Fast and reliable methods for the determination of thermal properties of core materials for vacuum insu-lation panels (VIPs) are needed. It is of great importance to know the thermal performance of a VIP core atdifferent levels of vacuum and external loads. In this study a new self-designed device, consisting of twocylindrical cavities connected to a Transient Plane Source instrument, is used to determine the thermalconductivity of low-density nanoporous silica powders, from atmospheric pressure down to 0.1 mbarwhile applying different levels of external pressure up to 4 bars. The study includes a brief theoreticaldiscussion of methods. The TPS is validated through comparison with available data for commercial silicaas well as through independent stationary measurements with a hot plate apparatus and with a TransientHot Bridge method. The different materials illustrate clear but different trends for the thermal conductiv-ity as a function of the level of vacuum and external pressure. The analysis of experimental results showsthat the transient methods are less suitable for measuring the thermal conductivity of low-density sil-ica powders, especially for the cases when the density is less than a limit at which the heat transfer byradiation becomes dominant compared to pure conduction.

In this study, the pore structure, tapped density and thermal conductivity properties of a new type of nanoporous silica material have been studied. We have applied nitrogen physisorption, high resolution scanning microscopy and Transient Plane Source thermal conductivity measurements to investigate these properties. The new mesoporous silica SNP have large BET surface area, 400–439 m² g⁻¹ and possess high porosity in the range of 95–97%. The results further show pore diameter centred at 43 nm or 47 nm for the two materials studied. Tapped densities as low as 0.077 g/cm³ have so far been obtained and the thermal conductivity of these materials has been measured to 0.0284 and 0.0294 W (m K)⁻¹ at room temperature and atmospheric pressure. The effects of tapped density, pore size diameter and particle morphology on thermal conductivity are discussed.

Long-term performance and durability of external walls made of rendered autoclaved aerated concrete was investigated within a research project, based on continuous monitoring of temperature and moisture in the materials employed in the weathering test conducted in Gavle, Sweden. The details of natural exposure test set-up and preliminary measurement and experiment results were published elsewhere. Among the external rendering systems applied on AAC wall panels, a variety of coatings including inorganic and organic coatings with and without hydrophobic agents were tested. Together with the surface and bulk temperatures and moisture contents of the tested materials, microclimate parameters were also continuously measured. In this paper, monitoring data collected during 10 years of natural exposure are examined, and some results, particularly on moisture performance of external rendering systems, are presented and briefly discussed. 

This paper presents the preparation of a porous (Mg, Ca) silicate structure, which could be employed as sorbent filter media. The sorbents have been prepared using sodium silicate precipitated with various ratios of magnesium and calcium salts. The sorbents obtained were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen physisorption isotherm. Further, the applicability and performance of the sorbent impregnate with potassium hydroxide for removal of sulphur dioxide (SO₂) has been demonstrated. From the isotherms, specific surface area, pore diameter and volume of pores were estimated. Results show that the chemical composition and textural properties of the resultant sorbents were highly dependent on Mg/Ca molar ratio. It was found that sorbents made with 68 mol% Mg and 32 mol% Ca (PSS-MgCa-68/32); and 75 mol% Mg and 25 mol% Ca (PSS-MgCa-75/25) exhibited even higher specific surface area and pore volume than the sorbents containing a single metal. The Mg/Ca-silica sorbents obtained contains interconnected bimodal porosity with large portions being mesopores of varied sizes. The pore size distribution (PSD) results further indicate that PSS-MgCa-68/32 sorbent exhibits wide PSD of interconnected pores in the size range of 1 to 32 nm while PSS-MgCa-50/50 and PSS-MgCa-75/25 exhibits narrow PSD of 1 to 5 nm. Using SO₂ as model contaminate gas, it was shown that the dynamic adsorption performance of the PSS-MgCa-sorbents impregnated with 8 wt% KOH exhibits SO₂ uptake, with impregnated PSS-MgCa-68/32 showing better performance. This shows that the materials prepared can be used as adsorbent for gas filtration.

A new MgCa–silica material with bimodal pore size is impregnated with KMnO₄ for dynamic adsorption of H₂S. The MgCa–silica was synthesized using sodium silicate and calcium and magnesium salts as precipitating agents. The KMnO₄ impregnation onto MgCa–silica was obtained through either direct addition into MgCa–silica wet coagulum or doping of dried MgCa–silica pellets into KMnO₄ solution. These chemisorbents were characterized by nitrogen physisorption, spectrophotometer, microscopy and dynamic H₂S adsorption test setup similar to ASHRAE standard I45.I. The results show that impregnation route and KMnO₄ wt% cause a reduction of surface area and total pore volume. The decrease in pore volume was slightly more in chemisorbents obtained via post doping compared to direct impregnation. Regardless of pore volume reduction the pore size range, 1–32 nm, was as in the parent MgCa–silica with micro and meso-pore diameter centered at 1.4 and 5.4 nm respectively. Thus obtained chemisorbents have their pore entrances neither blocked nor shifted. The MgCa–silica/KMnO₄ chemisorbents exhibits good H₂S uptake performance. The chemisorbent with 11.4 wt% KMnO₄ and obtained via direct impregnation possesses the highest uptake capacity. The lowest capacity was observed for chemisorbent with 8 wt% KMnO₄ and made by direct impregnation. The variations in uptake capacity are likely due to impregnation route, the KMnO₄ content and its location in the pore system. The results suggest that the MgCa–silica/KMnO₄chemisorbents can remove H₂S from indoor air at room temperature.

Three synthesis routes are presented here that leads to carbon–silica composites. These were characterized by nitrogen physisorption, by thermogravimetric analysis and by dynamic toluene adsorption test similar to Ashrae standard I45.1. The carbon–silica composites possess high microporosity and mesoporosity as well as large surface areas. Furthermore, the control of the microporosity as well as pore size distribution is possible because they depend on the amount of carbon used and of the synthesis route. Following routes I and III a wide micro-mesoporous pore size (1–32 nm) was obtained where as by route II narrow micro-mesoporous pore size (1–4 nm) was observed. In addition, pore diameters center in the range of 1.13–1.17 nm was observed when carbon content was 32 or 45 wt%. The dynamic adsorption of toluene was evaluated for carbon–silica composites obtained by three preparation routes at two different carbon contents, 32 and 45 wt%. The results showed that a composite with 45 wt% carbon content and obtained via preparation route I gave the highest toluene adsorption capacity (27.6 wt% relative to carbon content). The large uptake capacity of this composite was attributed to the presence of high microporosity volume and a wide (1–32 nm) bimodal pore system consisting of extensive mesopore channels (2–32 nm) as well as large surface area. These capacity values of carbon–silica composites are by weight relative to carbon content and are competitive to, results obtained for commercial coconut activated carbon (31.1 wt%) and significantly better than a commercial alumina-carbon composite(9.5 wt%) at 0% efficiency.

Vacuum insulation panels (VIPs) provide unprecedented opportunities for obtaining excellent thermal insulation with light and slender constructions. This article discusses the performance over time of VIPs, and the possibilities to overcome the current problems related to fragility and limited durability. Aerogels are together with fumed silica among the most competitive core materials for VIP's. The use of classical aerogels, as produced in autoclaves is, however, limited due to the high production costs. The fumed silica on the other hand requires vacuum levels that are difficult to maintain with the currently available vacuum envelopes. A material with comparatively smaller pores will on the other hand allow obtaining low thermal conductivity at higher pressure (less vacuum) and will therefore reduce the pressure difference over the envelope. There is therefore much to be gained by reducing the pore size. New cost and performance efficient silica aerogels offers opportunities to enhance the properties of the panels by customizing the pore structure and pore size distribution. Building technologies and how the panels are applied in a manner that improves the structural, thermal and hygroscopic performances of vacuum insulated constructions have been studied and are discussed.

The paper provides a review of the synthesis and adsorptive properties of a novel class of precipitated silica materials. To enhance or tailor the adsorption efficiency, various trapping chemicals (potassium hydroxide, potassium permanganate) or co-adsorbents (coconut activated carbon) are incorporated in the structure of the substrate material. Further, it discusses the applicability and performance over time of the material as adsorbents for removal of hydrogen sulphide, sulphur dioxide and toluene contaminants which are potentially hazardous to sensitive equipment and more importantly, human health. Chemical substances in the air are an unavoidable by-product of most human endeavours within industry and transportation. The need for adsorbents to combat Airborne Molecular Contamination (AMC) follows from the continued intensification of the global environmental movement as well as the rapid industrialisation of developing countries. The removal performance of modified precipitated silica adsorbent shows that the new adsorbent can be tailored to remove low concentrations of sulphur dioxide, hydrogen sulphide and toluene contaminants at indoor environment conditions. The results further shows that the new precipitated silica adsorbent impregnated with 8 wt% KOH shows better performance than commercial alumina impregnated with 8 wt% KMnO₄.The adsorbent material may find interesting and efficient uses as passive sinks for pollutants incorporated into more traditional building products such as acoustic baffles or as ingredients in various coatings. The filter material is environmentally friendly and consists of benign chemicals that are abundant worldwide. Performance over time aspects, re-use and recycling of exhausted filter materials are key issues addressed.

Möjligheterna att bereda hampa med tornadoteknik har studerats. Företaget Airgrinder AB i Skelleftehamn har en pilotanläggning som utnyttjats för att testköra hampa som skördats vid olika tillfällen under året. Tekniken innebär att hampan både sönderdelas och torkar under inverkan av den kraftiga luftström som pressas genom en speciellt utformad cyklon. Hampans fibrer passerar relativt opåverkade medan resten av stjälken samt eventuella blad och jordrester pulveriseras. Fibrerna kan därefter sållas fram och tillvaratas separat medan resten kan användas som t ex bränsle.

För tornadotekniken spelar det ingen roll när på året hampan skördas. Separeringstekniken fungerar lika bra för fuktig höstskördad hampa som för torr vårskördad hampa. Fiberkvaliteten beror av skördetillfället och den återfinns givetvis även i slutprodukten. Kapaciteten för processen är däremot starkt beroende av det ingående materialets fukthalt. Detta innebär att hampa med hög fukthalt kräver en längre uppehållstid i tornadon än vad ett torrare material gör.

Fibermaterialets egenskaper gör det lämpligt att användas som värmeisolering och provningar visar att egenskaperna blir lika bra som för andra cellulosabaserade isoleringsmaterial. Fibrerna kan även med fördel användas som armering i olika typer av kompositmaterial. För gips åstadkoms en förbättring av böjdraghållfastheten med 33% tack vare en tillsats av mindre än 0.5 vikt-% av tornadohampan. Liknande förbättringar är att räkna med även för andra kompositer med matriser av betong, plast och trä.

En investeringskalkyl utvärderad enligt nettonuvärdesmetoden har genomförts för en anläggning som kan betjäna en odling på ungefär 250 ha. Investeringskostnaden för en anläggning bestående av tornsilos med volymen 2000 m³ samt en tornado från Airgrinder AB uppskattats till 7 MSEK. Lönsamheten bestäms av en mängd olika faktorer där skördens storlek per hektar är särskilt betydelsefull. Även andelen fibrer i förhållande till andelen skävor samt fukthalten i det ingående materialet är viktiga parametrar i kalkylen. I slutänden spelar priset på fibrer och även skävor en avgörande roll. Mindre genomslag på investeringens lönsamhet har allt som förknippas med odling och skörd, löner, energipriser och underhållskostnader. Utnyttjande av spillvärme samt andra samkörningsmöjligheter med intilliggande industrier förbättrar kapaciteten hos anläggningen markant och därmed även lönsamheten.