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  Numarul 1/2015

Volumul 6 (2015), Nr. 1 - Vizualizare numar complet

Preliminary study of PTC use for human body heating dissipation mannequin
Tiberiu Adrian Salaoru, Marina Andrei

An important field of research for improving the efficiency of the Heating, Ventilation and Air Conditioning (HVAC) systems and for reducing the number of deaths occurred during the surgical procedures of the patients under effect of full anesthesy is the study of the human body heat loses mechanisms. A useful way to perform these studies is to manufacture a human body manikin which has maintained constant its surface temperature on a value close to real human body temperature. For heating the surface of the manikin can be used PTC (Positive Temperature Coefficient) thermistors mounted on the entire surface of the manikin. In this paper are presented preliminary results of the study performed on these devices, of the transient heating regime and the temperature stability.

Numerical study of air cooling photovoltaic panels using heat sinks
Sebastian Hudisteanu, Theodor-Dorin Mateescu, Nelu-Cristian Chereches, Catalin-George Popovici

In this paper is presented a numerical study for the air cooling of the photovoltaic panels integrated in buildings. The studied cases assume the integration of photovoltaic panel on a double skin facade. Numerical simulations were achieved in ANSYS-Fluent software, for 3D model, in forced convection and turbulent flow. The improvement of the air cooling is studied for different inlet velocities and also in case of using a heat sink with ribs. The investigation is focused on the influence of different heights of the ribs on the heat transfer between photovoltaic panel and circulating air. The results are aimed on the conversion efficiency of the photovoltaic cells that is dependent on the average temperature of it.

Analysis of the Flow Structure and its Influence on the Operation of a Wastewater Pumping Station
Nicolae Ioan Alboiu, Costin Ioan Cosoiu, Anton Anton

The hydraulic phenomena occurring at the entrance of a pumping station are crucial in order to ensure the required operation conditions. Under the circumstances of an undesired flow regime a faulty functioning of the pump units can occur. Such a case was studied by the authors of the present paper. As a consequence of the hydraulic system particularities and due to the local conditions at the inlet of the pumping station, the designed operation parameters were only occasionally achieved. Additionally, shortly after commissioning, the pump rotors were damaged. Starting this point on the Technical University of Civil Engineering Bucharest team studied, based on field measurement and using the expert software Fluent for CFD, the phenomena which caused the aforementioned operation problems. Thus, the streamlines and the velocity field in the given situation were modeled and analyzed. Based on this study several conclusions about the flow characteristics were driven, and a clearly point of view about the causes that are responsible for the poor operation parameter was issued.

Etude thermique d’un capteur solaire innovant à circulation d’air
Thermal study of a innvovative solar colector with air circulation
Cristiana Croitoru, Amina Meslem, Ramy Atta

L'utilisation des énergies renouvelables est une solution attractive pour satisfaire deux exigences: la qualité à l'intérieur et l'efficacité énergétique. Les systèmes solaires passifs sont faciles à mettre en œuvre et efficace dans les zones à fort potentiel solaire. Le mur solaire transpiré non vitré (UTSW) est en bardage métallique avec perforations, installé à plusieurs centimètres du mur du bâtiment, créant ainsi une cavité. Cette étude est une approche d'analyse préliminaire sur l'importance de la forme de l'orifice du panneau perforé pour le transfert de chaleur. L'article présente des données extraites de recherche expérimentale du transfert de chaleur entre la plaque perforée et la circulation de l'air. La comparaison entre deux géométries de perforations en termes de transfert de chaleur a montré de différence significative. La forme innovante de l'orifice lobes a été trouvée plus efficace en ce qui concerne le transfert thermique entre la plaque chauffée et l’air, grâce aux structures tourbillonnaires longitudinales caractéristiques.

The use of renewable energy is an attractive solution to fulfill two requirements: quality indoor and energy efficiency. Passive solar systems are easy to implement and effective in areas with high solar potential. The unglazed transpired solar wall (UTSW) is perforated with metal siding, installed several inches from the building wall, creating a cavity. This study is a preliminary analysis approach to the importance of the shape of the orifice of the perforated panel to the heat transfer. The article presents data from experimental research of heat transfer between the perforated plate and the flow of air. The evaluation between two geometries of perforations in terms of heat transfer showed significant difference. The innovative shape of the lobes orifice has been found more efficient as regards heat transfer between the heated plate and the air, thanks to the longitudinal vortex structures characteristics.

Aplicarea analizei statistice multivariate pentru evaluarea parametrilor la o statie de epurare a apei
Application of multivariate statistical analysis to evaluate parameters in a wastewater treatment
Marius-Daniel Roman

Autorul lucrarii de fata prezinta rezultatele in urma aplicarii analizei componentelor principale (PCA). Datele colectate de la influentul si efluentul statiei de epurare a apelor uzate Gherla in perioada (mai 2013- mai 2014), au fost analizate pentru a gasi o relatie intre parametrii fizico-chimici. PCA este conceput pentru a transforma variabilele originale in noi variabile necorelate (axe), numite componente principale, care sunt combinatii liniare ale variabilelor originale. Noile axe se afla de-a lungul directiei de variatie maxima. PCA ofera o modalitate obiectiva de a găsi indicii de acest tip, astfel incat variatia in date sa poata fi pe cat posibil concisa. Aplicarea PCA este utilizata pentru a obtine, pe langa datele statistice, imaginile care pot fi studiate si interpretate vizual.

The author of the present paper presents the results following the application of Principal Components Analysis (PCA). The collected data of influent and effluent from Gherla's wastewater treatment plant during ( May 2013- May 2014),were analyzed to find a relationship between physical-chemical parameters. PCA is designed to transform the original variables into new, uncorrelated variables (axes) called the principal components, that are linear combinations of the original variables. The new axes lie along the directions of maximum variance. PCA provides an objective way of finding indices of this type so that the variation in the data can be accounted for as concisely as possible. The application of PCA used to obtain, besides statistical data, the images which can be studied and interpreted visual.

Modelarea sistemelor cu purtatori multipli de energie in cladiri
Modelling of systems with multiple energy carriers in buildings
Pavel Atanasoae

In lucrare se prezinta un exemplu de modelare a sistemelor cu purtatori multipli de energie bazat pe conceptul de hub energetic. Modelul a fost personalizat pentru a putea fi utilizat in etapa de proiectare sau reabilitare a unei cladiri. Această abordare permite configurarea optima a diferitelor surse de energie disponibile, inclusiv a surselor regenerabile, pentru alimentarea cu energie a cladirilor.

The paper presents an example of modeling for systems with multiple energy carriers based on the concept of energy hub. The model was personalized to be used in the design or refurbishment stage of a building. This approach enables optimal configuration of the various available energy resources, including renewable sources, for the power supply of buildings.

Daylight in retrofiting office building design
Alexandru Mircea Iatan, Angel Madalin Dogeanu

Understanding the specifics of sustainable building and determining effective sustainable practices can be confusing. Daylighting analysis is an important component towards creating accurate simulations for sustainable design and visual health. Daylight has been utilized as a design element in buildings throughout history. One of the main reasons for using daylight in recent years is its benefit in reducing energy consumption through its use as a main or secondary illumination source in order to replace the use of electrical lighting. Daylight not only replaces artificial lighting, reducing lighting energy use, but also influences both heating and cooling loads. Planning for daylight therefore involves integrating the perspectives and requirements of various specialties and professionals. Daylighting design starts with the selection of a building site and continues as long as the building is occupied. This paper presents a numerical method based on Dialux to predict daylight factors and daylight uniformity factor into a retrofit office building in order to comply green and sustainability standards requirements.

Aiming to achieve net zero energy lighting in buildings
Energy consumption for interior lighting is rapidly increasing and takes up 17.5% of the total global electricity consumption on average. With European office buildings using 50% of their total electricity consumption for lighting alone, and other shares of electricity of 20-30% in hospitals, 15% in factories, 10-15% in schools and 10% in residential buildings, there is significant potential to reduce energy consumption for lighting. By implementing a combination of key measures, such as minimisation of lighting power density; use of highly-efficient lighting technologies based on renewable energy sources; use of appropriate lighting control systems; and maximisation of daylight use, energy saving targets can be pushed forward to aim at achieving net zero energy lighting in buildings. This paper presents findings from Building Research Establishment projects for public and private buildings to reduce lighting energy consumption whilst improving the quality of the internal luminous environment.

Fluid flow and heat transfer simulations for a box double-skin façade in Brasov, Romania
Gabriel NASTASE, Robert GAVRILIUC, Alexandru SERBAN, Ioan BOIAN

CFD - Computational Fluid Dynamics Method is the modern scientific method, for prediction of fluid flow, heat and mass transfer and other related phenomena, by numerical solving the mathematical equations governing those phenomena, such as the law of mass, momentum and energy conservation. CFD method is very useful when it comes to conceptual studies for new model of buildings, detailed development of certain parts of a building, useful for solving problems that appear during construction or exploitation of a particular system that is part of a building etc. CFD analysis complements the numerical modeling and experimental modeling, reducing the effort and cost for experiment and data acquisition systems. This paper presents a few results for heat transfer and fluid flow, made on a box double-skin façade, in Brasov, Romania, as a part of a PhD thesis.

Ecoshopping: energy efficient & cost competitive retrofitting solutions for retail buildings
A. J. Lewry, E. Suttie

"EcoShopping" project aims to build a holistic retrofitting solution for commercial buildings to reduce primary energy consumption down to less than 80kWh/m2 per year and increase the proportion of Renewable Energy systems (RES) to more than 50% using state of the art solutions. The project intends to use and integrate available products and technologies along with a network of low-cost equipment to accurately monitor the environmental and occupancy parameters to have better control of the Building Management System and full exploitation of the Building Thermal Mass, which serves as a "Thermal Battery" and stores the RES directly without using battery, tank or other expensive storage material and simplifying the system structure.

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