Artificial aeration system for aquaculture ponds becomes essential to meet the oxygen requirement posed by the aquatic species.The performance of an aerator is generally mea-sured in terms of standard aeration efficie...Artificial aeration system for aquaculture ponds becomes essential to meet the oxygen requirement posed by the aquatic species.The performance of an aerator is generally mea-sured in terms of standard aeration efficiency(SAE),which is significantly affected by the different geometric and dynamic parameters of the aerator.Therefore,to enhance the aer-ation performance of an aerator,these parameters need to be optimized.In the present study,a perforated pooled circular stepped cascade(PPCSC)aerator was developed,and the geometric and dynamic parameters of the developed aerator were optimized using the hybrid ANN-PSO technique for maximizing its aeration efficiency.The geometric parameters include consecutive step width ratio(W_(i-1)/W_(i))and the perforation diameter to the bottom-most radius ratio(d/R_(b)),whereas the dynamic parameter includes the water flow rate(Q).A 3–6-1 ANN model coupled with particle swarm optimization(PSO)approach was used to obtain the optimum values of geometric and dynamic parameters correspond-ing to the maximum SAE.The optimal values of the consecutive step width ratio(W_(i-1)/W_(i)),the perforation diameter to the bottom-most radius ratio(d/R_(b)),and the water flow rate(Q)for maximizing the SAE were found to be 1.15,0.0027 and 0.0167 m^(3)/s,respectively.The cross-validation results showed a deviation of 3.07%between the predicted and experimen-tal SAE values,thus confirming the adequacy of the proposed hybrid ANN-PSO technique.展开更多
To investigate the size effect on the characteristics of boiling heat transfer, boiling behavior of FC-72 in heated vertical miniature circular tubes immersed in a liquid pool was experimentally studied. Two AISI 304 ...To investigate the size effect on the characteristics of boiling heat transfer, boiling behavior of FC-72 in heated vertical miniature circular tubes immersed in a liquid pool was experimentally studied. Two AISI 304 stainless steel tubes with inner diameters of 1.10 mm and 1.55 mm correspondingly, were heated by swirled Ni-Cr wire heaters and sealed in Lucite blocks by silicon adhesive. Both the top and the bottom ends of the circular test sections were open to the liquid pool. The boiling curves and heat transfer coefficients were obtained experimentally. The boiling behaviors at the outlets of the miniature tubes were also visualized with a digital video camera. Experimental results show that the tube geometry has a significant effect on the boiling characteristics. Vapor blocking at the outlet of the smaller circular tube with a diameter of 1.10 mm caused severe boiling hysteresis phenomena. The CHF decreased with reducing in tube size.展开更多
文摘Artificial aeration system for aquaculture ponds becomes essential to meet the oxygen requirement posed by the aquatic species.The performance of an aerator is generally mea-sured in terms of standard aeration efficiency(SAE),which is significantly affected by the different geometric and dynamic parameters of the aerator.Therefore,to enhance the aer-ation performance of an aerator,these parameters need to be optimized.In the present study,a perforated pooled circular stepped cascade(PPCSC)aerator was developed,and the geometric and dynamic parameters of the developed aerator were optimized using the hybrid ANN-PSO technique for maximizing its aeration efficiency.The geometric parameters include consecutive step width ratio(W_(i-1)/W_(i))and the perforation diameter to the bottom-most radius ratio(d/R_(b)),whereas the dynamic parameter includes the water flow rate(Q).A 3–6-1 ANN model coupled with particle swarm optimization(PSO)approach was used to obtain the optimum values of geometric and dynamic parameters correspond-ing to the maximum SAE.The optimal values of the consecutive step width ratio(W_(i-1)/W_(i)),the perforation diameter to the bottom-most radius ratio(d/R_(b)),and the water flow rate(Q)for maximizing the SAE were found to be 1.15,0.0027 and 0.0167 m^(3)/s,respectively.The cross-validation results showed a deviation of 3.07%between the predicted and experimen-tal SAE values,thus confirming the adequacy of the proposed hybrid ANN-PSO technique.
基金This work was supported by the National Natural Science Foundation of China (No.50176039) and Hong Kong RGC Earmarked Research Grants (No. HKUST6038/02E).
文摘To investigate the size effect on the characteristics of boiling heat transfer, boiling behavior of FC-72 in heated vertical miniature circular tubes immersed in a liquid pool was experimentally studied. Two AISI 304 stainless steel tubes with inner diameters of 1.10 mm and 1.55 mm correspondingly, were heated by swirled Ni-Cr wire heaters and sealed in Lucite blocks by silicon adhesive. Both the top and the bottom ends of the circular test sections were open to the liquid pool. The boiling curves and heat transfer coefficients were obtained experimentally. The boiling behaviors at the outlets of the miniature tubes were also visualized with a digital video camera. Experimental results show that the tube geometry has a significant effect on the boiling characteristics. Vapor blocking at the outlet of the smaller circular tube with a diameter of 1.10 mm caused severe boiling hysteresis phenomena. The CHF decreased with reducing in tube size.
