Modelling Expansion valve/various pressure domains

Rehan

Hi I have been tracking this forum for sometime now. It was ever helpful to me. Like everyone i am stucking in problems every now and then. I am working with GAMBIT2.2.30/Fluent 6.2. 1. When i have two different fluid zones and both have different pressures e.g for one fluid zone the working pressure is about 6 bar and for the other is 2 bar, how to set them. I tried to set operating pressure to zero and giving individual pressures at my mass inflow boundary condition----result "divergence detected". I tried to set an operating pressure of 2 bar and then gave the other mass inflow pressure as 4 bar (corresponding to my operating pressure)----same result. 2. Has anyone proved the heat and mass transfer udf for flow boiling in an evaporator? 3. My problem is that when the fluid enter the evaporator it is already in 2 phase and then it should take the heat from the inner pipe fluid (double pipe evaporator) and completely change its phase to gas, i try mixture model to solve that and try with a 2d axis symmetry model, is this approach right? 4. How can one model an expansion valve which has on one side a fluid with high pressure and after expansion it lands into a two phase region with a lower pressure? Any one interested in further correspondence and helping me in the field of multiphase flows can contact me through this forum or at one of the following emails. rehan.yousaf@ise.fraunhofer.de rehanyousaf77@yahoo.com or rehan.yousaf@fbta.uni-karlsruhe.de Waiting for a feedback Thanks alot Rehan