Modeling of annular and intermittent flow condensation in micro- and mini- channels with experimental validation. (September 2021)

• Record Type: Journal Article
• Authors: Keniar, Khoudor; Garimella, Srinivas
• Is Part Of: International journal of heat and mass transfer. Volume 176(2021)
• Publication Date: 2021-09
• Subjects: Condensation -- Annular flow -- Intermittent flow -- Laminar -- Mechanistic models; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2021.121507
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: First principles modeling of intermittent and annular flow condensation in microchannels. Models validated with experiments at different mass fluxes, saturation temperatures and saturation-to-wall temperature differences. Annular model compared with data for square and circular geometries. First order, mechanistic intermittent flow regime model in square microchannels developed. Range of applicability of models in terms of mass flux and film Reynolds number established. Abstract: Mechanistic models for predicting condensation heat transfer in the annular and intermittent flow regimes are presented and compared with data for different working fluids (R134a and R245fa) over a range of mass fluxes, saturation temperatures (30 ≤ T sat ≤ 50 °C), saturation-to-wall temperature differences (1.5 < ΔT < 2.5 K), and channel geometries. The annular flow model is based on a laminar assumption and is applicable to arbitrarily shaped micro- or minichannels. Model predictions are validated using experiments focusing on low mass fluxes ( G ≤ 100 kg m −2 s −1 ), for which there are few analytical models or experimental data. The intermittent model developed here is also validated based on similar experiments. The annular model is found to be applicable for G ≤ 100 kg m −2 s −1, Re δ < 61 (square), and Re δ < 125 (circular), while the intermittent model is applicable for G ≤ 150 kg m −2 s −1 and 78 < Re δ < 365.