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Agricultural Engineerin, 2013, Issue 2 (143)
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143 # 3354
Creativity and work – the way to success

143 # 3355
Mobile and energy efficient machine for biomass harvesting and compaction with the curling method

The aim of this work was to elaborate the construction of a mobile machine implementing the process of briquetting with the curling method. The SolidWorks computer software was to design the construction of the mobile machine. As a result of the construction works, a machine attachable to the tractor field machinery was constructed. It consisted of seven main assemblies, which will be driven mechanically, hydraulically and electrically. A mechanical drive will be drawn with a tractor and transferred by the PTO. Moreover, hydraulic pumps will be driven from this box, which deliver hydraulic power to driving motors and servo-motors. The tractor electrical system will be powered by auxiliary drives. The expected capacity of the machine is approx. 1,5t·h-1, the power demand approx. 40kW. The mobile machine developed in PIMR, which performs the process of briquetting of stalk materials with the curling method constitutes a part of activities to increase the use of straw for energy purposes.

143 # 3356
Theoretical assessment of power transmission in a tractor exploited on various grounds

Results of the theoretical assessment with the use of traction research carried out in the field conditions were presented in the article. The assessment concerned the selection issue of the ratio in the power transmission system of a tractor, which met the requirements of universal tractors of 4.0kN class. The maximum power and the engine torque and the ratio of the power transmission system, of the accepted tractor was assumed. Theoretical analysis was carried out for three travelling speeds on four types of ground - such assumptions reflected the universal character of the tractor exploitation. Values of slide and traction force, determined earlier, were used for calculations. The result of the analysis was the power value determination, engine torque and the rotational speed of an engine on particular gears. On the basis of the analysis, which was carried out, the most advantageous ratio in the power transmission system of the tractor including variety of exploitation conditions was indicated. It was proved that exploitation of the tractor on various grounds with the same travelling speed requires the use of different ratios.

143 # 3357
Intraengine reduction of noxious substances emission in the engine of the outroad vehicle equipped with an EGR system

The paper includes information concerning the possibility of emission of noxious components of fumes due to the use of the advanced system of fumes recirculation in the farm tractor engine equipped with an innovative supply system basing on classical solutions of a high-pressure injection pump. Moreover, the paper includes the concept of the advanced fumes recirculation system. The use of a new type of EGR valve that regulates the amount of fumes which are returned to an engine, cooperating with an integrated sensor O2/NOx placed in the outlet collector allows effective use of a configuration of the particular engine with a fumes cleaning system. The paper presents the results of the stand research of NOx emission and PM of an engine equipped with the described fumes recirculation system EGR showing the possibilities of reduction, especially of NOx in comparison to the standard fumes recirculation system. The use of the suggested solution allows considerable reduction of emission of this component.

143 # 3358
The use of the sport facility and changes of its endurance parameters and changes of the condition and quality of the lawn

The objective of the research which was carried out was the assessment of the selected endurance parameters and the use value of the football pitch lawn in the spring and autumn measurement season. Moisture and compactness of the ground and the maximum shear stress was analysed. Moreover, variety composition of the lawn was determined. Higher values of these parameters were reported in the autumn season for lower moisture of the ground. Furthermore, it was proved that the compactness and the maximum shear stress had the lowest values in the highest layer. Intensive use of lawn in the central part of the football pitch resulted in a higher compaction of soil and in the increase of the endurance parameters. In this part of the pitch, a weaker sod formation of a higher disease sensibility was also reported.

143 # 3359
Preliminary investigation of moisture stability of extrudated products

The objective of the paper was to evaluate the influence of variable humidity conditions, especially dynamic water absorption from air, on the extrudated products. The material used for the research was the wheat - corn extrudate processed in a double-screw extruder. During the storage in the climatic chamber three factors influenced the investigated samples: temperature, relative humidity and the storage time. It was found that extrudates were characterized with considerable sensibility on variable conditions of the storage. Rapid growth of the absorbed humidity mass, particularly in the initial hours of the storage in the climatic chamber was reported.

143 # 3360
Analysis of auto-cistern utilization in the field of milk purchase on the example of a small dairy plant

The objective of the paper was to analyze some factors influencing the effectiveness of collection and transport of raw milk by auto-cisterns on the example of dairy production area in Mazowieckie province. Detailed investigations covered changes of milk production in the considered dairy area as well as some data resulting from operation of auto-cisterns, like transport distances and fuel consumption. Analysis of data from a dairy plant and the area of milk production confirmed the seasonality of milk production as a source of some monthly differences in auto-cistern utilization and management. Some relationships between milk purchase concentration and the fuel-use index were presented and discussed.

143 # 3361
The situation of agricultural distilleries and bioethanol industry in Poland

The paper presents problems of the agricultural distilleries business and the bio-ethanol sector in Poland based on current statistical data, literature data, official reports and information. The analysis and assessment of the attractiveness of the bioethanol sector in Poland in the period 2007-2012, based on the multi-criteria, ME Porter scoring method were conducted. Analyses show that as a result of new targets for the country's energy policy and legislative changes in Poland and the European Union there has been a significant decline in the number of investments related to the production of bioethanol, and therefore, a decline in the attractiveness (market position) of the bioethanol sector in Poland occurred. A number of agricultural distilleries decreased in recent years, in 2011 it was about 170.

143 # 3362
Modification of the outside characteristics of a diesel engine by means of change of fuel injection parameters

The paper presents issues concerning control of operation parameters of a high-pressure injection system of diesel engines used in farm tractors. Skilful modification of this control by means of electronics brings a considerable improvement of all exploitation characteristics of a tractor. However, success of adaptation depends on the producer’s professionalism and the class of measuring apparatus. It seems that such activities fill in a considerable gap on the farm tractors market and may constitute complementation of the factory offer of the producers of engines for utility vehicles. Successful modifications which have been carried out so far prove that modern diesel engines have high power and rotational moment reserves. It must be emphasised that it influences ecological parameters of the engine.

143 # 3363
Potential possibilities for the deveopment of biogas plants on the example of zachodniopomorskie voivodeship

The article assumes two research objectives. The first research objective is to indicate communities that have the best development conditions for agricultural biogas plants. The second research objective is the theoretical evaluation of the biomass potential as a substrate in agricultural biogas plants. The research was conducted on both the rural and urban-rural municipalities. The municipalities determinants levels were determined using the synthetic indicator. The research was conducted on substrates such as: manure, corn silage, grass silage, beet leaf silage, agro - food industry wastes. The research results indicate that the best conditions for the development of agricultural biogas plants are in the north-western part of the region. It was estimated that the maximum quantities of energy can be obtained from organic fertilizers and corn silage. Whereas, the total energy resources potential in the region amounts to 638.7GWh and can meet 10% of electricity demands.

143 # 3364
Analysis of the characteristics of raw materials used in production of solid biofuels

Many products which remain after agricultural and industrial production are characterized by relevant physico-chemical properties allowing their use as raw material for the production of pellets. The paper presents the analysis of physic-chemical properties and strength of pellets made of 100% rapeseed straw, rapeseed cake and rapeseed straw mixture of 5 and 10% share of cake weight, MONG and technical glycerin. The parameters concerning the moisture content and the calorific value as well as mechanical strength were analyzed. Overall, the investigated calorific value parameters showed that all lists used in these studies make the above raw materials a valuable material for the power industry.

143 # 3365
Modeling of fuel injection into the combustion chamber in a compression ignition engine with AVL Fire

This paper presents the modeling of fuel injection into the combustion chamber in compression ignition engine with different fuel types. During creation of these models, software AVL Fire from Computational Fluid Dynamics was used. Process of injection and its parameters were analyzed. Two-dimensional and three-dimensional data on the fuel injection are the conducted simulation results. The study object was the single-cylinder, high-pressure Farymann 18W engine with Common Rail direct injection. Design parameters of the power unit were the input data.

143 # 3366
Operational effectiveness of engine fed with the rape seed oil

There are presented the results of experimental investigations on utilization of pure rape seed oil to feeding the self-ignition engine mounted on the agricultural tractor. A two-tank fuel system with heating of rape seed oil was mounted in the engine. The engine starting was performed on diesel oil, then upon achievement of appropriate temperature the system was automatically shifted to a plant fuel. There was investigated the effect of engine design parameters on the power, torque and specific fuel consumption. The investigations showed that feeding of the engine with pure rape seed oil resulted in the decreased power by 12%, decreased torque by 9% and increased specific fuel consumption by 15%. The change in the fuel injection advance angle affected the specific fuel consumption; its best value was obtained at the angle of 15°.

143 # 3367
The Assessment of Damageability of Tractor Power Unit fed with Rapeseed Oil by Method of Event Tree Analysis – ETA

The paper presents investigations on damageability of agricultural tractor power unit fed with rapeseed oil, with the use of Event Tree Analysis – ETA. The work aimed at: evaluation of occurrence probability for the unfavorable events in the case of feeding engine with unprocessed rapeseed oil, checking the effects of applied protective systems and propositions of more effective protective solutions. The following initializing events were distinguished in the system: water content in rapeseed oil, mechanical and bacteriologic contamination of rapeseed oil. The event tree was developed for each initializing event. The quantitative analysis of damageability was carried out by calculating of result probability in each branch of event tree. There were used the safety barriers to reduce the negative results of occurrence of the initializing events in the forms of: appropriate procedures, tractor operator activities, and devices mounted in the fuel system. An example of such anticipated safety measure is the proposition of installation of special water separator in the fuel system as well as recommendations for tractor operator, who should undertake the specific actions under the determined situations.

143 # 3368
Comparison of the carbon black and nitric oxide emission in the diesel and rapeseed engine by means of modeling in AFL Fire programme

This paper describes research carried out by means of simulation software AVL FIRE. The paper presents detailed steps leading to the implementation of the simulation model of the self-ignition combustion chamber. As a result of the modeling process an animation was created which shows the behavior of the piston and the fuel injection temperature changes depending on the angle of rotation of the crankshaft. The simulation of the phenomena occurring during injection and combustion in the combustion chamber was conducted for the fluid of physical properties and chemical composition corresponding to the properties of diesel fuel and for the fluid with properties corresponding to the rapeseed oil. Simulation results of the carbon black and nitric oxide emission were presented for these two fuels. The aim of this study was to obtain information of the combustion chamber of the diesel engine adapted for feeding with rapeseed oil.

143 # 3369
Effect of fans operation control on uniformity of the air stream distribution in an aerodynamic tunnel

The paper presents experimental research on the character of air stream flow in an open aerodynamic tunnel with a closed measuring chamber, in which the velocity profile was regulated smoothly through 9 independent axial flow fans. Testing the aerodynamic tunnel was carried out in two stages. In the first stage basic parameters of the air stream were determined for 8 base frequencies of fans operation including dynamic pressure, velocity and quality indices of the tunnel: distribution of velocity uniformity and indices of turbulences intensity, which were referred to averages arithmetic velocities. In the second stage, the effect of regulation of particular fans operation on the distribution of velocities fields in a given measuring sphere of the aerodynamic tunnel, where a mini-wind power plant will be placed, were investigated. Both for a regulated as well as a non-regulated system within higher velocities of the stream approx. 15.80m•s-1 the value of the turbulences intensity index was approx. 1.5%. Control of fans allowed limitation of the range of turbulences intensity indices for the whole range of velocities from 2.8–1.5% to 2.0–1.2%. The presented analysis of results proved that the suggested solution of control of particular fans allows obtaining sufficiently homogeneous air stream, such that real objects of mini –wind power turbines could be tested there.

143 # 3370
The analysis of the selected quality properties of pellets made of plant raw materials

The paper presents the analysis of the selected quality properties of pellets produced of winter wheat straw, rye straw, Grenado and Fredro winter triticale, wheat mixture, buckwheat and and meadow hay. The following properties of the produced pellets were evaluated: moisture, calorific value and mechanical strength. Generally accepted methods, set forth in the standard PN-EN 14961 "Solid biofuels- fuel specifications and classes" were used. The research proved that the considered quality properties of the produced pellets on account of their energy use, transport and storing were on a high level and the obtained results were comparable to the data presented by other researchers. It was also reported that all discussed properties for each initial material, of which pellet was made, met the quality requirements of the used standard and the product could have been admitted for turnover on the biofuels market.

143 # 3371
Evaluation of the homogeneity of the eleven-component feed mixture

The aim of this study was to assess the homogeneity of feed for birds consisting of eleven components - grains varying in dimension, density, and shape. The research hypothesis was formulated as follows: concentration of individual components of the mixture is uniform throughout the volume of the feed mixture. The work included the research experiment, sampling during the bagging of the selected bags from three levels of bags, determining the content of samples and comparing the content of samples taken from three levels. For assessing the feed uniformity in all the bags univariate multivariative analysis of variance was used. The multivariative analysis of variance led to the acceptance of the homogeneous distribution hypothesis of the components in the entire volume of the feed mixture.

143 # 3372
The use of multivariate analysis of variance to assess the size of a sample of multicomponent fodder

The aim of this study was to determine the size of the sample collected to describe the quality of feed. The research hypothesis was formulated as follows: collecting one sample from the bag of feed is sufficient to properly determine the feed quality. The work included conducting two research experiments for feed mixtures (8 and 12 ingredients), sampling during the bagging of 20 bags from three levels of bags, determining the content of samples and comparing the content of samples taken from three levels. Statistical analysis was based on the use of multivariate analysis of variance to determine whether there were significant differences in percentage for three levels of sampling. Based on the statistical analysis it can be concluded that there are no statistically significant differences between the percentages of individual components for three levels of samples taken from bags (about 3% of volume), so it seems that one sample (about 1% of volume) is sufficient to assess the mixture quality on this basis.

143 # 3373
Production trend and equipment and the use of transport means in the selected farms

The objective of the paper was to determine the present state of equipment and the use of transport means depending on the production trend. The research proved that the transport means equipment was very diverse in relation to the trend. Two-trend objects had the best equipment on account of quantity while mixed farms were the worst. Annual use of farms was within 619.9 to 1252.5 hours, passenger cars from 41.3 to 207.0 hours. Only one-trend animal farms had delivery trucks and trucks. Each investigated group possessed loading devices and means, while engine power fork trucks occurred only in one-trend plant farms. However, their use was very low.

143 # 3374
Packaging waste management on the example of the selected farm located in the southern Poland

The objective of the paper was to describe waste management, especially to present the basic sources of obtaining packages by agricultural producers and methods of waste disposal. 80 agricultural farms from the southern Poland were covered by the research. The analysis was carried out in farms divided according to the degree of production simplification - 5 groups of simplification were distinguished depending on the number of groups of cultivated plants which are technologically homogeneous. It was determined that the weight of the stored waste is within 0.6-1.1t∙ha-1 AL depending on the degree of simplification and the level of segregation of packagings was at the average 58.8%. In the farm owners\\\' opinion, the social activity and the service activity as well as the supply processes are the main source of waste including packaging waste.

143 # 3375
Economic and ecological aspects of ethanol production in small agricultural distilleries

The paper’s objective is to check the economic feasibility of using a recycled material for ethanol production in a small agricultural distillery and of the environmental consequences of this operation. Using bakery waste as raw material for distillation seems to be a plausible solution for the still surviving agricultural distilleries. Some test runs on the full production scale have been performed. The methodology for this research included simple cost calculations and comparisons on the example of a typical small agricultural distillery. A sufficient supply can be secured in the vicinity of a big bakery. Sale of the produced ethanol may be facilitated due to the state regulations requiring a growing percentage of ethanol content in the transportation gasoline. The distillery effluents can be utilized as a component of animal feed and also as an agricultural fertilizer or as a raw material for biogas or butanol production, though a complete utilization is still dubious. The deal with new raw material in the agricultural distillate production has proved to be economically feasible for both the supplying bakery and the distillery in a typical case analysed in the paper. The cost of raw material for the distillery was more than 10 times less than in the case of processing rye or maize grain. This turns the ethanol production from unprofitable into profitable. The net cost for the bakery was null and it is getting significant savings in the cost of a traditional way of waste disposal. Various possible extensions to the agricultural utilization of waste from the distillate production are also indicated with a preliminary evaluation of their viability, hardly attainable in small distilleries.

143 # 3376
The method of mathematical modeling of the triticale grain shape with Bézier surface patches

Interest in the production of triticale in Poland is increasing due to the possibility of using grain to produce ethanol. The paper presents a method for computer-aided mathematical modeling of the shape of triticale grain. Wanad triticale grain was selected for modeling the shape: length 8.1mm, width 3.1mm, thickness of 3.4mm. The shape of the grain triticale was mapped with three Bézier patches. Calculations and visualization were implemented in a computer program Mathcad. Bézier patches may be used for modeling the shape of triticale grain. Development of a mathematical model of the 3D shape of the solid of triticale grain can be used for modeling of the biofuels production process. In future studies should develop A numerical method for selection of the control parameters of Bézier patch shape based on the basic dimensions of the modeled solid should be developed.

143 # 3377
Analysis of physical properties of plant biomass briquettes

Analysis of physical properties of plant biomass briquettes was presented. Wheat, maize and rapeseed straw, grain mixture and meadow hay were used for production of briquettes. The researched plant raw materials were ground with the use of a drum straw-cutter driven with an electric motor of 7.5kW capacity. Theoretical length of cutting plant materials was 20mm. Moisture and calorific value analysis of materials as well as bulk density and mechanical strength of pellets were carried out according to valid standards. Moisture of raw materials in a fresh state was 16-20% for rapeseed straw to 35–55% for maize straw while in a dry state respectively 11–13% to 13–15%. The average calorific value for the researched plant materials was between 16.1 to 17.2MJ·kg-1. For production of briquettes a screw briquetting machine JW-08 with a heated compression chamber was used. Bulk density and mechanical strength of briquettes depended on the type of the used material and temperature in the compression chamber of a briquetting machine. The lowest bulk density of briquettes was within 505–734kg∙m-3 for meadow hay and the highest was 643–827kg∙m-3 for maize straw at the temperature of the compression chamber 200 and 250°C. While mechanical strength was between respectively 50 to 75% for meadow hay and from 69 to 94% for maize straw for the accepted temperatures of the compression chamber of a briquetting machine.

143 # 3378
The use of waste heat from cooling milk for heating a rural residential building

The paper presents a theoretical discussion on the use of waste heat from cooling milk for heating purposes compared to the selected conventional technologies of producing heat in a rural residential building. Moreover, the article presents approximate results of the investment and exploitation costs account. The use of waste heat from technological processes is one of the elements of limiting the fuel consumption, which becomes more and more expensive with every year and in a wider perspective it influences the improvement of the natural environment condition through decrease of CO 2 emission to atmosphere. Waste heat from the process of cooling milk constitutes a significant source of thermal energy in the energy balance of farms, where diary cattle is bred. For many years on the national market there have been systems enabling recovery of thermal energy collected from the cooled milk and used for preparation of warm utility water, which may be used for production purposes in a cowshed or in a farm, depending on its amount and demand. Whereas, as it results from the literature review, there are no further information on the use of waste heat from cooling milk in installations of the central heating. Therefore, the purpose of the article is to complement knowledge in this scope.

143 # 3379
Impact of rapeseed oil cold extraction in a screw press on the selected physical and chemical properties of a product as engine fuel

The influence of the technological parameters of rape seed cold extrusion process with screw press on the amount of oil and contents of contaminants phosphorus compounds was investigated. The process parameters have a significant impact on the performance of rapeseed oil as a fuel.The results of investigations point out at necessity of phosphorus content determination in the extruded oil. Such investigations should be carried out depending on the variety of rape seed, used agricultural practices, site and date of harvesting storage and pre-treatment of seed. The incorrect selection of pressing parameters can result in considerable increase in the content of phosphorus compounds in the obtained fuel; that can affect very disadvantageously the engine operation and life.

143 # 3380
Impact of technical efficiency of an antidrop valve on the size of liquid outflow from slotted atomizers

The objective of the paper was to assess the impact of technical efficiency of two types of anti-drop valves on the intensity size of the liquid outflow from slotted atomizers. The paper presents research on two types of valves of a varied structure. Used, single filter-valves with anti-drop valves and an atomizer body equipped with membrane valves constituting their integral part were investigated. The research was carried out on a stand that serves for measuring the liquid outflow intensity from agricultural atomizers. The value of valves opening pressure, closing pressure and the liquid outflow intensity were investigated in four variants: A – orifice of 6 mm diameter, B – atomizer of 02 size, C – atomizer of 03 size and D – atomizer of 04 size. It was also determined that valves of individual filter-valves proved variable values of pressures during their opening and closing and a variable size of the liquid outflow. Membrane valves were characterized with high stability of the opening and closing pressure and the intensity of the liquid outflow.

143 # 3381
Analysis of potential selection decisions of tractors made by the farm owners

An analysis of the potential decisions of farmers on tractors choice. The study involved 41 farms. The research was conducted in the form of a directed interview, which was used to fill in the questionnaire. Study area consisted of farms in the province of Masovian Voivodship, which the owners were interested in buying the tractor under the PROW 2007–2013. The structure of the surveyed respondents were mostly owners of farms ranging in size from 20 to 50 ha, mostly one-way pursuing animal production. Studies have shown that respondents are interested farmers buying a new tractor with a power of 60 hp offered by John Deere, Massey Freguson or New Holland. The main criterion for selection is the engine power and fuel consumption.

143 # 3382
The analysis of conventional energy carriers with biomass for heating purposes. Part 1. Description of the issue and the research method

The paper presents the essence of the issue of using conventional energy sources (hard coal, natural gas, heating oil and electric energy obtained from the national electro-energy system - KSE) with reference to the renewable energy source - OZE (i.e. biomass). Methodology presented in the article constitutes a basis for realization of the economic and ecological analysis of the above mentioned energy carriers with reference to different climatic zones, located on the territory of Poland (zone I - Gdańsk, zone II - Piła, zone III - Toruń, zone IV - Białystok, zone V - Suwałki). Additionally, a reference object, that is a typical single-story one family house was presented with details. The material constitutes a thematic part of the issue, for which a next paper was devoted (Ambroziak et al.) and expansion and complementation of the material presented in papers (Redlarskiet et al. 2013a) and (Redlarski et al., 2013b).

143 # 3383
The analysis of conventional energy carriers with biomass for heating purposes. Part 2. Case study

The material constitutes continuance of the issue presented in (Ambroziak et al. 2013). The article presents the results of the economic and ecology analysis of biomass (pellets) compared to others, commonly applied energy carriers (hard coal, natural gas, heating oil and electric energy produced in the national electrical and energy system - KSE). The above analysis was carried out on the example of the residential building, constituting a one-family house located in various climatic zones on the territory of Poland (zone I - Gdańsk, zone II - Piła, zone III Toruń, zone IV - Białystok, zone V - Suwałki). Based on the above mentioned research a number of conclusions presenting advantages of biomass as a renewable energy source (RES) compared to other conventional energy sources were presented.

143 # 3384
Physical and mechanical properties of pellets made of pine tree sawdust with addition of deciduous tree sawdust

The paper presents results of physical and mechanical properties of pellets made of pine tree sawdust with addition of oak, ash, walnut and cherry tree sawdust. Average bulk density of the pelleted mixtures was within the range of 183.98 to 187.12kg·m-3. Mechanical strength depending on the composition of the pelleted mixtures of sawdust obtained values from 98.34 to 98.87%. The research that was carried out proved that more varied lengths were reported for pellets, which were produced in a pelleting machine with a matrix of 8 mm-diameter openings. Statistical analysis which was carried out did not prove any significant differences between the number of fractures and a diameter of pellets.

143 # 3385
Impact of soaking heat of pine tree sawdust on their selected physical and mechanical properties

The paper presents a relation between mechanical strength, length, diameter and pellets fractures and their soaking heat. The researched pellets were produced of pine tree sawdust in the pelleting machine matrix of 6- mm diameter openings. The research consisted in soaking pellets in the temperature from 20 to 70°C with a jump every 10°C. The maximum value of the average mechanical strength (97.59%) was obtained in the temperature of 30°C while the average minimum value (96.99%) was obtained by pellets fired in the temperature of 70°C. Statistical analysis which was carried out did not prove statistically significant impact of soaking temperature of pellets on the results of mechanical strength and their diameters. Statistically significant impact was reported for relations between soaking heat and the length and density of pellets.

143 # 3386
Modelling of temperature field in the ground with the use of spreadsheet

Modern world faces the challenge of satisfying constantly growing energy demand on one hand and increasing food demands on the other. New ways, alternative to conventional energy sources have been searched for. Heat pumps obtaining energy from the interior of the Earth have become very popular recently. In order to use them effectively, software that simulates temperature distribution in the ground are indispensable. Thanks to them, temperature state on any depth may be precisely determined and consequently controlling devices of heat pumps operation may be controlled optimally, etc. The paper herein presents an example of using the spreadsheet of MS Office with implemented language Visual Basic Application (VBA) for modelling temperature field in the ground. The authors' objective is to present and verify the usability of this solution for modelling the temperature distribution in the ground during the operation of a heat pump. On the basis of differential equation describing heat conduct in the ground, discretization of two-dimensional flat panel (differential net model) was carried out and then implementation in VBA language. Results of numerical simulation were set with real temperature measurements in the next stage. As a conclusion, it was found that spreadsheet is useful in modelling temperature field in the ground. This device is especially useful for teaching purposes.

143 # 3387
Diversity of additional activity in the selected ecological farms

The objective of the paper was to carry out an analysis of non-agricultural business activity in the selected 100 ecological farms. Research was carried out within the project NCBiR [National Centre for Research and Development] No NR 12 016510 “Innovative impact of technique and technology and IT support of management on the production efficiency in ecological farms”. The object of the research was to assess business activity in the aspect of the size and production trend and tractive force equipment. Activity was defined as a relation of the number of farms which carry out a particular activity to the total number of farms in a given analytical group. For analytical purposes the investigated farms were divided into four homogeneous groups. Acreage of arable land was the basic division criterion, determined based on commonly applied method of assessment of the standard gross margin. On account of the activity trend, the highest activity was reported in one-trend farms, i.e. field plants production. Approx. two times lower activity was reported in in intensively organized two-trend units, which may result from the lack of free time. The biggest and the smallest farms proved the highest activity on account of mechanization services. The first, due to a lot of free time, the other due to better equipment.

143 # 3388
Changes in species composition of plants used for energy purposes in the fallow irrigated with sewage

In 2010-12 research related to irrigation of fallows was carried out. Fallows were spontaneously settled by plants which mainly consisted of goldenrods (Solidago sp.) – a species which can be successfully used in agro-energy. The objective of the conducted research was to verify if sewage systematically delivered to a fallow fundamentally differentiates the floristic composition and biomass of the dominant species – goldenrod. Two irrigation rates: 10mm and 20mm on the patches of 1m2 each were applied on the fawn soil formed by clay sand. The effects of irrigation with initially purified sewage were compared to the object without irrigation (control). In the vegetative season, from May to September, 21 irrigation rates of sewage in total were applied with 7 days intervals. The irrigation contributed to the increase of the goldenrod shoots number (plants) on the area unit. The rest of species covering the fallow changed. The biggest group with the following species: Agropyron repens, Rumex crispus, Taraxacum officinale, Artemisia vulgaris, Trifolium repens, significantly increased its plants number due to irrigation. However, the second group with such species as: Poa pratensis, Calamagrostis epigejos, Tanacetum vulgare, Achillea millefolium, decreased its plants number. For the irrigation doses of 10mm, the increase of the number of plants of species reacting positively to irrigation was lower than the decrease of plants which decreased its number of plants. The situation connected with doses of 20mm irrigation was different. Hence, the total number of plants irrigated with doses of 10mm diminished comparing to the control object, however, it increased on the patches irrigated with 20mm doses. The irrigation caused significant increase of the goldenrod biomass as a dominant species in relation to the biomass of other taxons.

143 # 3389
Selected properties of rapeseed oil and aviation gasoline blends

The paper presents the results of a study aimed at determining the effect of rapeseed oil enhanced with aviation gasoline Jet-A1 on the properties of engine fuel mixtures. The properties of ingredients and mixtures composed of rapeseed oil and aviation gasoline Jet-A1 in the amount of 10%, 20% and 30% (v/v) were compared. The distillation process was analyzed, and the density and viscosity of each product were determined. The addition of 30% aviation gasoline Jet-A1 to the mixture with rapeseed oil reduced viscosity from 34.0mm2·s-1 to 15.6mm2·s-1 and density from 921.0kg·m-3 to 890.9kg·m-3.

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