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  Numarul 2/2017

Volumul 8 (2017), Nr. 2

Obtinerea confortului de vara fara utilizarea climatizarii, prin ventilare nocturna
Obtaining summer comfort without air condition through the use of nocturnal ventilation
Felicia Uciu, Andreea Vartires, Tiberiu Catalina, Iolanda Colda

Studiul realizat in vederea economisirii de energie pentru racirea cladirilor, a aratat eficienta tehnicii de ventilare nocturna in localitati din sudul Romaniei, zona afectata de temperaturi ridicate, cu grad de repetivitate inalt, in mod deosebit in ultimii ani. Introducerea utilizarii temperaturii de echilibru pentru studiul ventilarii nocturne, care permite determinarea numarului de grade zile pentru care nu este necesara climatizarea, a constituit o a doua etapa in stabilirea consumului de energie de racire, ca indicator cu continut multicriterial in functie de care se poate estima economia de energie. Alaturi de informatii utile cu referire la raspunsul cladirii supusa la sarcini externe, temperatura de echilibru este baza determinarii numarului de grade zile de racire. Conceptul de grade zile prezinta doua aspecte: primul se refera la baza de calcul si al doilea, la modul în care acesta este aplicat la analiza si construirea strategiei de economisire aenergiei. In ceea ce privește primul aspect, determinarea temperaturii de echilibru raspunde nivelului de confort propus. In al doilea caz, pe baza liniilor de performanta ale cladirilor studiate, se vor propune temperaturi interioare care sa raspunda cerintelor de confort si de eficienta termica.

Cuvinte cheie: eficienta energetica, ventilare nocturna, temperatură de echilibru, grade zile de racire

The study realized to establish the energy savings for cooling has tested the efficiency of nocturnal ventilation in cities in the south of Romania, an area that is affected by high temperatures that repeat often especially in the past years. By introducing the use of equilibrium temperature for the study of nocturnal ventilation, which allows the determination of the large number of degree days for which we do not require air conditioning, we are able to determine the number of degree days for which we do not require air conditioning; this has constituted the second step in establishing the thermal demand for cooling as an indicator with a multi-criteria inventory based on which we can estimate the saving. Alongside useful information revealed through the answer of the building which has undergone external demand, the equilibrium temperature is based on determining the number of cooling degree days. The concept of degree days is formed of two specific aspects: the first refers to the base of the calculation and the second to the way in which these are applied to the analysis and how we build the energy consumption strategy. When referring to the first aspect, determining the equilibrium temperature responds to the scope of the proposed comfort. In the second case, based on the lines of performance for the buildings we have studied, we will propose inside temperatures which would respond to the demanded comfort and efficiency.

Keywords: energy efficiency, nocturnal ventilation, equilibrium temperature, cooling degree days

Obtinerea unei expresii analitice pentru distributia anuala a concentratiilor de ozon (O3)
Obtaining an analytical expression for the annual distribution of ozone concentrations (O3)
prof. dr. ing. Florin Iordache - UTCB – FII

In lucrare se prezinta o procedura bazata pe transformata Fourier, utilizata in stabilirea unei forme analitice pentru o baza de date de tip serie de timp, privind concentratiile de ozon. Observatiile facute asupra bazei de date au condus la identificarea unor forme analitice pentru doua oscilatii suprapuse, oscilatia lunata si oscilatia diurna care in final se insumeaza.

The paper presents a procedure based on Fourier transform, analytical forms used in establishing a database for a type of time series on ozone concentrations. The observations made over the database has led to the identification of two forms analytical oscillations superimposed monthly oscillation and diurnal oscillation which finally are summed.

Noi abordari in standardul prEN 13791 „Evaluarea rezistentei betonului din structuri si elemente prefabricate”
New approaches in prEN 13701 standard „Assessment of in-situ compressive strength in structures and precast concrete components”
Dan Georgescu, Apostu Adelina

In februarie 2017 a fost publicat proiectul de revizuire a standardului European EN 13791 “Evaluarea in-situ a rezistentei la compresiune a structurilor si elementelor prefabricate din beton” care stabileste noi reguli privind determinarea/verificarea rezistentei carcteristice a betonului. In prezentul articol se prezinta principalele modificari propuse si implicatiile asupra actualului normativ romanesc NP 137 [2]. In articol se face o analiza comparativa intre prevederile actuale si propunerile de modificare a standardului european EN 13791 [1] a carui revizuire a avut drept obiectiv principal o mai buna armonizare cu alte standarde europene si, in special, cu Eurocodul EN 1990 [3].

Cuvinte cheie: beton, rezistenta, compresiune, evaluare

In february 2017 was published by CEN a proposal to revise the European standard EN 13791" Assessment of in-situ compressive strength in structures and precast concrete components" which establishes new rules for the determination of the characteristic in-situ strength for structural assessment. This article shows the main changes proposed and its implications on the current Romanian norm NP 137 [2]. The article makes a comparative analysis of the current rules and proposals for revision of the European standard EN 13791 [1] whose revision was aimed in accordance with other European standards, mainly with EN 1990, Annex D [3].

Keywords: concrete, strenght, compression, assesment

Semaforizarea inteligentă a unei intersecţii
Intelligent traffic lights used at crossroads
Cristina Gabriela Saracin, Marin Saracin, Adrian Alin Toader

Lucrarea de faţă prezintă modul de realizare al unei platforme pentru semaforizarea inteligentă a unei intersecții. Noţiunea de semaforizare inteligentă apare tot mai des întrucât, în ziua de astăzi, nevoia de mobilitate este tot mai acută și se caută continuu soluții pentru a rezolva problema congestiilor din trafic. O astfel de implementare a unui sistem inteligent de trafic, ca cel din lucrarea de față este absolut vitală pentru dezvoltarea și progresul mijloacelor de semaforizare. Această lucrare răspunde următoarelor cerinţe: cum se realizează dimensionarea unei intersecții, modul de realizare al senzorilor de detecție ai autovehiculelor, modul de amplasare al senzorilor, schema electrică a ansamblului, funcționarea platformei și a programului implementat în programmable logic controller (PLC). Automatizările realizate pe platformă au fost pentru semafoare și senzorii de detecție infraroșu. Pentru realizarea practică a acestei platforme am ales automatul programabil Easy 719 DC-RC.

Cuvinte cheie: semaforizare, dimensionare intersecție, automat programabil, senzori IR

This paper presents the embodiment of a platform for intelligent traffic lights used at crossroads. The concept of intelligent traffic lights occurs more often because, today, the need for mobility is increasingly acute and is continuously looking for solutions to solve the traffic congestion problem. Such implementation of an intelligent traffic system, as in the present work is absolutely vital to development and progress means traffic lights. This work meets the following requirements: how to size the intersection dimension, how to realize a detection sensor for cars, location sensors way, electrical diagram of the assembly, operation platform and program which is implemented in the programmable logic controller (PLC). The automation performed on the platform is made for traffic lights and infrared sensors. For the physical implementation of this platform, there were chosen Programmable Logic Controller such as Easy 719 DC-RC.

Keywords: traffic light, intersection sizing, programmable logic controller, IR sensors.

Evoluția sistemelor de climatizare de tip VRF – Partea a II-a
VRF HVAC system evolution
Drd. Ing. Cătălin NEGRUȚIU, Prof. Dr. Ing. Dragoș HERA

Curgerea neizoterma in regim nestationar a unui lichid printr-o conducta aflata in mediul exterior
Non-isothermal non-isothermal flow of a liquid through a conduit in the external environment
prof. dr. ing. Florin Iordache – UTCB-FII

In lucrare se prezinta relatiile concrete utile la evaluarea pierderilor de caldura ale agentilor termici care circula prin conductele de transport sau de distributie ai agentilor termici din retelele urbane de alimentare cu caldura. Relatiile prezentate se refera la tratarea regimului termic nestationar de curgere, important in special in cazul retelelor de transport. Datorita volumului relativ mare al acestor retelele in raport cu debitele de agent termic, apar defazari si amortizari importante ale undelor termice intre capetele aval si amonte ale acestora. Importanta se refera la ceea ce priveste reglajul termic centralizat si desigur si la economia de energie.

The paper presents specific relationships useful in assessing heat loss of the water that circulates through the pipes of transport or distribution of heat in urban heat supply networks. Relations presented, refers to the unsteady regime of heatflow, particularly important in the case of transport networks. Due to relatively large volume of these networks in relation to the flow of heat and amortization and phase differences appear significant heat wave between upstream and downstream ends of networks. Important concerns regarding control and centralized heat and energy saving of course.

Sisteme de încălzire prin pardoseală radiantă
Radiant floor heating systems
Gheorghe-Constantin Ionescu

Sistemul de încălzire cu ajutorul pardoselilor radiante de căldură este un factor de utilizare tot mai mare pentru încălzirea unor spații mari, cum ar fi săli de expoziție, săli de așteptare și săli de sport, săli de producție mari din fabrici și, nu în ultimul rând, locuințe.

The heating system by means of heat radiant flooring bolsters an ever increasing usage factor for heating large areas such as exhibition halls, waiting halls and rooms, sport halls, the large production halls within factories and last, but not least, living quarters.

Solutii moderne de Instalatii la HOTEL HILTON in orasul Augusta – Statul Maine – SUA
Modern Installations Solutions at HOTEL HILTON in Augusta - State of Maine – USA
Ing. Ilina Matei Traian – ABM Mechanical – Statul Maine –SUA Dr- ing. Ilina Mihai – Prof. Universitar

Sunt prezentate succint solutiile de instalatii de incalzire, climatizare si apa calda de consum la un Hotel Hilton cu patru niveluri si 135 de camare. Instalatiile de incalzire/climatizare pentru camere s-au prevezut cu agregate utilizand pompe de caldura cu tehnologie inverter. Procesul de incalzire/racire din interiorul incaperilor este monitorizat astfel incat microclimatul din interior sa fie asigurat numai in prezenta locatarului (lor), in rest instalatia asigura numai conditiile de conservare. Prepararea apei calde de consum s-a facut cu schimbatoare de caldura prevazute cu arzatoare cu gaz natural si acumulatoare de caldura, asigurand la punctele de consum apa calda intr-un timp foarte scurt (sub 5 secunde). Incalzirea anexelor s-a realizat cu aer cald preparat in centrale de tratare si distribuit prin canale la punctele terminale. De subliniat ca intregul proces de incalzire/racire/apa calda de consum se desfasoara cu consumuri reduse de energie termica, urmarindu-se asigurarea conditiilor de confort numai in perioada de utilizare efectiv a spatiilor din Hotel. Hotelul a fost dat in exploatare in luna iulie 2016.

In this article are presented the HVAC systems and domestic hot water preparation, designed and installed for a four levels Hilton Hotel with 135 guest rooms located in Augusta, Maine USA. Wall type package heat pumps and controlled room temperature with unoccupied setback were installed for the guest rooms. For offices and different other rooms in the hotel air hadling units with hot water and DX cooling coils with outdoor condensers were used. The fresh air for corridors and air handling units is supplied by three make-up air units with enthalpy wheel, Dx cooling coils and natural gas furnace. Air from the build is exhausted through these units as well. All units are controlled by a Building Management Controls System that monitor all ventilation zones with set-back for un-occupied mode. The domestic hot water is prepared with ten natural gas heat exchangers controlled and modulate in cascade. The domestic hot water has a recirculation piping that can bring the hot water at every faucet within seconds. The hotel has also a swimming pool with a separate de-humification system. The hotel is functional since June 2016.

 
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