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  Numarul 3/2015

Volumul 6 (2015), Nr. 3

Stadiul actual si tendinte noi in perspectiva cresterii performantelor energetice a cladirilor din Republica Moldova
Curent staj and new trends in the perspective increasing energy performance of buildings in Moldova
Constantin Tuleanu, Adrian Retezan, Andrei Binzari, Iulia Negar, Livia Leanca

In lucrare sunt tratate conceptiile specifice care pot fi puse la baza sporirii performantelor energetice si ecologice a cladirilor din Republica Moldova, precum si rezultatele obtinute prin auditarea energetica a unui spectru larg de cladiri publice din tara.

In this scientific article we are talking about specific concepts that can be used for energetical and ecological performance increasement of buildings in the Republic of Moldova and also the results that we abtain doing the energetical audits for a big varietes of buildings from our country

Posibilitatea trecerii unor consumatori energetici industriali de la combustibil gazos la combustibil biogenic - aplicatie la generatoarele de aer cald
Possibility of switching some industrial consumers from gaseous fuel to biogenic fuel - application for hot air generators
Nicolae Antonescu, Paul-Dan Stanescu

In multe aplicatii industriale de producere de aer cald pentru scopuri tehnologice sau de incalzire se folosesc arzatoare de combustibil gazos. Inlocuirea arzatoarelor de combustibil gazos cu unele utilizand combustibili biogenici, in particular peleti, prezinta o serie de avantaje. Pe langa aspectul ecologic de reducere a amprentei de CO2 se genereaza si importante economii materiale in paralel cu marirea gradului de independenta energetica a consumatorului. In prezenta lucrare se analizeaza functional o solutie de generator de aer cald de tip camera de ardere, oferindu-se caracterizarea parametrica atat pentru functionarea cu combustibil gazos cat si pentru functionarea cu combustibil biogenic de tip peleti din rumegus.

In many industrial applications gaseous fuels are used for the production of hot air for technological or heating purposes. Replacing fuel gas burners with ones using biogenic fuels, in particular pellets, provides a number of advantages. In addition to reducing the CO2 footprint, significant savings are generated along with enhancing the consumer energy independence. The present paper analyzes functionally a typical solution of hot air generator, combustion chamber type, offering parametric characterization for both functioning with gaseous fuel or biogenic fuel, namely sawdust pellets

Influenta tipului de casa de scara asupra consumurilor energetice ale unei cladiri
Staircase type influence on the energy consumption of a building
Margareta-Irina Tipel, Stefan Creiteanu, Vlad Iordache

In ultimii ani, mai multe studii au avut ca obiectiv determinarea celor mai importanti factori care influenteaza consumul de energie termica, dar niciunul dintre studii nu a vizat compararea de diferite structuri arhitecturale. In acest studiu am comparat trei tipuri diferite de casa scarii, in scopul de a intelege care este arhitectura ce conduce la cel mai mic consum de caldura si cea mai buna clasa energetica. Aceasta comparatie a fost realizata pentru parametrii diferiti ai cladirii (numarul de etaje, rezistenta termica a peretilor exteriori si ferestre) si parametrii legati de destinatia cladirilor (temperatura interioara, aporturi interne de caldura si rata de infiltrare a aerului). In urma calcului consumului si clasei energetice pentru fiecare structura arhitecturala a reiesit ca tipul casei scarii poate aduce o schimbare de maxim 40% din consumul anual specific dar nu aduce nici o schimbare a clasei energetica.

Over the last decade several studies aimed to find the most important factors that influence the thermal energy consumption, but none of them were carried out to compare different architectural structures. In this study we compared three different types of stairwell in order to understand which architecture leads to the smallest heat consumption and the best energy class. This comparation was carried out for different building parameters (number of floors, thermal resistance of the external walls and windows) and building opperation condition ( indoor temperature, indoor heat gains and air infiltration rate). The architectural structure of the stairwell was found to bring a maximum 40% change of thermal consumption but no change of the energy class.

Sistem sursa cu captatoare solare si pompe de caldura
Power system with solar collectors and heat pumps
prof. dr. ing. Florin Iordache; ing. Mugurel Talpiga

Obiectivul prezentei lucrari este de cel de modelare matematica a proceselor de transfer termic care au loc intr-un sistem sursa neconventional, compus din suprafata de captare a energiei solare cuplat cu un rezervor de acumulare si pompa de caldura cuplata la rezervorul de acumulare si la instalatia de incalzire a consumatorlului. Functionarea sistemului presupune doua etape, de incarcare si descarcare termica a rezervorului de acumulare in colaborare a acestuia cu suprafata de captare a energiei solare si cu pompa de caldura cuplata la instalatia de incalzire a consumatorului. Relatiile obtinute au fost utilizate in cadrul lucrarii intr-un studiu de caz unde se prezinta cateva aspect practice obtinute pe baza unui instrument de calcul automat care a permis simularea unui comportament dinamic al acestui sistem.

The objective of this study is to develop a mathematic algorithm of thermal transfer in unconventional heating source system, composed by surface for solar energy capturing, a tank for heat storage and a heat pump between storage tank and heating system of the load. The working principle of this unconventional heating system supposed two working stages, one for charging and another for discharging of heat, heat tank being in direct relation once with solar surface and also with the heat pump which is coupled to the load. Relations obtained were used to trace the behavior in a case study where are presented practical aspects using an automated calculation algorithm which make possible to simulate the dynamic behavior of the system.

Sistem inteligent de iluminare publica
Public Lighting Smart System
Cristina Gabriela Saracin, Flavius Gheorghe Buzea

Reducerea consumului global de energie primara cu 20% pana in anul 2020 reprezinta unul dintre obiectivele Comisiei Europene. Sistemul inteligent propus in cadrul lucrarii controleaza intensitatea fluxului luminos al corpurilor de iluminat public (stradal si rezidential). Intensitatea luminoasa variaza in functie de deplasarea persoanelor pe trotuar, intensitatea traficului rutier si fenomenele meteorologice. Scopul lucrarii consta in realizarea unei platforme de simulare a iluminarii publice conform CIE No. 115:2007. Pentru aceasta am utilizat microcontrolerul ATmega2560. Platforma are in componenta urmatoarele: senzor de lumina (fotorezistenta), senzor de miscare, senzor de umiditate si senzor de distanta (infrarosu). Ultimul senzor a fost amplasat astfel incat sa permita posibilitatea determinarii distantei la care se situeaza autovehiculul aflat in miscare. Pentru iluminare s-au utilizat corpuri de iluminat stradal si rezidential MATRIX-02 NG 30 LED/700 DIM 4000K.

The reducing of global primary energy consumption with 20% till 2020 is one of the objectives of the European Commission. The intelligent proposed system, within this paper work, controls the intensity of public lighting devices (street and residential). The luminous intensity varies depending on the movement of the people on the sidewalk, road traffic intensity and weather conditions. The paper's purpose consists in providing a simulation platform versus the public lighting system according to CIE No. 115: from 2007. In the respect to this purpose, I used microcontroller ATmega2560. The platform has the following components: Light sensor (photo resistor), motion sensor, humidity sensor and remote sensing sensor (infrared sensor). The last sensor has been placed in such a way as to enable the determination of the distance between sensor and a moving vehicle. For lighting, they have been used street and residential lighting devices such as LED MATRIX-02 NG 30/700 DIM 4000K.

Compararea performantelor unei instalatii frigorifice auto utilizand agentii R134a si HFO1234yf
Comparing the performance of a refrigeration car using R134a agencies and HFO1234yf
Razvan CALOTA‚ , Alexandru NITU

Uniunea Europeana propune interzicerea folosirii agentilor frigorifici care au coeficientul de incalzire globala (GWP) mai mare de 150, astfel incat se intentioneaza ca pe viitor freonul R134a, cu un GWP de 1430, sa fie inlocuit de noul freon HFO-1234yf, cu un GWP de 4, prevenind astfel distrugerea stratului de ozon, dar si reducerea efectului negativ asupra incalzirii globale. Lucrarea de fata prezinta o comparatie intre agentii frigorifici R134a si HFO-1234yf, avand in vedere reglementarile actuale din punct de vedere al protectiei mediului inconjurator. HFO-1234yf, este un agent frigorific de tip hidro-fluoro-olefina, cu un raport de comprimare mai scazut cu 9% decat R134a si este compatibil cu materialele din care sunt realizate echipamentele din sistemele frigorifice actuale.

EU proposes ban on the use of refrigerants that have coefficient of global warming (GWP ) below 150 , so it is intended that future refrigerant R134a , with a GWP of 1430 , to be replaced by the new refrigerant HFO - 1234yf , with a GWP 4 , thereby preventing destruction of the ozone layer and reduce the negative effect on global warming . This paper presents a comparison between R134a and HFO refrigerants - 1234yf , given current regulations in terms of environmental protection . HFO - 1234yf is a refrigerant -type hydro- fluoro -olefins with a compression ratio of 9% lower than R134a and is compatible with the materials they are made from refrigeration systems current equipment .

Estimarea coeficientilor de dispersie longitudinala utilizand marimi hidraulice usor masurabile
Estimation of longitudinal dispersion coefficient using hydraulic measurable sizes
Marius Iliescu, Elena Iatan

Situatia in care o substanta nedorita este deversata intr-o curgere constituie o problema pentru evaluarea calitatii apei din avalul punctului de deversare. Pentru a estima calitatea apelor curgatoare trebuie studiate fenomenele de transport asociate curgerii. Coeficientul de dispersie longitudinala este asociat celui mai important mecanism de transport si este absolut necesara estimarea acestuia. In lucrarea de fata este prezentat un scurt istoric al aparitiei relatiilor utilizate pentru evaluatea coeficientului de dispersie longitudinala si de asemenea sunt precizate simplificarile pe care acestea le introduc si efectele unei evaluari imprecise ale coeficientului de dispersie longitudinala

In case of an accidentally spill in a fowing water it is necessary to estimate the water quality downstream of the spill. In order to estimate the water quality we are interested in the study of transport phenomena. The dispersion coefficient is associated to the most effective transport mechanism. In this paper we present a brief historical development of the relations used to estimate the longitudinal dispersion coefficient, the introduced approximations and the effects of an imprecise estimation of the longitudinal dispersion coefficient.

Application of solar-photovoltaic systems in rural areas
Georgiana Corsiuc

In this paper two solar energy systems using photovoltaic panels are analyzed. Since the character of solar radiation is not continuous and constant a backup system is needed to cover the energy needs in periods when the PV panels do not produce energy. If the consumer is connected to the grid the solution it is much simpler. The energy uncovered by the solar system is purchased from the national energy system and the excess energy is sold. If the connection to the utility grid is impossible or too expensive the system needs to be equipped with batteries for energy storage and generators. Thus, a series of simulations are conducted to observe the functioning of the two systems.

The efficiency of harnessing thermal-solar energy in existing buildings connected to the district heating system
Teodora-Melania Soimosan, Raluca-Andreea Felseghi, Calin-Ovidiu Safirescu, Emil Moldovan

Valorificarea surselor regenerabile de energie (SRE) in scopul acoperirii cererii de energie pentru incalzirea cladirilor si prepararea apei calde menajere reprezinta una dintre solutiile majore de reducere a consumurilor de combustibili fosili respectiv a emisiilor asociate de CO2 si a cresterii securitatii in domeniul energetic. In aceasta directie, eficienta de utilizare SRE constituie unul dintre cele mai importante obiective in contextul energetic actual international. Pornind de la considerentul ca energia termosolara (SRE-S) reprezinta forma de energie cea mai raspandita, curata si usor valorificabila, in concluzie cea mai reprezentativa forma de energie cu potential scazut de temperatura convertibila in energie termica, obiectivul acestei lucrari este de a evidentia importanta crearii premiselor in vederea integrarii eficiente a acesteia in cladirile existente racordate la sistemul districtual de incalzire (DH). In acest sens, au fost efectuate un set de simulari operationale pe cladirea de referinta, pe parcursul unui an de operare, pentru diferite scenarii de anvelopare, in scopul de a evalua impactul configuratiei consumatorului asupra eficientei de utilizare SRE-S in cladiri

Using renewable energy sources (RES) in order to cover heat demands for space heating and domestic hot water preparation represents one of all major reduction solutions for diminishing the consumption of fossil fuels, lowering the quantities of CO2 associate emissions and increasing the energy security in this field. In this direction, the efficient use of the RES is one of the most important goals in the nowadays international energy context. Starting from the premise that solar energy (RES-S) represents the most widespread, the most representative and the most reachable form of renewable energy with lower potential that can be converted into thermal energy, the aim of the case-study is to highlight the importance of creating the optimal premises in order to effciently integrate it, into existing buildings connected to the district heating (DH) system. In this regard, a set of operating simulations were carried out on the targeted building, during one year of operation, for different types of configuration, in order to evaluate the impact of their performances on the solar-thermal using efficiency

 
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