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  Numarul 2/2015

Volumul 6 (2015), Nr. 2

Etude thermique d’un capteur solaire innovant à circulation d’air
Thermal study of a innvovative solar coletor 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.

Impact of freeze-thaw cycles on the performance of polymer modified bitumen
Bachir Glaoui, M'hamed Merbouh, Martin Van de Ven, Mahdjoub Bendjima

In seasonal frozen region, the performance of asphalt pavement is affected severely by the freeze-thaw cycles. The binder is the first factor that affected by these cycles. The objective of this study is to evaluate the performance of EVA polymer modified bitumen after freeze – thaw cycles. Before and after thermal cycling, the complex modulus and phase angle, creep and recovery, also m-value and creep stiffness, were experimentally determined by the rheometers DSR and BBR. Results obtained indicate that freezing – thawing cycles change the rheological behavior of polymer modified bitumen, which translated in reducing the performance of this binder.

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 gasi indicii de acest tip, astfel incat variatia in date sa poată 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.

Instalatie multischimbator pentru utilizarea peletilor in sisteme de incalzire industriala
Multiple-exchangers installation for industrial heating using wood pellets
Nicolae Antonescu, Laurentiu Tacutu

Incalzirea spatiilor industriale de tip hala, slab izolate termic si cu permeabilitate ridicata, cu convecto-radiatoare, este improprie, iar cea cu generatoare de aer cald, cu toate ca se preteaza mai bine aplicatiei, ramane totusi energofaga. Problemele care se pun la utilizarea combustibililor biogenici (ecologici si ieftini), ca alternativa la combustibilii clasici, sunt generate de imposibilitatea de a renunta la prezenta unui agent intermediar (in cazul folosirii cazanelor), de prezenta traseelor de temperatura foarte inalta (peste 750 oC) la folosirea camerelor de ardere cvasi-adiabate cuplate cu sisteme de disipare radiativa (tuburi radiante) si de imposibilitatea, in cazul folosirii unei instalatii monocomponent (cazan sau sistem de radiatie ori generator de aer cald), de a cupla pe aceeasi camera de ardere mai multi consumatori de tip diferit (aer cald si radiatie). Instalatia prezentata rezolva in mod integrat problemele enuntate anterior si constituie o solutie tehnico-economica optima de utilizare a combustibilului biogenic pentru realizarea incalzirii multisistem a halelor si incintelor industriale.

Heating with convecto-radiators the industrial buildings generally poorly insulated and with high permeability, is improper, and using air generators, although more suitable for the application, still remains a great energy consumer. Problems which arise at the use of biogenic fuels (ecological and cheap), as an alternative to classic fuels, are generated by the presence of an intermediate agent (in the case of using boilers), the presence of high temperature ducts (above 750 oC) at the use of quasi-adiabatic combustion chambers coupled with radiative dissipating systems (radiant tubes) and the impossibility, in the case of using a mono-component systems (boiler or radiation system or hot air generator), to connect on the same combustion chamber different types of consumers (hot air and radiation). The installation presented solves the problems previously mentioned and represents a solution for the optimal use of biogenic fuels for the multi-system heating of halls and industrial buildings.

Theoretical and experimental study on ice-slurry use in comfort air-conditioning
Rodica DUMITRESCU, Anica ILIE, Razvan CALOTA, Teodora Madalina NICHITA, Andrei DAMIAN

This paper develops a theoretical and experimental study on convective heat transfer characteristics in a mini-channel type air-cooler, operating with ice-slurry. Although ice slurry is usually employed as a secondary fluid in air conditioning systems, this paper investigates its behaviour as a primary fluid. Furthermore, since previous investigations on ice slurry mostly referred to plate heat exchangers, little information is yet available in the literature regarding ice slurry use in mini-channel heat exchangers, this study employed several correlations recommended by the open literature for binary mediums, such as ice-slurry, in order to identify the best fitted correlation in terms of best agreement with the experimental results obtained for the given geometrical configuration of the heat exchanger, ice mass fraction, and specific operating conditions. Besides the theoretical study, the authors have also developed an experimental study and a comparative analysis of theoretical vs. experimental results with respect to the heat transfer coefficient on ice-slurry side as a function of ice mass fraction, of ice-slurry flow rate and air flow rate.

Model experimental pentru studierea curgerii apei intr-o conducta de canalizare
Experimental model to study the water flow to a sewer pipe
Marius Iliescu, Elena Iatan, Mihnea Sandu

In aceasta lucrare se prezinta modelul experimental realizat în laboratorul Facultatii de Inginerie a Instalatiilor din cadrul Universitatii Tehnice de Constructii Bucuresti cu ajutorul caruia se realizeaza curgerea intr-o conducta de canalizare cu depuneri de sedimente la partea inferioara a conductei. Curgerea in interiorul conductei se face gravitațional, cu suprafata libera. Cu ajutorul unei vane de reglaj se poate fixa debitul de apa canalizat, in timp ce debitmetrul cu ultrasunete ofera posibilitatea reglarii cu acuratete a acestuia. Rezultatele preliminare, obtinute in urma determinarilor PIV pe acest model, sunt coerente, comparabile cu alte valori din literatura.

This paper is presenting an experimental model conceived in the Building Services Faculty Laboratory, part of the Technical University of Civil Engineering Bucharest, in order to experimentally study the flow in a sewage pipe with deposition. The flow inside the pipe is by gravity, with free surface. A setting valve is used to set the flow of the drained water, while a ultrasonic flowmeter offers the possibility to set the flow with accuracy. The preliminary results, which are obtained using the PIV method on this model, are coherent, and comparable to values presented in literature.

Management system for improving energy consumption in public buildings
Ion MICIU, Cristina OGESCU

Based on partners experience in past research energy projects, SIMENERG project successfully integrates and validates an Energy Management System (ENMAS) to save up to 30% of energy and CO2 emissions in buildings by monitoring and control systems in real-time conditions. The software developed improves the control and management of heating, ventilation, air conditioning, lighting and other energy-hungry devices; smart metering tools as well as the use of new lighting techniques and the integration of energy micro generation systems. The Energy Management Software monitors and controls the Energy produced with the implemented renewable energy sources and performs the energy balance (Production of Energy/Consumption of Energy). The software user interface is built to make the building's network as simple as possible to use, due to a selected combination of intelligent and interoperable services. SIMENERG designs local automation systems to promote a new role for buildings that will change the consumers' behavior from passive to active consumers. SIMENERG carries out a market analysis to explore what is the state-of-the-art and track emerging trends of ICT support for energy consumption awareness and strategies for conservation.

Influenta continutului si finetii filerului de calcar asupra proprietatilor cimentului cu adaos de calcar
Influence of limestone filler content and fineness on the properties of limestone filler cements
Nastasia Saca, Maria Georgescu

Lucrarea aduce informatii referitoare la influenţa continutului de calcar (10...40%) si finetii acestuia (suprafata specifica Blaine = 4600 cm2/g, 5200 cm2/g si 7000 cm2/g) asupra unor proprietati ale cimenturilor mixte care-l contin: timp de priza, rezistente mecanice si porozitate. Adaosul de filer calcaros accelereaza, in general, priza cimentului iar necesarul de apa pentru pasta de consistenta standard este redus fata de cimentul etalon, consecinta a unei distributii granulometrice mai buna in domeniul granulatiei fine. Un continut de 10% filer calcaros nu determina modificari majore ale rezistentei la compresiune. La cresterea continutului de filer calcaros rezistenta la compresiune a scazut, indiferent de finetea lui si durata de intarire.

This paper brings some data regarding to the influence of limestone filler content (from 10% to 40%) and its fineness (Blaine specific surface area of 4600 cm2/g, 5200 cm2/g and 7000 cm2/g) on some properties: setting time, mechanical strenghts and porosity. Both initial and final setting times were diminished by the limestone addition. Limestone filler addition diminished the water requirement for standard consistency in comparison with Portland cement, as consequence of improved particle size distribution in the range of the fine granulation. The presence of 10% limestone in cement does not cause significant changes in compressive strength. The increasing of limestone filler added to cement up to 40% determines a decreasing of compressive strength regardless the fineness of limestone and age of mortars.

Aplicaţii ale ciclului Rankine organic utilizând surse de energie regenerabile
Applications of the Organic Rankine Cycle using renewable energy sources
Pavel Atanasoae

Lucrarea prezintă utilizarea ciclului Rankine organic pentru producerea combinată a căldurii şi energiei electrice din surse de joasă temperatură cum este cazul surselor regenerabile de energie. Sunt analizate diferite tipuri de instalaţii de cogenerare cu ciclu Rankine organic existente pe piaţă, din punct de vedere al economiei de energie primară, comparativ cu producerea separată a căldurii şi energiei electrice.

This paper presents the use of organic Rankine cycle (ORC) for power and combined heat generation from low temperature heat sources as in the case of renewable energy sources. There is an analysis of different types of CHP plants with ORC existing on the market from a primary energy saving point of view comparative with the separate production of the heat and power.

Piaţa imobiliară rezidenţială sub aspectul crizei economice
Residential real estate market in terms of the economic crisis
Drd. Ec. Gabriela Mehedintu, Prof. Univ. Dr. Ing. Nicolae Postavaru

A market is a place where consumers and producers meet, where they make free choices after which the prices are defined, but where the state has to be involved through economic and politic decisions. The markets are interdependent, so changes in one market determines changes in other markets, due to the snowball effect. We consider the case of the financial crisis that developed to an economic crisis. At national level, the real estate sector is a reflection of the national economy; it evolves according to the effects of the economic crisis and governmental policies. In this context, each individual consumer has to make the best decisions regarding a mortgage or a rent.

Analiza energetica privind utilizarea unui sistem de cogenerare pentru alimentarea cu caldura a unui ansamblu de blocuri din mediu urban
Energy analysis on using a cogeneration system to supply heat to a series of urban residential buildings
Prof. dr. ing. Florin Iordache , drd. ing. Radu-Alexandru Baciu , drd. ing. Stefan Burchila

Lucrarea are ca obiectiv, asa cum se mentioneaza si din titlu, o analiza energetica comparata intre 4 categorii de structuri de sisteme de cogenerare care alimenteaza cu energie termica si electrica un grup de cladiri rezidentiale din mediul urban. Producerea combinata de energie termica si energie electrica se face in toate cele 4 cazuri cu motoare termice si centrale termice. Cele 4 cazuri analizate se disting intre ele prin capacitatea termica acoperita de motoare vis a vis de cea acoperita de centralele termice si prin tipul de combustibil utilizat (gaze naturale vis a vis de biogaz). Rezultatele obtinute vizeaza atat puteri termice si electrice cat si consumuri de energie termica si electrica si, de asemenea, randamentele sistemului pe diversele perioade ale distributiei climatice anuale.

This paper's objective, as mentioned in the title, is a comparative energy analysis between 4 architectural types of cogeneration systems that supplies heat and electricity to a group of residential buildings in an urban area. The combined heat and power production is done in all 4 cases with internal combustion engines and boilers. The 4 analyzed cases differentiate themselves by the heat contribution of internal combustion engine compared to the heat contribution of boilers and by the type of fuel used (natural gas vs. biogas ). The results cover both thermal and electrical power and heat and electricity consumption and also the systems efficiency on various periods of the annual climate distribution.

Aspecte privind modul de realizare a cladirilor si a instalatiilor aferente in SUA
Issues on the form of buildings and related facilities in the US
Dr.ing Ilina Mihai -Prof. Universitar, Ing. Ilina Matei Traian- Ilina Engineering PA - Statui Maine - SUA

Articolul cuprinde aspecte legate de modul in care sunt proiectate si realizate structurile si instalatiile din unele tipuri de cladiri in regiunea nordica a Coastei de Est a SUA denumita si Noua Anglie (New England) care cuprinde statele Maine, New Hampshire, Vermont, Massachussets, Rhode Island si Connecticut. S-a cautat sa se faca o descriere succinta a instalatiilor de incalzire/racire la cateva din cladirile cu destinatii diverse (locuinte, cabane turistice, azil de batrani, piscine si magazine cu vanzari de autoturisme). Au fost descrise sistemele de instalatii adoptate, particularitatile pe care le prezinta, subliniind si caracteristicile tehnice adecvate. Totodata s-au facut unele referiri si la partea de constructii (anvelopa, pereti interiori, acoperis, terasa etc) mentionand in special comportamentul lor termic (materialele termoizolante si eficienta energetica).

Article elaborate on how they are designed and manufactured structures and installations in some types of buildings in the northern region of the East Coast of the United States known as New England (New England) comprising states of Maine, New Hampshire, Vermont , Massachusetts , Rhode Island and Connecticut . It sought to make a brief description of the heating / cooling of buildings for several different (homes, chalets , nursing , swimming pools and shops with sales of cars) . Systems have been described systems adopted , they present particularities , highlighting features and technical resources. Also there were some references and the building ( envelope , interior walls , roof terrace etc ) citing in particular their thermal behavior ( insulation materials and energy efficiency )

 
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