Setting a Good Balanced Model

  • Always start with inflow known and pressure unknown
  • Must have one unknown inflow for each flow isolated sub-system in the model, at the node where inflow is set to unknown, make the pressure be known (Flow Isolated Region)
  • Must have one known pressure for each pressure isolated sub-system in the model (Pressure Isolated Region)
  • Other known pressure points can be downstream or upstream of a compressor or regulator, in doing so make sure the compressor or regulator control status is unknown.
  • The only nodes which can be both pressure and inflow known are downstream or upstream of a compressor or regulator.

Follow this process to build a good model

  • Understand the Pressure Isolation and Flow Isolation
  • Pressure Isolated Elements (pressure changing legs)
  • Compressor which is turned on, regulator in unknown pressure control, closed valve, closed check valve, etc…
  • Flow Isolated Elements (flow limiting legs or zero flow legs)
  • Closed valve, flow control regulator, closed check valve, shut – in compressor with closed valve in off mode, etc.