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  Numarul 1/2017

Volumul 8 (2017), Nr. 1 - Vizualizare numar complet

Building integrated solar thermal systems presentation and zoom on the solar potential
Gilles Notton

This work was realized in the context of the COST Action TU1205 “Building Integration of Solar Thermal System” (BISTS) The objectives for this Action focus on creating a platform from which a working environment is developed that generates methods to further the integration of Solar Thermal System in buildings. This action will be described and some integration examples will be presented. The aesthetic of solar thermal collectors can be an obstacle to their development and limits the growth of the market. Integrating a thermal solar collector in a building improves the aesthetics of the building and allows a best social acceptance of the energy system. But we might ask the question whether as a building integration reduces the choice of the inclination and orientation of the BIST, is there an influence on the solar energy available to be converted into thermal energy? We will try to reply to that question.

Keywords: Building Integrated solar systems, solar radiation potential

Estimative analysis of investment payback for industrial spaces heated with radiant tubes
Adriana Tokar, Adrian Retezan, Arina Negoițescu

Currently, energy consumption reduction can be considered a priority due to high fuel prices used for space heating. Therefore, for industrial buildings where technological processes which are taking place require specific climate conditions, the energy consumption reduction is achievable through the implementation of efficient heating systems in terms of energy.The paper presents an analysis of the radiation heating systems in terms of economic efficiency. In this regard, there are considered two types of radiant tube heating systems powered by three fuel types, in order to assess the investment payback. Thus, there were compared both the annual fuel consumption during the system operation and installation costs. Based on the obtained results, there was revealed the best version of the heating system for the considered industrial space.

Keywords: radiant tube, consumption, investment, energy saving

Instalatii de incalzire centrala. Reglajul termic calitativ centralizat
Central heating installations. Centralized quality heat setting
Prof. dr. ing. Florin Iordache

Pornind de la bilanturile termice ale instalatiei de incalzire centrala si ale cladirii alimentate cu caldura se stabilesc relatiile de reglaj termic calitativ centralizat, adica relatiile care fac corelatia dintre temperaturile agentului termic vehiculat in instalatia de incalzire si temperatura exterioara. Se descrie si procedura iterativa de lucru pentru determinarea practica a valorilor temperaturilor de agent termic. Rezultatele obtinute se prezinta si grafic pentru anumite cazuri in care conditiile de dimensionare a instalatiilor de incalzire centrala sunt diferite. De asemenea se discuta si o serie de situatii privind consecintele nerespectarii graficelor de reglaj termic calitativ centralizat.

Starting from the thermal balance of the central heating systems and the supplied building with thermal energy, I have established relationships between hot water temperature and the outside temperature. These relationships make the correlation between hot water temperatures circulated to the heating system and outside temperature. It is also describes the iterative procedure for determining practice working in heating system The results are presented graphically for certain cases in which the conditions for of central heating systems are different. Also discuss a series of statements on the consequences of failure graphs centralized control heat.

Sistem centralizat de producere si distributie a caldurii
Centralized production and distribution of heat
George-Lucian Ionescu

Continutul prezentat in cadrul acestei lucrari subliniaza avantajele si dezavantajele sistemului centralizat de incalzire si de distributie a energiei termice prin transformarea carbunelui in gaz, in timp ce se mentioneaza, de asemenea, eficienta termica, care se obtine prin aceasta metoda.

Cuvinte cheie: sistem, căldură

The contents presented within this paper outline the advantages and disadvantages of the centralized system for heating and heating distribution by means of converting coal into gas, while also mentioning the thermal efficiency that is obtained through this method.

Keywords: system, heat

Estimation of indoor temperatures on condition that building envelope is damaged
Viktor Petrenko, Kostiantyn Dikarev, Al’ona Skokova, Oleksandra Kuzmenko

The purpose of this paper is to represent inside temperature calculation algorithm provided that building envelope is damaged. Brick wall with erosion area was chosen as the building envelope. We examine one-dimensional thermal transfer in steadystate conditions. The temperatures at both sides of the wall are constant. The derived equation allows calculating the estimated inner temperature of the air on condition that outside wall is damaged by erosion.

Keywords: inner surface temperature, microclimate, thermal transfer, steady state condition

Analysis of rod systems under undefined load
Volchok Denys

The purpose of this paper is to represent influence of undefined data information on the results of rod systems design. We propose to use fuzzy sets as kind of uncertainty. As a calculation method we use the method of forces.

Keywords: rod systems, undefined information, fuzzy numbers, method of forces, system of linear algebraic equations

Identificarea hidro-termica a retelelor termice
Identification of hydro-thermal heating networks
Prof. Florin Iordache

Lucrarea se refera la retelele termice de distributie (secundare) din cadrul sistemelor centralizate de alimentare cu caldura, existente in majoritatea centrelor urbane din tara. Astfel de retele termice proiectate si construite inainte de 1990 au functionat ani de zile si functioneaza si astazi insa performantele lor au inceput sa scada datorita alterarii unor parametrii hidraulici si termici specifici tronsoanelor de conducta din care sunt alcatuite aceste retele. In lucrare se prezinta justificarea teoretica pentru 2 propuneri de proceduri experimentale de identificare a starii hidraulice si termice a tronsoanelor retelelor termice in vederea compararii cu starea initiala a acestora si remedierea deficientelor in cazul in care aceasta se impune.

Cuvinte cheie: retele termice

The paper refers to heating networks distribution (side) of the centralized heat supply systems, existing in most urban centers in the country. Such heating systems designed and built before 1990 have worked for years and still works today but their performance began to drop due to alteration of hydraulic and thermal parameters specific sections of pipe that makes up these networks. This paper presents the theoretical justification for the two proposals for experimental procedures identifying the condition thermal hydraulic and thermal networks sections for comparison with their initial state on deficiencies if it is necessary.

Keywords: heating systems

Instalatii de incalzire cu emitatoare de unde intunecoase
Heating with dark wave transmitters
George-Lucian Ionescu

Radiatia termica face parte din criteriile de radiatii utile care reprezinta radiatii inofensive in spectrul larg de lungimi de unda electromagnetice, in special undele infrarosii care au cel mai mare potential de incalzire din intregul spectru de lungimi de unda electromagnetice.

Cuvinte cheie: încălzire, emițătoare unde întunecoase

Heat radiation is part of the useful radiation criteria that represents harmless radiation within the large spectrum of electromagnetic wavelengths, particularly the infrared waves having the biggest heating potential out of the entire electromagnetic wavelength spectrum.

Keywords: heating, dark wave transmitters

Evolutia sistemelor de climatizare de tip VRF - PARTEA I - Evolutia sistemelor VRF HVAC
Evolution type VRF air conditioning systems - PARTEA I - VRF HVAC systems evolution
Drd. Ing. Catalin NEGRUTIU, Prof. Dr. Ing. Dragos HERA

Sisteme de climatizare pentru cladiri medii si mari sunt o necesitate pentru moment. Sistemele VRF reprezinta o solutie moderna HVAC pentru cladiri rezidentiale si comerciale. Pentru aceste tipuri de aplicatii cererea investitorilor este de a avea un consum redus combinat cu un nivel ridicat de confort. Acest studiu prezinta tehnologia si analizeaza evolutia sistemelor VRF avand in jur de 20 ani perioada de timp. Studiul contine valorile dezvoltarii coeficientilor de performanta, evolutia tehnologica si a agentilor frigorifici.

Cuvinte cheie: soluții de răcire, VRF, VRV, eficiență

Air conditioning systems for medium and large building are a necessity for the time being. The VRF systems represent a modern HVAC solution for residential and commercial buildings. For these kinds of applications the investors request is to have a low consumption combined with a high level of comfort This study presents the technology and analyzes the evolution of the VRF systems considering around 20 years period of time. The study contains the values of the performance coefficients, technological evolution and refrigerants development

Keywords: cooling solution, VRF, VRV®, efficiency

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