmarks in the energy performance certificate, a requirement of the 2002/91/EC Directive. Unfortunately, the existing knowledge on this subject is quite poor. As a remedy a research project supported by a national research grant is in operation since December 2008. This paper presents the outline, goals and methodology of this research project and the findings regarding the energy behaviour and other characteristics of the residential building stock of Cyprus. From the analysis of the results for about 500 residential buildings examined, it seems that the energy demand and primary energy required is lower than that of other European countries. Moreover, it seems that the age of residential buildings has low correlation with the energy demand. Finally, in contrast with other Northern and Central European countries, it is clear that the contribution of cooling energy requirements to the overall energy demand is quite significant.