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  Numarul 1/2014

Volumul 5 (2014), Nr. 1

The possibility of replacing solid walls with water curtain applicable to a large underground garage
Ivan Antonov, Rositsa Velichkova, Kamen Grozdanov, Ivancho Bogoev, Kiril Mavrov

The work is considered the replacement of fire barriers with hard water curtain sprinkler system created by the devices. The main focus is the duration of activation of sprinkler devices and parameters they generate water curtain. It is isolate specific cell cars using water curtain to prevent the spread of fire to neighboring and adjacent cars.

Experimental Study Of Acoustic Barriers In Urban Environment
Tiberiu Catalina, Vlad Iordache, George Craciunescu

Acest articol prezinta un studiu experimental detaliat al unei bariere acustice proiectate pentru protectia la zgomot a ocupantilor unui imobil de locuit. Studiul este bazat pe o situatie de mediu urban reala in care masurarile nivelului de zgomot au fost realizate inainte si dupa implementarea acestei bariere acustice. Sursele de zgomot au fost unitatile exterioare ale unei pompe de caldura aer-apa. Incepand cu protocolul de masura pana la concluzii, in acest articol sunt prezentate aspecte interesante privind protectia la zgomot a unei bariere acustice instalate in mediul urban. Atenuarea acustica maxima obtinuta in cadrul acestui studiu a avut valoarea de 18.96 dB pentru o frecventa de 125 Hz iar media a fost in jurul valorii de 15 dB. In cele din urma, s-a putut constata ca aceasta bariera a fost o solutie buna iar confortul acustic a fost asigurat.

This article presents a detailed experimental study of the design and analysis of an acoustic barrier used to protect the occupants of a building from the noise produced by a HVAC system installed outdoors. The study is based on a real urban situation in which noise measurements were conducted before and after implementation of the noise barrier. In this case the noise sources are the four fans of an air-water heat pump. From measurement protocol to conclusions in this article are present interesting insights about a noise barrier installed in urban areas. The highest acoustic attenuation obtained in this study had a value of 18.96 dB at a frequency of 125 Hz and the average was around 15 dB. At the end, the use of the noise barrier was found a good solution and the acoustic comfort was achieved.

The influence of different flow velocities on the heat transfer inside a ventilated fašade
Monica Chereches, Nelu-Cristian Chereches, Sebastian Hudisteanu

In this paper, a comparative numerical study has been conducted in order to analyze the thermodynamic behavior inside a channel of a double skin ventilated fašade in cold season with air supply ventilation mode. The study was performed in forced convection with CFD software Ansys-Fluent. A parametric investigation concerning the fluid inlet velocity has been conducted to study its influence on both fluid flow and heat transfer. The obtained results show the temperature and the velocity profiles, for different air velocities at the inlet section in order to calculate the heat loses through the surface of the interior glazing.

Conception of a simplified seated thermal manikin for CFD validation purposes
Angel Dogeanu, Bode Florin, Alexandru Iatan, Cristiana Croitoru, Ilinca Nastase

Aceasta lucrare prezinta unul dintre cele cinci prototipuri de manechine termice concepute la Facultatea de Inginerie a Instalatiilor de la Universitatea Tehnica de Constructii. Acest prototip a fost conceput pentru a avea o forma simplificata cu unghiuri drepte pentru validarea modelelor numerice in cadrul unor studii de tip CFD. Toate testele sunt coerente si indica posibilitatea utilizarii acestui prototip in cadrul unor studii viitoare. Modelul este functional si temperatura fiecarei zone a corpului poate fi usor modificata in conformitate conditiile la limita dorite de utilizator. Forma geometrica a manechinului are un rol important in generarea curgerilor convective din jurul lui, de aceea acest prototip nu este potrivit pentru studii experimentale de rezolutie fina a micro-climatului corpului uman. El poate fi utilizat in cadrul unor studii globale de confort atat pentru cladiri cat si pentru vehicule.

This paper is presenting one among the five prototypes of thermal manikins conceived at the Building Services Faculty (Thermal-Hydraulic Systems Laboratory) at the Technical University of Civil Engineering. This particular prototype was chosen to have a simplified square angled shape in order to be used for validation in CFD studies We designed a seated thermal manikin that can simulate the human presence in a room. All the tests are coherent and this manikin can be further used to validate our CFD models. The model is fully functional and the temperatures of each body zone can be easily modified in accordance to our needs. The shape have an important role in the air movement o around the human body and this manikin is not suitable for local and high resolution measurements around the human body but can be used for global measurement in a room or inside a vehicle

Experimental and theoretical study regarding the thermal performances of the heat exchangers with steel panels and extended surfaces
Anica Ilie, Razvan Calota

The present paper refers to the thermal performances of the heat exchangers with steel panels, used in the buildings' heating installations. The heat exchanger was set up in a thermostatic test room, built in conformity with SR EN 442-2:2002/A2:2004 and was tested in standard functioning conditions. The experimental were compared with those obtained by applying the correlations that characterize the heat transfer for the flow of liquids through narrow vertical spaces and the flow of air by natural convection in different situations.

Consecinte energetice ale incalzirii intermitente a cladirilor
Energetic consequences of intermittent heating of buildings
Florin Iordache, Vlad Iordache

Reducerea consumului de energie in domeniul consumatorilor civili este un deziderat intens urmarit in contextul preocuparilor actuale europene si internationale. Incalzirea spatiilor reprezinta un domeniu caracterizat de un consum considerabil de energie si preocuparea pentru reducerea acestora sta in atentia specializatilor de pretutindeni. Adoptarea regimului de incalzire intermitenta in locul regimului de incalzire continua poate fi o solutie in anumite situatii architectural constructive de cladiri. Lucrarea are ca obiectiv tocmai identificarea unor criterii de urmarit, utile in adoptarea regimului intermitent de incalzire in locul celui continuu, in vederea reducerii consumurilor energetice. Sunt vizati parametrii constructivi de natura termica cum ar fi rezistenta termica medie si masivitatea cladirii. Se au de asemenea in vedere si capacitatea instalata a sistemului de incalzire care face apel la investitiile necesare alaturi de consumurile energetice.

Reduction of energy consumption in the consumer civilians is a goal pursued extensively in European and international context of current concerns. Space heating is an area characterized by a considerable energy consumption and reduce their concern lies in attention specializatilor everywhere. Adoption heating regime in place intermittent continuous heating regime can be a solution in some situations constructive architectural buildings. This paper aims to identify just watched criteria useful in adopting intermittent instead of continuous heating, to reduce energy consumption. It covers the nature of design parameters such as thermal resistance thermal medium and massive building. We have also taken into account the installed capacity of the heating system that appeals to the investments required with energy consumption.

Analiza performantei energetice a unei instalatii solare de preparare a apei calde de consum in diverse conditii de utilizare
Analysis of the energy performance of a thermal solar system for DHW production, under different operating conditions
Razvan Popescu, Lelia Popescu, Andrei Damian

In lucrarea de fata se prezinta un studiu parametric aplicat unei instalatii de preparare a apei calde de consum ce deserveste o cladire de tip hotel situata in Romania. Studiul urmareste evidentierea anumitor factori de influenta precum: climatul local, tipul de panou, tipul de profil de consum, orientarea cardinala a panourilor solare sau inclinarea acestora fata de orizontala, asupra performantei energetice a instalatiei. Metoda de analiza este numerica, in regim dinamic si face apel la simulari pe un an de zile, realizate cu ajutorul programului de calcul SimSol. Rezultatele obtinute, in termeni de factori de acoperire solara, permit cateva recomandari practice privind dimensionarea acestor sisteme pentru diferite tipuri de cladiri.

In the present paper is presented a parametric study regarding the operation of a solar thermal system for DHW preparation, equipping a small hotel located in Romania. The study main goal is to outline the influence that several parameters, such as: local climate, solar panel type, solar panels orientation and slope, could have on the system energy performance. The method of analysis is numerical one, it is made under dynamic operational conditions, and it is performed by using the software SimSol, especially designed for the simulation of solar thermal installations. The results obtained by numerical simulations over one-year period could mean to practical recommendations regarding the design of this type of systems for different buildings.

The behaviour analysis of an anaerobic sludge digester exposed on thermic action
Sorohan Lucian Valentin

The anaerobic sludge digesters existing in wastewater treatment plants are exposed to temperature variations, due to permanent sludge heating at 35oC - 37oC and external weather temperature variation. This work presents the behaviour in time, as well as the calculation analysis of thermic effects action diminution for that kind of things, taking into account a small energetic balance

An experimental study on convective drying of quince
Tzempelikos Dimitrios, Bardakas Achilleas, Vouros Alexandros, Tsepenekas Dionysios, Filios Andronikos, Margaris Dionissios

A laboratory convective drying unit (LCDU) has been designed, constructed and equipped with an integrated measurement and control instrumentation, in order to evaluate the essential drying characteristics of various horticultural and agricultural products. The current paper presents experimental results from tests with quince slices. Drying kinetics was investigated as a function of drying conditions. Experiments were conducted at air flow temperatures of 40, 50 and 60oC and average velocities of 1, 2 and 3 m/s. Temperature changes of the drying quince samples, the relative humidity and the temperature of the drying air were measured during the drying processes and finally the moisture ratio (MR) was calculated. The experimental MR data were fitted with three mathematical models available in the literature and a good agreement was observed. In the ranges measured, Fick's 2nd law of diffusion was used to fit the experimental data for the determination of the effective moisture diffusivity. The activation energy was determined, assuming an Arrhenius type temperature relationship with moisture diffusivity.

 
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