In order to study the effects of ventilation modes and outlet height on the airflow field of a nursery piggery,computational fluid dynamics (CFD) technology was used to simulate the wind speed and temperature of an ex...In order to study the effects of ventilation modes and outlet height on the airflow field of a nursery piggery,computational fluid dynamics (CFD) technology was used to simulate the wind speed and temperature of an experimental pig house in the cold northern region.This study was conducted with simulation and a comparative analysis of transverse ventilation,longitudinal ventilation and roof air intake modes.Furthermore,the effects of the air outlet height of 0.7,0.6 and 0.5 m with the roof air inlet mode on the environment in the pig house were studied.Field experiments verified the model of roof air intake model.The results showed inadequate ventilation in both the vertical and horizontal ventilation.However,the airfield gradients were less variable and more balanced when using the rooftop air intake mode.The variation of outlet height significantly affected nursery pig houses’ airflow velocity and temperature.Roof air inlet mode with an outlet height of 0.7 m was better than the other two.The normalized mean square error (NMSE) of air velocity and temperature was less than 0.01,and the simulation analysis could genuinely reflect the distribution of the airflow field in the nursery.展开更多
To study axial/radial profiles of particle velocity in the affected region of an integrated riser outlet, a cold model was developed for the integrated riser reactor combining the gas-solid distributor with the fluidi...To study axial/radial profiles of particle velocity in the affected region of an integrated riser outlet, a cold model was developed for the integrated riser reactor combining the gas-solid distributor with the fluidized bed. Constraints, related to the gas-solid distributor and the upper fluidized bed, imposed on the particle flow in the riser outlet region, were investigated experimentally. The experimental results showed that with increasing superficial gas velocity, these constraints have strong influences on particle flow behavior, the particle circulation flux in the riser, and the height of the static bed material of the upper fluidized bed. When the constraints have greater prominence, the axial profile of the cross-sectionally averaged particle velocity in the outlet region initially increases and then decreases, the rate of decrease being proportional to the constraint strength. Along the radial direction of the outlet section, the region where the local particle velocity profile tends to decrease appears near the dimensionless radius r/R = 0.30 initially and then, with increasing constraint strength, gradually extends to the whole section from the inner wall. Based on the experimental data, an empirical model describing the constraint strength was established. The average relative error of the model is within 7.69%.展开更多
基金Supported by the National Natural Science Foundation of China(32072787)。
文摘In order to study the effects of ventilation modes and outlet height on the airflow field of a nursery piggery,computational fluid dynamics (CFD) technology was used to simulate the wind speed and temperature of an experimental pig house in the cold northern region.This study was conducted with simulation and a comparative analysis of transverse ventilation,longitudinal ventilation and roof air intake modes.Furthermore,the effects of the air outlet height of 0.7,0.6 and 0.5 m with the roof air inlet mode on the environment in the pig house were studied.Field experiments verified the model of roof air intake model.The results showed inadequate ventilation in both the vertical and horizontal ventilation.However,the airfield gradients were less variable and more balanced when using the rooftop air intake mode.The variation of outlet height significantly affected nursery pig houses’ airflow velocity and temperature.Roof air inlet mode with an outlet height of 0.7 m was better than the other two.The normalized mean square error (NMSE) of air velocity and temperature was less than 0.01,and the simulation analysis could genuinely reflect the distribution of the airflow field in the nursery.
基金supported by the key project of the National Key Research and Development Program"Science and Technology Powering Economy 2020"(Grant No. SQ2020YFF0426316)
基金support from the National Natural Science Foundation of China(Grant nos.21106028 and 20976190)the Hebei Province Natural Science Foundation of China(Grant no.B2013202125)
文摘To study axial/radial profiles of particle velocity in the affected region of an integrated riser outlet, a cold model was developed for the integrated riser reactor combining the gas-solid distributor with the fluidized bed. Constraints, related to the gas-solid distributor and the upper fluidized bed, imposed on the particle flow in the riser outlet region, were investigated experimentally. The experimental results showed that with increasing superficial gas velocity, these constraints have strong influences on particle flow behavior, the particle circulation flux in the riser, and the height of the static bed material of the upper fluidized bed. When the constraints have greater prominence, the axial profile of the cross-sectionally averaged particle velocity in the outlet region initially increases and then decreases, the rate of decrease being proportional to the constraint strength. Along the radial direction of the outlet section, the region where the local particle velocity profile tends to decrease appears near the dimensionless radius r/R = 0.30 initially and then, with increasing constraint strength, gradually extends to the whole section from the inner wall. Based on the experimental data, an empirical model describing the constraint strength was established. The average relative error of the model is within 7.69%.
