General Release info:
Improved pipe heat loss calculation with the addition of new correlation for estimating outside film heat transfer coefficient. Bug fixes.
* Crane Tee Junction TP410 pre 2009 relationships. New recommendation is to use for existing/legacy calculations ONLY. Input editor text now reflects this.
The relationships are just too simplistic to realistically predict the pressure losses over all possible operating conditions and totally ignore any pressure recovery effects.
* All Heat Transfer Coefficients in pipe results were shown as W/m C where units shown are W/m2 C. Coefficient values now normalised to W/m2C by multiplying original value by the log mean radius.
This is more in line with most literature sources. Change was made not because answers or calculations are incorrect but because it is now easier compare values directly with common literature sources.
* Following a suggestion from some of our German customers, we incorporated a new improved method for estimating the outside coefficient in pipe heat loss/gain calculations.
The literature source for the improved method is the Springer publication “VDI Heat Atlas (VDI Wärmeatlas)”.
Previously FluidFlow used ASTM Standard C680. It is still possible to use the original ASTM Standard C680 relationship, selected from the Options -> Calculations Dialog -> Global Settings tab.
* Co2 gas density and specific heat definitions have been adjusted to provide more accurate results over a wider temperature and pressure range.
* Diffusers at choked conditions show the inlet results as outlet results.
* In networks containing centrifugal pumps and more than one fluids with viscosities of > 800 cP, sometimes Pump viscosity corrections were made when this should not be the case.
* Outside heat loss convection was overestimated in rare cases for gas flow along medium/long pipes.
* Improved convergence testing to prevent the solver converging too soon. For gas calculations this sometimes resulted in incorrect downstream temperatures.
* Reservoir No Flow – Bug in creation of accumulator for solver.
* Pump derating and speed changes were not working when both effects occurred together.