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Abstract

Evaluation of thermodynamic efficiency of a power plant is usually performed using the method of so-called thermal diagnostics, based on energy balancing. Energetic analysis is however suitable only for a quantitative assessment and for comparing similar technologies. In order to properly assess the origins of energy losses in the given system, an exergetic analysis has to be applied. The paper describes the rules of exergetic diagnostics, which greatly extends the potential of classic thermal diagnostics. A calculation example of a combined cycle power plant is included. The example demonstrates the potential of exergetic diagnostics for locating exergy losses and explains the reasons for increased consumption of fuels by comparing two working conditions of the system: reference and operational.

Abstract

The following paper focuses on the electric vehicles sector development and its possible influence on power system load in Poland. The goal is to estimate the increase of power demand resulting from the electric cars charging. First of all, the current legal environment, which provides a framework for the e-mobility sector evolution, was described. Furthermore, the technical process of electric vehicles charging was depicted and the applicable methods of cooperation between e-mobility and power system were proposed. The quantitative analysis of the impact of the electric vehicles charging on the power demand in the National Power System was conducted. The input data and adopted assumption were specified. The structure of the calculation model and the differences between analyzed scenarios were described. The outcome obtained for the National Power System and Warsaw distribution area were presented.

Abstract

A study on natural gas saving and emissions decrease in the public health care sector is presented. The analyzed hospital complex belongs to the largest ones in Slovakia and uses both hot water and water steam for heating purposes. Visual steam system inspection revealed serious inefficiencies, including steam venting, missing pipelines insulation and obsolete steam sources with dysfunctional blow-down system. Defined experiment with stepwise steam appliances shutdown enabled quantification of excess natural gas consumption due to these inefficiencies. Measures proposed for the solution of this state are inexpensive, with a short payback period. The expected natural gas savings amount up to 3200 MWh/year, which represents roughly 50% of the total natural gas consumption in the hospital complex.

Abstract

Performance characteristics are an indicator of both, the technical as well as aesthetic state of buildings. Aesthetic needs are in disagreement with the merciless aging process. The beauty of a city is formed not only by the original forms of new residential buildings, but also by existing tenement housing; thus preserving their aesthetics becomes a necessity. One of the most important problems connected with using any building, but especially a residential building, is ensuring an adequate technical condition. Process of revitalization of residential buildings is connected with familiarity with the technical problems of passing. However, the secret of lasting is found, above all, in the propagation of aesthetics. The diagnosis of the technical condition is an initial stage of renovating historical buildings. Conclusions drawn from the diagnosis are a basis for planning revitalization works.

Abstract

This investigation focussed on the plasticity and swell-shrink behaviour of an expansive soil that was stabilized using electro kinetic stabilization (EKS) techniques with cationic fluids for enhancement of stabilization. 0.25 M solutions of calcium hydroxide and calcium chloride were used as cationic fluids. An electro kinetic (EK) cell of dimensions 500 mm x 150 mm x 160 mm with inert graphite electrodes of size 140 mm x 160 mm x 5 mm was adopted for the stabilization process, carried out at an applied voltage of 40 V over a period of 6 hours. After the duration of the test, stabilized soil sample was subjected to Atterberg limits and free swell tests to determine its plasticity and swell-shrink characteristics. The results of the investigation found that both fluids were capable of reducing the plasticity and swell-shrink behaviour of the soil with different levels of effectiveness.

Abstract

Carbon accounting has become a valuable tool for expressing the fossil energy demand of products, organizational entities, or entire countries. About a decade ago, cities also began accounting their carbon emissions. The first major city to do so was London in 2009, stating a carbon footprint of 4.84 tCO2eq/(year*capita) for 2008. Nowadays, multiple rankings compare the carbon emissions of cities. For example, the Urban Land Magazine lists São Paulo as the city with the world’s lowest carbon emissions (1.4 CO2eq/(year*capita)). Such listings typically present the depicted emission values as scientifically indisputable numbers. However, a closer look at the applied methodology frequently reveals a wide range of implicit, often undisclosed assumptions at the foundation of the calculations. This paper analyses the uncertainties of carbon accounting on the city scale, using the example of the Red Sea resort town of El Gouna. The estimated value of El Gouna’s carbon footprint for the year 2014 is 14.3 tCO2eq/(year*capita). Third Scope emissions constitute the majority of El Gouna’s carbon footprint. Varying their underlying assumptions only slightly can lead to alterations of the results of more than 50%, questioning the robustness of the findings. To increase the robustness and the comparability of carbon accounting across cities, this paper suggests emphasizing Scope 1 and Scope 2 emissions, while limiting the role of Scope 3 emissions.

Abstract

In this paper, authors present results of accuracy verification of the Trimble RTX technology. The GNSS receiver Spectra Precision SP60 was used in Cyprus (Kato Paphos Archaeological Park). To evaluate the accuracy of the receiver, two measuring test networks (consisting of 30 and 55 control points) were established. All points were determined in four measuring cycles. Additionally, in order to make more advanced analysis of the data, the bases were also measured by using another GNSS receiver - Geomax-Zenith 25. The point positions, in this case, were conducted in the local coordinate system of Kato Paphos Archaeological Park by using RTK positioning technology. To make a comparison, it was necessary to transform the coordinates based on different groups of fitting points. Analysis allowed to conclude that the Spectra Precision SP60 receiver and the RTX Trimble technology guarantee repeatable results (on the level of 4 cm) of point positioning measurements.

Abstract

The Miocene deposits of the Carpathian Foredeep are relatively poorly recognized in geotechnical terms. The article analyzes the properties of the Krakowiec clays of the Przemyśl region, in particular physical and deformation parameters. In this part of the Carpathian Foredeep, clay usually occurs at considerable depth under younger Quaternary deposits. Particular attention was paid to the structural characterization of the tested samples. Structural heterogeneity of the studied clay, noticeable already at the stage of macroscopic studies, causes difficulties in conducting laboratory tests of strength parameters, especially the angle of internal friction and cohesion. The specific, layered, claysilt structure may cause difficulties in assessing load-bearing capacity and stability of the ground made of this type of soil. The unusual structure should draw attention of the contractors of geological-engineering and geotechnical documentation and encourage them to check mechanical properties by testing material with direct methods. An important issue is also forecasting changes in strain parameters in relation to the estimation of the effects of settlements of engineering structures.

Abstract

In this paper, the bending resistance of three metal-concrete composite beams was compared in real car fires in an open car park. Steel and concrete composite beams are often used for the construction of ceilings in multi-storey car parks. The authors made an attempt to evaluate how the replacement of a non-alloy steel girder with a stainless steel or aluminium alloy girder affects the bending resistance of a composite beam under fire conditions. The analysed beams were not fire-protected. They consisted of a concrete slab and a girder made of: non-alloy (carbon) S235J2 (1.0117) steel, X6CrNiMoTi17- 12-2 (1.4571) stainless steel, and AW-6061 T6 (EN AW-Al Mg1SiCu) aluminium alloy.

Abstract

The aim of the studies was to determine the changes in the concentration of PAHs in sewage sludge stored under various light conditions. The sewage sludge samples were stored under aerobic conditions. Sewage sludge samples were deposed in darkness, in laboratory conditions and exposed to UV rays. The changes in the concentration of PAHs were analyzed in fourth series: in sludge samples taken from treatment plant (biotic samples), in sludge with the addition of a standard PAH mixture (biotic samples+PAHs), in sewage sludge with addition sodium azide (abiotic samples) and both a standard mixture and with added sodium azide (abiotic samples+PAHs). Changes in 6-ring of PAHs concentration in sewage sludge samples were studied at seven day intervals for 4 weeks. The concentration of PAHs was determination using gas chromatograph-mass spectrometry GC-MS. The losses of hydrocarbons after 4 weeks of research were in the range of 60 to 97%. It depends of kind of samples. In sewage sludge with standard mixture the effectiveness of PAHs decomposition were in the range of 60 to75%. In sewage sludge with standard mixture of PAHs the losses of hydrocarbons were the highest and reached 97%. The final concentration of PAHs in biotic samples was lower (2-13%) than the concentration of analysed compounds in abiotic samples.