Partitioning of MCHP‐TES system run time to incorporate transient system behaviour: a comprehensive exergy‐based analysis using simulation

By combining heat and power generation, mini‐combined and micro‐combined heat and power systems (MCHP) provide an efficient, decentralised means of power generation that can complement the composition of the electricity generation mix. Dynamic tools capable of handling transient system behaviour are required to assess MCHP efficiency beyond a mere static analysis based on steady‐state design parameters. Using a simulation of a cogeneration system, we combine exergetic definitions for different operational system states to quantify the overall system efficiency continuously over the whole period of operation. The concept of exergy allows direct comparison of different forms of energy. A sensitivity analysis was performed where we quantified the effect on MCHP overall performance under varying engine rotational speed, thermal energy storage size and fluid storage temperature in a range of MCHP simulations. We found that the exergetic quantity of natural gas used by the MCHP decreased slightly at higher engine speeds (?2% to ?4%). While the total amount of electricity generated is almost constant across the range of different engine output, more thermal exergy (up to +21%) can be recovered when the engine is operating at elevated speeds. Furthermore, selection of specific optimal thermal storage fluid temperatures can aid in improving system efficiency. Copyright © 2016 John Wiley & Sons, Ltd.     

Experimental quantification and modelling of reaction zones in a cyclic watergas shift reactor

The cyclic watergas shift reactor (CWGSR) is a cyclically operated fixed bed reactor for the production of hydrogen. It is based on the alternating reduction of an iron oxide fixed bed with synthesis gas and its subsequent oxidation with steam. We show experimental data of moving reaction zones in a tubular CWGSR. Based on this data and to help further design of these reactors, we propose a dynamic, one-dimensional model of the reactor. The formulated process model was fitted to experimental data by adjusting only two parameters describing the catalytic activity and the oxygen capacity of the fixed bed. Exemplary simulation results are shown.     

Nano-Design für Makroschichten

Nano design for macroscopic coatings – new application potentials by PVD coatings up to 100 μm thickness Non-homogeneous coatings still limit the application of thicker layers due to defect growth and irregular layer thickness distribution along the surface of complex shaped components. Therefore, the layer thickness is usually limited to about 10 μm. In order to limit the surface roughness by the growing layer, multilayer coating systems are deposited by highly ionized plasmas. This allows significantly smoother layers to be produced, which until now could only be produced by mechanical finishing. Furthermore, by combining selected material systems and targeted parameter selection, structures can be deposited during coating, especially on edges, which result in a reduction of the cutting edge radius. In future, edge geometries should therefore be able to be specifically adjusted through the coating process.     

Three-dimensional chemo-thermomechanically coupled simulation of curing adhesives including viscoplasticity and chemical shrinkage

Based on the one-dimensional material model developed by Liebl et al. (Arch Appl Mech, 2011) a three-dimensional viscoelastic-viscoplastic material model for small deformations of curing adhesives on the basis of continuum mechanics is proposed in this contribution. The model describes the most relevant phenomena which occur during curing processes in the automotive industry and includes the effects of temperature and degree of cure on the mechanical properties of the material. Thermal expansion as well as chemical shrinkage are also contained. The yield stress for the viscoplastic part of the model goes back to the work of Schlimmer and Mahnken (Int J Numer Meth Eng 63:1461–1477, 2005), but is formulated in reference to the degree of cure and the temperature. Therefore this model considers chemo-thermomechanical coupling and extends the plasticity approach of Schlimmer and Mahnken, which is devised for cured adhesives, to the whole curing range, from the uncured to the fully cured adhesive. A peculiar focus is hereby laid on epoxy resins used in the automotive industry as structural adhesives.     

Investigation of long-term engine oil performance using lab-based artificial ageing illustrated by the impact of ethanol as fuel component

The effect of ethanol and its combustion products on the lubrication system is not very well understood. In this paper, a novel lab-based artificial ageing method for the evaluation of engine oils for bio-fuelled automotives and the results thereof are presented. Artificial ageing of three fully formulated engine oils with addition of ethanol, acetaldehyde, and acetic acid was carried out. The oil formulations chosen represent a consequent series of optimisation steps based on the engine oil performance in terms of preservation of typical oil parameters, e.g. base reserve and oxidation, observed during the artificial ageing procedure. It was shown that ethanol as well as acetaldehyde has almost no effect on the oil degradation especially in the case that advanced additive technology was used. On the contrary, acetic acid significantly affected the formulated oil showing influence on the detergent chemistry and even caused sludge formation. The use of the novel artificial ageing method proved to clearly differentiate the impact of the respective compounds added with the possibility to simulate enhanced stress conditions without the need of time-consuming and expensive engine bench tests. Hence, the novel setup offers valuable input for the formulation and the pre-selection of future engine oils suitable for bio-fuel.     

Molecular Dynamics Simulation of the Crystallizable Fragment of IgG1—Insights for the Design of Fcabs

An interesting format in the development of therapeutic monoclonal antibodies uses the crystallizable fragment of IgG1 as starting scaffold. Engineering of its structural loops allows generation of an antigen binding site. However, this might impair the molecule’s conformational stability, which can be overcome by introducing stabilizing point mutations in the CH3 domains. These point mutations often affect the stability and unfolding behavior of both the CH2 and CH3 domains. In order to understand this cross-talk, molecular dynamics simulations of the domains of the Fc fragment of human IgG1 are reported. The structure of human IgG1-Fc obtained from X-ray crystallography is used as a starting point for simulations of the wild-type protein at two different pH values. The stabilizing effect of a single point mutation in the CH3 domain as well as the impact of the hinge region and the glycan tree structure connected to the CH2 domains is investigated. Regions of high local flexibility were identified as potential sites for engineering antigen binding sites. Obtained data are discussed with respect to the available X-ray structure of IgG1-Fc, directed evolution approaches that screen for stability and use of the scaffold IgG1-Fc in the design of antigen binding Fc proteins.     

Advancement of an Interferometric Flow Velocity Measurement Technique by Adaptive Optics

Flow measurements often take place under difficult conditions. Optical flow measurement techniques are affected by variations of the refractive index, caused e.g., by temperature, concentration, or pressure gradients. This will give rise to an increased measurement uncertainty or cause the measurement to fail. To overcome these limitations, we propose the employment of adaptive optics. In this contribution we present interferometric flow velocity measurements through a fluctuating air-water interface by the use of adaptive optics. Using the adaptive optics, the rate of valid measurement signals can be improved from 28% to 83%. The results are promising to enable measurements in difficult environments affected by refractive index variations which were not accessible so far.