The flow and heat transfer characteristics of Maxwell fluid in a pipe under pulsating pressure gradient were studied. The governing equations were made dimensionless. The Rubin boundary condition was adopted. The flow...The flow and heat transfer characteristics of Maxwell fluid in a pipe under pulsating pressure gradient were studied. The governing equations were made dimensionless. The Rubin boundary condition was adopted. The flow field was solved theoretically and the temperature field was obtained using finite volume method. A general model suitable for various fluctuating characteristics and physical parameters was established. The Deborah number(De) was used to characterize the fluidity of the fluid. The influence of De on flow and temperature fields was evaluated. The Nusselt number and start-up process of Maxwell fluid were studied. Results showed that the influence of De on flow field was greater than that on temperature field. The effect of De on Nusselt number was irregular and related to the oscillation parameters. The over-shooting amplitude and oscillation time of axis center velocity in start-up flow grow larger with De.展开更多
Catalytic co-pyrolysis of biomass and plastic is an effective method to improve bio-oil produced by biomass pyrolysis.To further exploit the synergistic mechanism between biomass and plastic,co-pyrolysis of polypropyl...Catalytic co-pyrolysis of biomass and plastic is an effective method to improve bio-oil produced by biomass pyrolysis.To further exploit the synergistic mechanism between biomass and plastic,co-pyrolysis of polypropylene(PP)and deuterated glucose(G)(1:1 wt%)over mesoporous catalysts MCM-41(M)and Al-MCM-41(Al)was studied using a thermal gravimetric analyser(TGA)and pyrolysis-gas chromatography-mass spectrometry.The findings show that M and Al overlap the decomposition of PP and G,making synergy possible.With catalysts M and Al,the yield of olefins increases sharply to 36.75% and 13.66% more than the calculated value.Additionally,hydrogen transfers from G to 4C-13C olefins and aromatic products are influenced by the catalysts.Without a catalyst,there is no deuterium in all the co-pyrolytic products.However,catalysts M and Al can help transfer one to four deuterium atoms from G to the products.M and Al provide the pool for the intermediates of PP and G to form synergetic products.Additionally,Al helps break the carbon chain and transfer more deuterium into the products by reducing carbon atoms.展开更多
基金sponsored by China National Key Research and Development Program via Project No.2018YFB0605105。
文摘The flow and heat transfer characteristics of Maxwell fluid in a pipe under pulsating pressure gradient were studied. The governing equations were made dimensionless. The Rubin boundary condition was adopted. The flow field was solved theoretically and the temperature field was obtained using finite volume method. A general model suitable for various fluctuating characteristics and physical parameters was established. The Deborah number(De) was used to characterize the fluidity of the fluid. The influence of De on flow and temperature fields was evaluated. The Nusselt number and start-up process of Maxwell fluid were studied. Results showed that the influence of De on flow field was greater than that on temperature field. The effect of De on Nusselt number was irregular and related to the oscillation parameters. The over-shooting amplitude and oscillation time of axis center velocity in start-up flow grow larger with De.
基金the funding support by the National Natural Science Foundation of China(No.51576111)Fundamental Research Funds for the Central Universities(2019MS029).
文摘Catalytic co-pyrolysis of biomass and plastic is an effective method to improve bio-oil produced by biomass pyrolysis.To further exploit the synergistic mechanism between biomass and plastic,co-pyrolysis of polypropylene(PP)and deuterated glucose(G)(1:1 wt%)over mesoporous catalysts MCM-41(M)and Al-MCM-41(Al)was studied using a thermal gravimetric analyser(TGA)and pyrolysis-gas chromatography-mass spectrometry.The findings show that M and Al overlap the decomposition of PP and G,making synergy possible.With catalysts M and Al,the yield of olefins increases sharply to 36.75% and 13.66% more than the calculated value.Additionally,hydrogen transfers from G to 4C-13C olefins and aromatic products are influenced by the catalysts.Without a catalyst,there is no deuterium in all the co-pyrolytic products.However,catalysts M and Al can help transfer one to four deuterium atoms from G to the products.M and Al provide the pool for the intermediates of PP and G to form synergetic products.Additionally,Al helps break the carbon chain and transfer more deuterium into the products by reducing carbon atoms.
