Assessment of building service systems process integration applying exergy critrerion ; Pastato inžinerinių sistemų procesų integravimo vertinimas taikant eksetrgijos kriterijų

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• Publié par: vilnius_gediminas_technical_university
• Publié le: 01 janvier 2008
• Nombre de lectures: 26

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          Darius BIEKŠA         ASSESSMENT OF BUILDING SERVICE SYSTEMS PROCESS INTEGRATION APPLYING EXERGY CRITERION       Summary of Doctoral Dissertation Technological Sciences, Energetics and Thermal Engineering (06T)       1449 M

 

Vilnius 

   

 2008

 

VILNIUS GEDIMINAS TECHNICAL UNIVERSITY                    Darius BIEKŠA         ASSESSMENT OF BUILDING SERVICE SYSTEMS PROCESS INTEGRATION APPLYING EXERGY CRITERION           Summary of Doctoral Dissertation Technological Sciences, Energetics and Thermal Engineering (06T)        

 

Vilnius

  2008 

 

Doctoral dissertation was prepared at Vilnius Gediminas Techni cal University in 2003–2007.    Scientific Supervisor Prof Dr Habil Vytautas MARTINAITIS (Vilnius Gediminas Technical University, Technological Sciences, Energetics and Thermal Engineering – 06T). Consultant   Assoc Prof Dr Artur ROGOŽA(Vilnius Gediminas Technical University, Technological Sciences, Energetics and Thermal Engineering – 06T). The dissertation is being defended at the Council of Scientif ic Field of Energetics and Thermal Engineering at Vilnius Gediminas Technica l University:  Chairman  Prof Dr Habil Alfonsas Kazys SKRINSKA(Vilnius Gediminas Technical University, Technological Sciences, Energetics and Thermal Engineering – 06T).  Members:  Prof Dr Habil Benediktas ČöSNA (Vilnius Gediminas Technical University, Technological Sciences, Energetics and Thermal Engineering – 06T),  Prof Dr Habil Rimantas KAČIANAUSKAS (Vilnius Gediminas Technical University, Technological Sciences, Energetics and Thermal Engineering – 06T), Dr Vaclovas KVESELIS (Lithuanian Energy Institute, Technological Sciences, Energetics and Thermal Engineering – 06T)  , Prof Dr Habil Gintautas MILIAUSKAS (Kaunas University of Technology, Technological Sciences, Energetics and Thermal Engineering 06T). – Opponents:  Prof Dr Egidijus Saulius JUODIS (Vilnius Gediminas Technical University, Technological Sciences, Energetics and Thermal Engineering – 06T), Prof Dr Habil Povilas Algimantas SIRVYDAS(Lithuanian University of Agriculture, Technological Sciences, Energetics and Thermal Engineering – 06T).   The dissertation will be defended at the public meeting of the C ouncil of Scientific Field of Energetics and Thermal Engineering in the Senate Hall of Vilnius Gediminas Technical University at 2 p. m. on 10 March 2008. Address: Saul÷tekio al. 11, LT910223 Vilnius, Lithuania. Tel.: [phone]52, [phone]56; fax [phone]; e9mail: [e-mail] The summary of the doctoral dissertation was distributed on 8 February 2008. A copy of the doctoral dissertation is available for review at the Library of Vilnius Gediminas Technical University (Saul÷tekio al. 14, LT910223 Vilnius, Lithuania).   © Darius Biekša, 2008  

 

 

 

VILNIAUS GEDIMINO TECHNIKOS UNIVERSITETAS                   Darius BIEKŠA       PASTATO INŽINERINIŲ SISTEMŲ PROCESŲ INTEGRAVIMO VERTINIMAS TAIKANT EKSERGIJOS KRITERIJŲ           Daktaro disertacijos santrauka Technologijos mokslai, energetika ir termoinžinerija (06T)          

 

Vilnius 

  2008 

 

Disertacija rengta 2003–2007 metais Vilniaus Gedimino technikos universitete. Mokslinis vadovas prof. habil. dr. Vytautas MARTINAITIS Gedimino technikos (Vilniaus universitetas, technologijos mokslai, energetika ir termoinžinerija – 06T). Konsultantas  doc. dr. Artur ROGOŽA Gedimino technikos universitetas, (Vilniaus technologijos mokslai, energetika ir termoinžinerija – 06T).  Disertacija ginama Vilniaus Gedimino technikos universiteto Energetikos ir termoinžinerijos mokslo krypties taryboje: Pirmininkas  prof. habil. dr. Alfonsas Kazys SKRINSKA (Vilniaus Gedimino technikos universitetas, technologijos mokslai, energetika ir termoinžinerija – 06T). Nariai:  prof. habil. dr. Benediktas ČöSNA(Vilniaus Gedimino technikos universitetas, technologijos mokslai, energetika ir termoinžinerija – 06T), prof. habil. Dr. Rimantas KAČIANAUSKAS (Vilniaus Gedimino technikos universitetas, technologijos mokslai, energetika ir termoinžinerija – 06T), dr. Vaclovas KVESELIS(Lietuvos energetikos institutas, technologijos mokslai, energetika ir termoinžinerija – 06T), prof. habil. dr. Gintautas MILIAUSKAS universitetas, technologijos (Kauno technologijos mokslai, energetika ir termoinžinerija – 06T). Oponentai:  prof. dr. Egidijus Saulius JUODIS(Vilniaus Gedimino technikos universitetas, technologijos mokslai, energetika ir termoinžinerija – 06T), prof. habil. dr. Povilas Algimantas SIRVYDAS(Lietuvos žem÷s ūkio universitetas, technologijos mokslai, energetika ir termoinžinerija – 06T).

  Disertacija bus ginama viešame Energetikos ir termoinžinerijos mo kslo krypties tarybos pos÷dyje 2008 m. kovo 10 d. 14 val. Vilniaus Gedi mino technikos universiteto senato pos÷džių sal÷je. Adresas: Saul÷tekio al. 11, LT910223 Vilnius, Lietuva. Tel.: (8 5) 274 452, (8 5) 274 456; faksas (8 5) 270 0112; el. paštas [e-mail] Disertacijos santrauka išsiuntin÷ta 2008 m. vasario 8 d. Disertaciją galima peržiūr÷ti Vilniaus Gedimino technikos universiteto bibliotekoje (Saul÷tekio al. 14, LT910223 Vilnius, Lietuva). VGTU leidyklos „Technika 144 M mokslo literatūros knyga. “   © Darius Biekša, 2008

 

 

General characteristic of the dissertation   Relevance.A significant part of world energy consumption balance, approx. 40 %, is utilized in buildings. Maintenance of comfortable conditions and improvement in the living, working or recreational environment is a desire for every human. Therefore it is no surprise that there has been a sudden increase in scientific research in the field of building energy efficiency. Energy demand for buildings’ heating, ventilation and cooling are based on a formulation of balance equations that stand on the provisions of the first law of thermodynamics (FLT). According to this law all energy is defined as absolutely realizable i.e. can not disappear but only changing its form. This approach is applied when estimating the benefits introducing energy efficiency measures in buildings, calculating amounts of saved energy and so on. But the energy flows emerging in building are different not only in a quantitative but also in a qualitative way. It is traditionally settled that for maintenance of rather low temperature in a room high quality energy sources are employed. And the result, taking in to consideration the final energy consumer, energy with high quality potential is wasted for the generation of low potential heat (approx. +20 °C). This situation has to be changed by estimating buildings’ sufficient quality energy demand and by putting maximum efforts into utilizing internal and external energy gains or ways for their removal. In this work thermodynamical method is applied that is based on the second law of thermodynamics (SLT). SLT states the energy degradation or inevitable entropy generation principle. The employment of this criterion grants a correct comparison of different energy flows in the light of SLT, enables estimation of their thermodynamical efficiencies and provides guidelines for the proper orientation of a sustainable energy development process. Concluding it could be stated that the problem is that energy efficiency measures, particularly in building service systems, are evaluated using only FTL. More than this, systems are analysed only under the steady state conditions with no respect to the various systems operational regimes during the system’s exploitation period. Research object.This work analyses possibilities to increase qualitative energy consumption efficiency in buildings by applying the exergy analysis method. Research object is office buildings’ service systems. Research involves analysis of heating, ventilation, cooling and lighting systems and elements through different periods of exploitation. Aim and tasks of the work.The aim of the work is to evaluate the possibilities for applying exergetical process and system integration method in the design, operation and normalization of the office building service systems:  

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to prepare design solutions that increase buildings’ service systems’ thermodynamical efficiency and covers individual processes and elements chain systems. The tasks of the work are: 1. To create a thermodynamical model of building service systems’ that enables the performing of qualitative and quantitative analysis of the energy transformation processes that are taking place in buildings’ service systems and elements. 2. Evaluate minimal building exergy demand “on building boundary” on the other hand formulating a task for the external energy suppliers to deliver to the buildings boundary sufficient potential and amount of energy. 3. Ensure possibly minimal exergy demand “on building boundary” by applying today’s technological measures and reaching available degree of integrity. 4. Perform analysis of buildings’ service systems not only under standard design conditions but also examining intermediate operational regimes. 5. Estimate the structure of building exergy demand ”on building boundary”. Identify the of different energy form components. Methodology of the research. In this work the building service systems’ analysis incorporates three interconnected methods: system analysis, life cycle and thermodynamical analysis. Application of system analyses enables an estimation of service system’s elements (subsystems) and their interconnections. Life cycle analysis allows estimation of total exergy demand through the whole system’s life cycle. Thermodynamical analysis provides tools for the proper calculation and comparison of different quality energy. Scientific noveltyA thermodynamical model of building service systems’. is created that enables analysis of energy transformation processes in separate building service systems and their elements. This empowers thermodynamical availability assessment of systems and implemented energy efficiency measures. The created thermodynamical model of building service systems’ is used for the analysis of building micro climate conditioning systems by evaluating characteristic periods of their operation. Exergy demand and structure is estimated on the basis of annual and typical operation periods. Practical value. The problematic covered in this work is actual because it involves a qualitatively new and still rather rarely applied flow evaluation method. The building service system research performed includes not only exergy capacity demand estimation analysis during the most unfavourable outdoor conditions but also detailed analysis energy flows during typical operation periods.

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The presented energy efficiency measures evaluation method allows estimation of service systems exergetical efficiency that enables a proper orientation of a sustainable energy development process Approval of dissertation’s results and application of the results.The main statements of the dissertation were published in 2 scientific journals and 3 conference proceedings, presented and discussed at 2 international and 3 national conferences in Lithuania and abroad. The scope of the scientific work.The work is written in Lithuanian language. It consists of an introduction, 3 main chapters, conclusions, a list of literature and a list of publications. The total scope of the dissertation – 6 pages, 38 pictures and 3 tables.   1. Review of the research methods   This work analyses exergy efficiency increase possibilities in building service systems. Systems’ efficiency is identified as thermodynamical  efficiency when systems’ perfection is evaluated not only on the basis of FTL but including STL provisions. In order to successfully fulfil the research objectives it is necessary to prepare a coherent and structuralized research execution methodology. Paying attention to the research object – building service systems – for their analysis it is necessary to apply a system analysis method that enables the indication of relationships between separate systems elements and functions for systems’ operation. Application of a system analysis method permits the creation of a thermodynamical model of building service systems’. The investigation covers not only analysis of systems’ operation regimes but also evaluates primary energy demand during systems’ life cycle. In order to carry out this task life cycle analysis is presented and applied. Energy transformation process efficiency is evaluated including both quantitative and qualitative approaches. For the realization of this assessment exergy analysis is invoked. It has to be pointed out that the estimation of building service systems’ energy demand by applying qualitative approaches distinguishes this work from others.   2. Theoretical investigation   A building is a complex engineering system. Its operation directly depends on its compounding elements and processes that take place in its supersystem. In this case supersystem is considered as the surroundings of a building system that link together all external factors that influence the building. These factors

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are atmospheric air, sun radiation, precipitation, wind speed and so on. The influence of the supersystem to the building system cannot be directly controlled but it could be relatively predicted. A building system could be separated in to three closely interacting elements: building structural element – envelope; second element room or – space where comfort conditions have to be maintained ant the third element – building service systems. A building subsystems’ (elements) scheme is presented in Fig 1.  

  Fig 1.Scheme of building’s system elements   Architectural design solutions and estimation of optimal envelope combinations has a significant impact effecting future buildings’ exergy demand. Rational solutions for the selection of envelope combinations grant smaller energy consumption level during a building exploitation period. On the other hand correct architectural solutions for the building’s composition allow maximal utilization of internal and external energy gains. The second building system element is a room in which comfort conditions have to be maintained. In this work comfort conditions in the room are identified as a favourable thermal environment and necessary fresh air flow. A room’s thermal environment parameters are generally settled by the building’s envelope and internal gains, when the room air quality directly depends on room occupation regimes and local pollution sources. The third building system element is building service systems. Their function actively controls comfort conditions in the room. Buildings microclimate. Rooms’ energy demand is determined by three main factors: requirements for room comfort conditions, the thermodynamical  properties of envelopes that borders room system and the building’s (room’s) surroundings. Heat losses (gains) which cross room system boundaries can be compensated for using passive and active microclimate conditioning systems.

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The energy flows in passive microclimate conditioning systems is effected by building envelope can not be actively controlled. Theses flows are heat gains from solar radiation, heat accumulated in building constructions, heat gains from occupants, lighting system, and electrical devices used in the room. Active microclimate conditioning systems consists of energy supply technical systems, where supplied energy is obtained by burning (transforming) fuel (energy). These systems have energy generation (transformation), supply and consumption subsystems. These systems also include systems that use renewable energy sources.   3. Theoretical model of building service systems   Building service systems are complex technical systems that have an abundance of internal and external relationships. Before starting to create a thermodynamical model of building service systems’ it is necessary to identify these dependencies and write their mathematical functions. A building service system function consists of an independent variable that defines the formation of exergy demand in the room and a dependent variable. These describe the system’s operations modes, their regimes and so on. The building service system function can be written mathematically as:   =    ) .       (1)   The index t used in the equation indicates that function is time dependant. The building service system function is presented in Fig 2.   Function value function argument Building service Structure of building Parameters for building system exergy service systems heat balance flows Systems control Comfort conditions  strategies parameters  Building occupation Annual variations of  regimes outdoor air  temperature  Transportable flows  amounts  System elements  efficiency

Fig 2.Components of building service systems function

Function argument consists of independent and dependent variables. To the independent variables could be assigned such parameters as outdoor air

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temperature, intensity of solar radiation. The variations of values for these parameters are unknown but can be conditionally predictable. The dependent variable parameters include thermodynamical characteristics of the building envelope, building service systems’ elements’ technical specifications, parameters defining comfort conditions in the room. The relation between the set of variables and the value of the function is realized by applying rules that prescribe arguments interconnections.  

  Fig 3.Scheme of typical building service systems   In order to elaborate the combination of systems, used in the building, it is necessary to define types of separate systems, indicate elements, describe operation modes and so on.  

Fig 4.Scheme of systems elements  

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