The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na_(2)SO_(4) circulating fluidized bed evaporator.The partic...The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na_(2)SO_(4) circulating fluidized bed evaporator.The particle collision signals are analyzed with standard deviation by varying the amount of added particles ε(1%–3%),circulation flow velocity u(0.37–1.78 m·s^(-1)),and heat flux q(7.29–12.14 kW·m^(-2)).The results show that the enhancement factor reach up to 14.6%by adding polytetrafluoroethylene particles at ε=3%,u=1.78 m·s^(-1),and q=7.29 kW·m^(-2).Both the standard deviation of the particle collision signal and enhancement factor increase with the increase in the amount of added particles.The standard deviation increases with the increase in circulation flow velocity;however,the enhancement factor initially decreases and then increases.The standard deviation slightly decreases with the increase in heat flux at low circulation flow velocity,but initially increases and then decreases at high circulation flow velocity.The enhancement factor decreases with the increase in heat flux.The enhancement factor in Na_(2)SO_(4) solution is superior to that in water at high amount of added particles.The empirical correlation for heat transfer is established,and the model results agree well with the experimental data.展开更多
A vapor-liquid-solid horizontal circulating fluidized bed evaporation setup was constructed to study the thermal-exchange properties and pressure change.The influences of the operating variables,including the amount o...A vapor-liquid-solid horizontal circulating fluidized bed evaporation setup was constructed to study the thermal-exchange properties and pressure change.The influences of the operating variables,including the amount of added particles,heat flux,and circulating flow velocity,were systematically inspected using resistance temperature detectors and pressure sensors.The results showed that the heat transfer eff ect was improved with the increase in the amount of added particles,circulating flow velocity,and particle diameter,but decreased with increasing heat flux.The pressure drop fluctuated with the increase in operating parameters,except circulating flow velocity.The enhancing factor reached up to 71.5%.The enhancing fac-tor initially increased and then decreased with the increase in the amount of added particles and circulating flow velocity,fluctuated with increasing particle diameter,and decreased with increasing heat flux.Phase diagrams showing the variation ranges of the operation variables for the enhancing factor were constructed.展开更多
The present investigation shows that comparing with the evaporation of vapor-liquid two-phase flow boiling system, heat transfer is enhanced by adding proper inert solid particles into the traditional Chinese medicine...The present investigation shows that comparing with the evaporation of vapor-liquid two-phase flow boiling system, heat transfer is enhanced by adding proper inert solid particles into the traditional Chinese medicine liquid which is under evaporation. As a result, fouling prevention effects are evident in such three-phase flow boiling evaporator.展开更多
A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China’s papermaki...A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China’s papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20%～40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.展开更多
A cold-model vertical multi-tube circulating fluidized bed evaporator was designed and built to conduct a visualization study on the pressure drop of a liquid–solid two-phase flow and the corresponding particle distr...A cold-model vertical multi-tube circulating fluidized bed evaporator was designed and built to conduct a visualization study on the pressure drop of a liquid–solid two-phase flow and the corresponding particle distribution.Water and polyformaldehyde particle(POM)were used as the liquid and solid phases,respectively.The effects of operating parameters such as the amount of added particles,circulating flow rate,and particle size were systematically investigated.The results showed that the addition of the particles increased the pressure drop in the vertical tube bundle.The maximum pressure drop ratios were 18.65%,21.15%,18.00%,and 21.15%within the experimental range of the amount of added particles for POM1,POM2,POM3,and POM4,respectively.The pressure drop ratio basically decreased with the increase in the circulating flow rate but fluctuated with the increase in the amount of added particles and particle size.The difference in pressure drop ratio decreased with the increase in the circulating flow rate.As the amount of added particles increased,the difference in pressure drop ratio fluctuated at low circulating flow rate but basically decreased at high circulating flow rate.The pressure drop in the vertical tube bundle accounted for about 70%of the overall pressure drop in the up-flow heating chamber and was the main component of the overall pressure within the experimental range.Three-dimensional phase diagrams were established to display the variation ranges of the pressure drop and pressure drop ratio in the vertical tube bundle corresponding to the operating parameters.The research results can provide some reference for the application of the fluidized bed heat transfer technology in the industry.展开更多
基金This work is supported by the open foundation of State Key Laboratory of Chemical Engineering(SKL-ChE-18B03)the Municipal Science and Technology Commission of Tianjin,China under Contract No.2009ZCKFGX01900.
文摘The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na_(2)SO_(4) circulating fluidized bed evaporator.The particle collision signals are analyzed with standard deviation by varying the amount of added particles ε(1%–3%),circulation flow velocity u(0.37–1.78 m·s^(-1)),and heat flux q(7.29–12.14 kW·m^(-2)).The results show that the enhancement factor reach up to 14.6%by adding polytetrafluoroethylene particles at ε=3%,u=1.78 m·s^(-1),and q=7.29 kW·m^(-2).Both the standard deviation of the particle collision signal and enhancement factor increase with the increase in the amount of added particles.The standard deviation increases with the increase in circulation flow velocity;however,the enhancement factor initially decreases and then increases.The standard deviation slightly decreases with the increase in heat flux at low circulation flow velocity,but initially increases and then decreases at high circulation flow velocity.The enhancement factor decreases with the increase in heat flux.The enhancement factor in Na_(2)SO_(4) solution is superior to that in water at high amount of added particles.The empirical correlation for heat transfer is established,and the model results agree well with the experimental data.
基金supported by the open foundation of State Key Laboratory of Chemical Engineering(No.SKL-ChE-18B03)by the Municipal Science and Technology Commission of Tianjin,China(No.2009ZCKFGX01900).
文摘A vapor-liquid-solid horizontal circulating fluidized bed evaporation setup was constructed to study the thermal-exchange properties and pressure change.The influences of the operating variables,including the amount of added particles,heat flux,and circulating flow velocity,were systematically inspected using resistance temperature detectors and pressure sensors.The results showed that the heat transfer eff ect was improved with the increase in the amount of added particles,circulating flow velocity,and particle diameter,but decreased with increasing heat flux.The pressure drop fluctuated with the increase in operating parameters,except circulating flow velocity.The enhancing factor reached up to 71.5%.The enhancing fac-tor initially increased and then decreased with the increase in the amount of added particles and circulating flow velocity,fluctuated with increasing particle diameter,and decreased with increasing heat flux.Phase diagrams showing the variation ranges of the operation variables for the enhancing factor were constructed.
文摘The present investigation shows that comparing with the evaporation of vapor-liquid two-phase flow boiling system, heat transfer is enhanced by adding proper inert solid particles into the traditional Chinese medicine liquid which is under evaporation. As a result, fouling prevention effects are evident in such three-phase flow boiling evaporator.
文摘A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China’s papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20%～40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.
基金supported by the open foundation of State Key Laboratory of Chemical Engineering (SKL-ChE-18B03)the Municipal Science and Technology Commission of Tianjin (No. 2009ZCKFGX01900)
文摘A cold-model vertical multi-tube circulating fluidized bed evaporator was designed and built to conduct a visualization study on the pressure drop of a liquid–solid two-phase flow and the corresponding particle distribution.Water and polyformaldehyde particle(POM)were used as the liquid and solid phases,respectively.The effects of operating parameters such as the amount of added particles,circulating flow rate,and particle size were systematically investigated.The results showed that the addition of the particles increased the pressure drop in the vertical tube bundle.The maximum pressure drop ratios were 18.65%,21.15%,18.00%,and 21.15%within the experimental range of the amount of added particles for POM1,POM2,POM3,and POM4,respectively.The pressure drop ratio basically decreased with the increase in the circulating flow rate but fluctuated with the increase in the amount of added particles and particle size.The difference in pressure drop ratio decreased with the increase in the circulating flow rate.As the amount of added particles increased,the difference in pressure drop ratio fluctuated at low circulating flow rate but basically decreased at high circulating flow rate.The pressure drop in the vertical tube bundle accounted for about 70%of the overall pressure drop in the up-flow heating chamber and was the main component of the overall pressure within the experimental range.Three-dimensional phase diagrams were established to display the variation ranges of the pressure drop and pressure drop ratio in the vertical tube bundle corresponding to the operating parameters.The research results can provide some reference for the application of the fluidized bed heat transfer technology in the industry.
