Complete Condensation of Forced Convection Two-Phase Flow in a Miniature Tube

Abstract

A physical and mathematical model of annular film condensation in a miniature tube has been developed. In the model the liquid flow has been coupled with the vapor flow along the liquid-vapor interface through the interfacial temperature, heat flux, shear stress, and pressure jump conditions due to surface tension effects. The model predicts the shape of the liquid-vapor interface along the condenser and the length of the two-phase flow region. The numerical results show that complete condensation of the incoming vapor is possible at comparatively low heat loads. Observations from a flow visualization experiment of water vapor condensing in a horizontal glass tube confirm the existence and qualitative features of annular film condensation leading to the complete condensation phenomenon in small diameter (d < 3.5 mm) circular tubes.

Mathematical model of a loop heat pipe with cylindrical evaporator and integrated reservoir

“…In the model of the condenser tube, the main assumption made is that the two-phase pattern is the annular flow, which is correct for typical diameters of LHP condenser and mass flow rates, as described by other studies [29,18]. This main approach for condenser modeling is the same as used in EASY2000 software for LHP [22].…”

“…The approach for local energy balance over the condensing film was taken from [18]. The radiator-condenser assembling is divided by 110 isothermal elements and shown in Fig.…”

“…Most of mathematical models were developed for local processes, either for the evaporator or condenser tube, with welldefined fixed boundary conditions. From the broad variety of such models, it can be cited those developed for element of CPL evaporator [15], the evaporation process from meniscus of porous wicks [16], completed researches on evaporation from evaporator bulk of a CPL [17] and the most complete steady-state model of full condensation developed by Begg et al [18]. There were several attempts to develop the model on the loop level.…”

Unsteady steam condensation flow patterns inside a miniature tube

“…The aim of the research in this field is to maximize the heat transfer coefficient and to minimize the pressure drop in the heat exchangers. Several experimental studies were conducted previously for condensation inside the sub-millimeter-scale diameter channels [1][2][3][4][5][6][7]. Numerous experimental results and empirical correlations were reported in the literature for condensation inside a large hydraulic diameter of the channel [8][9][10].…”

Non-Isothermal Spontaneous Imbibition Process Including Condensation Effects and Variable Surface Tension

“…Therefore, a fundamental understanding of the condensation process in minichannels and capillaries is important to optimize design considerations. In this direction, for possible use in electronic cooling applications, Begg et al [1] developed a mathematical model of annular film condensation in a miniature tube. In this model, the liquid flow has been coupled with the vapor flow along the liquid-vapor interface through the interfacial temperature, heat flux, shear stress and pressure jump conditions.…”