In this paper, the measurement of liquid mixing in a downcomer of segmental type of distillation column is presented. The extent of liquid mixing is calculated by means of a mixing pool model. The results indicate tha...In this paper, the measurement of liquid mixing in a downcomer of segmental type of distillation column is presented. The extent of liquid mixing is calculated by means of a mixing pool model. The results indicate that liquid mixing in a downcomer is actually incomplete. It is a significant correction to the assumption of complete downcomer mixing or no downcomer mixing which is generally adopted in many distillation calculations. Besides, the present results are used in a two dimensional eddy diffusion model to calculate the distillation tray efficiency. It is shown that the assumption of complete downcomer mixing is closer to the actual situation than that of no downcomer mixing.展开更多
Making use of the DEA nonparametric method and the limited Tobit model, this article estimates the relative efficiency of Chinese provincial governments＇ fiscal expenditure following financial decentralization reform...Making use of the DEA nonparametric method and the limited Tobit model, this article estimates the relative efficiency of Chinese provincial governments＇ fiscal expenditure following financial decentralization reform, and explains the factors that influence the changing pattern of such expenditure efficiency.展开更多
Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three- dimensienal discrete-hole film cooling arrangement. The effects of basic geometrical characteristics of th...Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three- dimensienal discrete-hole film cooling arrangement. The effects of basic geometrical characteristics of the holes, i.e diameter D, length L and pitch S/D were studied. Different turbulent heat transfer models based on constant and variable turbulent Prandtl number approaches were considered. The variability of the turbulent Prandtl number Prt in the energy equation was assumed using an algebraic relation proposed by Kays and Crawford, or employing the Abe, Kondoh and Nagano eddy heat diffusivity closure with two differential transport equations for the temperature variance ko and its destruction rate εθ The obtained numerical results were directly compared with the data that came from an experiment based on Transient Liquid Crystal methodology. All implemented models for turbulent heat transfer performed sufficiently well for the considered case. It was confirmed, however, that the two- equation closure can give a detailed look into film cooling problems without using any time-consuming and inherently unsteady models.展开更多
文摘In this paper, the measurement of liquid mixing in a downcomer of segmental type of distillation column is presented. The extent of liquid mixing is calculated by means of a mixing pool model. The results indicate that liquid mixing in a downcomer is actually incomplete. It is a significant correction to the assumption of complete downcomer mixing or no downcomer mixing which is generally adopted in many distillation calculations. Besides, the present results are used in a two dimensional eddy diffusion model to calculate the distillation tray efficiency. It is shown that the assumption of complete downcomer mixing is closer to the actual situation than that of no downcomer mixing.
文摘Making use of the DEA nonparametric method and the limited Tobit model, this article estimates the relative efficiency of Chinese provincial governments＇ fiscal expenditure following financial decentralization reform, and explains the factors that influence the changing pattern of such expenditure efficiency.
文摘Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three- dimensienal discrete-hole film cooling arrangement. The effects of basic geometrical characteristics of the holes, i.e diameter D, length L and pitch S/D were studied. Different turbulent heat transfer models based on constant and variable turbulent Prandtl number approaches were considered. The variability of the turbulent Prandtl number Prt in the energy equation was assumed using an algebraic relation proposed by Kays and Crawford, or employing the Abe, Kondoh and Nagano eddy heat diffusivity closure with two differential transport equations for the temperature variance ko and its destruction rate εθ The obtained numerical results were directly compared with the data that came from an experiment based on Transient Liquid Crystal methodology. All implemented models for turbulent heat transfer performed sufficiently well for the considered case. It was confirmed, however, that the two- equation closure can give a detailed look into film cooling problems without using any time-consuming and inherently unsteady models.
