Experimental Characterization and Modeling of Advanced Polymer Composite Window Frames

Jan Jakub Zajas

Experimental Characterization and Modeling of Advanced Polymer Composite Window Frames

Jan Jakub Zajas

Publikation: Ph.d.-afhandling

Abstract

Selv om vinduesrammer kun er en relativ lille del af den samlede bygnings klimaskærm er de ansvarlig for en stor mængde varmetab, hvilket skyldes deres dårlige isoleringsegenskaber, hvis man sammenligner med andre bygningselementer. Med fokus på den nuværende trend i forhold til at reducere bygningers energiforbrug er det tydeligt, at der er behov for at forbedre den termiske ydeevne af nutidige rammer, således at bygningerne opfylder de nye og mere skrappe krav.

Denne PhD afhandling vil fokusere på forbedringerne af den termiske ydeevne af vinduesrammer lavet af glasfiberforstærket plastik (FRP). Dette materiale er for nyligt blevet introduceret på markedet for vinduesrammer, og det er blevet et interessant valg grundet dets fine termiske og mekaniske egenskaber, hvilket kan medføre en forbedring af isoleringsevnen for vinduesrammer.

Der er adskillige måder at forbedre den termiske transmission af vinduesrammer. Varme overførsel via en vinduesramme er en kombination af varmeledning, konvektion og stråling og hver af disse mekanismer kan reduceres på forskellig vis. Et eksempel kunne være at inddele hulrummene for at reducere konvektionsvarme flowet eller benytte emissitvity materialer for at mindske den radiation. Disse samt adskillige andre løsninger er undersøgt i første del af Phd afhandlingen. Simuleringer af simple geometrier er udført i forhold til at kunne evaluere potentialet ved forskellige løsninger. Resultaterne viser, at anvendelse af forskellige modifikationer til en vis grad giver en betydelig reduktion af termisk transmission. For at opnå ydereligere forbedringer kræver dette mere drastiske forandringer.

På den baggrund er der foretaget en omfattende undersøgelse af, hvorledes rammegeometrien kan forbedres på et overordnet niveau. Ordinære vinduesrammer kan blive udformet i mange forskellige former, hvilket giver udviklerne en stor designmæssig frihed. Selv om der kan designes et uendeligt antal versioner af vinduesrammer er det ikke alle rammer, der vil have tilfredsstillende termiske egenskaber. Det er vigtigt at klarlægge, hvorledes et korrekt design af en ramme vil biddrage til at forbedre de termiske ydeevner. Derefter kan hele rammegeometrien blive optimeret i forhold til den termiske transmission, størrelse og materialevalg.

Optimeringsprocessen kan blive foretaget ved at designe et stort antal vinduesrammers geometri og derefter evaluere deres termiske egenskaber, fortrinsvis på en automatisk måde. En stor del af denne PhD afhandling er dedikeret til udviklingen af et parametrisk designværktøj, som kan benyttes til et sådant formål. Derefter er det endelig værktøj brugt til at optimere rammerne. Optimeringen har fokus på flere formål, hvilket gør opgaven endnu mere kompliceret. Undersøgelsen foreslår to fremgangsmåder: en vægtet sum fremgangsmåde og en genetisk algoritme.

Et andet formål med PhD afhandlingen var at udvikle en ny kombination af materialer, der kan bruges til at forbedre vinduesrammer. Denne kombination består af på ydersiden højstyrke kompositlaminat, og isolerende skum på indersiden. Resultatet blev udviklingen af et funktionelt gradueret materiale med rummeligt varierende egenskaber. Denne usædvanlige konstruktion skaber en udfordring i forhold til eksperimentel karakterisering af produktet. Problemstillingen kan løses ved at benytte laser flash metoden, som kan tilpasses dette specifikke formål. Der er foretaget mindre modifikationer i LFA 447 laser flash apparatet, som med en fin opløsning tillader afledning af de lokale transportegenskaber af forskellige materialer. Denne metode var valideret og blev med succes benyttet til formålet.

Originalsprog	Engelsk
Vejledere	Heiselberg, Per Kvols, Hovedvejleder
Udgivelsessted	Aalborg
Udgiver	Department of Civil Engineering, Aalborg University
Status	Udgivet - 2014

Emneord

Window Frames
Heat Loss
Energy Use
Thermal Performance
Fiberglass Reinforced Plastic (FRP)
Conduction
Convection
Radiation
Frame Geometry
Parametric Design Tool

AUB Link

Søg efter materialet i Aalborg Universitetsbiblioteks søgemaskine

Citationsformater

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abstract = "Even though the window frames cover a relatively small fraction of the entire building envelope, they are responsible for a major amount of heat loss, due to their poor insulation properties compared to the other envelope elements. With the current trends to reduce energy use in buildings, it is obvious that the thermal performance of contemporary frames needs to be improved, so that buildings can fulfill the new, more rigorous demands.This study will focus on improving the thermal performance of window frames made of fiberglass reinforced plastic (FRP). This material has been recently introduced to the window frame market and is becoming an increasingly interesting choice, due to its fine thermal and mechanical properties which can lead to a significant improvement of the insulation properties of a window frame.There are several ways to improve the thermal transmittance of a window frame. Heat transfer through a frame is a combination of conduction, convection and radiation and each of these mechanisms of heat transfer can be diminished in certain ways. An example could be subdividing the cavities to reduce convective heat flow or using low emissivity materials to limit the thermal radiation. These, and several other solutions, are investigated in the first part of the study. Simulations on simple geometries are conducted to evaluate the potential of different solutions. The results show that by applying different modifications the thermal transmittance of a frame can be significantly reduced, but only to a certain extent. To reach further improvement, more drastic changes need to be done.Therefore, an extensive study is done on how to optimize the frame geometry on a broader level. Contemporary frames can be crafted into various shapes, giving the engineers a large freedom of design. Almost an infinite number of window frame geometries can be created, but not all of them will result in a frame with satisfying thermal properties. It is important to determine how a proper design of the frame can contribute to the improvement of its thermal performance. Afterwards, the entire frame geometry can be optimized in terms of the thermal transmittance, size and material use.The optimization process can be conducted by designing very large number of window frame geometries and evaluating their thermal properties, preferably in an automated way. A large part of this study is devoted to the development of a parametric design tool that could be used for this purpose. Afterwards, the final tool is used in a process of optimizing the frames. Optimization is done with regard to several objectives, what makes the task more complicated. Two approaches to this problem are suggested in this study: a weighted sum method and a genetic algorithm.Another objective of the project was to develop a new combination of materials that could be used in improved window frames. This combination consists of a high strength composite laminate on the outside and highly insulating foam on the inside. As a result, a functionally graded material with spatially varying properties was developed. This unusual construction creates a challenge for experimental characterization of this product. This issue can be solved by using laser flash method, which can be adapted for these specific purposes. Small modifications have been done in the LFA 447 laser flash apparatus that allow for derivation of the local transport properties of various materials, with a fine resolution. The method was validated and successfully used for this purpose.",

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author = "Zajas, {Jan Jakub}",

year = "2014",

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publisher = "Department of Civil Engineering, Aalborg University",

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N2 - Even though the window frames cover a relatively small fraction of the entire building envelope, they are responsible for a major amount of heat loss, due to their poor insulation properties compared to the other envelope elements. With the current trends to reduce energy use in buildings, it is obvious that the thermal performance of contemporary frames needs to be improved, so that buildings can fulfill the new, more rigorous demands.This study will focus on improving the thermal performance of window frames made of fiberglass reinforced plastic (FRP). This material has been recently introduced to the window frame market and is becoming an increasingly interesting choice, due to its fine thermal and mechanical properties which can lead to a significant improvement of the insulation properties of a window frame.There are several ways to improve the thermal transmittance of a window frame. Heat transfer through a frame is a combination of conduction, convection and radiation and each of these mechanisms of heat transfer can be diminished in certain ways. An example could be subdividing the cavities to reduce convective heat flow or using low emissivity materials to limit the thermal radiation. These, and several other solutions, are investigated in the first part of the study. Simulations on simple geometries are conducted to evaluate the potential of different solutions. The results show that by applying different modifications the thermal transmittance of a frame can be significantly reduced, but only to a certain extent. To reach further improvement, more drastic changes need to be done.Therefore, an extensive study is done on how to optimize the frame geometry on a broader level. Contemporary frames can be crafted into various shapes, giving the engineers a large freedom of design. Almost an infinite number of window frame geometries can be created, but not all of them will result in a frame with satisfying thermal properties. It is important to determine how a proper design of the frame can contribute to the improvement of its thermal performance. Afterwards, the entire frame geometry can be optimized in terms of the thermal transmittance, size and material use.The optimization process can be conducted by designing very large number of window frame geometries and evaluating their thermal properties, preferably in an automated way. A large part of this study is devoted to the development of a parametric design tool that could be used for this purpose. Afterwards, the final tool is used in a process of optimizing the frames. Optimization is done with regard to several objectives, what makes the task more complicated. Two approaches to this problem are suggested in this study: a weighted sum method and a genetic algorithm.Another objective of the project was to develop a new combination of materials that could be used in improved window frames. This combination consists of a high strength composite laminate on the outside and highly insulating foam on the inside. As a result, a functionally graded material with spatially varying properties was developed. This unusual construction creates a challenge for experimental characterization of this product. This issue can be solved by using laser flash method, which can be adapted for these specific purposes. Small modifications have been done in the LFA 447 laser flash apparatus that allow for derivation of the local transport properties of various materials, with a fine resolution. The method was validated and successfully used for this purpose.

AB - Even though the window frames cover a relatively small fraction of the entire building envelope, they are responsible for a major amount of heat loss, due to their poor insulation properties compared to the other envelope elements. With the current trends to reduce energy use in buildings, it is obvious that the thermal performance of contemporary frames needs to be improved, so that buildings can fulfill the new, more rigorous demands.This study will focus on improving the thermal performance of window frames made of fiberglass reinforced plastic (FRP). This material has been recently introduced to the window frame market and is becoming an increasingly interesting choice, due to its fine thermal and mechanical properties which can lead to a significant improvement of the insulation properties of a window frame.There are several ways to improve the thermal transmittance of a window frame. Heat transfer through a frame is a combination of conduction, convection and radiation and each of these mechanisms of heat transfer can be diminished in certain ways. An example could be subdividing the cavities to reduce convective heat flow or using low emissivity materials to limit the thermal radiation. These, and several other solutions, are investigated in the first part of the study. Simulations on simple geometries are conducted to evaluate the potential of different solutions. The results show that by applying different modifications the thermal transmittance of a frame can be significantly reduced, but only to a certain extent. To reach further improvement, more drastic changes need to be done.Therefore, an extensive study is done on how to optimize the frame geometry on a broader level. Contemporary frames can be crafted into various shapes, giving the engineers a large freedom of design. Almost an infinite number of window frame geometries can be created, but not all of them will result in a frame with satisfying thermal properties. It is important to determine how a proper design of the frame can contribute to the improvement of its thermal performance. Afterwards, the entire frame geometry can be optimized in terms of the thermal transmittance, size and material use.The optimization process can be conducted by designing very large number of window frame geometries and evaluating their thermal properties, preferably in an automated way. A large part of this study is devoted to the development of a parametric design tool that could be used for this purpose. Afterwards, the final tool is used in a process of optimizing the frames. Optimization is done with regard to several objectives, what makes the task more complicated. Two approaches to this problem are suggested in this study: a weighted sum method and a genetic algorithm.Another objective of the project was to develop a new combination of materials that could be used in improved window frames. This combination consists of a high strength composite laminate on the outside and highly insulating foam on the inside. As a result, a functionally graded material with spatially varying properties was developed. This unusual construction creates a challenge for experimental characterization of this product. This issue can be solved by using laser flash method, which can be adapted for these specific purposes. Small modifications have been done in the LFA 447 laser flash apparatus that allow for derivation of the local transport properties of various materials, with a fine resolution. The method was validated and successfully used for this purpose.

KW - Window Frames

KW - Heat Loss

KW - Energy Use

KW - Thermal Performance

KW - Fiberglass Reinforced Plastic (FRP)

KW - Conduction

KW - Convection

KW - Radiation

KW - Frame Geometry

KW - Parametric Design Tool

KW - Window Frames

KW - Heat Loss

KW - Energy Use

KW - Thermal Performance

KW - Fiberglass Reinforced Plastic (FRP)

KW - Conduction

KW - Convection

KW - Radiation

KW - Frame Geometry

KW - Parametric Design Tool

M3 - PhD thesis

T3 - DCE Thesis

PB - Department of Civil Engineering, Aalborg University

CY - Aalborg

ER -

Experimental Characterization and Modeling of Advanced Polymer Composite Window Frames

Abstract

Emneord

AUB Link

Fingeraftryk

Citationsformater