In recent years, changes have been made in the structure of primary energy use in the European
Union In addition, a reduction in the use of primary energy has also been observed. According to
the forecasts of the International Energy Agency, the European energy market will be subject to
further changes in the perspective of 2040. These may include the reduction of the energy consumption
and the change in the structure of the energy balance as a result pro-ecological activities.
Natural gas will be the only fossil energy carrier whose role in covering the energy demand will not
change. Along with the changes taking place in the European energy market, global changes can
also be observed. The EU Member States will continue to strive to diversify natural gas supplies.
One of the main elements of diversification of natural gas supplies is the use of LNG regasification
terminals. The reasons for that include the increasing production of natural gas, particularly in the
case of unconventional deposits, the ongoing development of liquefaction terminals, and, as a consequence,
an increase in the LNG supply in the global market. The article presents the utilization of
regasification terminals in the EU Member States and plans for the development of LNG terminals.
Europe has the opportunity to import natural gas through LNG terminals. However, until now,
these have been used to a limited extent. This may indicate that in addition to diversification tasks,
terminals can act as a safeguard against interruptions in gas supplies.
Underground spaces having features such as stability, resistance, and being undetected can play a key role in reducing vulnerability by relocating infrastructures and manpower. In recent years, the competitive business environment and limited resources have mostly focused on the importance of project management in order to achieve its objectives. In this research, in order to find the best balance among cost, time, and quality related to construction projects using reinforced concrete in underground structures, a multi-objective mathematical model is proposed. Several executive approaches have been considered for project activities and these approaches are analyzed via several factors. It is assumed that cost, time, and quality of activities in every defined approach can vary between compact and normal values, and the goal is to find the best execution for activities, achieving minimum cost and the maximum quality for the project. To solve the proposed multi-objective model, the genetic algorithm NSGA-II is used.
Compared to other European countries, Poland has scarce drinking water resources and exhibits
significant variation in annual runoff. On the other hand, the geothermal water resources present in sedimentary/structural basins, mostly in the Polish Lowlands and the Podhale geothermal system, not only provide a
valuable source of renewable energy, which is utilized, although only to a limited extent, but can also be used
for many other purposes. The paper presents the results of studies related to the desalination of low dissolved
mineral content geothermal waters from the Bańska IG-1 well using a dual hybrid system based on ultrafiltration and reverse osmosis. The desalination of geothermal waters may be considered a possible solution leading
to the decentralization of drinking water supply. In many cases, using cooled waters for drinking purposes may
be considered an alternative method of disposing of them, in particular for open drain arrangements, i.e. where
cooled water is dumped into surface waters.
The article is focused onthe energetical balance of a technical system for the conversion of crushed tyres by pyrolysis. Process temperatures were set in the range from 500 to 650°C. Mass input of the material was 30 kg per hour. The aim of the article is to answer the following questions as regards the individual products: Under which process conditions can the highest quality of the individual products related to energy be reached? How does the thermal efficiency of the system change in reaction to various conditions of the process?
On the basis of the experimental measurements and calculations, apart from other things, it was discovered that the pyrolysis liquid reaches the highest energetic value, i.e. 42.7 MJ.kg-1, out of all the individual products of the pyrolysis process. Generated pyrolysis gas disposes of the highest lower calorific value 37.1 MJ.kg-1 and the pyrolysis coke disposes of the maximum 30.9 MJ kg-1. From the energetic balance, the thermal efficiency of the experimental unit under the stated operational modes ranging from about 52 % to 56 % has been estimated. Individual findings are elaborated on detail in the article.
Balance, thermodynamic and mainly kinetic approaches using methods of process engineering enable to determine conditions under which iron technology can actually work in limiting technological states, at the lowest reachable fuel consumption (reducing factor) and the highest reachable productivity accordingly. Kinetic simulation can be also used for variant prognostic calculations. The paper deals with thermodynamics and kinetics of iron making process. It presents a kinetic model of iron oxide reduction in a low temperature area. In the experimental part it deals with testing of iron ore feedstock properties. The theoretical and practical limits determined by heat conditions, feedstock reducibility and kinetics of processes are calculated.
Many precision devices, especially measuring devices, must maintain their technical parameters in variable ambient conditions, particularly at varying temperatures. Examples of such devices may be super precise balances that must keep stability and accuracy of the readings in varying ambient temperatures. Due to that fact, there is a problem of measuring the impact of temperature changes, mainly on geometrical dimensions of fundamental constructional elements of these devices. In the paper a new system for measuring micro-displacements of chosen points of a constructional element of balance with a resolution of single nanometres and accuracy at a level of fractions of micrometres has been proposed.
The paper presents abilities and advantages following from the use of the harmonicbalance method for analysis of steady state of a multiphase system with switching devices on example of a matrix converter. Switching elements are modelled as resistances with step-wise variable parameters, what allows to describe the converter by a linear infinite set of equations. The analysis in frequency domain is presented on example of the one-periodic control strategy. External systems were also added using the Thevenin method approach. The numerical calculation results of a linear equations set were verified by the variable structure method in a time domain and the numerical convergence was confirmed. Furthermore, the exemplary complex system was analysed using the cascade method and current waveforms were obtained.
Traditional mass balance measurements by stake readings and snow surveying have been conducted annually since 1996 on the Waldemar Glacier (= Waldemarbreen) in northwest Spitsbergen, Svalbard. Several indirect methods were also used for estimating its mass balance. These methods were divided into two major groups: climatological and geodetic. A comparison of the latest map (2000) with that of 1978 and climatological records enable us to calculate the change in the mass balance of Waldemarbreen over 34 years. These methods include air temperature and degree-day (PDD) models. The average mass balance of Waldemarbreen, computed by climatological methods, was -0.42 m a-1 of water equivalent (w.e.) for the period 1970-2004, and -0.51 m w.e. for 1996-2004. These balances were compared with the glaciological balance for the period 1996-2004, -0.53 m w.e.. The mass balance was also computed using geodetic method, giving -0.52 m of w.e. from 1978 to 2000. It is suggested that, from these results, the approach used for Waldemarbreen might be also useful for estimation the mass balances of other small Svalbard glaciers which terminate on land.
The main topic of this study is the mathematical modelling of bubble size distributions in an aerated stirred tank using the population balance method. The air-water system consisted of a fully baffled vessel with a diameter of 0.29 m, which was equipped with a six-bladed Rushton turbine. The secondary phase was introduced through a ring sparger situated under the impeller. Calculations were performed with the CFD software CFX 14.5. The turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the MUSIG method with 24 bubble size groups. For the bubble size distribution modelling, the breakup model by Luo and Svendsen (1996) typically has been used in the past. However, this breakup model was thoroughly reviewed and its practical applicability was questioned. Therefore, three different breakup models by Martínez-Bazán et al. (1999a, b), Lehr et al. (2002) and Alopaeus et al. (2002) were implemented in the CFD solver and applied to the system. The resulting Sauter mean diameters and local bubble size distributions were compared with experimental data.
In many systems of engineering interest the moment transformation of population balance is applied. One of the methods to solve the transformed population balance equations is the quadrature method of moments. It is based on the approximation of the density function in the source term by the Gaussian quadrature so that it preserves the moments of the original distribution. In this work we propose another method to be applied to the multivariate population problem in chemical engineering, namely a Gaussian cubature (GC) technique that applies linear programming for the approximation of the multivariate distribution. Examples of the application of the Gaussian cubature (GC) are presented for four processes typical for chemical engineering applications. The first and second ones are devoted to crystallization modeling with direction-dependent two-dimensional and three-dimensional growth rates, the third one represents drop dispersion accompanied by mass transfer in liquid-liquid dispersions and finally the fourth case regards the aggregation and sintering of particle populations.
The work is a part of research into the reduction of energy consumption in the production of EPSthrough the modernization
of technological equipment used. This paper presents the results of research and analysis of heat transfer process between the water vapor
that was provided to machine, the mold, the product and the environment. The paper shows the calculation of the heat balance of the
production cycle for two types of mold: standard and modernized. The performance tests used an infrared imaging camera.
The results were used to develop a computer image analysis and statistical analysis. This paper presents the main stages of the production
process and the construction of technological equipment used, changing the mold surface temperature field during the production cycle
and the structure of the heat balance for the mold and its instrumentation. It has been shown that the modernization of construction
of technological equipment has reduced the temperature field and as a consequence of decreased of demand for process steam production
cycle.
This paper gives the results of investigations carried out in the Fugleberget basin which lies on the northern shore of the Hornsund Fiord, in the unglaciated region of raised sea terraces and on the slopes of the Fugleberget (569 m a.s.l.) and the Ariekammen (511 m a.s.l.). The investigations were carried out between 23 July, 1979 and 4 September, 1980, including the polar night. The Fugleberget basin represents well the area of sea terraces and coastal mountains uncovered with glacier and occupying large areas in West Spitsbergen. These areas are characterized by the presence of permafrost. The aim of investigations was to determine such fluvial processes as the duration of the hydrological period, the manner of water supply to the basin and an attempt to define the elements of the water balance. In addition studies were made on hydrological processes, particulary changes in the chemical composition of water, and the magnitude of denudation determined.
This paper contains thsults of hydrological and hydrochemical investigations carried out in the basin of Werenskiöld Glacier against the background of determining climate elements. It also gives chosen elements of the water balance and mass balance determined from year-long investigations of the polar hydrological year 1979-1980.
On the basis of a year-long series of actinometric measurements performed in the vicinity of Polish Polar Station at Hornsund, this paper presents the characteristic of the value of solar radiation incoming at the active surface, of absorbed and net radiation. The maximum intensity of the direct solar radiation was 822 Wm-2, the annual sum total of total radiation was 2611 MJm-2, whereas the mean yearly albedo was 59%. The zero-crossing of the 24-hour sums of the net radiation towards negative values occurred at the turn of September and October.
Wetlands play a significant role in agricultural landscape. They are the areas of exception-ally great natural values able to regulate water cycling in river catchments. In many cases they are the basic food source for bred animals.
Large areas of wetlands (c. 4 million ha) have been drained for agricultural purposes in Poland. Nevertheless, there are still numerous natural (or close to natural) wetlands, part of which is protected in nature reserves or national parks.
Having in mind the transformation of agriculture and the need of protecting water resources and natural environment, it is necessary to regulate the principles of utilisation and management of re-claimed wetlands. Water management should be adjusted to the type of an area and to environmental requirements. Regardless of the type and intensity of agricultural use of wetlands one has to aim at limiting rapid outflow of spring thaw and rainfall waters which means the reconstruction and increas-ing of natural retention capacity of the river catchment. It is necessary to provide an appropriate num-ber of water lifting facilities and their proper exploitation in land reclamation objects.
It is as well necessary to create appropriate organizational, legal and financial conditions stimu-lating actions to improve water balance and wetland protection.
Permanent grasslands – according to the Water Framework Directive – are typical water related ecosystems so they largely affect water quality, its cycling and balance and therefore deserve protection. They are an element of landscape structure (ecosystem function or service) commonly considered a factor stabilising environmental changes.
Most threats posed to waters in Poland originate from present cropland structure with its definite predominance of arable lands over grasslands. Agriculture should therefore focus on the improvement of land use structure in order to minimise environmental hazards and to guarantee at the same time optimum economic effects. This could be achieved by turning arable lands into grasslands (where justified e.g. on light soils) or at least by maintaining present grassland area (condition in negotiations with the EU) and management that would consider environmental protection.
Increasing the contribution of grasslands to cropland structure or at least maintaining their pre-sent status quo would help to achieve compromise between the goals of farmers and environmental protection. Purposeful utilisation of ecosystem services, particularly those of grasslands, allows to maintain more intensive farming without environmental hazard. Limited should be only such activi-ties whose intensity exceeds regenerative or buffering environmental capacity e.g. on grounds par-ticularly subjected to water pollution or those included into Natura 2000 network.