Intensification of mass transfer processes through the impact of the velocity gradient on hydrodynamics and stability of liquid droplets in a gas flow

Results are given for the comparative numerical simulation of heat-and-mass transfer processes in the cooling passages of a cylinder head in diesel locomotive engine 16 FN 26/27 running under rated power conditions at different engine boost levels. The advanced numerical methods used are shown to ensure a high degree of accuracy and information content when simulating heat-and-mass transfer processes, and enable evaluating the local values of flow parameters with account of the complex configuration of the flow parts in the cooling passages and the impact of operating parameters. The results show that an increasing boost level of a diesel engine and, respectively, a growing thermal load degrade drastically the conditions of heat rejection from the most thermally stressed zones of the cylinder head – the central part of the bottom face in the area of the injector bore and of the bridge between the bores of exhaust valve seats. The paper assesses the impact of the boost level on the effectiveness of heat rejection from the most thermally stressed areas of the cylinder head of a diesel locomotive engine. Conclusions and recommendations for improving the operating conditions of the cylinder head are given.

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SIMULATION OF HEAT AND MASS TRANSFER PROCESSES UNDER GRANULES CAPSULATION IN FLUIDIZED BED

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/tcct.20186104-05.5624 ◽

2018 ◽

Vol 61 (4-5) ◽

pp. 98

Author(s):

Andrey A. Lipin ◽

Vladimir O. Nebukin ◽

Aleksandr G. Lipin

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Fluidized Bed ◽

Residence Time ◽

Solid Particles ◽

Process Time ◽

Coating Film ◽

Transfer Processes ◽

Mass Transfer Processes ◽

The Impact

The paper studies capsulation of solid particles in a spout fluidized bed. A capsulation is used to protect the particles surface from the negative impact of environmental factors as well as to regulate of active component release rate. In this work, the capsulation is carried out by spraying of polymers dispersions on fluidized bed particles by means of pneumatic nozzles. Drops of polymer dispersion having faced with the particles are spred on their surface, forming a liquid film. Solvent removing by drying causes solidification of the film. Existing calculation methods of capsulation in the apparatuses with fluidized bed have a significant disadvantage. They do not consider the impact of capsule formation on the heat and mass transfer process of the solvent removing from the coating film. Combined modeling these processes allows more accurately predicting the required residence time of the capsulated material in the apparatus. The mathematical model, which allows predicting the change in coverage degree, the moisture content, the temperature of the particles in process time as well as required residence time in the apparatus, was developed. The comparison of the calculated and experimental data shows their good agreement. Taking into account the changes in evaporation surface due to the increasing of particles coverage degree in the capsulation process allows to describe the evolution of the particles parameters more adequately and to select of the process rational parameters.Forcitation:Lipin A.A., Nebukin V.O., Lipin A.G. Simulation of heat and mass transfer processes under granules capsulation in fluidized ber. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 98-104

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