TY - JOUR A1 - Dechant, Eduard A1 - Fedulov, Feodor A1 - Chashin, Dmitri V. A1 - Fetisov, Leonid Y. A1 - Fetisov, Yuri K. A1 - Shamonin (Chamonine), Mikhail T1 - Low-frequency, broadband vibration energy harvester using coupled oscillators and frequency up-conversion by mechanical stoppers JF - Smart Materials and Structures N2 - The frequencies of ambient vibrations are often low (below 30 Hz). A broadband (3 dB bandwidth is larger than 10 Hz at an acceleration amplitude of 9.81 m s(-2)) vibration based energy harvester is proposed for transducing mechanical energy at such low frequencies into electrical energy. The mechanical setup converts low frequency mechanical vibrations into high frequency resonance oscillations of the transducer. This conversion is done by mechanical impacts on two mechanical stoppers. The originality of the presented design is that both low-frequency and high-frequency oscillators are permanently mechanically coupled. In the equivalent mechanical circuit, this coupling is achieved by connecting the ends of the stiff spring to both seismic masses, whereas one seismic mass (collison member) is also attached to the soft spring used as the constitutive element of a low-frequency oscillator. Further, both mechanical oscillators are not realized as conventional cantilever beams. In particular, the high frequency oscillator with the natural frequency of 340 Hz is a disc-shaped diaphragm with attached piezoelectric elements and a seismic mass. It is shown that it is possible to convert mechanical vibrations with acceleration amplitude of 9.81 m s(-2) in the region between approximately 7 and 25 Hz into electrical power larger than 0.1 mW with the maximum value of 0.8 mW. A simplified mathematical model based on piecewise linear coupled oscillators shows good agreement with experimental results. The ways to enhance the performance of the harvester and improve agreement with experiments are discussed. KW - broadband KW - efficiency KW - frequency up-conversion KW - low frequency KW - mechanical stoppers KW - Modeling KW - OUTPUT KW - Piezoelectric transducer KW - vibration energy harvesting Y1 - 2017 U6 - https://doi.org/10.1088/1361-665X/aa6e92 VL - 26 IS - 6 PB - IOP Publishing ER - TY - JOUR A1 - da Silva Mota, Fabio Antonio A1 - Hinckel, Jose Nivaldo A1 - Rocco, Evandro Marconi A1 - Schlingloff, Hanfried T1 - Modeling and Analysis of a LOX/Ethanol Liquid Rocket Engine JF - Journal of Aerospace Technology and Management N2 - This work studies the performance and dry mass of the under development LOX/Ethanol L75 liquid rocket engine. To this end, an object-oriented program written in C++ was developed. The program is intended to be versatile and easily extensible in order to analyze different configurations of liquid rocket engines. The UML (Unified Modeling Language) tool is used to model the architecture of the codes. UML diagrams help to visualize the code structure and the communication between objects, enabling a high degree of abstraction. The cryogenics Vulcain and HM7B engines power cycles along with the staged-combustion SSME engine perform the verification of the codes. Finally, the influence of changes in design parameters on the performance and dry mass of the L75 rocket engine is analyzed. KW - Ethanol KW - Liquid rocket engines KW - Modeling Y1 - 2018 U6 - https://doi.org/10.5028/jatm.v10.914 VL - 10 PB - Inst Aeronautica & Espaco-IAE ER - TY - JOUR A1 - Dawoud, Belal T1 - On the development of an innovative gas-fired heating appliance based on a zeolite-water adsorption heat pump; system description and seasonal gas utilization efficiency JF - Applied Thermal Engineering N2 - The main objective of this work is to introduce an innovative hybrid heating appliance incorporating a gas condensing boiler and a zeolite-water adsorption heat pump. The condensing boiler is applied to drive the zeolite-water heat pump for the heating base-load and to assist the heat pump in the so called “mixed operation” mode, in which both the heat pump and the condensing boiler are working in series to cover medium heating demands. Peak heating demands are covered by the condensing boiler in the so called “direct heating” mode. The three operation modes of the hybrid heating appliance have been technically described. In addition, the laboratory test conditions for estimating the seasonal heating performance according to the German Guideline VDI 4650-2 have been introduced. For both heating systems 35/28 °C and 55/45 °C, which represent the typical operating conditions of floor and high temperature radiating heating systems in Europe, seasonal heating gas utilization efficiencies of 1.34 and 1.26 have been measured, respectively with a ground heat source. In two field test installations in one-family houses in Germany, the introduced heating appliance showed 27% more seasonal gas utilization efficiency for heating and domestic hot water production, which is equivalent to a CO2-emission reduction of 20% compared to the gas condensing boiler technology. KW - Adsorption heat pump KW - Falling film evaporator KW - Gas utilization efficiency KW - Seasonal performance KW - Zeolite-water Y1 - 2014 U6 - https://doi.org/10.1016/j.applthermaleng.2014.09.008 VL - 72 IS - 2 SP - 323 EP - 330 PB - Elsevier ER - TY - JOUR A1 - Palomba, Valeria A1 - Dawoud, Belal A1 - Sapienza, Alessio A1 - Vasta, Salvatore A1 - Frazzica, Andrea T1 - On the impact of different management strategies on the performance of a two-bed activated carbon/ethanol refrigerator: An experimental study JF - Energy conversion and management N2 - In the present work, an experimental study on a lab-scale adsorption refrigerator, based on activated carbon/ethanol working pair is reported. An extensive testing campaign has been carried out at the CNR ITAE laboratory, with multiple aims. First, the performance has been evaluated in terms of both COP and Specific Cooling Power (SCP), under different boundary conditions, including both air conditioning and refrigeration applications. Attractive SCPs, up to 180 W/kg and 70 W/kg for air conditioning and refrigeration, respectively, were measured. Under the same conditions, COP between 0.17 and 0.08 were obtained. In addition, different management strategies, namely, heat recovery between adsorbers and re-allocation of phase durations, were evaluated to identify their influence on the system. Both strategies confirmed the possibility of increasing COP and SCP up to 40% and 25%, respectively. Moreover, a design analysis based on the experimental results has been carried out, to suggest possible improvements of the system. The obtained results demonstrated the possibility of employing a non-toxic refrigerant like ethanol reaching performance comparable with other harmful refrigerants like ammonia and methanol. (C) 2017 Elsevier Ltd. All rights reserved. KW - Activated carbon KW - Adsorption refrigeration KW - ADSORPTION REFRIGERATOR KW - CARBON KW - Corrosion KW - DRIVEN KW - DYNAMICS KW - Ethanol KW - ETHANOL ADSORPTION KW - experimental testing KW - HEAT-RECOVERY KW - IMPROVEMENT KW - Management strategy KW - MASS KW - waste heat Y1 - 2017 U6 - https://doi.org/10.1016/j.enconman.2017.03.055 VL - 142 SP - 322 EP - 333 PB - Elsevier ER - TY - JOUR A1 - Niemetz, Michael A1 - Hänninen, Risto A1 - Schoepe, Wilfried T1 - On the Transition from Potential Flow to Turbulence Around a Microsphere Oscillating in Superfluid 4He JF - Journal of low temperature physics N2 - The flow of superfluid around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity that scales as and is temperature independent below 1 K, the flow is laminar (potential flow). Below 0.5 K, the linear drag force is caused by ballistic phonon scattering that vanishes as until background damping, measured in the empty cell, becomes dominant for K. Increasing the velocity amplitude above leads to a transition from potential flow to turbulence, where the large turbulent drag force varies as . In a small velocity interval % above , the flow is unstable below 0.5 K, switching intermittently between both patterns. From time series recorded at constant temperature and driving force, the lifetimes of both phases are analyzed statistically. We observe metastable states of potential flow which, after a mean lifetime of 25 min, ultimately break down due to vorticity created by natural background radioactivity. The lifetimes of the turbulent phases have an exponential distribution, and the mean increases exponentially with . We investigate the frequency at which the vortex rings are shed from the sphere. Our results are compared with recent data of other authors on vortex shedding by moving a laser beam through a Bose-Einstein condensate. Finally, we show that our observed transition to turbulence belongs to the class of "supertransient chaos" where lifetimes of the turbulent states increase faster than exponentially. KW - Bose-Einstein condensates KW - Critical velocity KW - DYNAMICS KW - EINSTEIN CONDENSED GAS KW - HE-4 KW - HELIUM KW - LAMINAR KW - MK TEMPERATURES KW - ONSET KW - Oscillatory flow KW - Quantum turbulence KW - Superfluid helium KW - Vortex shedding Y1 - 2017 U6 - https://doi.org/10.1007/s10909-017-1745-7 VL - 187 IS - 3-4 SP - 195 EP - 220 PB - Springer Nature ER - TY - JOUR A1 - Braun, Peter A1 - Gebhard, Jürgen A1 - Matysik, Frank-Michael A1 - Rabl, Hans-Peter T1 - Potential Technical Approaches for Improving Low-Temperature NOx Conversion of Exhaust Aftertreatment Systems JF - Chemie Ingenieur Technik N2 - Lean-burn engines, such as diesel engines, are widely used in mobile and stationary applications. Operation of lean-burn engines leads to formation of distinct amounts of nitrogen oxides (NO and NO2). Efficient aftertreatment is mandatory to meet legal requirements, especially at low exhaust temperatures, as for the future a decline of the exhaust temperature level can be predicted due to improved engine efficiencies. Within this review, potential technical solutions to enhance the DeNO(x)-aftertreatment efficiency at low exhaust temperatures are presented. KW - DECOMPOSITION KW - Diesel Engine KW - Exhaust aftertreatment KW - IMPACT KW - Low-temperature DeNO(x) KW - NH3 KW - NITRIC-OXIDE KW - Nitrogen oxides KW - OXIDE CATALYST KW - PERFORMANCE KW - PYROLYSIS KW - SCR KW - Selective catalytic reduction KW - SELECTIVE CATALYTIC-REDUCTION KW - UREA HYDROLYSIS Y1 - 2018 U6 - https://doi.org/10.1002/cite.201700122 VL - 90 IS - 6 SP - 762 EP - 773 PB - WILEY-VCH ER - TY - JOUR A1 - Kaspar, Marcel A1 - Rabl, Hans-Peter A1 - Mayer, Wolfgang T1 - Ion-Molecule Reaction for the Selective Detection of Hydrocarbons in Diesel Exhaust Gas JF - Chemie Ingenieur Technik N2 - The hydrocarbons present in the diesel exhaust gas are analyzed. A mass spectrometer is used for the measurements, and it operates on the basis of an ion-molecule reaction. This method is especially suitable because it is selective, is as free of fragments as possible, and is highly sensitive to the species that need to be measured. The study shows that numerous hydrocarbons in diesel exhaust gas can be identified. In particular, three molecules, ethyne, ethene and propene, were analyzed online in-depth on an engine test bench under different engine operating conditions. KW - Diesel exhaust gas KW - Hydrocarbons KW - Ion-molecule reaction KW - Mass spectrometry Y1 - 2018 U6 - https://doi.org/10.1002/cite.201700075 VL - 90 IS - 6 SP - 826 EP - 834 PB - WILEY-VCH ER - TY - JOUR A1 - Barz, Tilman A1 - Seliger, Dominik A1 - Marx, Klemens A1 - Sommer, Andreas A1 - Walter, Sebastian F. A1 - Bock, Hans Georg A1 - Koerkel, Stefan T1 - State and state of charge estimation for a latent heat storage JF - Control Engineering Practice N2 - A nonlinear state observer is designed for a thermal energy storage with solid/liquid phase change material (PCM). Using a physical 2D dynamic model, the observer reconstructs transient spatial temperature fields inside the storage and estimates the stored energy and the state of charge. The observer has been successfully tested with a lab-scale latent heat storage with a single pass tube bundle and the phase change material located in a shell around each tube. It turns out that the observer robustly tracks the real process data with as few as four internal PCM temperature sensors. © 2017 Elsevier Ltd. All rights reserved. KW - Heat conduction in cylindrical shell KW - Kalman filter KW - Latent heat thermal energy storage (LHTES) KW - MODEL KW - Nonlinear state observer KW - OF-THE-ART KW - Orthogonal collocation KW - PCM KW - PERFORMANCE ENHANCEMENT TECHNIQUES KW - PHASE-CHANGE MATERIAL KW - POLYETHYLENE KW - Reduced model KW - simulation KW - Solidification KW - State of charge (SOC) KW - SYSTEMS KW - THERMAL-ENERGY STORAGE Y1 - 2018 U6 - https://doi.org/10.1016/j.conengprac.2017.11.006 VL - 72 SP - 151 EP - 166 PB - Pergamon-Elsevier d. ER - TY - JOUR A1 - Rösel, Birgit T1 - Just-in-Time Teaching für einen Grundkurs Regelungstechnik – Ergebnisse und Auswirkungen der Profistufe des Zertifikats Hochschullehre JF - Didaktiknachrichten Y1 - 2018 UR - https://diz-bayern.de/DiNa/06_2018 IS - 06 SP - 66 EP - 71 PB - Zentrum für Hochschuldidaktik (DiZ) ER - TY - CHAP A1 - Mühlbauer, Christian A1 - Rabl, Hans-Peter A1 - Rottengruber, Hermann T1 - Acoustic Optimization of Mechatronic Direct Injection Systems and Analysis of the Effects on Robustness in System Operation T2 - SAE International Journal of Advances and Current Practices in Mobility N2 - The tightening of the emission legislation and political and social demands for sustainable mobility are forcing the automotive industry to develop complex, high precision mechatronic drive systems. The increasing precision of mechatronic components generally leads to an increase in structural excitation and thus to a rise in noise. The so-called ticking of the fuel injection system has a rather low sound pressure level compared to the residual engine noise. Nevertheless, the impulsive and high frequency noise character leads to a decline concerning the perception of comfort and sound quality. In order to identify the sound quality of fuel injection systems as a frontloading measure, a system test bench has been developed which represents the structure-borne and airborne sound radiation of the stand-alone injection system in a close to series configuration. In this paper, measures for the acoustic optimization of injection systems and their effects on the robustness of the system are discussed. The focus is on engine idling, since at this operating point the ticking of the injectors and high-pressure pump can be perceived most clearly due to the low masking effects of other noise sources. For this purpose, the injection parameters were measured during full engine operation and transferred to the system test bench. By using a special development control unit, it was possible to modify the parameters, quantify their influence on the acoustic behavior and, based on this, define NVH optimized control strategies. For the robustness evaluation of the NVH optimized control strategies, key functions of the injection system were analyzed under varying boundary conditions in system operation on an injection rate test bench. Y1 - 2021 U6 - https://doi.org/10.4271/2021-01-0671 SN - 2641-9645 VL - 4 IS - 1 SP - 68 EP - 77 PB - SAE International, Warrendale, PA, United States ER -