Thermodynamic analysis of free convection film condensation on an elliptical cylinder

Abstract

This paper aims to perform thermodynamic analysis of saturated vapor flowing slowly onto and condensing on an elliptical cylinder. This is the first approach to investigate how the geometric parameter-ellipticity and surface tension affect local entropy-generation rate during film-wise condensation heat transfer process. The results observe that entropy generation decreases with decreasing ellipticity. It indicates that the entropy generation number is nearly unaffected by surface tension forces at small ellipticity like e ≤ 0.7, but somewhat influenced at large ellipticity for the whole perimeter. From the second law point of view, local entropy generation increases with ellipticity as local heat transfer coefficient does. Furthermore, the entropy-generation rate due to gravity-driven film flow friction is proportional to Brinkman group parameter. The irreversibility ratio indicates that film flow friction irreversibility starts to dominate over heat transfer irreversibility in the lower half of streamwise length for higher values of Brinkman group parameter (Br/Θ = 1).

Entropy generation minimization of free convection film condensation on an elliptical cylinder

“…The second law analysis of the film condensation outside cylinders still remains an unsettled question so far. More recently, we first conducted a study [11] on the local entropy generation rate of laminar free convection film condensation on an elliptical cylinder. That paper investigated how the geometric parameter-ellipticity affects local entropy-generation rate during film-wise condensation heat transfer process.…”

Theoretical Analysis of Effects of Wall Suction on Entropy Generation Rate in Laminar Condensate Layer on Horizontal Tube

“…Their results showed that the optimal group Rayleigh parameter exists over the parametric range investigated for horizontal tube at which the entropy is generated at a minimum rate. Li and Yang [14] applied the entropy generation minimization method to optimize the heat transfer performance of a horizontal elliptical cylinder in a saturated vapor flow. In a recent study, Chang and Wang [15] investigated the heat transfer characteristics and entropy generation rate of a condensate film on a horizontal plate and found that the overall entropy generation rate induced by the heat transfer irreversibility effect is equivalent to the Nusselt number.…”

Entropy generation of forced convection film condensation on a horizontal elliptical tube

“…Their results indicated that the optimal entropy generation number is proportional to amplitude of non-isothermal wall temperature variation. Li and Yang [24] investigated thermodynamic analysis of free convection film condensation on an elliptical cylinder. Their results expressed that the effect of surface tension forces on the entropy generation number is significant for the larger values of ellipticities (around e > 0.7).…”