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Virtual poster session
Modelling of the mechanisms of heat transfer in glass foams at different temperaturesWednesday (07.10.2020) 18:55 - 18:58 Room 1 Part of:
In recent years, commitments for a steep CO2 emission reduction have led governments to cut consumption and improve the efficiency of materials in construction. Therefore, traditional insulating materials are looking to be replaced by more environmentally friendly alternatives. For its sustainability, foam glass has enormous potential as structural and insulting element in the building sector. It is prepared with high percentages of recycled glass, it shows excellent mechanical performance, and it is completely non-flammable and non-toxic. Novel routes to produce lightweight, closed porous and high insulating glass foams are being explored. As the production routes become more complex several questions arise about where lies the lower limit for the thermal conductivity of these materials and how to push this limit even further down.
For this study, a set of foams with different relative densities (ranging from 0.03 to 0.07) were produced with more than 90% recycled glass. The gaseous and solid phase of the foams cellular structure were characterized using high-resolution X-ray Tomography and scanning electron microscopy. The percentage of open porosity and the composition of gas inside the cells has also been assessed. From the experimental data and some previously reported analytical equations, a specific model to predict the conductivity of these materials has been built. The model considers the contribution of all existing heat transfer mechanisms inside the foam and its evolution with varying density and temperature. Furthermore, the key compositional and structural parameters characterizing these foams are considered. The predicted thermal conductivity reveals the existence, at low temperatures, of a plateau region around 0.035 relative density, this plateau shifts towards higher relative densities as the foam temperature increases. All the data has been contrasted with experimental measurements on the thermal conductivity and the weight of each mechanism of heat transfer has been estimated using the developed model.