Det er stipendiat Anna Szszotoks-Piechaczek ved Avdeling for ingeniørfag som har kommet frem til dette i sin ferske doktorgradsavhandling. Hennes spennende betongstudier sto til toppkarakter da hun nylig disputerte ved Revista Molecula, Universidad de Castilla-La Mancha i Spania. Komiteen besto av professor Gilles Lefebvre (Université Paris-Est Créteil), professor Filomena Barreiro (Instituto Politécnico de Bragança) and professor Manuel Carmona (University of Castilla La Mancha).
Videre i denne artikkelen forteller Szszotoks-Piechaczek mer inngående om sitt doktorgradsarbeid. Resten av nyhetsssaken foreligger kun på engelsk.
The PhD Thesis titled "Development of Microcapsules with Thermal Energy Storage (TES) Capability for Concrete Applications" was performed under supervision of professor Anna-Lena Kjøniksen (HiØ) and professor Juan Francisco Rodriguez Romero from University of Castilla La Mancha. The thesis focuses on the synthesis and characterization of microcapsules containing phase change materials (PCMs) for structural concrete.
What are your most important conclusions or results?
- An improved class of microcapsules has been developed at lab and semi-industrial scales obtaining product with similar physical and thermal properties. The introduction into the recipe of high level of crosslinking allows to obtain particles with enhanced physical resistance and thermal stability. The incorporation of microcapsules into concrete reduces the thermal conductivity and provides higher thermal storage capacity with a low impact on its mechanical resistance.
Anna says this about the relevance of the study/research:
- The total energy consumption is increasing every year whereas the production of green energy is not enough to cover the energy demand. Phase change materials absorb energy from excess heat during the day and release it back during night. On the other hand, microencapsulation of the PCMs prevents disadvantages such as leakage of melted PCM, flammability, and volume change during the phase transition. Increasing both the thermal comfort and energy savings by reducing the temperature fluctuations are an important benefit of microencapsulated PCMs.
How did you reach your conclusion?
- Initially, optimization process of microencapsulation was performed at lab scale (0.5L reactor), then the scale up to 100L reactor and production of 100 kg were conducted. Microcapsules were produced by suspension polymerization. Wide number of characterization methods was used, Nevertheless the most important techniques include scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis and particle size distribution. Additionally, diffusion of PCM from microcapsules was modeled to define their stability at higher temperature. Microcapsules from pilot scale was used to replace part of sand in Portland cement concrete. It was characterized in terms of energy saving and mechanical properties.
Addition of thermoregulating microcapsules to concrete can provide more energy efficient buildings and reduce the energy consumption used for heating and cooling, thereby decreasing CO2 emission.
Anna Szszotoks-Piechaczek, scientist
According to Szszotoks-Piechaczek some interesting topics related to further studies on the subject could be:
- Improving the formulation for the synthesis of microcapsules with fire retardant properties in order to obtain a smooth surface and continues shell.
- Completing the study of the physical and mechanical properties of the microcapsules with different polymeric shells by nanoindentation to measure their mechanical resistance.
- Developing nanosized microcapsules with enhanced TES capacity and lower impact into the mechanical properties of concrete.
- Optimizing the pilot plant operational conditions based on economic criteria and market trends.
- Performing an economical evaluation and life cycle assessment of the production of microcapsules in industrial scale and incorporation to the concrete.
She says phase change materials absorb energy from excess heat during the day and release it back during night.
- The total energy consumption is increasing every year whereas the production of green energy is not enough to cover the energy demand. Microencapsulation of the PCMs prevents disadvantages such as leakage of melted PCM, flammability, and volume change during the phase transition. Increasing both the thermal comfort and energy savings by reducing the temperature fluctuations are an important benefit of microencapsulated PCMs”, she says.
More about the research methods:
Microcapsules containing paraffins and environmentally-friendly fatty acids as phase change materials were prepared by a suspension-like polymerization technique using copolymers as a shell material. The resulting microcapsules exhibited enhanced physical resistance and thermal stability. The incorporation of a flame retardant co-monomer into the polymer network improves the fire and thermal resistance of the particles. The microcapsules were characterized in terms of thermal and morphological stability at high temperatures. The diffusion of phase change material from microcapsules was modeled to examine how well the PCM could be retained within the capsules. Finally, the process was successfully scaled up to a 100 L reactor resulting in the production of 100 kg microcapsules for the project. Addition of thermoregulating microcapsules to concrete can provide more energy efficient buildings and reduce the energy consumption used for heating and cooling, thereby decreasing CO2 emission.