Homogeneous versus separated two phase flow models: Adiabatic capillary tube flow in a transcritical CO2 heat pump

Liquid film thickness of two‐phase slug flows in capillary microchannels: A review paper

“…Two models, the separated flow model (SFM) and the homogeneous flow model (HFM), have been used by many investigators to classify two-phase flows in numerical analysis. [16][17][18][19][20] Based on the SFM, each phase can be considered as a region with its velocity and temperature fields; however, having the temperature and velocity distributions of both phases is necessary to solve the problem and some corrections also must be applied to the solution due to the interface between phases. Meanwhile, the same flow and temperature fields are assumed for two phases.…”

“…In contrast, Chingulpitak and Wongwises [18] indicated that the HFM was more effective for designing and optimizing the helical capillary tubes working with different refrigerants. Agrawal and Bhattacharyya [17] compared both models in an adiabatic capillary circular tube and proved that the SFM predicted pressure distribution along the tube better than the HFM. Another comprehensive comparison between both models was performed by Furlong and Schmidt, [19] who found that the SFM shows a smaller error when determining the mass flow rate and has higher accuracy for simulations.…”

Study of helically coiled adiabatic capillary tubes for transcritical CO2 expansion

“…Transcritical expansion of CO 2 in a straight adiabatic capillary tube was simulated employing a homogeneous two-phase flow model. Additionally, a comparative study of flow characteristics of a straight adiabatic capillary tube in a transcritical CO 2 heat pump system was investigated employing separated and homogeneous two-phase flow model [31].…”

“…The expansion process from point 1 to 4 is shown in Fig.1on the pressure-enthalpy plane cycle plot.It is assumed that the capillary tube is straight with constant inner diameter and roughness; further, the flow is one-dimensional, steady, with no heat and work interactions. Homogeneous two-phase flow is assumed since Agrawal and Bhattacharyya[31] has shown that homogeneous flow model predicts such phenomena reasonably well. As mentioned earlier, as the flow progresses in the subcooled region, temperature decreases due to the unique shape of the isotherms, unlike the subcritical system where temperature remains constant in the subcooled region.…”