In the feeding process of aluminum electrolytic, feeding quantity of alumina affects eventually dissolved quantity at the end of a feeding cycle. Based on the OpenFOAM platform, dissolution model coupled with heat and...In the feeding process of aluminum electrolytic, feeding quantity of alumina affects eventually dissolved quantity at the end of a feeding cycle. Based on the OpenFOAM platform, dissolution model coupled with heat and mass transfer was established. Applying the Rosin-Rammler function, alumina particle size distribution under different feeding quantities was obtained. The temperature response of electrolyte after feeding was included and calculated, and the dissolution processes of alumina with different feeding quantities (0.6, 0.8, 1.0, 1.2, 1.4, 1.6 kg) after feeding were simulated in 300 kA aluminum reduction cell. The results show that with the increase of feeding quantity, accumulated mass fraction of dissolved alumina decreases, and the time required for the rapid dissolution stage extends. When the feeding quantity is 0.6 kg and 1.2 kg, it takes the shortest time for the electrolyte temperature dropping before rebounding back. With the increase of feeding quantity, the dissolution rate in the rapid dissolution stage increases at first and then decreases gradually. The most suitable feeding quantity is 1.2 kg. The fitting equation of alumina dissolution curve under different feeding quantities is obtained, which can be used to evaluate the alumina dissolution and guide the feeding quantity and feeding cycle.展开更多
Effective thermal performance of oscillating heat pipe(OHP)is driven by inside pressure distribution.Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP c...Effective thermal performance of oscillating heat pipe(OHP)is driven by inside pressure distribution.Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP charged with aqueous Al2O3 and MWCNTs/Al2O3 nanoparticles.The influences on thermal resistance of aqueous Al2O3,MWCNTs as well as the hybrid of them in OHP having 3 mm in inner diameter were investigated at 60% filling ratio.Experimental results show that thermal characteristics are significantly inter-related with pressure distribution and strongly depend upon the number of pressure fluctuations with time.Frequency of pressure depends upon the power input in evaporative section.A little inclusion of MWCNTs into aqueous Al2O3 at 60% filling ratio achieves the highest fluctuation frequency and the lowest thermal resistance at any evaporator power input though different nanofluids cause different thermal performances of OHPs.展开更多
According to 350 MW and 600 MW boilers,under oxygen fuel condition,through the reasonable control of the primary and secondary flow and the correct option and revision of mathematical model,the temperature distributio...According to 350 MW and 600 MW boilers,under oxygen fuel condition,through the reasonable control of the primary and secondary flow and the correct option and revision of mathematical model,the temperature distribution,heat flux distribution and absorption heat distribution,etc.was obtained which compared with those under air condition.Through calculation,it is obtained that the primary and secondary flow mixed well,good tangentially fired combustion in furnace was formed,the temperature under air condition obviously higher than the temperature under O26 condition.The adiabatic flame temperature of wet cycle was slightly higher than that of dry cycle.The maximum heat load appeared on the waterwall around the burner area.The heat load gradually decreased along the furnace height up and down in burner area.The heat absorption capacity of the furnace under O26 was lower than that under the air condition.The heat absorption capacity of the platen heating surface under 026 was equal to that under air condition.And the heat absorbing capacity of waterwall under O26 was about 7%~12% less than that under air condition.展开更多
基金Project(2010AA065201) supported by the High-Tech Research and Development Program of ChinaProject(2018zzts157) supported by the Fundamental Research Funds for the Central Universities,China
文摘In the feeding process of aluminum electrolytic, feeding quantity of alumina affects eventually dissolved quantity at the end of a feeding cycle. Based on the OpenFOAM platform, dissolution model coupled with heat and mass transfer was established. Applying the Rosin-Rammler function, alumina particle size distribution under different feeding quantities was obtained. The temperature response of electrolyte after feeding was included and calculated, and the dissolution processes of alumina with different feeding quantities (0.6, 0.8, 1.0, 1.2, 1.4, 1.6 kg) after feeding were simulated in 300 kA aluminum reduction cell. The results show that with the increase of feeding quantity, accumulated mass fraction of dissolved alumina decreases, and the time required for the rapid dissolution stage extends. When the feeding quantity is 0.6 kg and 1.2 kg, it takes the shortest time for the electrolyte temperature dropping before rebounding back. With the increase of feeding quantity, the dissolution rate in the rapid dissolution stage increases at first and then decreases gradually. The most suitable feeding quantity is 1.2 kg. The fitting equation of alumina dissolution curve under different feeding quantities is obtained, which can be used to evaluate the alumina dissolution and guide the feeding quantity and feeding cycle.
基金Project(NRF-2012R1A1A4A01002052)supported by Basic Science Research Program through the National Research Foundation(NRF)funded by the Ministry of Education,Science and Technology of Korea
文摘Effective thermal performance of oscillating heat pipe(OHP)is driven by inside pressure distribution.Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP charged with aqueous Al2O3 and MWCNTs/Al2O3 nanoparticles.The influences on thermal resistance of aqueous Al2O3,MWCNTs as well as the hybrid of them in OHP having 3 mm in inner diameter were investigated at 60% filling ratio.Experimental results show that thermal characteristics are significantly inter-related with pressure distribution and strongly depend upon the number of pressure fluctuations with time.Frequency of pressure depends upon the power input in evaporative section.A little inclusion of MWCNTs into aqueous Al2O3 at 60% filling ratio achieves the highest fluctuation frequency and the lowest thermal resistance at any evaporator power input though different nanofluids cause different thermal performances of OHPs.
文摘According to 350 MW and 600 MW boilers,under oxygen fuel condition,through the reasonable control of the primary and secondary flow and the correct option and revision of mathematical model,the temperature distribution,heat flux distribution and absorption heat distribution,etc.was obtained which compared with those under air condition.Through calculation,it is obtained that the primary and secondary flow mixed well,good tangentially fired combustion in furnace was formed,the temperature under air condition obviously higher than the temperature under O26 condition.The adiabatic flame temperature of wet cycle was slightly higher than that of dry cycle.The maximum heat load appeared on the waterwall around the burner area.The heat load gradually decreased along the furnace height up and down in burner area.The heat absorption capacity of the furnace under O26 was lower than that under the air condition.The heat absorption capacity of the platen heating surface under 026 was equal to that under air condition.And the heat absorbing capacity of waterwall under O26 was about 7%~12% less than that under air condition.
