Subsea Spool Heat Transfer Simulation Help.
I am trying to evaluate the thermal efficiency of a subsea warming spool at -47.3C submerged in sea water with an ambient temperature of 4C , in a variety of arrangements In 2D in a 50mby 50m domain. Firstly, single straight Pipe, then a 2 Pipe set-up with offset in the X Direction with the distance between the pipes as a factor of the pipe diameter (i.e 2*D, 3*D , 4*D etc), and finally a 2 Pipe set-up with offset in the Y-Direction with the distance between the pipes as a factor of the pipe diameter (i.e 2*D, 3*D , 4*D etc).
Firstly, as I am trying to model to evaluate the Total heat transfer rate and surface heat transfer coefficent through the pipe to the surrounding sea water and the surface heat transfer coefficent. Do I input the properties of the pipe in the reference value section or of seawater in the reference value, boundary conditions and operating conditions section . In addition, for the pressure in the reference value and operating conditions section do I input the hydrostatic pressure at the water depth. If so the bottom of the seafloor is 800m below sea water and the pipe is in the midldle of the domain. Do I use the Hydrostatic pressure at a depth 800m or at 750m
The variation of seawater density with temperature has been inputed using the piecewise linear function in ANSYS for 50 data points from -47.3C to 4.7C.
Secondlly, there is no velocity for the sea-water so is it necessary to use a turbulence model in my set up. When Using the laminar model I see the covective wake I expect at the bottom of the pipe and the build up and jetting of cold fluid at the bottom of the pipe:
When using the K-omega model (with and without low Re-correction) I dont see this result, I see no covective wake at all. I do understand that the K-omega model is best suited for aerofilols and turbomachineries but i dont understand why. Finally when trying to get a value for the Surface Heat Transfer Coeefficent out of ANSYS Fluent and CFD POST (+/-) Xe16 which is very far away from the hand calculated value of 218.
Looking forward to hearing from you soon.