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  Numarul 1/2021

Volumul 12 (2021), Nr. 1 - Vizualizare numar complet

Experimental analysis of the noise produced by burners inside a boiler plant in an educational building
Catalin Bailescu, Vlad Iordache

One of the most important parameters of comfort in a building is acoustic comfort for which designer engineer typically given little or no attention during project planning and design. The purpose of this article is to highlight the noise produced by boilers in a technical room of a faculty in Romania. Different measurements were performed for the gas flow and noise level in the boiler room. The measurements resulted in several values of the noise level for different thermal loads of the boilers. The result obtained confirm that noise level depends on the thermal load and that increase of thermal load is directly proportional to the noise level inside the plant room. After the measurements, the values of the noise level were processed and compared with literature predicted values and the maximum limit values from the Romanian norm. The results of this article highlighted the noise produced in a technical space of a modern power plant, correctly installed and calibrated. This study can by used by design engineers and all participants in designing and installing equipment in a new educational building, but also in an existing building to meet the comfort conditions of the students. Key words: acoustic comfort, noise level, faculty, measurements, boiler plant

Evaluation of the potential of natural ventilation in different Algerian climates
Meriem Mezouari, Naima Fezzioui, Mohamed El-mir, Roulet Claude-Alain

The purpose of our research is to test the effectiveness of some basic configurations of natural ventilation on the thermal comfort of occupants for different climates. The study focuses on the Algerian climate. Seven cities were selected from the new climate zoning of Algeria proposed by [1]. To evaluate the potential of the selected configurations and given the diversified nature of the Algerian climate, the study will focus on the mid-season period that includes the months of May September and October and the summer season for the months of June, July and August. The study was carried out through numerical simulations using the TRNSYS software coupled with the COMIS aeraulic software. The results of the simulations showed the contribution of natural chimney ventilation caused by the stairwell to improve occupant comfort Its integration, however, requires a judicious and permanent control to guard against the falls of temperatures or the risks of overheating.

Keywords: Algerian climate; natural ventilation, thermal comfort; TRNSYS- COMIS.

Durabilitatea betoanelor fibrate de inalta performanta obtinute din materii prime locale in doua medii agresive de acid clorhidric si sulfati de bariu
Durability of ultra-high performance fibered concretes made from local raw materials in two aggressive media of hydrochloric acid and barium sulphates
Farida Ait Medjber, Mohammed Saidi

The durability of ultra high performance fiber-reinforced concrete (UHPFC) made from local raw materials has been studied in this manuscript. An experimental study was carried out on the best variants of UHPFC using finely ground dune sand as ultrafine. The UHPFCs studied were developed from Portland cement (PC), dune sand (DS), fine sand (FS), metal fibers (MF) and superplasticizer additive (SP). The results show that it is possible to manufacture a more ductile and durable fiber concrete of 41.96 and 35.28 MPa for flexural tensile and 95.5 and 85.36 MPa for compressive strength for UHPFCs made from dune sand and immersed respectively in two chemical solutions concentrated at 5M hydrochloric acid and barium sulfate for one year. The manufacture of a concrete based on local raw materials with good mechanical properties and durability can reduce the consumption of cement.

Keywords: Dune sand, ultra fine, ultra high performance fiber-reinforced concrete (UHPFC), durability, mechanical properties.

About the production and interconnection of electricity obtained from geothermal energy
Carmen Marza, Georgiana Corsiuc

In the context of sustainable development, the use of renewable energy sources and the decrease of greenhouse gas emissions have become global priorities. Geothermal energy represents an important potential for many countries, including our country. If the exploitation of thermal energy has a relatively widespread, the production of electricity is less developed, even if there are countries that cover a significant part of the electricity demand from this resource. In this paper, the authors aim to present the main technical solutions that produce electricity from geothermal sources, but also present some topological models for integrating the obtained electricity in the public network.

Keywords: geothermal energy, electricity, renewable energy sources, interconnectation of electricity

Modelarea si actionarea electrica a unei masini de gravat/taiat cu laser
Modeling and electric drive of a laser engraving / cutting machine
Cristina Gabriela Saracin, Mihai Sorin Dinca

Aceasta lucrare prezinta o solutie viabila de realizare practica a unui masini de taiere si gravare cu laser ce poate fi actionata manual sau in regim automat. Aparatul propus este portabil si este ideal pentru gravura simpla si rapida a diferitelor tipuri de materiale. Aparatul poate grava lemn, carton, plastic, piele, plastic dar, nu poate grava sticla, ceramica, metal, piatra, marmura. Este un dispozitiv de mici dimensiuni, ce incape pe orice fel de birou si poate fi transportat cu usurinta. Transmiterea informatiilor din procesul de gravare se poate face printr-un program de calculator sau gravarea se poate face manual cu ajutorul unui joystick. In aceste conditii, devine posibila comanda manuala cat si automata a dispozitivului de taiere sau gravare cu laser. Avand in vedere acest aspect, lucrarea pune accentul atat pe managementul comandarii automate a dispozitivului de gravare cat si pe realizarea unei comenzi electronice manuale cu ajutorul unui joystick. Puterea de 1000mW a laserului este suficienta pentru proiecte cum ar fi personalizarea de huse pentru telefon, personalizarea unor obiecte de mici dimensiuni, realizarea de invitatii sau carti postale decupate, semnarea unor obiecte de design. Aparatul nu poate inlocui un aparat de gravura profesional, de putere mult mai mare, capabil sa taie sau sa graveze orice fel de material

Cuvinte cheie: gravare cu laser, joystick

This paper presents a viable solution for the practical realization of a laser cutting and engraving device that can be operated manually or automatically. The proposed device is portable and is ideal for simple and fast engraving of different types of materials. The device can engrave wood, cardboard, plastic, leather, plastic, but it cannot engrave glass, ceramics, metal, stone, marble. It is a small device that fits on any desk and can be easily transported. The transmission of the information from the engraving process can be done through a computer program or the engraving can be done manually with the help of a joystick. Under these conditions, it becomes possible to manually and automatically control the laser cutting or engraving device. Given this aspect, the paper focuses on both the management of the automatic control of the engraving device and the realization of a manual electronic control with a joystick. The 1000mW power of the laser is sufficient for projects such as customizing phone cases, personalizing small objects, making cut invitations or postcards, signing design objects. The machine cannot replace a professional engraving machine with much higher power, capable of cutting or engraving any kind of material.

Keywords: laser engraving, joystick

Contribution of compressed stabilized earth bricks (CSEB) to the control of indoor air quality in buildings: case study of Algeria
Fezzioui Naïma, Miloudi Yassine, Roulet Claude-Alain

The aim of this work is to examine the thermohydric behavior of a building made of compressed stabilized earth bricks (CSEB), by testing its effectiveness in stabilizing the quality of indoor air, compared to four conventional materials. The study is carried out using TRNSYS-COMIS software with its Buffer Storage Humidity Model for three types of climates: desert, Mediterranean, and dry and cold semi-arid climate. The results highlight the contribution of the CSEB material in regulating the indoor relative humidity of buildings, also in limiting the effects of condensation thanks to its adsorption effect.

Keywords: Indoor air quality, condensation, compressed stabilized earth bricks, simulation, hygrothermal behavior

Valorization of local kaolin in sustainable concrete and on the environment through their exploitation deposit
Tayeb Rikioui, Soltane Lebaili, Ahmed Tafraoui, Mekkaoui Abderahmane

The exploitation of clays in the cement sector creates a great influence on the geological monuments as well as on the general geological environment. In this context, this article aims to valorize kaolin from southwestern Algeria in sustainable concrete and to exploit their deposit site as a landfill. In order to obtain metakaolin, this kaolin is subjected to a thermal transformation controlled by an apparatus designed to test the ecological efficiency of this material. Subsequently, a mass substitution of 10% of cement with metakaolin in concrete was made for the study the performance of this new concrete.

Keywords: Kaolin; Metakaolin; Environment, CO2 gas; landfill site; Durability

Modelarea functionarii unui sistem neconventional cu panouri solare fotovoltaice si pompa de caldura care alimenteaza cladiri cu utilitati de incalzire si preparare a apei calde de consum
Modeling the operation of an unconventional system with photovoltaic solar panels and heat pump that supply buildings with heating and hot water utilities
Florin Iordache, Mugurel Talpiga

In lucrare se prezinta modelarea functionarii unui sistem neconventional format din panouri solare fotovoltaice care alimenteaza cu energie electrica o pmpa de caldura pentru furnizare de putere termica in instalatia de incalzire centarala a unei cladiri sau de prepararea a apei calde. Se prezinta atat relatiile corespunzatoare determinarii puterii electrice furnizate de suprafata de panouri solare fotovoltaice cat si relatiil de determinare dinamica a puterii termice livrate de pompa de caldura catre instalatiile consumatorului. In ultima parte a lucrarii se realizeaza o analiza energetica si economica privind impementarea acestori tipuri de sisteme neconventionale

Cuvinte cheie: Sistem hibrid, panou fotovoltaic, pompa de caldura

In this paper is it presented functional modelling of an unconventional system composed by fotovoltaic panels which are producing electric energy to drive the compressor of a heat pump to produce termal power for central heating unit of a building or to be used for daily hot water. Can be seen in tha paper the corresponding equations to evaluate electrical power from sollar cells and equations to establish the dynamic termal power given by heat pump to final costumer. At the end will be realized an energetic analyze and economic aspects to conclude the implementation of such unconventional systems

Keywords: hibryd system, fotovoltaic cells, heat pump

Influenta performantelor la foc ale placilor din aschii de lemn (PAL) asupra dezvoltarii unui incendiu simulat la scara naturala, intr-un spatiu inchis
Influence of fire performance of wood chipboards on the development of a natural scale simulated fire, in a confined space
Alexandru-Florin CHIOJDOIU, Ion ANGHEL, Valentin ENCIU, Ionel-Alin MOCIOI, Emil Florin TUDOR

In acest studiu se analizeaza contributia arderii Placilor din Aschii de Lemn (PAL) la un incendiu care se manifesta intr-un spatiu inchis, la scara naturala. Lemnul are o importanta deosebita in dezvoltarea incendiilor la constructii, deoarece este folosit pe scara larga in structura de rezistenta, pentru placare, pardoseli sau articole de mobilier. Studiul porneste de la descrierea fenomenelor fizice si chimice care au loc pe timpul procesului de ardere a lemnului si se ajunge la prezentarea performantelor la foc in conditii de utilizare finala. De asemenea, sunt prezentate rezultatele obtinute in urma testarii la foc a PAL-ului pentru metodele de incercare ISO 9705 si SBI. Studiul se incheie cu simularea, la scara naturala, a contributiei placilor de PAL la dezvoltarea incendiilor care se manifesta in spatii inchise, prin utilizarea programului de simulare a incendiilor B-RISK, utilizat in cazul celor doua metode de testare la foc, in baza a doua scenarii de incendiu, astfel: 1. Incaperea de testare nu este prevazuta cu material de finisaj interior, peretii acesteia fiind din beton cu grosimea de 100 mm, respectiv 2 mm. Incaperea de testare este prevazuta cu un lambriu din PAL de 12 mm grosime, folosit ca material de finisaj interior. Rezulta, astfel, o analiza comparativa a temperaturii stratului superior de gaze fierbinti si a plafonului, pentru valorile rezultate in urma utilizarii programului B-RISK in cele doua situatii si metode de incercare. In urma analizei, sunt precizate cateva recomandari care pot imbunatati securitatea la incendiu in cazul spatiilor inchise ce contin lemn sub forma de PAL.

Cuvinte cheie: piroliza, performanta la foc, PAL, simularea incendiilor

This study analyses the contribution of wood chipboards combustion to a natural scale fire that manifests in a confined space. Wood is of particular importance in the development of fire in buildings, because it is widely used in building’s frame structures, for cladding, floors or furniture objects. This study starts from the description of the physical and chemical phenomena occurring during the wood combustion process and continues with the presentation of the fire performance under final use conditions. The results obtained from the fire test of the wood chipboards for ISO 9705 and SBI test methods are presented, also. The study ends with the natural-scale simulation of the wood chipboards contribution to the development of confined space fires, by using the B-RISK fire simulation program, based on the two fire test methods and the two fire scenarios. There are two fire scenarios: 1st. The test room is not cladded with interior lining material, its walls made of concrete with a thickness of 100 mm and 2nd. The test room is cladded with 12 mm thickness wood chipboards used as interior lining material. Thus, a comparative analysis of the temperature of the upper layer of hot gases and of the ceiling results from the use of the B-RISK program in the two test situations and methods is obtained. Following the analysis, some recommendations are given that can improve fire safety in the case of confined spaces containing wood in the form of chipboards.

Keywords: pyrolysis, fire performance, chipboard (PAL), fire simulation

Studiu comparativ privind coroziunea in timp a electrozilor in sol, Partea 1 – Introducere
Comparative study regarding corrosion in time of the ground electrodes, Part 1 - Introduction
Stefan PAVEL, Ioan Bogdan PASCU, Nicoleta NEMES, Romeo NEGREA, Emilia DOBRIN, BURIAC Oana

Obiectivul lucrarii este de a prezenta, aspecte referitoare la: coroziunea metalelor acoperite si neacoperite cu zinc in solul orasului Timisoara (electrozi de impamantare a Instalatiei de Legare la Pamant aferenta Instalatiilor Electrice din Constructii), analiza parametrilor de sol, prototipuri de electrozi, masuratori electrice, microbiologice si analiza de prognoza-predictie matematica, materiale si dictionare de termeni aferenti. Un alt aspect prezentat in acest material este efectuarea de masuratori ale spectrului campului elecromagnetic oscilografiat al elementelor de metal acoperite si neacoperite cu zinc din sol.

Cuvinte cheie: coroziune, electrod de impamantare, sol, legare la pamant, microbiologia solului

The objective of this paper is to present aspects related to: corrosion of metals covered, and not covered with zinc in the soil of Timișoara (grounding electrodes of a grounding installation related to Electrical Installations of Constructions), analysis of soil parameters, prototype electrodes, electrical, microbiological measurements and mathematical prognosis analysis-prediction, materials, and dictionaries of related terms. Another aspect presented in this material are the measurements related to the spectrum of the oscillograph electromagnetic field of the grounding electrodes, which are covered, and not covered with zinc.

Keywords: corrosion, ground electrode, soil, grounding, soil microbiology

Study of the durability against carbonation of the concrete formulated with the partial replacement of cement with marble powder

. The first aim of this study is the use of marble waste powder as a partial replacement with cement (CEMI 42.5) in concrete in order to reduce greenhouse gas emissions results in the cement production and consequently on the manufacturing concrete with less environmental impact. Moreover, the carbonation phenomenon influences significantly the durability of reinforced concrete structures, in this context, the second aim of this work is the study of the effect of the accelerated carbonation on the durability of concretes formulated with the cement containing the marble waste (MDP) with different percentages. For this purpose, four concrete mixtures containing 0%, 10%, 15%, and 30% MDP as cement replacement by weight basis have been prepared. These mixtures of concretes were submitted to accelerated carbonation to study their durability against this phenomenon. The series of tests are conducted to study the effect of 10%, 20% and 30% replacement of cement with marble powder on carbonation depth and compressive strength and compare it with the conventional concrete. The result of this present investigation indicates that the carbonation depth increases with the increase of the rate of the replacement of cement with waste marble powder (10 % to 30%) and the compressive strength decreases slightly with the increase of replacement. the compressive strength remains within the acceptable range of M25 concrete.

Keywords: waste marble powder, concrete durability, carbonation depth, compressive strength, environment

Aspecte privind utilizarea dispozitivelor de amortizare cu masa acordata
Aspects regarding the use of the Tuned Mass Dampers
Zainulabdeen K. Abdulfattah Abdulfattah, Vlad Stefan Niculae, Daniel Stoica

Una dintre alternativele de proiectare a cladirilor noi dar si de interventii la cladirile existente este pe baza utilizarii dispozitivelor de amortizare cu masa acordata. Avand in vedere ca acestea sunt eficiente numai la cladiri cu regim mare de inaltime, s-au realizat studii de caz pentru cladiri cu 10, 20, 30 si 40 de niveluri, avand 3 tipuri de forme diferite in plan (circulare, patrate si dreptunghiulare) si doua tipuri de structuri de rezistenta (cadre din beton armat si duale din beton armat). S-au realizat comparatii intre raspunsurile structurale obtinute pentru modele de calcul corespunzatoare cladirilor cu si fara utilizarea dispozitivelor de amortizare cu masa acordata.

Cuvinte cheie: amortizor, masa, acordata, deformatii

One of the alternatives of designing new buildings but also for interventions to existing buildings is based on the use of the Tuned Mass Dampers (TMD). Given that they are effective only in high rise buildings, case studies have been carried out for buildings with 10, 20, 30 and 40 levels, having 3 different types of shapes in plan (circular, square and rectangular) and two types of structures (reinforced concrete frames and reinforced concrete dual systems). Comparisons were made between the structural responses obtained for the calculation models corresponding to the buildings with and without using the TMD.

Keywords: damper, mass, tuned, deflections

Experimental study on the phenomenon of cracking of a reinforced element in sand concrete

With the diversity of concrete quality, sand has taken a big place in the composition of sand concrete. However, reinforced concrete based on sand is undergoing experimental tests and validation tests, and its cracking in this concept has become a very paramount parameter when sizing this material. In this context, this work of an experimental nature, has for main objective to study the cracking of an element of reinforced concrete based on sand by the variation of the spacings of cracks using a reduced model in reinforced concrete.

Keywords: sand concrete - Cracking - tensile test - average crack spacing.

Experimental and numerical study on the performance of different fire ventilation systems
Marius Dorin Lulea

In the fire safety design of buildings, it is common practice to consider a smoke and heat exhaust ventilation system. The choice is made between either natural ventilation or a mechanical ventilation system. In case of a fire, the main requirement for building designers is to save users. For the safety of users during a fire, low temperatures, high oxygen concentration and good visibility for a certain period must be ensured. Three different cases of ventilation in case of fire were analyzed in this study: mechanical ventilation (CASE1) and natural ventilation (CASE2- wall hatches and CASE3- roof hatches). The results of an experimental study were used to validate a numerical model (CASE0- no ventilation system) using FDS software. The action of the fire in a room with an area of 18(m2) has been studied. Indoor temperatures, oxygen concentration and visibility are determined and used to establish the performance of different ventilation system. The three parameters play an important role in assessing the environmental conditions necessary to save users. The study shows that natural or mechanical ventilation in case of fire considerably improves the evacuation conditions, saving users' lives. Both types of ventilation ensure good performance in the situation of a correct dimensioning and designs.

Keywords: CFD, FDS, fire, real- scale fire tests, ventilation

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