Heat and mass transfer in two-phase annular flows in channels with capillary-porous walls under first-type boundary conditions

•Effect of regime parameters of gas and liquid on heat and mass transfer intensity is determined.•Empirical relationship for determining initial thermal section length is obtained.•Empirical relationship for determining heat and mass transfer coefficients at stabilized heat transfer section is obtained. In order to create and perfect modern technologies, it is necessary to have a deep understanding of the processes they are based upon. The classical approach to the study of heat and mass transfer using mathematical modeling involves solving a system of differential equations under appropriate boundary conditions. When studying gas–liquid systems, one needs to determine the driving force of the process. The differential equations for each phase are considered under adjoint boundary conditions, which complicates the mathematical model. Since the solution involves determining local parameters with a required degree of accuracy, it is almost impossible to obtain an exact solution of this mathematical model analytically. The numerical research method requires certain data on the characteristics of the process, namely the local values of heat and mass transfer coefficients. This paper presents the results of a physical study of one of the possible liquid–gas interaction types: cooling of the gas phase with isothermal liquid film using passive intensification methods. Having analyzed the obtained results, the authors determine the system parameters that affect the processes intensity the most and obtain similarity equations for determining local and average heat and mass transfer coefficients at the initial heat section and the stabilized heat transfer section in the range of Reynolds numbers Re=1140⋯8490. Using the obtained dependences allows solving the mathematical model of the process numerically and improving the existing methods of calculating contact heat and mass exchangers.