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Thermodynamics Kinetics of Dynamic Systems Part 4

Tham khảo tài liệu 'thermodynamics kinetics of dynamic systems part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Modeling and Simulation for Steady State and Transient Pipe Flow of Condensate Gas 79 Fig. 9. The steady state liquid velocity variations of the condensate gas pipeline Fig. 10. The steady state liquid holdup variations of the condensate gas pipeline The feature of condensate gas pipelines is phase change may occur during operating. This leads to a lot of new phenomena as follow 1. It can be seen from Fig.6 that the pressure drop curve of two phase flow is significantly different from of gas flow even the liquid holdup is quite low. The pressure drop of gas flow is non-linear while the appearance of liquid causes a nearly linear curve of the pressure drop. This phenomenon is expressed that the relatively low pressure in the pipeline tends to increase of the gas volume flow the appearance of condensate liquid and the temperature drop reduce the gas volume flow. 2. It can be seen from Fig. 7 that the temperature drop curve of two phase flow is similar to single phase flow. The temperature drop gradient of the first half is greater than the last half because of larger temperature difference between the fluid and ambient. 80 Thermodynamics - Kinetics of Dynamic Systems 3. It can be seen from Fig. 8 and Fig.9 that the appearance of two phase flow lead to a reduction of gas flow velocity as well as an increase of liquid flow velocity. The phenomenon also contributes to the nearly linear drop of pressure along the pipeline. 4. The sharp change of liquid flow velocity as shown in Fig. 9 is caused by phase change. The initial flow velocity of liquid is obtained by flash calculation which makes no consideration of drag force between the phases. Therefore an abrupt change of the flow rate before and after the phase change occurs as the error made by the flash calculation cannot be ignored. The two-fluid model which has fully considerate of the effect of time is adopted to solve the flow velocity after phase change and the solutions are closer to realistic. It is still a .