Technical Transactions. Vol. 3

Technical Transactions. Vol. 3

Type: Collection of magazine numbers
Release date

Collection items (18)


A thermodynamic and technical analysis of a zero-emission power plant in Pomerania

Ziółkowski, Paweł, Badur, Janusz
Article
2017
This paper presents the results of a thermodynamic analysis and a method of selecting individual devices and their components to design a zero-emission power plant project in Pomerania. Another aim of the paper is to present the technological abilities of the application of gas-steam turbines with a particular emphasis on enhanced energy conversion in the construction of a wet combustion chamber using cooling water transpiration and a gas-steam expander.

Mathematical modelling of the unsteady operation of a plate and fin heat exchanger for the time-varying mass flow rate of liquid and air velocity

Korzeń, Anna, Taler, Dawid
Article
2017
The mathematical simulation of a plate fin and tube heat exchanger is presented in this paper. The simulation of the transient operation of the heat exchanger was carried out using a general numerical model that was previously developed by the authors. The Reynolds number of the water flowing inside the tubes varied in the range from 4000 to 12000. A detailed analysis of the transient response of a heat exchanger to sudden increase in water mass flow rate and the simultaneous reduction in air flow velocity was modelled. Heat transfer correlations for air and water were determined based on the experimental data. Unknown parameters appearing in the relationships for the Nusselt numbers on the airand water-sides were estimated using the least squares method. A set of partial differential equations for the temperature of water, air, tube wall, and fins was solved using the finite volume method. The results of the numerical simulations of a heat exchanger using experimentally determined air and water-side heat transfer formulas for the calculation of heat transfer coefficients were compared with the experimental data. Excellent agreement between computation results (air and water temperatures at the outlet of the heat exchanger) and experimental results was obtained.

An algorithm for the determination of the control parameters of a multisource drive system

Kędzia, Krzysztof
Article
2017
This article presents an application of the kinetostatic method. The kinetostatic method is a universal method for determining optimum control of unit components in a multisource drive system with regard to selected energetic or ecological criteria. The method’s algorithm and mathematical models for components with descriptions are presented. Example results of this method when applied to a hydrostatic multisource drive system composed of hydrostatic transmission, gas-loaded accumulator and IC engine as the primary source of energy, are presented.

The efficiency of the aeration process in airlift reactors with moving beds

Kujawiak, Sebastian, Makowska, Małgorzata, Matz, Radosław, Gawrońska, Anna
Article
2017
The current work consisted of performing tests on the prototype airlift reactor, examining the efficiency of oxygenation in an airlift reactor equipped with an airlift pump and an additional nozzle to aerate and mix water in the tank. In particular, the objective was to find the optimal submergence of the nozzle which would allow achieving the best possible oxygenation of water with adequate lift efficiency. The testing was performed in two series: with a tank fully filled with water; with a tank filled with 80% water and 20% moving bed. The use of a moving bed with a high specific surface area significantly improved aeration conditions and decreased mixture flow velocity thus causing an increase of gas and liquid contact time. The research has shown the effect of nozzle position on the aeration and circulation conditions in the reactor.

Polybrominated flame retardants in sewage sludge and sediments (review)

Kryłów, Małgorzata, Rezka, Piotr
Article
2017
This paper is a wide review of literature concerning the presence of flame retardants in sediments, treated wastewater, sewage sludge and the possibilities of their biodegradation. These compounds are widely applied in, for example, the textile and electronics industries. Flame retardants (FRs) are hydrophobic with very low solubility in water; however, they are released slowly during the washing of clothing, and as a result of the discarding of waste electronic products, etc. FRs show low mobility in the environment and can accumulate in wastewater, sewage sludge, in sediments in the beds of rivers and lakes, and in soil. Total concentrations of polybrominated diphenyl ethers (PBDEs) ranged from 0.59 to 48.000 ng/g d.w and decaBDE (BDE 209) concentrations from 0.4 to 47,400 ng/g d.w. BDE 209 dominated the congener profile.

Analysis of the technical condition of the sewage collector with the use of numerical simulation

Popielski, Paweł, Kodura, Apoloniusz, Smoliński, Błażej
Article
2017
This article presents a comprehensive analysis of the technical condition of the sewage collector located under Krakowska Avenue in Warsaw. The cross section of the collector is an extended ovoid with the dimensions of 1400 × 800 mm. Current operational problems as well as the reasons for specific faults and failures were discussed. The numerical models generated according to the collected data and the technical documentation were presented. Boundary and initial conditions taken into account in the analysis process and the assumed calculation scenarios were also described. The results obtained as well asthe considered modernization projects, along with selected optimal technical solutions, were discussed.

Influence of fly ash from the thermal treatment of municipal sewage sludge on chosen properties of hardening slurries

Falaciński, Paweł
Article
2017
Over recent years in Poland, there has been a rapid accumulation of sewage sludge – a by-product of the treatment of urban wastewater. This has come about as a result of infrastructure renewal, specifically, the construction of modern sewage treatment plants. As a consequence, the amount of fly ash resulting from the thermal treatment of municipal sewage sludge has grown significantly. The aim of this experiment was to evaluate the possibility of using the fly ash that results from municipal sewage sludge thermal treatment (SSTT) as an additive to hardening slurries. The article presents the technological and functional parameters of hardening slurries with the addition of fly ash obtained by SSTT. Moreover, the usefulness of these slurries is analysed on the basis of their basic properties. The mandated requirements for slurries employed in the construction of cut-off walls in flood embankments are listed as a criterion of usefulness. On the basis of this experiment, the usefulness of fly ash obtained through SSTT as an addition to hardening slurries was identified.

Influence, of time randomness execution of work, on lenght of the construction cycle

Więckowski, Andrzej
Article
2017
The objective of this paper is to analyse the time reserves in scheduling periods for conducting processes that ensure construction deadlines can be met. By using the probability account and numerical analyses methods, including ‘Monte Carlo’, execution cycles have been analysed, as well as summary stoppage times for executing teams and working areas. On the basis of calculations made using data from studies made during the construction office building in Krakow it was stated that in order to keep to the planned deadline, must be smaller periods of performance of works by individual brigades, an average of 0,103 times of rhythm.

Stress corrosion of epoxy-glass composites monitored using acoustic emission

Świt, Grzegorz, Adamczak, Anna
Article
2017
In the building industry, polymeric matrix composites filled with glass, carbon, graphite, polypropylene, or Kevlar filaments are commonly used. However, it is notable that the wider use of composites is limited by a lack of sound knowledge regarding their properties their responses to exposure to various environments. In this respect, the alkaline and acid environments may have a significant influence on the response of epoxyglass composites which are most commonly in use. They may undergo stress corrosion and the resulting cracks reduce the strength of the composite. Within this work, a method based on acoustic emission measurement is devised which allows the determination of the beginning of cracking and of the intensity of the corrosive cracking of filaments in a loaded composite. This is substantial in terms of the diagnosing of the functioning structures.

The influence of underground coal mining on an overhead high-voltage power line

Majcherczyk, Tadeusz, Niedbalski, Tadeusz
Article
2017
The primary aim of this study is the analysis of the influence of multi-seam coal mining on a specific 110 kV overhead high-voltage power line. The paper presents the results of geodesic measurements of surface deformation in the area of the analysed location. The study also analyses mining-induced changes in the construction and the inclination of the transmission pylons. Some proposals for the reinforcement of the pylons are suggested. Additionally, pressing issues are identified indicating the necessity for the replacement of the existing pylon system of the overhead high-voltage power line.