Direct contact condensation heat transfer characteristics of vapor with noncondensable gases in horizontal tubes

Abstract

Direct contact heat transfer characteristics of vapor condensation with noncondensable gases in horizontal tubes are studied in this paper. A three-dimensional computational model is proposed and effects of cross-flow and droplet particles interactions are investigated. During the vapor condensation process, the convective heat transfer is attenuated due to the presence of noncondensable gases and the condensation rate is significantly reduced by 34% in the horizontal tubes due to gravity effects. A pair of counter-rotating vortex pair (CVP) is formed as influenced by adding droplet particles. Because of the centrifugal effect of vortical pair, the droplet particles are not uniformly distributed. This is not beneficial to the heat and mass transfer phenomenon. The cross-flow turbulence intensity is increased by 41.6%, as confirmed between the coherent structure in the main flow region and the CVP structure. The coherent structure can transfer energy between the CVP structure and the mainstream region, and suppress the droplet particle diffusion. In addition, the operating pressure up to 3 MPa is found to enhance the heat transfer performance. The optimal flow ratio is 1 to 8. The work provides new insights into the direct contact flow and heat transfer characteristics of vapor with noncondensable gases.