Microreactors offer several advantages compared to the industrial scale when developing new chemical processes. Especially the production and investment costs are low if polymer microreactors are generated by ultrasonic processes. In order to observe the chemical reaction and the flow configuration, these microreactors need to be optically transparent, mechanically stable, and chemically inert to several reagents. The manufacturing process of a transparent polymer plate reactor with a chemically inert surface coating by ultrasonic fabrication is described. Experimental characterization of the microreactors showed that they are leak tight up to a pressure difference of at least 300 kPa and the mixing times are in the range of milliseconds. 相似文献
A techno‐economic analysis for four different types of biogas plant realizations was performed, including one biogas biorefinery concept. For each concept detail, a process flow diagram was created. Mass and energy balances were estimated. The net present value and payback were calculated for each concept for a better feasibility understanding. The results showed that with the used expensive substrate, namely, wheat straw, the obtained paybacks appeared to be more than 100 years. Sensitivity analysis was done for the price range of a substrate. Critical factors were defined to improve feasibility. 相似文献
Rhodium acetate effectively promotes the carboxylate‐directed ortho‐arylation of (hetero)aromatic carboxylates with aryl bromides. The main advantage of this phosphine‐free, redox‐neutral method arises from its efficiency in assembling biologically meaningful electron‐rich arylpyridines, which are problematic substrates in known C−H arylations using Pd, Ru, and Ir catalysts.
In the processing industry, frequent faults call for assistance in diagnosis, and case‐based reasoning (CBR) can provide solutions applied by other operators in the past. This study investigated whether salient case ratings promote an uncritical acceptance of solutions. In 2 experiments, subjects diagnosed faults with a simulated CBR system, and ratings were presented in graphical or verbal format. In most trials, the case with the highest rating provided the correct solution, while in catch‐trials, it did not. Graphical ratings were hypothesized to speed up solutions but discourage cross‐checking and lead to errors in catch‐trials. These hypotheses were not confirmed, even though Experiment 2 maximized the incentive of relying on case ratings. While graphical ratings led subjects to start with the most highly rated case, they did not impair situation analysis and accuracy. The results suggest that during fault diagnosis people are not easily misled into overtrusting a CBR system. 相似文献
As the PV market shows enormous potential with huge growth rates especially in climatic‐sensible regions, specific artificial ageing test procedures are a key point for an efficient and fast product development of new PV modules/materials optimized for the use in specific climatic regions. Based on the definition of four climate profiles (dry and hot—arid, moderate, humid, and hot—tropical and high irradiation—alpine), a program was worked out with 14 climate specific test conditions for accelerated ageing tests. The big challenge in this respect was the adaption/advancement of existing standard procedures for PV modules/components testing in a way that reliable testing for certain climatic conditions optimized PV modules is possible. The time‐dependent repeated application of combined climatic and environmental stresses (temperature, temperature cycles, humidity, irradiation, mechanical load, salt mist) was used to induce performance losses, material degradation, and failures in test modules which resemble those effects occurring in real‐life PV installations under comparable climatic and environmental conditions. For this demanding task, a large number of identical test modules with respect to composition and module design was manufactured. A detailed nondestructive analysis/characterization of all modules was performed: (1) before; (2) during (six intermediate stages); and (3) after the accelerated ageing test. The nondestructive characterization methods used to follow the module's ageing processes throughout the whole accelerated ageing procedure were current‐voltage characteristics measurements and electroluminiscence images for the electrical performance evaluation and ultraviolet fluorescence (spectroscopic and imaging) measurements, Fourier transform infrared spectroscopy as well as colour measurements of the backsheets outer layer for recording of chemical changes of the encapsulant and backsheet. The electrical and material characterization data were incorporated in an optimized database. As stated above, a set of three identical modules was exposed together in the respective climate specific ageing tests and subsequently characterized in order to increase statistical reliability of the measuring results. The analysis of the data and first approaches of advanced data treatment have already clearly shown that the electrical and material degradation of the test modules is dependent on (1) the type and combination, (2) duration, and (3) mode (sequential versus constant) of the stresses applied. On the one hand, the simulation of environmental stresses like heavy snow and wind load and enhanced frequency of temperature cycling resulting in cell cracks and cell connector breakage could be demonstrated. Additional treatment in salty atmosphere, on the other hand, did not show an accelerating effect on degradation on the electrical or material side. The accelerating effect of enhanced temperature, humidity, or additional irradiation on the degradation of power and materials could be shown very well. Direct evidence for the formation of acetic acid and lead‐acetate in the encapsulant ethylene vinyl acetate after prolonged damp‐heat exposure could be found and directly related to cell corrosion effects paralleled by power losses. 相似文献
The main aim of this experimental work is to find out possible improvement in thermal protective performance of firefighter protective clothing when subjected to different level of radiant heat flux density. Firefighter protective clothing normally consists of three layers: outer shell, moisture barrier and thermal liner. When thermal protective performance of firefighter protective clothing is enhanced, the time of exposure against radiant heat flux is increased, which will provide extra amount of time to firefighter to carry on their work without suffering from severe skin burn injuries. In this study, the exterior side of outer shell was coated with nano-silver metallic particle through magnetron sputtering technology. Coating of outer shell with nano-silver particles was performed at three level of thickness, i.e. 1, 2 and 3?µm, respectively. All the uncoated and silver coated specimens were then characterized on air permeability tester, Permetest and radiant heat transmission machine. It was observed that coating has insignificant difference on the air and water vapor permeability of specimen and a significant decline was recorded for the value of transmitted heat flux density Qc (kW/m2) and percentage transmission factor (%TF Qo) as compared to uncoated specimen when subjected to 10 kW/m2 and 20?kW/m2 indicating improvement of thermal protective performance. These values go on further reduction with increase in thickness of coating layer of nano-silver particles. 相似文献
An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content. 相似文献
