Simulation model

We make the following assumptions while constructing the simulation:

• The integration time step (dt) is 1E-4 seconds for the very fast dynamics of this system. You can set the time step on the Simulation Manager while in the Model Writing role.

  

• Heat transfer is negligible for the short duration of the transients of interest.

• The tube ruptures instantly as a conservative assumption.

• The high-pressure fluid only flows into the outlet channel. High-pressure fluid would also flow into the opposite return channel. However, since the reference paper2 assumes that this does not occur, we do not introduce a second flow of rupture material into the return channel.

• The entire low-pressure section (cooling water side) splits into control volumes in the following sequence:

  1. Supply header

  2. Inlet piping

  3. Inlet channel

  4. First tube pass bundle

  5. Middle channel

  6. Second tube pass bundle

  7. Outlet channel

  8. Outlet piping

  9. Return header

• Each individual control volume is a combination of a PipeFlow and PipeWall model. The PipeFlow helps to calculate the inertia of the low-pressure fluid and the PipeWall model helps to calculate the pressure based on flow, fluid bulk modulus, and elasticity.

• We assume pressure is uniform throughout each pipe wall, which includes the pipe wall where the tube high-pressure fluid enters.

• The equivalent length of each tube bundle pass is based on the total cross sectional area of all of the tubes, and the pressure drop provided from the exchanger data sheet.