The paper presents dynamic model of hot water storage tank. The literature review has been made. Analysis of effects of nodalization on the prediction error of generalized finite element method (GFEM) is provided. The model takes into account eleven various parameters, such as: flue gases volumetric flow rate to the spiral, inlet water temperature, outlet water flow rate, etc. Boiler is also described by sizing parameters, nozzle parameters and heat loss including ambient temperature. The model has been validated on existing data. Adequate laboratory experiments were provided. The comparison between 1-, 5-, 10- and 50-zone boiler is presented. Comparison between experiment and simulations for different zone numbers of the boiler model is presented on the plots. The reason of differences between experiment and simulation is explained.
Inter-specific adoption is an intriguing topic in behavioural and evolutionary ecology. Being a rare phenomenon is rarely documented in the literature and thus reports of inter-specific adoption based on solid data are particularly valuable. Here, owing to a long-term and extensive monitoring of a local population of the European blackbird (Turdus merula, hereafter blackbird), we describe observations of alloparental behaviour exhibited by blackbirds towards fieldfare (Turdus pilaris) nestlings (single nest, first record ever) and fledglings (twelve cases in total). We discuss the observations in respect to available literature.
The paper presents results of the field tests on membrane biogas enrichment performed with the application of mobile membrane installation (MMI) with the feed stream up to 10 Nm 3 /h. The mobile installation equipped with four hollow fibre modules with polyimide type membranes was tested at four different biogas plants. Two of them were using agricultural substrates. The third one was constructed at a municipal wastewater plant and sludge was fermented in a digester and finally in the fourth case biogas was extracted from municipal waste landfill site. Differences in the concentration of bio-methane in feed in all cases were observed and trace compounds were detected as well. High selectivity polyimide membranes, in proper module arrangements, can provide a product of high methane content in all cases. The content of other trace compounds, such as hydrogen sulphide, water vapour and oxygen on the product did not exceed the values stated by standard for a biogas as a vehicle fuel. The traces of hydrogen sulphide and water vapour penetrated faster to the waste stream enriched in carbon dioxide, which could lead to further purification of the product -methane being hold in the retentate (H 2 O > H 2 S > CO 2 > O 2 > CH 4 > N 2 ). In the investigated cases, when concentration of N 2 was low and concentration of CH 4 higher than 50%, it was possible to upgrade methane to concentration above 90% in a two-stage cascade.To perform simulation of CH 4 and CO 2 permeation through polyimide membrane, MATLAB was used. Simulation program has included permeation gaseous mixture with methane contents as observed at field tests in the range of 50 and 60% vol. The mass transport process was estimated for a concurrent hollow fibre membrane module for given pressure and temperature conditions and different values of stage cut. The obtained results show good agreement with the experimental data. The highest degree of methane recovery was obtained with gas concentrating in a cascade with recycling of the retentate.
Summary Membrane-based techniques for biomethane production from biogasThe enrichment of biogas in methane involves the removal of carbon dioxide, water vapor, and hydrogen sulphide, which contribute to the reduction of thermal parameters of raw biogas. Biogas purification is generally carried out using the following processes: absorption (in water, polyethylene glycol, amines), adsorption (molecular sieves, activated carbon), and low temperature distillation or membrane separation. Compared with these methods, membrane techniques produce the same performance at lower operating costs and significantly lower energy requirements and surface. This technique is also characterized by modular construction, which allows for easy scale-up. In addition, it does not contribute to the production of additional waste streams and the process does not require the use of additional reagents. Enrichment of biogas to methane concentration higher than 70% by volume. CH 4 gives ability to use this gas as an alternative, clean fuel.Słowa kluczowe: OZE, biogaz, biometan, separacja membranowa
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