In the technical field the energy balances are derived from the 1st thermodynamic law, which covers merely the instantaneous quantitative aspects of heat flows. In terms of energy conservation law these balances are expressed in the form of constant sums of exergy and anergy. And that is why they cannot, or can only to a very limited extent, be used to define the transformation of part of the energy (exergy) to the less valuable energy (anergy). Using the 2nd thermodynamic law we have a chance to trace the energy transformation through entropy, a quality indicator of every heat process and an accompanying symptom of process irreversibility. The plate air-to-air heat exchanger, whose exergy analysis is in the spotlight of our interest, operates, in terms of the laws above, in irreversible changes, while the change of entropy induced by the heat flows depends on the construction and surface of the heat exchange areas. The article analyses the influence of air inlet temperatures on the thermal exergy efficiencies of the heat exchanger and the heat loss exergy. Assessment is based on extensive measurements of the temperature, humidity and flow rate of the heated and cooled air in the plate heat exchanger. Both ...
The work contains the evaluation of work of the small rural sewage treatment plant servicing citizens of the Michniów village (Suchedniów community, Świętokrzyskie Province). The basic element of process line is the activated sludge reactor of sequential work, so called SBR. The bases for evaluation elaboration were data allowed by a user of the object. There were: results of treated sewage volume and results of BOD5, COD5 and total suspension in not treated and treated wastes determinations, coming from years: 2004-2005. In the regarded two-years period hydraulic charge amounted meanly: in the first year about 75%, in the next year about 89% of designed output, that is 35 m3·d-1. In the same period in raw sewage average content of BOD5 (577,8 mgO2⋅dm-3) and total suspension (488,8 mg⋅dm-3) were 1,5 times higher, and CODCr content (1124,9 mgO2⋅dm-3) even 2 times higher than the ones taken in the object design stage. This conjuncture, in situation when sewage treatment plant rejected sewage which were bringing by waste removal tankers could be a proof of illegal pumping contents of house cesspools into sewers sanitary, in case of this properties, which are not connect with yet. In these exploitation conditions the waste purification effects in ...
This paper aims at sharing feedback about dry dams. These structures are efficient to mitigate floods, while little disruption of the continuity of the main channel and its flows outside the flood periods. Five sets of dams are presented here. They were selected so as encompass the diversity of the structures and of the problems. The oldest structures are presented first. These are dams built in the beginning of the twentieth century in Poland and in the USA, which are still in operation today. Then, recent realisations in France are presented. Large dams in Gard catchment and small dams upstream the nearby town of Nîmes are described, with analyses of behaviour during intense floods. Finally, small dams in Seine-Maritime allow to address the issue of an efficiency diagnostic at catchment's scale, when both dams and stakes are spread out. This article gives key references for further information about structures design. ...
The high precipitations, which appears now very frequently, are the main causes of damages in the infrastructure and the properties. Protection against flood should be still developed, but with the special attention on ecology and keep-ing the continuity of water and sediment flow throughout the river channel. Dry dam structure is efficient to mitigate floods, while little disruption of the continuity of the main channel and its flows outside the flood periods. In the paper we ana-lyse the efficiency of selected dry dams during the flood events. We have studied the dry dams located in southern France. In few cases the studies have shown, that dry dams had to be reconstructed in order to protect the area against the flood. ...
The work aimed at the assessment of working of a household sewage treat-ment plant based on a horizontal flow sand filter.Physicochemical analyses of chosen pollution indexes (BZT5, ChZTCr, total suspension, total phosphorus) were carried out and compared with currently in force values of these indexes according to the Regulation of the Minister of the Environment of 24th July 2006. On this basis the operation of the sewage treat-ment plant was assessed. Raw, initially treated and treated sewage samples were taken from December 2008 to March 2009. Physicochemical analysis was carried out in the Laboratory of the Department of Sanitary Engineering and Water Man-agement of the University of Agriculture in Kraków. The gathered results of tests and their analysis conducted in the paper showed the proper working of the household sewage treatment plant.
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Economic conditions of our country make the land consolidation in Poland is an urgent necessity. Strong competition from EU agriculture imposes on manu-factures obtain ever cheaper products, while better quality. To meet these re-quirements it becomes necessary to organize agricultural space in a rational way so as close as possible to natural habitats. Land consolidation directly transforms the structure of the possession, changing the system of roads, and indirectly affect the use changes, intensification of agricultural production - food and other. Farms, because of poor spatial organization, they lose an average of 20-30% of agricultural income. It is necessary to create effective solutions for conditional very rapid economic and spatial transformation of rural areas, enabling the absorption of EU financial resources and their supporting resources. An excellent means to achieve these objectives is precisely the land consolidation process. This article will present some results the land consolidation procedure on the village of Brzozowy Kat, district Ostroleka, community Czarnia.
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The aim of the study is to analyze the productivity and efficiency of two types irrigation systems. First one, with using traditional hose, and second one, with using drip line system. The study was conducted in specialized vegetable farm in Karpicko near Wolsztyn, in years between 2009 to 2011, in two tunnels with an area of 180 m2 either. Cultivation areas of tomatoes, however, took up respectively 87 m2. In each of tunnels 400 tomatoes' seedlings (Nita® Nickerson - Zwann variety) were planted. The volume of water used for irrigation was checked by two independent water meters, whereas the crop took place once a week. The scope and labour intensity of treatment, protective attendance, and associated works with fertilization based on the actual number of man-hours were recorded. The efficiency of water production was much higher in the drip line system; in order to obtain one kilogram of tomatoes the system needed 33 liters of water, whereas the traditional system almost 58 liters. It means that production efficiency of drip irrigation was about 75% higher than using the traditional irrigation system. ...
The article presents the most important causes of energy losses in magnetic circuits of electrical machines and describes a new design of a synchronized induction motor. The basic operational parameters of two structures: induction machine with squirrel cage (IM) and newly designed machine with a rotor with permanent magnets and a copper squirrel cage (induction machine synchronized with self-starting (LSPMSM) have been identified and compared. Performance characteristics were determined for work in steady states. In both cases the stator, type Sg 100L-4B of 3 kW induction motor was used. It has been shown that the PSPMSM supplied from the public mains grid shows the efficiency approx. 5% higher than the conventional motor. The influence of the change in the supply voltage frequency on the work of both structures was tested, i.e. on the measured efficiency, power factor and the electricity from electrical grid. Studies have shown that the LSPMSM can be a replacement for an induction motor. It has been shown that the torque pulsations occurring in the new structure (cogging torque) do not increase the environmental risks. ...
