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Full-Text Articles in Engineering

Non-Isothermal Reaction-Diffusion Systems With Thermodynamically Coupled Heat And Mass Transfer, Yaşar Demirel May 2006

Non-Isothermal Reaction-Diffusion Systems With Thermodynamically Coupled Heat And Mass Transfer, Yaşar Demirel

Papers in Analytical Chemistry

Non-isothermal reaction-diffusion (RD) systems control the behavior of many transport and rate processes in physical, chemical, and biological systems. A considerable work has been published on mathematically coupled nonlinear differential equations of RD systems by neglecting the possible thermodynamic couplings among heat and mass fluxes, and reaction velocities. Here, the thermodynamic coupling refers that a flux occurs without its primary thermodynamic driving force, which may be gradient of temperature, or chemical potential, or reaction affinity. This study presents the modeling equations of non-isothermal RD systems with coupled heat and mass fluxes excluding the coupling of chemical reactions using the linear …


Exergy Use In Bioenergetics, Yaşar Demirel Nov 2004

Exergy Use In Bioenergetics, Yaşar Demirel

Papers in Analytical Chemistry

Every developed and adapted biological system extracts useful energy from outside, converts, stores it, and uses for muscular contraction, substrate transport, protein synthesis, and other energy utilizing processes. This energy management in a living cell is called the bioenergetics, and the useful energy is the exergy, which is destroyed in every irreversible process because of the entropy production. The converted exergy is the adenosine triphosphate (ATP) produced through the oxidative phosphorylation coupled to respiration in which the exergy originates from oxidation of reducing equivalents of nutrients. A living cell uses the ATP for all the energy demanding activities; it has …


Simultaneous Correlation Of Excess Gibbs Energy And Enthalpy Of Mixing By The Uniquac Equation, Yaşar Demirel, Hatice Gecegörmez Jun 1989

Simultaneous Correlation Of Excess Gibbs Energy And Enthalpy Of Mixing By The Uniquac Equation, Yaşar Demirel, Hatice Gecegörmez

Papers in Analytical Chemistry

Using data for excess Gibbs energy gh and enthalpy of mixing hE, temperature dependent parameters of the UNlQUAC equation have been estimated for twenty four systems of binary mixtures. Fifteen of them include data for gh and hE at more than one isotherm. These parameters are later tested in predicting the gh and hE data simultaneously and representing the effect of temperature on such data. The UNIQUAC equation with temperature dependent parameters represents larger values of maximum heat of mixing than does the UNlQUAC equation with the parameters independent of temperature.