Agricultural Engineering Research, Volume 7 (2001)

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An Ammonia-Controlled Ventilation System for Fattening Pigs
(2001) Grotz, Walter; Rathmer, Barbara; Gronauer, Andreas; Schön, Hans
In farm animal housing, a good stall climate is the prerequisite for ani- mals and humans in the stall to stay healthy. Taking this into account, the legislator has set maximum limits for certain gaseous pollutants such as ammonia (NH3 ) in the calf- and pig husbandry decrees. At the Bavarian Research Center for Agricultural Engineering, an ammonia-controlled ventilation system with NH3 as an additional regulation variable besides the temperature was developed in cooperation with ventilation compa- nies and successfully tested in a stall for fattening pigs. Low-cost NH3 sensors, which were tested during the project at a gas dilution station in the laboratory and in practical trials in the stall, currently do not yet seem suitable for long-term, reliable use in an ammonia-controlled ven- tilation system.
Animal Health in Outside Climate Housing with Kennels for Fattening Pigs
(2001) Hornauer, Norbert; Haidn, Bernhard; Schön, Hans
For the assessment of the health status of fattening pigs in two outside climate stalls with resting kennels and a conventional warm house, their nasal flora was tested for four pathogens. Pasteurella haemolytica and Actinobacillus pleuropneumoniae could not be found. It was possible to isolate Pasteurella multocida and Bordetella bronchiseptica from ani- mals in every stall compartment. The percentage of germ carriers deve- loped non-uniformly in the systems and mostly without significant diffe- rences. A clear connection between detectable pathogens and lung dia- gnoses in the slaughterhouse could not be established. Damage to the integument (bursae auxiliares at the limbs) did not show any clear diffe- rences between the housing systems. With regard to the locomotor system, all three systems are characterized by few lame animals and prove flawless housing.
Chemosensor Systems and Odour Measurement - Current Developments in Electronic Olfactometry
(2001) Boeker, Peter
Chemosensor measuring systems termed “electronic noses” have been introduced which, very generally speaking, imitate the biological sense of smell. Even though these systems cannot primarily analyze odour char- acteristics, but rather compositions of gas mixtures, they are also used for “electronic olfactometry”. In this contribution, the background and the problems of their use and application for odour measurement are discussed. The methods which have been employed so far do not provide meaningful results. In addition, perspectives and research goals for future development are Described.
Comparison of Room- and Floor Heating in Piglet Houses
(2001) Büscher, Wolfgang; Kluge, Jens; Frosch, Werner
After two years of investigations, different ventilation- and heating sy- stems for piglet houses can now be evaluated comprehensively. In additi- on to the economic viability of the variants, the lying behaviour, indoor air quality, and the emission of noxious gases have been taken into ac- count. As compared with standard fans, low-energy „EC fans“ allow electricity consumption to be reduced by an average of more than 50%. With regard to heating energy, gas burners instead of hot-water floor heating with gas boilers also enabled consumption to be reduced by more than 50%. Floor heating, however, is advantageous for the lying beha- viour of young piglets and the air quality parameters.
Dynamics of Odour Release from a Pig House - Part 1 : Methodological Realization with Olfactometry and an ?EURoeElectronic Nose?EUR?
(2001) Brose, Gregor; Hartung, Eberhard
Due to varying operating conditions, odour emissions from pig houses are subject to large fluctuations. The appropriate selection of representa- tive sampling times as well as the more realistic calculation and evalua- tion of odour levels in ambient air requires more precise knowledge about the dynamics of odour emissions. The investigation programme of the presented project comprises the measurement of seasonal (fattening period), daytime-related, and short- term (feeding) dynamic effects of odour release as well as the identifica- tion of potential factors which influence the amount of odour emission. Parallel to “classic” olfactometry, an “electronic nose” with a chemo- sensor array of ten metal oxide sensors is used. Initial results clearly show the potential of “electronic noses” for the measurement of dynamic fluctuations in gas composition, which also includes odorants. In the second part, evaluation methods adapted to the problem will be used to determine possible connections between the sensor signals of the “electronic nose” and the odour concentrations analyzed by means of olfactometry.
Economic Evaluation of Biofilters
(2001) Martinec, Milos; Hartung, Eberhard
During studies on the optimization of biofilters for the reduction of odours from piggeries, two filter materials and different designs were tested parallel in a stall for fattening pigs. Measured mean odour reduc- tion amounted to 70 to 80%. Odour concentration in the waste air consti- tutes the main influencing factor for odour reduction. Sufficient material moisture in the entire volume of the filter material is an essential prereq- uisite for odours to be reduced significantly and as continuously as pos- sible. The use of coarsely structured materials such as biochips allows larger bulk heights and filter volume loads to be reached, which reduces the investment cost considerably. However, flow resistance and, hence, operating expenses for electricity, grow disproportionately. Therefore, these effects must be given special attention when designing a biofilter and calculating the resulting total cost.
Electrolytic Clarification of Vegetable Washing Water : Fundamentals of the Electrolytic Process
(2001) Geyer, Sabine; Linke, Bernd; Geyer, Martin; Pille, Erhard
For the clarification of washing water from potato- and vegetable washing, the electro-chemical method proves superior to conventional sedimentation techniques because, after the necessary amount of electric energy has been ex- pended, the wastewater is clear within a short time and requires a reduced ba- sin surface for sedimentation. The present report describes the procedural prin- ciple of electrolysis, as well as its operational and performance parameters ba- sed on experimental studies during which standardized model washing water is subject to electrolytic clarification in a batch reactor. Appropriate setting of the parameters allows the electrolytic clarification of ve- getable washing water to be influenced: there is a direct connection between the electrolytic current and the process time required for electrolysis. The product of both parameters releases a defined quantity of electrode material for the pre- cipitation of a certain pollutant load (Faraday´s law). The amount of electroly- tic current also depends on the set electrolytic voltage, the properties and the size of the electrolytic unit, and the conductibility of the liquid to be treated. High electrolytic tensions, which result in very short process times for clarifi- cation, cause the development of large quantities of gas so that the amount of electricity employed cannot entirely be converted into chemical precipitation material. Therefore, the cost of electric work increases disproportionately. At low tensions, electrolytic treatment is more cost-efficient. Longer process times result in improved clarification performance. For the reduction of the COD, however, which is present in a dissolved form, even significantly prolonged cla- rification periods do not provide substantial improvement. The electrode com- bination aluminium/chromium steel (Al/XSt) allowed for high current densities and led to the best clarification results with regard to COD reduction.
Environmentally Compatible and Energy-Efficient Production of Energy Plants
(2001) Scholz, Volkhard; Krüger, Karen; Höhn, Axel
In the foreseeable future, energy plants could become an integral part of the energy mix in Germany. However, this requires that these plants are produced in an environmentally friendly way and that the energy yield justifies the input. The present contribution describes results concerning the cultivation of 10 energy plant species suitable for combustion. Over a period of 6 years, yield, energy gain, and environmentally relevant sub- stances in the plant and the soil were determined under practical condi- tions. Fertilization was carried out in 4 variants each ranging from 0 to 150 kg N/ha and with wood and straw ashes, as well as basic mineral fertilizer. Plant protection products were entirely dispensed with. The re- sults show that, except for topinambur haulm and wood with undersown crops, the mean yield ranges between 8 and 12 t DM /ha and that a reduc- tion of nitrogen application from 150 to 75 kg N/ha causes only slight yield losses. Without fertilization, yields diminish by 20 to 40 % after 6 years, except for poplars (without undersown crops), which with ap- proximately 10 t DM /ha reach a similarly high yield level as with fertiliza- tion. The contents of the emission- and combustion-relevant plant nutri- ents, such as nitrogen, potassium, sulfur, and chlorine, are significantly lower in poplars and willows than in grass, rye, triticale and hemp. The input of heavy metals, such as cadmium, copper, zinc, and lead, which is caused by fertilizers and energy-related input, is absorbed differently with trees making a particular contribution towards the decontamination of the soil. Hemp, poplars, and winter rye allow high energy yields to be achieved. Even if nitrogen fertilization is reduced (in the case of poplars even at zero fertilization), net energy gains of more than 3,200 liters of oil equivalent per hectare and per year are reached.
Instrumented Wheel for the Measurement of Rear Axle Wheel Forces
(2001) Späth, Ralf
In the project “load spectra in the tractor chassis” (sponsored by Deut- sche Forschungsgemeinschaft), the loads which act on a tractor chassis are being investigated. In this respect, the forces at the driving wheels have great significance. The wheel load, for example, is often impossible or virtually impossible to measure by determining axle housing deforma- tion. An instrumented wheel provides more accurate results and additio- nally enables lateral and draft forces to be measured. The functional principle of an instrumented wheel for the tractor rear axle designed and built by the author of this article, as well as the particularities of constructive design and dynamic behaviour are presented. Contactless energy- and signal transmission, as well as the calibration technique are explained. Finally, the use of the instrumented wheel is described using the results of test rides.
Internal Contour of a Tractor Tyre on Firm and Soft Ground
(2001) Schlotter, Volkmar; Kutzbach, Heinz Dieter
The prediction of the forces and moments which a tyre can transmit to the ground requires precise knowledge of the contact area. At Hohenheim University, a laser measuring set was integrated into the existing single wheel tester. A laser sensor in the wheel allows the distance to the internal contour in the tread and in the sidewall area to be measured. Initial results show a significant deformation of the tyre even outside the contact area, which are not taken into account by existing models for contact area calculation.
Measurement of Greenhouse Gases : Air-Conditioned Perspex Chambers for the Measurement of Soil Respiration and Trace Gases in Undisturbed Plant Populations
(2001) Motz, Ilona; Koch, Inge; Kutzbach, Heinz Dieter; Stahr, Karl
Various anthropogenic causes contribute to the increasing greenhouse effect. Carbon dioxide from agricultural areas plays a significant role in this respect. Usually, chamber methods are used for the quantification of CO2 from the plant-soil system. This leads to problems caused by cham- ber effects which are primarily seen in a temperature increase and a re- duction in the amount of photosynthetically active light; therefore, a measuring system was developed during the present investigation which allows these effects to be minimized. These measurements are based on the closed measuring chamber developed in Hohenheim, which, during the present study, was extended to comprise Perspex covers and air con- ditioning.
Measurements of Odour Emissions : Use of Means of Olfactometry and Chemical Sensor Arrays for the Comparison of Different Housing Systems for Fattening Pigs
(2001) Maier, Barbara; Rathmer, Barbara; Riess, Gisbert; Zeisig, Hans-Dieter; Gronauer, Andreas
Due to the increasing sensitivity of the population, the measurement of undesirable odours from agricultural animal husbandry has become a problem which may no longer be neglected. For this reason, objective odour registration is necessary. In this contribution, the results of a comparison of different housing sy- stems for fattening pigs by means of olfactometry and a multisensor array are documented. The great advantage of the chemical sensor array measurements over olfactometry mainly resides in the continuous regi- stration of measurement values as compared with the small number of samples collected during olfactometric measurements. A long-term com- parison of a conventional warm house and two different outdoor climate stall compartments on the same farm allowed the odour emissions of the different housing systems to be assessed. During three measuring periods distributed over one year, olfactometric measurements were taken daily. In addition, continual chemical sensor array measurements were con- ducted during one of the observation periods. As compared with the con- ventional temperature-insulated, partially slatted stall with forced venti- lation, a reduction of the odour emission potential of the outdoor climate experimental compartments with partially slatted floors or litter was pro- ved during all three measuring periods.
Outdoor Climate Kennel Housing : Functional Areas and Their Frequentation by Fattening Pigs
(2001) Hornauer, Norbert; Haidn, Bernhard; Schön, Hans
Animal behaviour was analyzed under practical conditions in an out- door-climate kennel house with a partially slatted floor, an outdoor cli- mate stall with a littered dung area, and a conventional warm stall. No fundamental differences were found. However, influences of the outdoor- and stall climate, the animal weight, and the functional areas were shown. Good ventilation of the kennel in the summer is decisive for suc- cess. In comparison with the conventional warm stall, the percentage of the different modes of behaviour is similar.
Piglet Rearing in Large Groups - Sensor Feeding, Animal Behaviour and Biological Performance
(2001) Snell, Hinrich; Schlichte, Ralph; Van den Weghe, Herman
In large group husbandry with liquid sensor feeding, the behaviour and the fattening performance of rearing piglets were studied. The animal- feeding place ratio was given particular attention. The results prove that the examined technique provides high performance while keeping animal losses very low. However, they also indicate that modern feeding tech- nology alone cannot guarantee evenly good piglet development if stock- ing intensity is high.
Principles of Mechanical Cleaning Tools for Sugar Beet
(2001) Degen, Peter
Sugar beet and soil particles can be found as loose and adhesive compo- nents in a common multi-component pile. The soil content in the pile is reduced by means of removing- and separating processes. During the harvest, mechanical cleaning devices are used for this purpose. Two mo- dels are employed to analyze the function of these tools. A model which analyzes the relevant operating surfaces is used to describe the tool structure and to compare different design types. In a dynamic working model, the two key processes removal and separation are defined. Both processes are based on impacts of the cleaning tool on the sugar beet- soil pile. Interacting adhesion- and cohesion bonds are broken up so that adhesive soil particles are converted into loose ones. The impact flow during separation also causes the pile to be mixed so that loose particles are separated. A detector is used to measure the quantative and qualitative impact flow caused by the cleaning tool. This data is correla- ted with the parameters which describe the quality of sugar beet, such as soil tare and surface damage.
Reduction of the Measuring Gas Dew Point - Concentration Changes and Washing Out of Noxious Gases and Odorous Compounds
(2001) Boeker, Peter
Gas cooling devices are used as a means of conditioning humid measur- ing gas flows. In these devices, the dew point is lowered. This causes the surplus quantity of water to condense. Two resulting effects influence the concentration of noxious gases and odorous compounds. The condensa- tion part of the humidity reduces the total gas flow. Therefore, the con- centrations of the other gas components rise. Water-soluble components, however, cause additional washing-out due to absorption in the conden- sate. The concentration of these components diminishes. Both effects are influenced by the degree of dew point reduction and the temperature in the cooler. At low temperatures, gas solubility and the quantity of con- densing water increase. Therefore, the largest washing out effect occurs here. In the case of odorous compounds, the washing-out effect must be taken into special consideration. In order to pass the mucous membrane which covers the olfactory receptors in the nose, odorous molecules must be water-soluble. Depending upon the degree of water solubility, different concentration shifts occur. The resulting odour impression may therefore alter significantly due to the change in relative composition. The alter- native dilution of the measuring gas with dry air for dew point reduction results in a considerable reduction of the concentrations. In this contribution, the fundamental procedures and methods for the calculation of these effects are presented.
Simulation of a Pressure-Controlled Clamping System for Continuously Variable Belt- and Chain Transmissions
(2001) Stöckl, Bernhard
The transmittable power of continuously variable belt- and chain trans- missions has been steadily increased in recent years so that they can be used on tractors of the lower and medium power classes. In the current common designs, the hydraulic system, which is required for clamping and adjustment, exerts a strong influence on the total losses. In order to increase the overall efficiency of such a transmission, new, pressure- controlled clamping hydraulics with significantly higher system-related efficiency were examined with the aid of computer simulation. These stu- dies focused on the realization of highly dynamic clamping pressure supply in cases of sudden torque increase, which occur frequently in tractors. For the optimization of efficiency, excess clamping must be avoided. For further examinations, a real-time simulation system was set up which, in addition to measurement data collection on the test bench, allows for the speedy and efficient development of control strategies.
The Effects of [alpha]-Amylase on the Flow Behaviour of Liquid Feed
(2001) Türk, Meno; Heinzl, Wolfgang
Feed enzymes have been used for a long time in pig feeding. A new ob- jective is the reduction of the viscosity of liquid feed through the addition of α-amylase. Using the same measuring method, the most important feedstuffs and feed mixtures for pigs were analyzed. Mixing- and flow curves were measured, compared and assessed. An [alpha]-amylase marketed by BASF (Natustarch ®) reduces the viscosity of liquid feed rich in starch.
The Modelling of the Cutting Process During the Dry Peeling of Potatoes
(2001) Winkelmann, Jörg; Fürll, Christian
On their way to the consumer, a very large part of the potatoes is freshly peeled before being cooked. A newly designed peeling technique allows the currently high losses and environmental pollution to be minimized. Modern peeling techniques use knife-like blades in order to give the cut crops a smooth surface. Based on the examination of a mechanical peel- ing technique with a spatially swinging knife plate, a modelling approach for the simulation of the cut, which is carried out through the interaction between hole-shaped blades and freely movable potato tubers, is pre- sented. This modelling approach for the cut is closely coupled with the modelling of the impact behaviour of potato tubers, which has already been described in a separate contribution in this journal [1].
Tracer Measurements for the Validation of Odour Dispersion Models
(2001) Boeker, Peter; Wittkowski, Martin; Wallenfang, Oliver; Koster, Frank; Griebel, Michael; Diekmann, Bernd; Schulze Lammers, Peter
Dispersion models are computer-based numerical models which are spe- cially developed for the prognosis of the dispersion behaviour of sub- stances in natural wind flows. They integrate different theoretical sub- models from fluid, gas, and particle dynamics. Since efficient modelling requires simplifications and additional assumptions, the simulation re- sults provided by these models must be compared with real-world data in order to prove the validity of the model. This is called validation. Odour perception at the input location is determined by the fluctuations of local immission concentration. Odour perception begins only when the threshold value is exceeded. Therefore, the determination of values in ex- cess of the threshold level requires that, in addition to the mean input value, its fluctuation be known. Due to the turbulence of natural wind flows, odorants are diluted to a varying degree during transmission. Mo- reover, changing wind directions lead to a shift in the main direction of propagation, which causes the odour plume to meander. The new NaSt3D model was examined as an example of the validation of odour dispersion models. For this reason, field measurements were taken in or- der to determine odour propagation. A mobile tracer measurement technique with simultaneous recording of the meteorological data, the measuring positions, and the tracer concentration allowed measurements with high temporal and spatial resolution to be carried out. Comparisons of model calculations and measurements showed a high degree of consi- stency and proved the applicability of the NaSt3D model for detailed odour dispersion simulation.

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