The results of the calculation of thermodynamic properties in liquid state for ternary Al-Ni-Zn alloys using the newest version of the general solution model for thermodynamic prediction are presented. Nine sections w...The results of the calculation of thermodynamic properties in liquid state for ternary Al-Ni-Zn alloys using the newest version of the general solution model for thermodynamic prediction are presented. Nine sections with different molar ratios of Ni to Zn, Zn to Al and Al to Ni were investigated in a temperature interval of 1800-2000 K. Partial and integral molar thermodynamic properties in liquid phase for the Al-Ni-Zn ternary system are determined and discussed.展开更多
The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct-contact heat exchangers,was investigated computationally by introducing a ther...The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct-contact heat exchangers,was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in subcooled water.The condensation model presented was a two resistance model which takes care of the heat transfer process on both sides of the interface and uses a variable steam bubble diameter.The injection of supersonic steam jet in subcooled water tank was simulated using the Euler-Euler multiphase flow model of Fluent 6.3 code with the condensation model incorporated. The findings of the computational fluid dynamics（CFD） simulations were compared with the published experimental data and fairly good agreement was observed between the two,thus validating the condensation model.The results of CFD simulations for dimensionless penetration length of steam plume varies from 2.73-7.33,while the condensation heat transfer coefficient varies from 0.75-0.917 MW·（m ^2 ·K）^ -1 for water temperature in the range of 293-343 K.展开更多
On the base of nonlinear liquidus and solidus,an extended model for dendrite growth in bulk undercooled melts was developed under local non-equilibrium conditions both at the interface and in the bulk liquid.In terms ...On the base of nonlinear liquidus and solidus,an extended model for dendrite growth in bulk undercooled melts was developed under local non-equilibrium conditions both at the interface and in the bulk liquid.In terms of thermodynamic calculations of the phase diagram,the model predictions are relatively realistic physically,since few fitting parameters are used in the model predictions.Adopting three characteristic velocities,i.e.the critical velocity of absolute solute stability(VC*),the velocity of maximal tip radius(VRm),and the velocity of bulk liquid diffusion(VD),a quantitative agreement is obtained between the model predictions and the experimental results in undercooled Ni-0.7%B and Ni-1%Zr(molar fraction) alloys,and the overall solidification process can be categorized.展开更多
Refrigerant is a medium used in refrigeration cycle. Until now in thermodynamic models calculations of refrigerant is not considered with lubricant and moist air but as an ideal pure gas （without any contaminants）. ...Refrigerant is a medium used in refrigeration cycle. Until now in thermodynamic models calculations of refrigerant is not considered with lubricant and moist air but as an ideal pure gas （without any contaminants）. This is also the case in refrigeration cycle where the refrigerant is very often considered as an ideal one. Lubricant, air and water vapour are not considered in thermodynamic calculations in spite of their existence. The problems in the existing research are summarized. A further study is suggested on refrigerant systems. This circulation of such calculations is at the origin of a deviation from a theoretical behaviour. This article aims at reviewing the researches of oil-refrigerant, air-refrigerant, moist air-refrigerant or oil-moist air-refrigerant mixtures and focuses particularly on mixture enthalpy calculation. This paper deals with the description of the real mixture of refrigerant and contaminants （lubricant, water, moist air and other remains of refrigerants at elevated pressures and temperatures） which flow in a refrigerating cycle and the main point of this paper is to appoint thermodynamic parameters of such a mixture using the thermodynamic formulas.展开更多
PHEs （plate heat exchangers） are among the most common thermal equipments in diverse industries particularly in oil and gas companies. This wide usage is obviously due to significant benefits of these heat exchanger...PHEs （plate heat exchangers） are among the most common thermal equipments in diverse industries particularly in oil and gas companies. This wide usage is obviously due to significant benefits of these heat exchangers over other types. In this article, a behavioral analysis of heat transfer in fiat plates of these heat exchangers in laminar flow situation through CFD （computational fluid dynamics） simulation using FLUENT 6.3.26 software is done. The study reveals results graphically based on fluid＇s behavior in co-current and counter current flows and discusses thermal indexes consisting of heat transfer coefficient, Nusslet and total heat flux in both conditions. Eventually, a comparison via the graphical results is presented between the two types of flow directions.展开更多
A mathematic model for packed air-cooling tower thermodynamic calculation is set up in this paper on the basis of fundamental heat and mass transfer equations. Based on the Double Film theory, direct equation-solving ...A mathematic model for packed air-cooling tower thermodynamic calculation is set up in this paper on the basis of fundamental heat and mass transfer equations. Based on the Double Film theory, direct equation-solving method is used to simulate air-cooling tower, and variation of parameters is taken to analyze the data and results of the program.展开更多
基金the frame of Project OI 172037 financed by the Ministry of Science and Technological Development Republic of Serbia and bilateral scientific and technological cooperation project between Republic of Serbia and China
文摘The results of the calculation of thermodynamic properties in liquid state for ternary Al-Ni-Zn alloys using the newest version of the general solution model for thermodynamic prediction are presented. Nine sections with different molar ratios of Ni to Zn, Zn to Al and Al to Ni were investigated in a temperature interval of 1800-2000 K. Partial and integral molar thermodynamic properties in liquid phase for the Al-Ni-Zn ternary system are determined and discussed.
文摘The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct-contact heat exchangers,was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in subcooled water.The condensation model presented was a two resistance model which takes care of the heat transfer process on both sides of the interface and uses a variable steam bubble diameter.The injection of supersonic steam jet in subcooled water tank was simulated using the Euler-Euler multiphase flow model of Fluent 6.3 code with the condensation model incorporated. The findings of the computational fluid dynamics（CFD） simulations were compared with the published experimental data and fairly good agreement was observed between the two,thus validating the condensation model.The results of CFD simulations for dimensionless penetration length of steam plume varies from 2.73-7.33,while the condensation heat transfer coefficient varies from 0.75-0.917 MW·（m ^2 ·K）^ -1 for water temperature in the range of 293-343 K.
基金Projects(50501020, 50395103, 50431030) supported by the National Natural Science Foundation of ChinaProject(NCET-05-870) supported by Program for New Century Excellent Talents in Chinese UniversityProject(CX200706) supported by the Doctorate Foundation of Northwestern Polytechnical University,China
文摘On the base of nonlinear liquidus and solidus,an extended model for dendrite growth in bulk undercooled melts was developed under local non-equilibrium conditions both at the interface and in the bulk liquid.In terms of thermodynamic calculations of the phase diagram,the model predictions are relatively realistic physically,since few fitting parameters are used in the model predictions.Adopting three characteristic velocities,i.e.the critical velocity of absolute solute stability(VC*),the velocity of maximal tip radius(VRm),and the velocity of bulk liquid diffusion(VD),a quantitative agreement is obtained between the model predictions and the experimental results in undercooled Ni-0.7%B and Ni-1%Zr(molar fraction) alloys,and the overall solidification process can be categorized.
文摘Refrigerant is a medium used in refrigeration cycle. Until now in thermodynamic models calculations of refrigerant is not considered with lubricant and moist air but as an ideal pure gas （without any contaminants）. This is also the case in refrigeration cycle where the refrigerant is very often considered as an ideal one. Lubricant, air and water vapour are not considered in thermodynamic calculations in spite of their existence. The problems in the existing research are summarized. A further study is suggested on refrigerant systems. This circulation of such calculations is at the origin of a deviation from a theoretical behaviour. This article aims at reviewing the researches of oil-refrigerant, air-refrigerant, moist air-refrigerant or oil-moist air-refrigerant mixtures and focuses particularly on mixture enthalpy calculation. This paper deals with the description of the real mixture of refrigerant and contaminants （lubricant, water, moist air and other remains of refrigerants at elevated pressures and temperatures） which flow in a refrigerating cycle and the main point of this paper is to appoint thermodynamic parameters of such a mixture using the thermodynamic formulas.
文摘PHEs （plate heat exchangers） are among the most common thermal equipments in diverse industries particularly in oil and gas companies. This wide usage is obviously due to significant benefits of these heat exchangers over other types. In this article, a behavioral analysis of heat transfer in fiat plates of these heat exchangers in laminar flow situation through CFD （computational fluid dynamics） simulation using FLUENT 6.3.26 software is done. The study reveals results graphically based on fluid＇s behavior in co-current and counter current flows and discusses thermal indexes consisting of heat transfer coefficient, Nusslet and total heat flux in both conditions. Eventually, a comparison via the graphical results is presented between the two types of flow directions.
文摘A mathematic model for packed air-cooling tower thermodynamic calculation is set up in this paper on the basis of fundamental heat and mass transfer equations. Based on the Double Film theory, direct equation-solving method is used to simulate air-cooling tower, and variation of parameters is taken to analyze the data and results of the program.
