SIMULATION AND NUMERICAL INVESTIGATION OF THE NONSTATIONARY HEAT TRANSFER PROCESS IN THE STATIONARY PACKED BED

• Datum: 2018
• Автори та афіліації: B. Rokhman — Coal Energy Technology Institute NAS of Ukraine
• Ключові слова: keywords
• 1. Verfasser: Rokhman, B.
• Format: Artikel
• Sprache: Ukrainisch
• Veröffentlicht: Institute of Renewable Energy National Academy of Sciences of Ukraine 2018
• Schlagworte: fixed packed bed; straw; husk; coal; thermal conductivity; density; conductive; radiation.
• Online Zugang: https://ve.org.ua/index.php/journal/article/view/177
• Назва журналу: Vidnovluvana energetika

An axisymmetric nonstationary model of the heat transfer process in a stationary cylindrical packed bed is developed with allowance for the heat flux through the gas phase due to thermal conductivity and radiation, and heat transfer through the particles due to conductive and radiative heat exchange between them. Using the developed model, extensive numerical studies of the influence of diameter, thermal conductivity and particle density (biomass, coal) on the heating rate of a fixed bed at any time were carried out. An estimateof the warm-up time of the fixed bed for various types of coke-ash particles of coal and biomass was made, which can be used in commissioning modes of plants for the thermochemical processing of solid fuels. It is shown that: 1) the rate of heating of the fixed bed depends mainly on three parameters: density, thermal conductivity and particle diameter; 2) a decrease in the coefficient of thermal conductivity and the diameter of the particles and an increase in their density increases the heating time of the particles in a fixed bed; 3) the warm-up time of the fixed bed of straw particles is significantly lower than when heating gas coal due to the lower bulk density of biomass particles; 4) the heating time of the husk particles and gas coal is commensurate; 5) with increasing warming time of the fixed bed, the temperature profile deforms due to an increase in the coefficients of effective thermal conductivity, heat transfer by radiation between adjacent particles, heat transfer from a particle through a gas past neighboring grains due to an increase in temperature values of coke-ash particles at all points of the cross section of the bed.