Geopolymer Betong med Mikrokapslede Faseendringsmaterialer for Energieffektive Bygninger

This study aims to develop new environmentally friendly construction materials with high energy storage capacity by using geopolymer concrete containing microencapsulated phase change materials (MPCM) to reduce energy consumption for buildings, which plays a key role to reduce global warming. The rheological behavior of microcapsule suspensions revile the important role of nonencapsulated phase change materials on the physical properties and structure of microcapsules. This initial investigation provided valuable information for selecting the right kinds of microcapsules to integrate into concrete. MPCM was integrated into Portland cement concrete (PCC) and geopolymer concrete (GPC), and a comparative analysis between PCC and GPC based on the thermal and mechanical properties was conducted. The influence of the hygroscopic nature of polymer shell, core/shell ratio and size of the microcapsules on the microstructure, thermal properties and compressive strength of geopolymer concrete was investigated and discussed. The combination of a polymer shell containing polar functional groups and a small size of MPCM has a significant impact on the dispersion of MPCM in the GPC matrix and the porosity enhancement of GPC, which causes a reduction of both thermal conductivity and compressive strength. In addition, a high core/shell ratio contributes to an increase of the energy storage heat capacity during the phase change and a reduction of compressive strength when PCM changes from solid to liquid state. A better understanding of the effect of microcapsule properties on GPC is important to further investigations to maximize the thermal performance and minimize the mechanical strength reduction of GPC containing MPCM for building applications. Thermal performance of GPC after incorporating MPCM was also investigated. Numerical modeling regarding the thermal performance of the materials was conducted and validated by experimental data. Systematic analysis of the effect of various climate conditions (outdoor temperature, maximum solar radiation) and MPCM-concrete design (wall thickness, MPCM concentration and core/shell ratio) on the energy efficiency of buildings using geopolymer concrete containing MPCM was examined. The possibility of utilizing GPC containing MPCM at the environmental conditions of Oslo and Madrid during a one year period was numerically evaluated. It was found that the powerv consumption for a heating/cooling system could be significantly reduced in both Oslo and Madrid after adding microcapsules into GPC walls. The wall orientations and the season have significant effect on energy efficiency of buildings, with the largest energy saving on the south and west facing walls and during summer.Formålet med dette studiet er å utvikle miljøvennlige konstruksjonsmaterialer med høy energilagringskapasitet ved å bruke geopolymerbetong som inneholder mikroinnkapslede faseovergangsmaterialer (MPCM) for å redusere bygningers energibehov og derved medvirke til redusert global oppvarming. Reologiske målinger på suspensjoner av mikrokapslene viser at faseovergangsmaterialer som ikke er innkapslet har stor innvirkning på de fysiske egenskapene og strukturen til mikrokapslene. Resultatene fra dette innledende studiet resulterte i ny kunnskap som er essensiell for valg av riktig type mikrokapsler for bruk i betong. MPCM ble blandet inn i Portland sement betong (PCC) og geopolymerbetong (GPC), og de termiske og mekaniske egenskapene til disse ble sammenlignet og analysert. Påvirkningen av de hygroskopiske egenskapene til polymerskjellet, kjerne/skjell ratioer og størrelsen til mikrokapslene på mikrostrukturer, termiske egenskaper og trykkfasthet til geopolymerbetong ble undersøkt. Kombinasjonen av et polymerskjell som inneholder polare grupper og mikrokapsler med små størrelser har en signifikant innvirkning på dispersjonen av mikrokapsler i GPC-matrisen og på porøsitetsøkningen til GPC. Dette reduserer både den termiske konduktiviteten og slagstyrken til GPC. I tillegg vil en høy kjerne/skjell ratio øke energilagringskapasiteten under faseovergangen og redusere slagfastheten når faseovergangsmaterialet går fra fast til flytende form. En bedre forståelse av effekten av egenskapene til mikrokapslene er viktig for videre studier for å maksimere den termiske energisparingen og minimere styrkereduksjonen av betongen for videre bruk som bygningsmaterialer. De termiske egenskapene til GPC med MPCM ble også undersøkt. Resultater av numerisk modellering av de termiske egenskapene til materialene ble validert ved sammenligning med eksperimentelle data. Effekten av forskjellige klimatiske forhold (utendørstemperatur, maksimal solstrålingsstyrke) og MPCM-betong design (veggtykkelse, MPCM-konsentrasjon og kjerne/skjell ratio) på energieffektiviteten til bygninger med geopolymerbetong med tilsatt MPCM ble systematisk studert og analysert. Muligheten for å bruke GPC som inneholder MPCM under klimaforholdene i Oslo og Madrid under en ett års periode ble nummerisk modellert. Resultatene viste at energikonsumpsjonen for et varme/kjølesystem ble signifikant redusert i både Oslo og Madrid når MPCM ble tilsattvii til vegger av GPC. Veggenes retning har en stor innvirkning på energieffektiviteten. Mest energi ble spart på syd- og vestvegger under sommeren

Recovered Energy from Salinity Gradients Utilizing Various Poly(Acrylic Acid)-Based Hydrogels

Hydrogels can be utilized to extract energy from salinity gradients when river water mixes with seawater. Saline-sensitive hydrogels exhibit a reversible swelling/shrinking process when they are, alternately, exposed to fresh and saline water. We present a comparison of several poly(acrylic acid)-based hydrogels, including poly(acrylic acid) (PAA), poly(acrylic acid-co-vinylsulfonic acid) (PAA/PVSA), and poly(4-styrenessulfonic acid-co-maleic acid) interpenetrated in a poly(acrylic acid) network (PAA/PSSA-MA). The hydrogels were synthesized by free radical polymerization, copolymerization, and by semi-IPN (interpenetrating polymer network). The hydrogels were placed in a piston-like system to measure the recovered energy. Semi-IPN hydrogels exhibit a much higher recovered energy compared to the copolymer and PAA hydrogel. The recovered energy of 60 g swollen gel was up to 4 J for the PAA/PSSA-MA hydrogel. The obtained energy per gram dried gel was up to 13.3 J/g. The swelling volume of the hydrogels was maintained for 30 cycles without decline in recovered energy.publishedVersio

TÍNH TOÁN KHẢ NĂNG TIẾP NHẬN CHẤT Ô NHIỄM CỦA ĐẦM THỊ NẠI (TỈNH BÌNH ĐỊNH)

Based on the surveys at Thi Nai lagoon in rainy season (October, 2013) and dry season (May, 2014) and the documents on natural conditions, socio-economic status of Thi Nai lagoon, receiving capacity of pollutants in the lagoon was calculated on the basis of environmental standards, using Delft3D model. Calculation results showed that at present Thi Nai lagoon no longer has capacity to receive ammonium and nitrate. Until 2025, besides two parameters, Thi Nai lagoon will no longer have capacity to receive phosphate. In addition, the receiving capacity of the lagoon will be reduced for most of parameters while receiving capacity of lagoon for BOD5 and TSS will increase. Regarding heavy metals, receiving capacity of lagoon will be reduced, especially for Zn (12.18%).Dựa trên các số liệu khảo sát về chất lượng nước tại đầm Thị Nại mùa mưa (tháng 10/2013) và mùa khô (tháng 5/2014), các tài liệu thu thập về điều kiện tự nhiên, kinh tế - xã hội ven đầm và các tiêu chuẩn môi trường, đã tính toán khả năng tiếp nhận các chất ô nhiễm trong đầm thông qua sử dụng mô hình Delft3D. Kết quả tính cho thấy, hiện tại đầm Thị Nại không còn khả năng tiếp nhận amoni, nitrat. Tới năm 2025, ngoài 2 thông số này đầm Thị Nại sẽ không còn khả năng tiếp nhận phosphat. Ngoài ra, khả năng tiếp nhận của đầm sẽ giảm đi đối với hầu hết các thông số (3,44%, 1,84%, 0,02%, 12,18%, 0,46% đối với COD, Cu, Pb, Zn và As, tương ứng), trong khi khả năng tiếp nhận BOD5 và vật lơ lửng tăng lên. Liên quan đến các kim loại nặng, khả năng tiếp nhận của đầm cũng giảm đi nhiều nhất là Zn (12,18%)

Thermal analysis of multi-layer walls containing geopolymer concrete and phase change materials for building applications

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Energy Lost in a Hydrogel Osmotic Engine Due to a Pressure Drop

Utilizing hydrogels to harvest salinity gradient energy from solutions of different salinities has recently attracted interest. Polyelectrolyte hydrogels exhibit cyclic swelling/deswelling when alternately exposed to freshwater and seawater. This can be utilized to convert the mixing energy of the two solutions into mechanical energy. Hydrogels consisting of a semi-interpenetrating network (semi-IPN) of poly(4-styrene sulfonic acid-co-maleic acid) sodium salt and polyacrylic acid was prepared at various cross-linking densities. The energy lost due to a pressure drop in the system during the deswelling/swelling process of these hydrogels is examined, and the effects of tubing dimensions, hydrogel cylinder size, gel particle size, and the volume fraction within the hydrogel cylinder occupied by the flowing liquid (ε) are investigated. In addition, a small-scale osmotic engine was compared to a scaled-up system. ε was found to be the factor that had the largest effect on the energy loss. It was found that ε is strongly dependent on the degree of swelling of the hydrogels. When the hydrogels swell, they deform more easily under pressure. This markedly decreases ε, thereby inducing a high pressure drop in the system and a correspondingly large energy loss. Accordingly, the pressure drop when pumping through the hydrogel is the major contributor to the energy loss in the system. When the hydrogel particles deform too much, the energy needed to pump the flowing liquid through the hydrogels exceeds the energy produced by the system. Developing a hydrogel system that deforms less in its swollen state is therefore essential for improving the energy efficiencies of these osmotic engines.publishedVersio

Osmotic engine converting energy from salinity difference to a hydraulic accumulator by utilizing polyelectrolyte hydrogels

Efficient harvesting of the mixing energy from the salinity gradient between sea and river water remains a challenge. Recently, utilization of the swelling/shrinking properties of hydrogels has been explored as a new means for extracting this energy. However, former investigations are mainly limited to examining the performance of the hydrogels when lifting applied weights, and calculating the energy that could potentially be extracted. In this study, we demonstrate a novel osmotic engine with a mechanical energy transmission prototype, which can convert and store the green mixing energy in a form that can be utilized to perform mechanical work. The osmotic engine includes a cylinder containing the hydrogel, an oil-hydraulic cylinder and a hydraulic accumulator. The lifting energy from the hydrogel is transferred to the oil-hydraulic cylinder through a lever, which acts as a pump and accumulate the hydraulic oil under high pressure in the hydraulic accumulator. The system was tested with a hydrogel of poly(acrylic acid) semi-interpenetrated with poly(4-styrenessulfonic acid-co-maleic acid) sodium. This hydrogel produced up to 36 J per shrinking/swelling cycle, and exhibited an efficiency of 0.53% at optimum conditions.publishedVersio

In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

Doped ZnO thin films have attracted much attention in the research community as front-contact transparent conducting electrodes in thin film silicon solar cells. The prerequisite in both low resistivity and high transmittance in visible and near-infrared region for hydrogenated microcrystalline or amorphous/microcrystalline tandem thin film silicon solar cells has promoted further improvements of this material. In this work, we propose the combination of major Ga and minor In impurities codoped in ZnO film (IGZO) to improve the film optoelectronic properties. A wide range of Ga and In contents in sputtering targets was explored to find optimum optical and electrical properties of deposited films. The results show that an appropriate combination of In and Ga atoms in ZnO material, followed by in-air thermal annealing process, can enhance the crystallization, conductivity, and transmittance of IGZO thin films, which can be well used as front-contact electrodes in thin film silicon solar cells

Time-dependent structural breakdown of microencapsulated phase change materials suspensions

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Salinity Gradient Energy from Expansion and Contraction of Poly(allylamine hydrochloride) Hydrogels

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Synthesized BiVO4 was by the co-precipitation method for Rhodamine B degradation under visible light

Recently, BiVO4 photocatalysts has been received much attention in field of catalysts. Because it can be used to degrade harmful organic catalysts in visible light, irradiation produces CO2, H2O and less harmful organic matter. In this study, we have successfully synthesized a BiVO4 photocatalysts via co-precipitation method in the presence of urea and different calcined temperatures. The survey calcined temperatures as 300°C; 350°C; 400°C and 450°C. The obtained materials were characterized by Scanning electron microscope (SEM) and X-ray diffraction (XRD). The photocatalytic activity was evaluated by the photocatalytic degradation of rhodamine B (RhB) degradation under visible compact Philip lamp (40W) light irradiation. The result indicates that all samples calcined are monoclinic scheelite structure of BiVO4. The BiVO4-350°C sample performed the best in the photodegradation of RhB