Currently, numerous methods are introduced to reduce the loss of mechanical energy of the engine using various materials for anti-wear coatings. The paper presents the results of measurements of the ...motor torque for 18 multilayer AlN/CrN (20–30N2) and CrN/AlN (20–30N2) coatings. The coatings were applied in an Ar/N2 plasma environment with a variable N2 flow rate by reactive magnetron sputtering. The results were compiled for two oil temperatures, 80 and 100 °C, in the engine speed range from 800 to 4000 rpm. The test results show that highly hydrophilic coatings reduce the loss of mechanical energy of the engine in the lower engine speed range and in the oil environment with a high 4% soot content. Highly hydrophobic coatings enable the reduction of torque and resistance to movement of the engine for higher speed ranges, above 2000 rpm. This work is the first work that indicates the need to take into account hydrophilic and hydrophobic properties coatings in determining engine energy losses. The influence of these properties is much greater than the surface texture of the coatings, hardness, Young's modulus and other parameters of the coatings. It is a new look at the issue of reducing friction losses in the engine.
•Hydrophilic coatings help to reduce the drag torque of the motor.•The soot content causes greater friction losses.•Oil viscosity determine the positive hydrophilic and hydrophobic properties.•The number of coating layers is important for the wettability properties.•Wettability has a greater influence on wear than hardness and Young's modulus.
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•A new 2 S opposed pistons engine architecture has been designed and assembled.•The engine is conceived for automotive range extender of plug-in hybrid vehicles.•Main engine ...attributes: simplicity, low-vibration and mechanical losses reduction.•After the Experimental campaign a 1-D model was developed for forward studies.•Port injection, direct injection and lean combustion strategies are assessed.
As pollutants and fuel consumption requirements become more constraining, new internal combustion engines generation arise to fulfill future automobile market regulations. In these context spark ignition (SI) engines working under hybridized structures are expected to represent one of the most viable and feasible technical approaches. In parallel to the already implemented 4-stroke turbocharged engines, new engine concepts are being conceived from their birth to meet nowadays standards. This work shows a new engine concept assessed to fit series hybrid configurations from the earliest design stages, and to fulfil requirements of the named “zero-emissions” urban areas. In this research work, a new opposed piston 2-stroke engine architecture based on rod-less innovative kinematics is described. The potential of this engine is based on its compactness, absence of vibrations and simplicity, going in hand with very competitive figures in terms of power density and fuel consumption. The engine unit has been designed, assembled, and tested to analyze several performance aspects, such as gas exchange and combustion. Taking advantage of the experimental campaign, a one-dimensional (1D) gas-dynamics engine model was developed and validated. Finally, the engine model was used for analyzing several potential upgrades and results have been discussed in detail. The target has always been to improve fuel consumption figures, below the best standards in market available internal combustion engines, while keeping engine concept simplicity and building costs.
•A simplified heat transfer model of turbochargers is developed.•Semi-empirical correlations are proposed.•Validation is performed on two different engines.•Engine simulation accuracy is improved ...particularly for temperatures.
Available turbocharger characterization maps are usually obtained on a gas stand where the turbine intake temperature is high, resulting in heat transfer affecting both the compressor and turbine. A correction is then mandatory to take into account heat transfer and calculate the real amount of work produced or consumed.
An experimental campaign is conducted to characterize heat transfer and friction losses on two different turbochargers. Then, semi-empirical correlations are developed minimizing the sum of square errors of a multiple regression to modelize these two phenomena. Compared to existing methodologies, these correlations minimize the requested input data: only the supplier maps are required whereas no additional test or calibration is needed.
The methodology to transform efficiencies and model heat transfer is presented. A gain of 10 % is observed on the confidence interval +/−3 °C on the compressor outlet temperature calculation (passing from 42.2 to 53 %), beside the turbine outlet temperature +/−10 °C interval is improved by around 20 %. These improvements are observed on two engine 1D models using two different turbochargers. The second engine's turbocharger is not involved in the establishment of the correlations and then demonstrates the good predictability of the proposed methodology.
•A field-scale problem of pumping energy consumption minimization was solved.•Coupling of a groundwater flow model with an optimization algorithm was performed.•The optimization algorithm is based on ...an analytical solution.•The optimal pumping strategy under various problem setups was examined.•The importance of including friction losses in such problems was highlighted.
Global population growth and rapid economic development, along with modern goals for creating sustainable communities, render it necessary to focus on fundamental, finite resources such as water and energy. The interdependencies between water and energy are well known, while recently the interest of the scientific and policy communities on their dependency relationship has grown noticeably. On the one hand, water is used throughout the energy industry, while, on the other hand, the water system needs energy for collecting, pumping, supplying and treating water. Considering the latter case, great importance should be given when specifically referring to groundwater resources for the abstraction of which a large amount of energy is generally required. Therefore, minimizing the energy consumed for pumping groundwater is extremely important, and, for this reason, a large number of studies have been conducted in order to address this certain issue. However, most of the studies dealing with pumping cost minimization problems ignore the effect of friction losses on the total energy consumed for pumping and transporting groundwater. Under this perspective, the present paper attempts to highlight the importance of including friction losses in such type of problems by combining a simulation model and an optimization algorithm. Through the formulation of different setups of the same problem, that is the energy cost minimization for pumping groundwater from a system of wells and transporting it through transmission lines, it was found that only when including friction losses in the optimization problem, all managed wells are being used for pumping water, thus resulting in more reasonable and workable solutions.
The performance of microchannel with sidewall dimples and fillet profile in the bottom surface is investigated. Two dimple sizes of (0.5 mm and 1 mm) are systematically clustered along the channels ...with and without fillet are considered. The laminar flow regime is assumed with Reynolds numbers ranging from 200 to 1200. The results show that the dimples and fillet profile have a significant effect on the thermal performance of microchannel. The Nusselt number of the microchannels with 1 mm dimples is 20% higher than the plain microchannel. However, an increase in pressure drop of 10% was obtained. In addition, the fillet profile impacts the thermal performance of microchannels without pressure drop penalty increase. Combining both dimples and fillet profile causes a significant enhancement in the thermal performance. Nusselt number of microchannels heat sink with 1 mm dimple size and fillet profile is 60% higher compared to the plain microchannel.
Religion as a discontinued model – that is how the narrative of modernity likes to see it. Empirically, the situation is more complex: even if secularisation often makes religious institutions appear ...as losers, important areas of religion have proven to be innovative and productive. How, then, do gain and loss explain themselves in this frictional relationship? This is what the contributions to this volume explore using examples from different regions of global modernity. They are grouped around questions on which religions have worked particularly hard: the ethos of freedom in modernity, the challenges posed by modern sciences, the relationship to authority, new perspectives on one's own tradition and participation in 'modern' discourse. With contributions by Reiner Anselm | Martin Baumann | Reinhold Bernhardt | Anne Beutter | Amir Dziri | Silke Gülker | Michael Hochgeschwender | Frank Neubert | Almut-Barbara Renger | Valérie Rhein | Markus Ries | Erdal Toprakyaran | Andreas Tunger-Zanetti | Margit Wasmaier-Sailer
This paper presents a model for analysis of the chaotic turbulence in a touchdown bearing due to surface waviness. A multibody model of a bearing with surface waviness is presented. The model ...estimates the work done by the friction forces between the bearing components. Different waviness orders in the bearing inner and outer ring are examined by analyzing the friction losses in the touchdown bearing. The obtained results are compared with results reported in the literature. The proposed model supports selection of appropriate surface manufacturing accuracy for touchdown bearings to mitigate undesirable effects from surface waviness in a potential contact event.
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•A detailed multibody model of a touchdown bearing with surface waviness is presented.•The model is used for detailed estimation of the work done by the friction forces.•Different waviness is examined in the bearing inner and outer ring, and in the rotor.•The obtained results are compared with results reported in the literature.•The model supports selection of manufacturing accuracy to decrease heat generation.
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