Hydrosystem version 4.0 released

In 2017 Hydrosystem celebrates its 40th anniversary. PSRE Co has released large «anniversary» version 4.00 of Hydrosystem program, which includes many significant improvements:

1. Сalculation of two-phase gas-liquid flows with boiling and condensation in branched pipelines (without recycles) is implemented.
   
2. Group pipeline elements selection, group copy/cut/delete operations for both tree and graphic windows are added.
   
3. Waterhammer calculation has been improved:
   1. Speed of waterhammer calculation has been dramatically increased;
   2. Column separation (cavitation) effect is now considered;
   3. Several consecutive pipeline components can now be calculated;
   4. Viewpoints are now checked to be not too close to the reflecting node or an element with a changing statein order to accurately calculate the magnitude of the pressure and velocity peaks;
   5. Waterhammer caused by the opening/closing of the butterfly valve is now more accurately calculated;
   6. Corrections has been made in the waterhammer calculation for pipelines with manually entered inflows/outflows in nodes;
   7. A bug has been fixed that deals with invalid reducer length at calculation.,.
4. Significant changes have been made to the two-phase flow calculation module:
   1. Severe slugging flow in pipelines with gas-liquid flow is now predicted.
   2. Phase change calculation algorithm has been improved - phase transitions points are now determined more accuratey.
   3. Calculation of Mach numbers for water-steam mixtures using the WaterSteamPro library now is more precise.
   4. Some corrections have been made to the calculation of pipelines containing branches with negative flowrates.
   5. The inaccuracy in two-phase flow calculation of temperature and enthalpy after the orifice has been corrected.
   6. The inaccuracy of hydraulic resistance calculation for two-phase flow on vertical pipes is fixed.
   7. The error in the two-phase calculation settings files causing frictional losses on bends, elbows and reducers to be considered differently than on straight pipes has been fixed.
5. Refinements and improvements to other calculation functions of the program have been made:
   1. Internal heat transfer coefficient (from the fluid to the pipe wall) at heat analysis was corrected, thus improving the accuracy of calculations of uninsulated pipelines with strong cooling/warming during flow.
   2. Normalization algorithm of the fluid compounds compositions has been improved.
   3. A bug causing static pressure differences in the closed branches of the pipeline to be inaccurately considered has been fixed.
   4. A rare bug of the incorrect Mach numbers and velocities calculation and output before the pipe enter and after pipe exit has been fixed.
6. Significant improvements have been made to the user interface of the program:
   1. Flow distribution calculation convergence criteria can be now defined by the end user that enables analysis of complex pipelines with convergence problems and speeds up the calculation by reducing its accuracy.
   2. The modeling of pipelines with looped circuits is optimized.
7. Design of the output forms has been improved – their structure is now adapted to export to editable formats (.docx and .rtf).
8. A rare bug causing problems with the printing of the pipeline input data on has been fixed.
9. Some other minor bugs and typos have been fixed.