Centrum AdMaS

Browse

Now showing 1 - 5 of 12

Evaluation of the Effectiveness of Treatments to Remove Per- and Polyfluoroalkyl Substances from Water—Are We Using the Right Approach? Proposal of a Paradigm Shift from “Chemical Only” towards an Integrated Bio-Chemical Assessment
(MDPI, 2023-09-28) Carnevale Miino, Marco; Halešová, Taťána; Macsek, Tomáš; Raček, Jakub; Hlavínek, Petr
Per- and polyfluoroalkyl substances (PFASs) have been under intense investigation by the scientific community due to their persistence in the environment and potentially hazardous effects on living organisms. In order to tackle the presence of these compounds in water, to date, the research has been strongly focused on the evaluation of the effectiveness of different types of technologies. Considering the extreme complexity of the matter of PFASs and our relatively low knowledge in this topic, the following question arises: is the “chemical only” approach that is followed for evaluating the effectiveness of technologies for PFAS removal from water reliable enough? In this work, some limitations of the present approach are discussed, highlighting the reasons why it cannot be considered a reliable tool to correctly estimate the effectiveness of technology when referring to emerging compounds such as PFASs. Bioassays can play a key role in moving towards an integrated bio-chemical evaluation (chemical analysis and ecotoxicological evaluation), which is strongly encouraged. This represents the only way to completely characterize a water matrix and fully evaluate the impact of technologies when dealing with micropollutants in water, such as PFASs. Future research should focus on defining an optimal battery of bioassays that specifically fit to best represent changes in water quality in terms of short- and long-term impacts on living organisms.
Investigation of the process of heat transfer in the structure of thermal insulation materials based on natural fibres
(Elsevier, 2016-08-03) Zach, Jiří; Slávik, Richard; Novák, Vítězslav
Thermal insulation materials based on natural fibres are some of the promising materials that are currently emerging on the construction market. These materials are important especially in terms of sustainable development, since they utilise renewable raw material resources or secondary materials and their production does not consume too much energy. However, a problem with these materials is the rather different behaviour during heat and moisture transport compared with conventional insulation, which is made from synthetic (foam polystyrene) or inorganic (mineral wool) materials. The paper presents the results of a practical investigation into the process of heat transfer through the structure of thermal insulation materials based on natural fibres.
Study of the Use of Vacuum Insulation as Integrated Thermal Insulation in Ceramic Masonry Blocks
(Elsevier, 2016-08-03) Zach, Jiří; Novák, Vítězslav
Vacuum insulation panels (VIP) are thermal insulation materials with very low thermal conductivity. VIPs are commonly used in a broad spectrum of technical fields; however, they only see a small-scale application in civil engineering. The reason is mainly their high price and difficulty of installation. VIPs are very vulnerable to mechanical damage, which typically causes the loss of their thermal insulation properties. This paper deals with the possibility of effective incorporation of these insulation materials into masonry blocks designed for exterior walls, where VIPs become integrated insulation. This application minimises the hazard of mechanical damage provided the insulation is placed in the block correctly. In this paper, four kinds of materials, applicable as the core of VIPs, are compared. This is a standard mineral wool, commercial VIP based on pyrogenic silica and two experimental types of VIPs based on cotton. Four application possibilities were proposed and thermal properties of individual variants were compared.
Technology of concrete with low generation of hydration heat
(Elsevier, 2013-10-23) Zach, Jiří; Sedlmajer, Martin; Peterková, Jitka; Nevařil, Aleš
Modern technology of concrete includes a comprehensive elaboration of proposal related to concrete composition depending on the required parameters of fresh and hardened concrete. One of the fields related to the technologies of concrete is the issue of the generation of hydration heat. Heat generation in the process of hydration is observed mainly in concretes. Here, we emphasize the need of avoiding potential cracking due to thermal expansion, which is mainly the case of putting concrete in massive units and also other cases in which critical stress and damaging to the concrete may occur due to the influence of high temperature gradients. Hydration of concrete is a very difficult and complex process that depends on a number of direct and indirect factors. Speed indicators of hydration reactions are represented by the intensity of the hydration heat generation. The paper deals with the general methodology for the proposal of prescriptions for concrete mass intended for structures with high demands on low level of hydration heat generation. There are various intermediate steps presented, those leading to a successful proposal of concrete composition, including verification of the proposed measures and creation of a 3D model of calculation.
The Effect of Shielding Barriers on Solar Air Collector Gains
(Elsevier, 2013-08-22) Šikula, Ondřej; Plášek, Josef; Hirš, Jiří
The paper deals with numerical simulations of the impact of location and orientation of the solar air collector located on the roof of a building and on its thermal performance. The solar collector is used to preheat an air, which then is supplied into the building. The solar collector is placed on the roof, which is shielded from barriers. To achieve the desired objective, numerical simulation of the annual operations of the collector in the software BSim was performed. Real climate data for Central Europe were used. The result of this work is to determine the effect of shielding barriers on the usable annual heat gain, which is represented by preheating of external air.

Browse

Recent Submissions