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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Devitrification behaviour of alkaline-earth silicate fibre

Li, Ruihua January 1997 (has links)
The alkaline-earth silicate fibres are a new generation of man-made insulation materials. The materials are amorphous on manufacture and have been shown to be soluble in physiological solutions and to be cleared from the lung in animal exposure trials. This reported study provides a thorough investigations of the devitrification behaviour of Superwool X-607 (Morgan Materials Technology), and two further compositions, code names A2 and B3.Thermal exposures were made within the region extending from 700 to 1250°C and 10 minutes to 3240 hours in clean furnace environments. The devitrified microstructures and products were identified using X-ray powder diffraction and analytical electron microscopy. Details are provided of the development of specimen preparation techniques to enable fibre cross-sections to be analyzed in the TEM.The devitrification products are presented as a function of exposure temperature and time for all 3 compositions. The amorphous glass separated into a silica-rich phase and an alkaline-earth silicate rich phase and the development of these amorphous phases is presented and discussed. The subsequent devitrification of these separated phases into associated silica crystalline phases and alkaline-earth silicate crystalline phases, and, in each case, the subsequent phases and transformations with increasing thermal exposure are also presented and discussed. For the crystalline silica phases, the following unusual transformation situation was identified in all 3 compositions: amorphous silica → alpha-quartz → alpha-cristobalite → tridymite. In comparison with established understanding of silica phase transformations, the following anomalies were identified and explained: a) the formation of quartz as the primary crystalline silica phase at temperatures ≥1000°C, and b) the subsequent formation of alpha-cristobalite, the low-temperature form, other than B-cristobalite, the high-temperature form, which was the only silica phase identified in the devitrified aluminosilicate fibres. For the alkaline-earth silicate phases, two forms of wollastonite solid solution were characterised. The low-temperature form, containing more Mg[2+], transforms to the high-temperature form and diopside at temperatures above 900°C. The low-temperature anomaly, ie the formation of the immature high-temperature form below 900°C is possibly due to a secondary phase separation. Pseudowollastonite was found to be metastable in the investigated temperature region. It is suggested that the detailed transformation process among these alkaline-earth silicate phases has been identified for the first time. This thesis also includes a detailed review of published studies concerning this materials systems as well as recommendations for further work.
2

Functionalisation of clay aerogel composites for applications in construction

Abo Madyan, Omar January 2018 (has links)
Clay aerogels are relatively a new class of materials with number of merits suitable for many applications in various industrial sectors. With the current mandate to utilise environmentally friendly materials to produce functional materials, clay aerogels provide an attractive potential green solution to overcome thermal issues in construction. However for it to be effectively used as an insulation material, research work is required to address several critical issues and setbacks: the first of these is poor mechanical properties highlighted in the literature as its main weakness; the second is there extremely high hydrophilic and hygroscopic nature identified as the main research gap, which not only can cause a significant increase in thermal conductivity but also can disintegrate the aerogels. This thesis investigates and develops novel methodologies to overcome the associated setbacks through comprehensive characterisation and better understanding of mechanisms of formulation, architecture, behaviour and corresponding performance of clay aerogel constituents and composites: (I) The anisotropic structure of the aerogel was thoroughly investigated and its influence on properties was established; (II) By adjusting and tuning the mixing temperatures, the compressive modulus was enhanced by more than 7 folds; (III) Ultrasonic technologies were used to prepare organoclay- polyvinyl alcohol aerogel composites with 40% less moisture absorption in addition to lower thermal conductivity; (IV) Implementing organosilanes and isocyanates to prepare clay-PVA aerogels resulted in an effective method to reduce the moisture absorption by more than 40% with a 6 fold increase in compressive modulus; (VI) soluble water repellent was incorporated to prepare hydrophobic aerogel composites with contact angles of 140°; and (VII) Organosilanes and isocyanates are combined with a water repellent to generate highly functional clay aerogel composites. Overall this thesis paves the way for the industrialisation of functional clay-aerogel insulation materials for construction and other sectors.
3

Vibro-acoustic products from re-cycled raw materials using a cold extrusion process : a continuous cold extrusion process has been developed to tailor a porous structure from polymeric waste, so that the final material possesses particular vibro-acoustic properties

Khan, Amir January 2008 (has links)
A cold extrusion process has been developed to tailor a porous structure from polymeric waste. The use of an extruder to manufacture acoustic materials from recycled waste is a novel idea and the author is not aware of any similar attempts. The extruder conveys and mixes the particulates with a reacting binder. The end result is the continuous production of bound particulates through which a controlled amount of carbon dioxide gas that is evolved during the reaction is used to give the desired acoustic properties. The cold extrusion process is a low energy consuming process that reprocesses the post manufacturing waste into new vibro-acoustic products that can be used to meet the growing public expectations for a quieter environment. The acoustical properties of the developed products are modelled using Pade approximation and Johnson-Champoux-Allard models. Applications for the developed products are widespread and include acoustic underlay, insulation and panels in buildings, noise barriers for motorways and railway tracks, acoustic insulation in commercial appliances and transport vehicles.
4

Vibro-acoustic products from re-cycled raw materials using a cold extrusion process. A continuous cold extrusion process has been developed to tailor a porous structure from polymeric waste, so that the final material possesses particular vibro-acoustic properties.

Khan, Amir January 2008 (has links)
A cold extrusion process has been developed to tailor a porous structure from polymeric waste. The use of an extruder to manufacture acoustic materials from recycled waste is a novel idea and the author is not aware of any similar attempts. The extruder conveys and mixes the particulates with a reacting binder. The end result is the continuous production of bound particulates through which a controlled amount of carbon dioxide gas that is evolved during the reaction is used to give the desired acoustic properties. The cold extrusion process is a low energy consuming process that reprocesses the post manufacturing waste into new vibro-acoustic products that can be used to meet the growing public expectations for a quieter environment. The acoustical properties of the developed products are modelled using Pade approximation and Johnson-Champoux-Allard models. Applications for the developed products are widespread and include acoustic underlay, insulation and panels in buildings, noise barriers for motorways and railway tracks, acoustic insulation in commercial appliances and transport vehicles.
5

The design of a fabric retained-heat cooker from a user’s perspective

Hunkin, Justine 18 March 2014 (has links)
M.Tech. (Industrial Design) / This study investigated the user’s perspective with reference to the regular use of the WonderbagTM retained-heat cooker in low-income communities in a South African context. This research addresses the limitations of the literature available to support the investigation of the design of a fabric retained-heat cooker from a user’s perspective. As with the WonderbagTM retained-heat cooker, products aimed at underserved low-income communities are often designed without the participation of the end-user. This research focuses on the user’s experience of the fabric retained-heat cooker and seeks to include the user in the process of improving the design of these products. Participatory action research and user-centred design were utilised as the chosen methodologies for this study. The history of retained-heat cookers has been reflected upon when considering the use of insulation materials and alternative fabric improvements. Methods of manufacture, material cost and usage have been considered as critical elements of the design process as well as the skill level of the existing users. Participants indicated their personal interest in the design and development of the prototype retained-heat cooker. They were intensively involved in the design process from the focus group discussion where their perceptions were elicited, right through to their testing of the final prototype. A final workshop concluded the last of three workshops where participants provided individual feedback in terms of their personal experiences of using the prototype retained-heat cooker. Participants were able to selectively customise their prototypes, which brought about a sense of ownership and pride that was not evident in their use of previous retained-heat cookers. Participants indicated personal interest in creating their own retained-heat cookers from the experience that they acquired during the research process. As a result of this experience, the participants believed that they could manufacture their own retained-heat cookers to sell within their community, which could provide income for themselves and other members of their community. The saving of energy in terms of the fuel required to complete the cooking process translated into a direct saving of money, which was highlighted as a recurring theme and identified benefit of retained-heat cooking. By encouraging the use of energy-efficient retained-heat cookers, low-income communities could directly benefit from spending less on fuel costs and more on other essentials.
6

Obrábění elektroizolačních materiálů / The machining of electrical insulation materials

Svoboda, Marek January 2009 (has links)
This work aims to provide an analysis and definitions of problems during the machining of electrical insulation composite materials. The main objective of this work is to put forward innovative alternatives in order to deal with technological conditions. The chosen alternative is then subjected to both testing and economic evaluation.
7

Alternativa isoleringsmaterial : Aerogel inom sjöfarten / Alternative Insulation Materials : Aerogel in shipping

Johansson, Daniel January 2019 (has links)
Detta arbete handlar om att med en teoretisk modell kunna beräkna fram de olika mängder värmeförluster som vissa isoleringsmaterial släpper igenom.  Syftet med detta arbete är att undersöka om ett specifikt isoleringsmaterial som vanligtvis inte används inom sjöfarten har möjligheten att sänka energin som försvinner igenom isoleringsmaterialen. De metoder som användes är en teoretisk modell som byggdes för att  kunna använda de olika isoleringsmaterialens värmekonduktivitet för sedan kunna beräkna de teoretiska värmeförlusterna. Resultatet visar att aerogel skulle vara lämpligt för användning inom sjöfarten tack vara sina egenskaper och isoleringsförmåga som är mycket bättre än mineralull. / This work is about using a theoretical model to calculate the various amounts of thermal losses that some insulation materials release. The purpose of this work is to investigate whether a specific insulation material that has not been properly tested in shipping has the potential to lower energy that passes through the insulation materials. The methods used are that a theoretical model was built to use the thermal conductivity of different insulation materials in order to calculate the theoretical heat losses. The result shows that aerogel would be suitable for use in shipping thanks to its properties and insulation ability, which is much better than mineral wool.
8

Surface Topography and Aesthetics of Recycled Cross-Linked Polyethylene Wire and Cable Coatings

Xie, Wa 12 1900 (has links)
Our research focuses on re-using a waste a material, cross-linked polyethylene abbreviated XLPE, which is a widely used coating for wires. XLPE is strong and has excellent thermal properties due to its chemical structure - what leads to the significance of recycling this valuable polymer. Properties of XLPE include good resistance to heat, resistance to chemical corrosion, and high impact strength. A wire is usually composed of a metal core conductor and polymeric coating layers. One creates a new coating, including little pieces of recycled XLPE in the lower layer adjacent to the wire, and virgin XLPE only in the upper layer. Industries are often wasting materials which might be useful. Mostly, some returned or excess products could be recycled to create a new type of product or enable the original use. This method helps cleaning the waste, lowers the costs, and enhances the income of the manufacturing company. With the changing of the thickness of the outer layer, the roughness changes significantly. Moreover, different processing methods result in surfaces that look differently.
9

Towards holistic net-zero : Ecological and energy-efficientBuilding in Utsikten

Wso, Dana, Aliramaei, Saman January 2022 (has links)
Global warming is one of the biggest challenges today, and the construction sector is one of the main sectors contributing to climate change. Due to this, using environmentally friendly materials in construction is an important decision against global warming. This thesis aims to evaluate the most important building envelope components to achieve a house in Sweden to become near net-zero energy building (ZEB). Due to this, different ecological insulation materials, and window types were presented, analyzed, and evaluated to choose the most energy-efficient alternatives for the Utsikten village project. In terms of reduction of electricity bought, renewable energy on-site photovoltaic (PV) and ground source heat pump systems are used. In this study, numerical simulations for building envelope components such as windows, ground floor, external walls, and roofs were performed to evaluate the thermal performance of the components by IDA ICE and UBAKUS. The primary energy for different building cases has been calculated to evaluate thermal performance and energy classification levels to identify the most environmentally friendly solutions. There is a variation of ecological material for insulation that can be used for different parts of the building envelope. In general, ecological insulation material has less life expectancy but a much lower environmental impact compared to minerals and synthetic materials. However, there are also some limitations to using some ecological insulation materials in the ground construction. This study also shows how several pane glasses, gap dimensions, gas fill gap, and Low-E coating impact the energy performance of the windows and the building. Simple solar PV panel simulation shows that the maximum electricity production on a site is very related to orientation, tilt, and sun exposure. The result of this master thesis shows that it is possible to reach near-net-zero energy building by enhancing building envelope components and using renewable energy sources for heating, cooling, and electricity production.
10

Ekonomické zhodnocení investice do zateplení panelového domu v Bytči / Economic Evaluation of Investment in the Insulation of a Block of Flats in Bytča

Sobola, Martin January 2017 (has links)
The aim of the diploma thesis is to evaluate the economic efficiency of the investment in the complete insulation of a reference panel apartment building located in Bytča. The issue of the ETICS external contact system, the energy performance of the building, its thermal protection and the possibilities of financing and evaluation of the economic efficiency of the investment in question are approached in this thesis. The output of the diploma thesis will be an evaluation of the current state of the reference building, with a propper proposal for a thermal insulation. The optimal thermal insulation option and the financial provision of the investment will be selected based on economic efficiency indicators.

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