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Kühlen mit Wärme
(2009)
Die Hochschule Offenburg begleitet seit Juli 2006 in Zusammenarbeit mit dem Fraunhofer ISE in Freiburg, die solar unterstützte Klimatisierung der Festo AG & Co. KG in Esslingen im Rahmen des Forschungsvorhabens Solarthermie2000plus. Dabei wurde die bereits bestehende Adsorptionskälteanlage, die bisher mit Gaskesseln und Kompressorenabwärme betrieben wurde, durch eine Solaranlage als dritte Wärmequelle ergänzt.
Flows in nature and technology are often associated with specific structures and pattern. This paper deals with the development and behaviour of such flow pattern. Flow structures are important for the mass, momentum and energy transport. The behaviour of different flow pattern is used by engineers to obtain an efficient mass and energy consumption. Mechanical power is transmitted via the momentum of rotating machine parts. Therefore the physical and mathematical knowledge of these basic concepts is important. Theoretical and experimental investigations of principle experiments are described in the following. We start with the classical problem of the flow between two concentric cylinders where the inner cylinder rotates. Periodic instabilities occur which are called Taylor vortices. The analogy between the cylindrical gap flow, the heat transfer in a horizontal fluid layer exposed to the gravity field and the boundary layer flow along concave boundaries concerning their stability behaviour is addressed. The vortex breakdown phenomenon in a cylinder with rotating cover is also described. A generalization to spherical sectors leads then to investigations with different boundary conditions. The spherical gap flow exhibits interesting phenomena concerning the nonlinear character of the Navier-Stokes equations. Multiple solutions in the nonlinear regime give rise to different routes during the laminar-turbulent transition. The interaction of two rotating spheres results in flow structures with separation and stagnation lines. Experimental results are confirmed by numerical simulations.
Geothermal Energy in Germany
(2009)
After approximately 200 years, a comprehensive access to the texts of Humboldt's extraordinary exploration of the Americans is within sight. To open the legacy to the public for free access the Humboldt Digital Library (HDL) Project has been developing a dynamic amount of data related to studies of Alexander von Humboldt. The Library includes a range of texts, tables and images, as well as many tools that assist mining the data and navigating the system.
The HDL aims to provide an environment in which researchers can work more effectively with a wider variety of primary source materialsùtextual as well as visual. Moreover, the greatest advantage of this dynamic system is its capability to connect data from diverse locations in Humboldt's twenty-nine volumes and allow comparison with modern scientific knowledge and developments.
HDL can recreate the context of a particular text, making it possible to view images, geo-referenced and interactive maps, information about plants and animals, as well as scientific data relevant to Humboldt's observations. By introducing Web 2.0 technology implementations, we are providing new visualizations of the information published in this Digital Library. The perception of the Information Architecture is changing in the era of Web 2.0. By providing more search facilities, creating an academic network around our library and implementing new ways of multi-dimensional navigation we argue that Information Architecture can be extended to new methods of information representation. Facilitating the user navigation to the required information will always be an aim for the managers of high volume data systems. This can be achieved by implementing Information Retrieval modules based on user profiling and by improving the visualization features.
Plant oils may be used as a sustainable, nearly CO2neutral fuel for diesel engines. This work investigates experimentally the particulate and gaseous emissions of diesel engines fuelled with different non-esterified, pure plant oils. The data are collected from three engines: a) Common rail 1.7 liter passenger car engine from Opel AG b) 12.8 liter truck engine from VOLVO c) Truck engine from MAN AG.
The emissions of the MAN engine have been used to perform AMES tests to analyze possible health impacts of plant oil operation. Finally, all emission results with plant oils have been compared to traditional gas oils.
Non-Esterified Plant Oils as Fuel -Engine Characteristics, Emissions and Mutagenic effects of PM-
(2009)
Plant oils may be used as a sustainable, nearly CO2 neutral fuel for diesel engines. This work investigates experimentally the particulate and gaseous emissions of diesel engines fuelled with non-esterified, pure plant oils with the quality standard of DIN V 51605 (Weihen-stephan RK-Qualitätsstandard 05/2000). The data are collected from three engines:
Common rail passenger car engine from OPEL AG
Truck engine from VOLVO
Truck engine from MAN AG
All engines have been correctly adjusted to plant oil operation.
The OPEL and VOLVO engines served for the basic investigations. The emissions of the MAN engine have been used to perform AMES tests to analyze possible health impacts of plant oil operation.
The experimental data show a reduction of particulate matter compared to traditional gasoil which may yield up to 50 % for. The particulate matter shows same primary particle sizes but the agglomerates as collected on TEM grids are different - the plant oil soot particles tend to form larger aggregates [4]. The gaseous emissions of CO and hydrocarbons HC are generally lower compared to the operation with gasoil. However, the NOX emissions are slightly higher. This may be contributed to the measured higher combustion chamber pressures and temperatures when fuelled by plant oils.
Emission samples have been extracted from ESC cycles of 13 step tests to perform the AMES test which give indication on carcinogen substances. The AMES test results gave no indication of mutagenic effects exceeding the detection limits. No significant differences could be found comparing the emissions of plant oil and gasoil operation. Thus, it can be stated that the emission from plant oil operation does not have a health impact different to traditional gas oil. This is in contrast to some other publications — a deeper insight shows that these investigations did not properly modify the engine for plant oils. It is mandatory to make the engine modification to pre-warm the plant oils to approx. 90°C prior to injection. The engine's warm-up phase needs special care to avoid any coking at the injection system and combustion chamber surfaces. The publications where a higher health risk was claimed to be found in the exhaust of plant oil fuels, did not pre-warm the plant oils — cold plant oils have been injected in the combustion chamber instead. This results in incomplete atomization and incomplete combustion with a lot of hazardous emission species (see also [4,11]. Such an operation will damage the engine after relatively short times and is, therefore, not realistic.
The investigated fuels had some influence on the engine characteristics. Higher temperatures and pressures in the cylinder have been detected for some plant oils compared to gasoil. This increase is explained by the higher oxygen content within the plant oils.
Im Fahrzeug stehen große Wärmeströme zur Verfügung, die nicht genutzt werden. Die Energie des Abgases weist gegenüber der des Motor/Kühlsystems eine wesentlich höhere Arbeitsfähigkeit auf. Untersuchungen zielen dahin, diese thermische Energie zum Beispiel mithilfe eines thermoelektrischen Generators wieder in das System einzukoppeln und als Energiequelle für Verbraucher zu nutzen.
We report improved separation of the highly toxic contact herbicides paraquat, diquat, difenzoquat, mepiquat, and chloromequat by HPTLC. Quantification was based on a new derivatization reaction using sodium tetraphenylborate. Measurements were in the wavelength range from 440 to 480 nm or from 440 to 590 nm. An LED emitting very intense light at 365 nm was used for excitation. The quantification limits of paraquat and diquat in water, using improved solid-phase extraction, was in the low ng L −1 range. The linear range covered more than two orders of magnitude. Recovery was investigated for all the compounds, and was insufficient, ranging from 11 to 92%, but the method is inexpensive, rapid, and works reliably.
A diode array HPTLC method for dequalinium chloride in pharmaceutical preparations is presented. For separation a Nano TLC silica gel plate (Merck) is used with the mobile phase methanol-7.8% aqueous NH(4)(+)CH(3)COO(-) (17:3, v/v) over a distance of 6 cm. Dequalinium chloride shows an R(F) value of 0.58. Pure dequalinium chloride is measured in the wavelength range from 200 to 500 nm and shows several by-products, contour plot visualized in absorption, fluorescence and using the Kubelka-Munk transformation. Scanning of a single track in absorption and fluorescence measuring 600 spectra in the range from 200 to 1100 nm takes 30s. As a sample pre-treatment of an ointment it is simply dissolved in methanol and can be quantified in absorption from 315 to 340 nm. The same separation can also be quantified using fluorescence spectrometry in the range from 355 to 370 nm. A new staining method for dequalinium chloride, using sodium tetraphenyl borate/HCl in water allows a fluorescence quantification in the range from 445 to 485 nm. The linearity range of absorption and fluorescence measurements is from 10 to 2000 ng. Sugar-containing preparations like liquids or lozenges with a reduced sample pre-treatment can be reliably quantified only in fluorescence. The total for the quantification of an ointment sample (measuring four standards and five samples), including all sample pre-treatment steps takes less than 45 min!
Hydrogen chloride and sulphur dioxide are gaseous by-products of chloridization processes that employ thionyl chloride. Absorption would be a feasible method to clean the rich gas stream. Two serial connectable absorption columns were equipped with the latest generation of packings to effect product recovery. Therefore, several tests concerning the baffle properties had to be performed. In the first experimental section, the hydraulic parameters pressure drop and hold-up were investigated. The hold up value range of the new baffles Raschig Super Ring (RSR) and Raschig Super Pak (RSP) was clearly below that of the former installed packing, Raschig Ring (RR). However, due to the low maximal flow rate, the range of stagnation and flooding could not be measured. The maximal measured pressure drop value was, for RR, only 0.3 mbar/m, which is very low compared to the measurement error. Batch experiments, where the waste gases were produced by reaction of thionyl chloride in water, showed that for the steady state determination of the separation steps it is advisable to use just one column in simplex mode with a defined gas supply by a gas cylinder. The HTU determination for RSR and a HCl/H2O system delivered a value of HTUHCl,OG = 0.14 ± 0.01 m with a variation coefficient of 24.2%.