Agricultural Engineering Research, Volume 9 (2003)

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Assessment of the Cost-Reduction Potential of Different Technology Improvements for a Competitive Biogas Production
(2003) Grundmann, Philipp
A substantial reduction of biogas production costs is necessary to reach cost-competitiveness of electricity produced from biogas using energy crops. Cost reduction opportunities are identified for several technologi- cal parameters within a sensitivity analysis. The analysed parameters are then evaluated based on theoretically achievable cost reductions. Results show that even under favourable operational, economic and political conditions, the achievement of competitive cost targets for electricity production from biogas using energy crops depends on the development of highly cost efficient methods and concepts, that substantially reduce production costs and increase market shares.
Biogas from Energy Crops - Results from Long-Term Lab Scale Experiments
(2003) Linke, Bernd
Biogas production from crushed rye grain and fodder sugar beets was studied in long-term lab scale experiments. For both energy crops and co- fermentation with animal waste slurry anaerobic digestion did not fail. The VS-biogas yield from mixtures of energy crops and slurry was proportional to the VS-portion of the single substrates. Application of a SBR (sequencing batch reactor) the for anaerobic digestion of fodder sugar beets at 55°C resulted in VS methane yield and methane produc- tion rate of 1.1 m3kg-1 and 3 m3m-3d-1, respectively.
The Feed Level Controlled Mash Feeder vs. the Conventional Tube Feeder in Piglet Rearing
(2003) Hessel, Engel F.; Cordes, Katrin; Van den Weghe, Herman
In the present study, the influence of a feed level controlled mash feeder on the rearing performance and the eating behaviour of piglets was ex- amined in comparison with a conventional tube feeder. For this purpose, a compartment featuring two pens for 25 piglets each was available. In one group, the feed level controlled mash feeder was used for the first 14 days. As of the 15th day, the animals were fed with the aid of a tube feeder. In the second group, the tube feeder was employed immediately after weaning. Piglets which were fed using the feed level controlled mash feeder showed a significantly higher weight increase during the first 14 days. This advantage was able to be statistically proven even after a five-week rearing period, especially in piglets which weighed less than 5.0 kg when stalled up. In the first two weeks, an additional weight gain of 660 g was achieved, while additional feed consumption was 815 g. In addition, more unrest in the feeding place area was observed in this trial group. Significantly more piglets tried to reach the trough, but were not able to eat because all feeding places were occupied.
Calculation of Characteristic Curves of Helical Toothed Rotary Lobe Pumps Considering Wear
(2003) Brückner, René; Verhülsdonk, Burkhard; Türk, Meno; Zenke, Thomas
A Dual Sensor for Simultaneous Investigation of Soil Cone Index and Moisture Content
(2003) Sun, Yurui; Schulze Lammers, Peter; Damerow, Lutz
A dual sensor combining dielectric and mechanic principles was developed. The geometric structure of this sensor has been designed according to the ASAE- standard for penetrometer cones, and the sensor can provide a pair of output signals when inserted into soil. By analyzing both signals, one can determine the correlation among cone index, soil bulk density, and moisture content. Some preliminary experiments were performed in a laboratory environment, and the sensor will be ready for use in the field in the near future.
Influence of Abrasive Wear on Pump Behaviour of Rotary Lobe Pumps
(2003) Türk, Meno; Zenke, Thomas; Verhülsdonk, Burkhard; Brückner, René
Double shaft rotary lobe pumps are often used for conveying slurries in liquid manure, biogas and sewage plants. Increasing abrasive wear enlarges the gaps and decreases the backflow leakage accordingly. The effects on the pump characteristic of helical toothed rotary lobe pumps were systematically analyzed and the influence factors were valuated. The research is carried out on the test stand for pumps at ATB (Fig. 1). The most important influence factors are the dimensions of head gaps and front gaps (Fig. 2, 3) as well as the viscosity of fluid. The effect of viscosity on the gap flow rate is considerably important (Fig. 4). The gap leakage rate is reduced due to increasing liquid viscosity. The effective flow rate as well as the total efficiency (Fig. 5) increases with increasing viscosity. This effect makes clear that enlarged gap dimension should be taken into consideration when pumping high viscous fluids. The effect of the pump speed on the leakage rate is negligible. Gap flow rates meas- ured on a blocked pump therefore can be taken as the leakage rates of a running pump. The effect of lobe shape (straight or helically toothed) on the leakage rate is nearly insignificant. Helically toothed lobes with high number of wings have better pump behavior then lobes with less number of wings. At high pump pressure double-side bearing rotary lobe pumps should preferably applied instead of pumps with cantilevered shafts (Fig. 6). Double-side bearing pumps have less abrasion at the lobe’s wing tips and better suction behaviour (Fig. 7). The pressure-flow characteristic curve p = f (n p ) plotted at closed discharge pipe (Fig. 8) or the direct measurement of leakage flow QS = f (p) is able to describe the pump’s wear status. Based on these tests the real pump characteristic curve can be calculated (Fig. 9).
The Hohenheim Biogas Yield Test : Comparison of Different Laboratory Techniques for the Digestion of Biomass
(2003) Helffrich, Dominik; Oechsner, Hans
For the planning of agricultural biogas plants, the achievable biogas yields of the substrates used must be known. In general the biogas yield potential is determined in discontinuous laboratory reactors with a vol- ume of more than three litres. The Hohenheim biogas yield test is a novel technique for the determina- tion of the methane yield of organic substance, which can be carried out with the aid of commercial laboratory equipment. The small dimension of the experimental facility allows to carry out a large number of repetitions or parallel tests with a reduced need of working hours and a minimised space requirement. Extensive exemplary studies based on cattle slurry, grass silage, and kitchen waste as substrates proved that the results achieved with a simple experimental set-up were at least as good as those obtained using the systems employed otherwise.
Litterless Housing Systems in the Farrowing Area II
(2003) Kamphues, Barbara; Snell, Hinrich; Hessel, Engel F.; Van den Weghe, Herman; Lücke, Wolfgang
Three housing systems (conventional farrowing crate, opening crate, ac- tivity pen) for nursing sows were compared in the present study. In addition, the importance of straw supply, to allow the sows to exhibit nest building behaviour was investigated. The present second contribution deals with selected pathological and ethological criteria as well as biological performance. The improved freedom of motion for the sows resulted in a smaller percentage of soiled animals. The number of lying downs with the sow lying its rear quarter down opposite the grouped piglets was considerably higher in the activity pens. Piglet mortality from crushing occurred more often in activity pens than in conventional farrowing crates or opening crates.
Litterless Housing Systems in the Farrowing Area I : Project Overview and Housing Environment
(2003) Snell, Hinrich; Kamphues, Barbara; Hessel, Engel F.; Van den Weghe, Herman; Lücke, Wolfgang
In the project presented here, three housing variants (conventional crate stall, opening crate stall, activity pen) for nursing sows featuring identi- cal environmental conditions were compared over a period of several years. In addition, the objective was to study the effects of a temporally and quantitatively limited straw supply. This first contribution provides an overview of the project. In addition, the results of stall climate meas- urements and the evaluation of pen soiling will be presented. The improved freedom of motion for the mother animals did not result in measurable effects on the stall climate. Small quantities of straw did not lead to any increase in the concentration of suspended dust in the stall air. In quantitative terms, the soiling of otherwise clean pen areas in the activity pens due to the increased mobility of the sows was insignificant.
Practice-Oriented Leaf Temperature Measurements in Heated Greenhouses
(2003) Rath, Thomas; Masemann, Sabine
The use of different techniques of leaf temperature measurement in greenhouses was studied in a practice-oriented trial with ornamental plants. Measurements with contact thermocouples, injection sensors, in- frared sensors, and thermographical methods were carried out and com- pared in a conventional greenhouse with convection heating pipes and in a greenhouse with a special radiation heating system. It was shown that leaf temperature distribution within the greenhouse is very important, especially if radiation heating systems are used. Furthermore, it was demonstrated that injection temperature sensors can be employed for greenhouse climate control. The use of infrared sensors proved difficult, though possible in principle. In contrast to this, temperature measure- ment through image-based thermography did not provide satisfactory results.
Perennial Experiences with Site-Specific Fertilization and Harvest
(2003) Isensee, Edmund; Thiessen, Eiko; Treue, Peter
The “site-specific farming” adjusts the technical operations of the small scale altering growing conditions. First of all the main ideas and the re- alisations to identify the sites are given. The practical realization of the specific production techniques requires specialised functions of the fertil- izer distributor and the harvesting machine, especially the accurateness and control of the yield measurement. The essence of this production sys- tem is to determine the amount of N application precisely for each site at a certain date. There are several models and methods: the consultant or the reflection System. As a result increasing yield or saving of fertilizer has to be expected. An overview about yield and fertilization does not give a clear picture. The values of all variants are compared with the customary values. The economic viability is based on several effects, which are compared to the expenses.
Load Distribution Plans for Forwarders
(2003) Weise, Günther
The load distribution diagrams known from commercial goods traffic were used to assess the loading capacity of a forwarder. In order to be able to integrate the centre of gravity of the timber load into the diagram, it was assumed that the cross section of the stanchion basket was fully loaded. Based on this assumption, a linear load model was developed. For the loading calculation to be combined with the calculation of axle carrying capacity in a diagram, the coordinates of the permissible axle loads shown needed to be transformed so that the timber assortment length, which is more clearly understandable for the user, is employed in the diagram. This adapted load distribution diagram allows possible load, capacity, possible assortments, and load overhang to be determined. In addition to the possible load, this method provides the user with other significant information, such as axle load distribution, load weight, and gross vehicle weight. This technique is employed in KWF tests and the development of forestry machines.
Play and Exploration Behaviour of Fattening Pigs : Influence of different housing systems
(2003) Bea, Wolfgang; Hartung, Eberhard; Jungbluth, Thomas; Troxler, Josef
The goal of this study was the comparison of two housing systems for fat- tening pigs under the aspect of animal welfare. The study was carried out on a scale similar to practice. The experimental stable was composed of two entirely independent compartments. The first compartment was de- signed as a conventional housing system, while the second compartment was conceived as an alternative housing system. For the comparative evaluation of the degree of animal welfare in the two systems, data re- garding animal behaviour (play and exploration behaviour during four fattening periods), alterations in the integument of the animals, animal health, and the performance parameters of the pigs were collected during five fattening periods. Data concerning air quality (temperature, humid- ity, concentration of greenhouse gases) inside the stable were supplied by a parallel project. In this article, results from data regarding animal be- haviour (in particular play and exploration behaviour) will be described.

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