• Energy Research
• Closed Access close
• PL close
• University of Szczecin close

A comparative parametric analysis is carried out of a small-scale combined heat and power plant incorporating a heat pump and the conventional system in which heat is produced in a hot water boiler and electrical energy is drawn from the power grid. Relative exergetic efficiency is defined as the quotient of exergetic (rational) efficiencies of the cogeneration plant and the related conventional system. Dependence of this efficiency on the power-to-heat ratio for chosen values of parameters characterizing the compared systems is calculated and shown pictorially.

Abstract The purpose of this investigation was to select the lowest energy-consuming configuration of a ribbon agitator. The criterion of the selection was mixing energy. The interaction between power consumption, mixing time and the geometric parameters of a non-typical helical ribbon agitator was also investigated.

In this paper, the new approach of the description of the grinding process during the mixing of the granular material by means of the simple kinetic equation is realized on the basis of the combination of the statistical and informational characteristics. The analysis is carried out using the probability density function for the studies of a size distribution variation at the different moments of the mixing process including the informational theory.

AbstractHorse withers height is frequently estimated based on skeletal remains during archeozoological analyses. The routinely used methods (Vitt and Kiesewalter) do not allow withers height estimation without complete long bone and skull osteometry. The modified Wyrost and Kucharczyk formula is based on the internal dimensions of the cranial cavity. This method can be used even when the neurocranium is the only surviving portion of the skull. Earlier investigation demonstrated that it can be used as a substitute for the Kiesewalter method. The statistical analyses of the results achieved using metapodial bones are strongly correlated with the results achieved using the Wyrost and Kucharczyk method. A unique horse skull assemblage, dating back to medieval times, was unearthed from several archeological sites in Poland (Silesia, Kuyavia, Grater Poland, Western Pomerania, and Eastern Pomerania). This study aimed to estimate the withers height of this assemblage using the modified Wyrost and Kucharczyk method. Subsequently, these estimations were compared with accessible literature data from both medieval Poland and surrounding territories. The literature indicates that the horses from Western Pomerania, Silesia, and Kuyavia were larger than the animals from Eastern Pomerania. Our results show that horses from Western Pomerania were larger than those from Silesia, Kuyavia, and Eastern Pomerania. In both cases, the Western Pomeranian horses are the largest. In general, according to our results and the accessible literature, it seems true that Polish medieval horse populations can be described as medium‐ and small‐sized, according to Vitt's classification. The modified Wyrost and Kucharczyk formula can be used as an additional or alternative method of calculating withers height in routine archeozoological studies.

To prepare biological activated carbon (BAC), raw surface water was circulated through granular activated carbon (GAC) beds. Biological activity of carbon filters was initiated after about 6 months of filter operation and was confirmed by two methods: measurement of the amount of biomass attached to the carbon and by the fluorescein diacetate (FDA) test. The effect of carbon pre-washing on WG-12 carbon properties was also studied. For this purpose, the nitrogen adsorption isotherms at 77K and Fourier transform-infrared (FT-IR) spectra analyses were performed. Moreover, iodine number, decolorizing power and adsorption properties of carbon in relation to phenol were studied. Analysis of the results revealed that after WG-12 carbon pre-washing its BET surface increased a little, the pH value of the carbon water extract decreased from 11.0 to 9.4, decolorizing power remained at the same level, and the iodine number and phenol adsorption rate increased. In preliminary studies of the ozonation-biofiltration process, a model phenol solution with concentration of approximately 10mg/l was applied. During the ozonation process a dose of 1.64 mg O(3)/mg TOC (total organic carbon) was employed and the contact time was 5 min. Four empty bed contact times (EBCTs) in the range of 2.4-24.0 min were used in the biofiltration experiment. The effectiveness of purification was measured by the following parameters: chemical oxygen demand (COD(Mn)), TOC, phenol concentration and UV(254)-absorbance. The parameters were found to decrease with EBCT.

AbstractThe electron density distributions in crystals of five previously studied DMAN complexes and five Schiff bases (two new ones) have been analysed in terms of various properties of bond critical points (BCPs) found in the pair‐wise interactions in their lattices. We analysed the continua of interactions including covalent/ionic bonds as well as hydrogen bonds and all other types of weak interactions for all pairs of interacting atoms. The charge density at BCPs and local kinetic and potential energy densities vary exponentially with internuclear distance (or other measures of separation). The parameters of the dependences appear to be characteristics of particular pairs of atom types. The Laplacian and the total (sum of kinetic and potential) energy density at BCPs show similar behaviour with the dependence being of the Morse type. The componentsλ1,λ2,λ3of the Laplacian at BCPs vary systematically with internuclear distance according to the type of atom pair. Forλ1andλ2the distribution is of the exponential type, whereasλ3does not seem to follow any simple functional form, consistent with previous theoretical findings. Analytical nonlinear dependences of Laplacian on charge density have been found. They agree reasonably well with those obtained by least square fit of the Laplacian to charge density data. There are four distinct regions of the ∇2ρBCP/ρBCPspace, generated byEBCP=0 andGBCP/ρBCP=1 conditions. Two regions clearly correspond to the shared‐shell and closed‐shell interactions and the other two to some intermediate situation.

Abstract The aim of this work is to assess the possibility and usefulness of accessing geothermal energy from the existing production well, Jachowka K-2. Discussions of both, a heat flow transferred between a deposit and a heat carrier and a heat flow permeated through the barrier are presented. A computational model, was designed to determine the volume of a gained geothermal heat flux with the use of a double-pipe geothermal heat exchanger with the dead centre [12] . Lastly, the article there are the results of calculations of available heat flux in the investigated well at the depth of L =3950 m are analyzed.

An electromagnetic field (EMF) has been shown to have various stimulatory or inhibitory effects on microorganisms. Over the years, growing interest in this topic led to numerous discoveries suggesting the potential applicability of EMF in biotechnological processes. Among these observations are stimulative effects of this physical influence resulting in intensified biomass production, modification of metabolic activity, or pigments secretion. In this review, we present the current state of the art and underline the main findings of the application of EMF in bioprocessing and their practical meaning in process engineering using examples selected from studies on bacteria, archaea, microscopic fungi and yeasts, viruses, and microalgae. All biological data are presented concerning the classification of EMF. Furthermore, we aimed to highlight missing parts of contemporary knowledge and indicate weak spots in the approaches found in the literature.