Computational fluid dynamics for condensation in mini and microchannels

Abstract

Computational fluid dynamics (CFD) analysis was performed to evaluate and compare the condensation of steam in mini and microchannels with hydraulic diameter of 2mm, 2.66mm, 200μm and 266μm respectively. The simulation was run at various mass flux values ranging from 0.5 kg/m²s and 4 kg/m²s. The length of the mini and microchannels were in the range of 20 mm to 100 mm. CFD software’s GAMBIT and FLUENT were used for simulating the condensation process through the mini and microchannels. Steam flowed through the channels, whose walls were cooled by natural convection of air at room temperature. The outlet temperature of the condensate was in the range of 25ºC to 90ºC. It was found that the outlet temperature of the condensate decreased as the diameter of the channel decreased. It was also evident that the increase in length of the channel further decreased the outlet temperature of the condensate and subsequently the condensation heat flux. The investigation also showed that the pressure drop along the channel length increased with decreasing hydraulic diameter and length of the mini and micro channel. Conversely, the pressure drop along the channel increased with increasing inlet velocity of the stream.