| Due to compact structure, high efficiency, in a high emission and confined space, Two-phase plate fin heat exchanger has a wide application prospect. At present, The mechanism of two-phase plate fin heat exchanger and the design technology have not been sloved, for more clearly understanding the mechanism of boiling heat transfer, this paper establish a simple physical model based on a structure of plate fin heat exchanger. Set initial conditions and boundary conditions to analyse the mechanism of boiling heat transfer and pressure drop for R21 in a vertical rectangular minichannel. This paper uses ANSYS CFX to simulate the process of saturated boiling heat transfer and pressure drop. Choose inhomogeneous two-fluid model and thermal phase change model to set control equations, and compares the simulation results with experimental data, it shows that the simulation model is reliable.Mass flus, vapor quality,heat flux and fluid pressure are key paramiters to decide the operating condition. This paper analyses the trends by changing only one of them respectively. With increasing the mass flux and vapor quality, the boiling heat transfer and pressure drop will be enhanced, but the heat flux almost doesn’t influnce them. In addition, increase the fluid pressure, the boiling heat transfer will be weakened, and the pressure drop will be reduced. By analysing the phasical parameters and interior force, give the mechanism of saturated boiling heat transfer and pressure drop and the simulation results shows that the leading mechanism is convective mechanism.By comparing the simulation results and correlation calculations, the deviations are all too large.In a minichannel, the effect of surface tension is very significant, so add the non-dimensional parameter We to correct the correlations, compared the simulation results and the datas by the new correlations, it shows that the new correlations are agreed well with the simulation results. |
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