PipeDiameter

[bramvdh91]

Currently used pipes (Buildings.Fluid.FixedResistances.Pipe) calculate pipe diameter based on nominal mass flow rate and the assumption that the fluid velocity at nominal flow is 0.15 m/s. However, data from pipe manufacturers shows that the pipe velocity is higher in DH context and varies with the pipe diameter. I suggest to use the actual pipe diameter as an input instead, and if needed the nominal mass flow rate as well.