Prediction of heat and fluid flow in microchannel condensation

Abstract

The condensing flow inside the microchannel has gained importance as the microchannel heat exchangers are widely used in the industry. In this study, a number of numerical simulations on condensing flow inside the microchannel were conducted to investigate heat transfer characteristic. Circularmicrochannel geometries with the various diameters were considered. The Volume of Fluid model was used to model twophase flow. The phase change at the saturation temperature was modeled by the Lee model.In the considered geometries, different from the conventional channels, surface tension forces can be importantcomparedto other forces. Therefore, surface tension was considered in the simulations. Constant wall heatflux and constant saturation temperature were applied as simulation conditions, similar to actual operating conditions. The predictions were validated by comparisons with the experimental results that exist in the literature. A satisfactory agreement of the present predictions with the experimental data was observed.

Condensation Flow of Refrigerants Inside Mini and Microchannels: A Review

“…Many studies on refrigerant condensation inside micro/minichannels exist in the literature, but they investigate condensation flow, especially for Hydro-Fluoro-Carbons (HFCs), Hydro-Cloro-Fluoro-Carbons (HCFCs), and mixtures of them. It is important to highlight that the existing literature lacks comprehensive investigations that accommodate a broad spectrum of working fluids, mass fluxes, saturation temperature, pressures, channel geometries, and dimensions [6,7]. As stated, previous experimental and numerical investigations have predominantly concentrated on the condensation behaviour of HFCs, HCFCs, refrigerant blends in microchannels.…”

“…Another transition criterion based on flow phenomena was proposed by Nema et al [27]. They proposed the critical Bond number (Bo cr ), as defined in Equation (7), which delineates the shift from macroscale to microscale, serving as a gauge for the relative significance of surface tension over gravity. Nema et al [27] stipulate that when the Bond number (Equation ( 5)) is less than the critical Bond number (Equation ( 7)), surface tension supersedes gravity in influence.…”

“…Employing the volume of fluid (VOF) model, they utilised the SST-k-ω turbulent model to simulate both vapour and liquid phases. A steady-state numerical simulation of the condensation flow of R600a was conducted by Basaran et al [7]. The authors numerically investigated the heat transfer characteristic condensation flow at mass fluxes ranging from 200 to 600 kg/m 2 s inside a single circular microchannel with varying diameters.…”

Experimental Investigation of InTube Condensation of HFO-1234yf

“…HTC by MM Sha's correlation [18] ... (10) ... (11) ... (12) ... (13) ... (14) Jg is a dimension less velocity factor defined as ... ( 15) MM Shah et.al [14] defined three regimes I, II, and III. Jg for regime I is defined as J g1 ... (16) Jg for regime II is defined as J g2 ... ( 17) MM Sha's HTC calculated asper following condition If Jg = J g1 then regime is I regime ... (18) If Jg =J g2 then regime is II regime ... (19) ... (20) The HTC of refrigerant is calculated as per the regime condition that occur during condensation. And equations from 12 to 17 solved by using MAT Lab and Refprop software's.…”

“…Thome et al [4], Garimella et al [3], Dalkilic et al [11], Kim and Mudawar et al [15], Awad et al [16], and Del Col et al [18] examined and compared the MM Sha correlation extensively. The results showed a mean deviation of 22%.…”