Film condensation heat transfer on a horizontal tube in presence of a noncondensable gas
The double boundary layer model has been developed to study the behavior of film condensation heat transfer outside a horizontal tube in presence of air treated as a noncondensable gas. And the coupled heat and mass transfer on a smooth horizontal tube is numerically solved with the finite difference method. The local mass concentration of the noncondensable gas, the distributions of velocity and temperature in the boundary layers are presented and discussed. The numerical results have shown that the mass concentration and velocity of the noncondensable gas increase from the bulk mixture to the interface while the temperature decreases from the bulk mixture to the interface. Although the mass concentration of the noncondensable gas in the bulk mixture could be small, the reduction in average heat transfer coefficient is obvious. The comparisons of heat transfer coefficient show that the numerical predictions agree well with available experimental data.
The time sequences of the molecular dynamics simulation for the folding process of a protein is analyzed with the inherent structure landscape which focuses on configurational dynamics of the system. Time dependent energy and entropy for inherent structures are introduced and from these quantities a conformational temperature is defined. The conformational temperature follows the time evolution of a slow relaxation process and reaches the bath temperature when the system is equilibrated. We show that the nonequilibrium system is described by two temperatures, one for fast vibration and the other for slow configurational relaxation, while the equilibrium system is by one temperature. The proposed formalism is applicable widely for the systems with many metastable states.