Atomization is often accompanied by phase change, which could significantly affect performance parameters such as the cooling efficiency and combustion efficiency of atomization. Nevertheless, the effect of phase change on jet atomization is rarely numerically studied due to the complexity of the coupling of the aerodynamics and the thermodynamics as well as the modelling difficulty caused by the cross-scale flow. In this study, comprehensive direct numerical simulations were carried out to evaluate the effects of phase change on the primary breakup and secondary atomization. Two methods dealing with phase-interface movement and mass transfer across the interface are built to meet the requirements of different modelling scales and Weber numbers. Simulation results indicate that phase change affects the flow behaviours and volume distribution of broken droplets in the primary breakup. In the secondary atomization, phase change leads to significantly different deforming morphologies of droplets with low Weber number and a more thorough breakup of droplets with high Weber number.
Based on 12 well-preserved skeletons of postmetamorphic individuals, a new crown-group frog taxon is named and described from the Lower Cretaceous Guanghua (upper part of Longjiang) Formation (stratigraphic equivalent of the world-famed Yixian Formation) exposed in Dayangshu Basin, Hulunbuir, in the far northeast of Inner Mongolia, China. The new taxon, Genibatrachus baoshanensis, documents another Early Cretaceous anuran having reduction of the presacral vertebrae to eight in number, similar to several frog taxa of roughly the same age from Spain and Brazil. The new frog also displays several features that are ontogenetically and phylogenetically informative, including ontogenetic fusion of the palatine to the sphenethmoid, and ontogenetic fusion of ribs to the diapophyses of the posterior trunk vertebrae. In addition, the new discovery extends the geographic range of Early Cretaceous frogs of the Jehol Biota northward to near the 50th parallel north in East Asia.
Abstract:With the rapid growth in demand for industrial gas in steel and chemical industries, there has been significant emphasis placed on the development of China's large-scale air separation technology. Currently, the maximum capacity of a single unit has been able to attain 120 000 Nm 3 /h (oxygen), and the specific power consumption of 0.38 kWh/m 3 . This paper reviews the current state-of-the-art for large-scale cryogenic air separation systems being deployed in China. A brief introduction to the history and establishment of the large-scale cryogenic air separation industry is presented. Taking the present mainstream large-scale air separation unit operating at 60 000 Nm 3 /h (oxygen) as an example, the technological parameters and features of the involved key equipment, including a molecular sieve adsorber, air compressor unit, plate-fin heat exchanger, turbo-expander and distillation column are described in detail. The developing 80 000-120 000 Nm 3 /h air separation processes and equipment are also introduced. A summary of the existing problems and future developments of these systems in China are discussed.
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