对于refprop9.0以前版本处理ammonia-water混合物出错的问题，在refprop9.1中得到了改进，之前在NIST购买过正版refprop9.0的用户可以免费升级为9.1。此外，官方还贴出了以下文件。
For ammonia/water mixtures, there are a number of issues with the Tillner-Roth and Friend equations that have caused problems. These include a 6% error in the speed of sound in the liquid phase for pure ammonia (and thus in the mixture model with higher ammonia concentrations), and incompatibility with the latest excess Helmholtz mixture models. Both the ammonia equation of state and the mixture model are currently being refitted. With the 9.1 DLL, you will find that the new ammonia/water fits are extremely fast compared to the equations in version 9.0. However, the accuracy is not quite as good, and calculations will have slightly higher errors. This will change as we finalize the fits. To use the latest fits, copy the AmmoniaL.fld file below to your Refprop\Fluids directory. This will only work with version 9.1, not anything earlier. The AmmoniaL.fld file does not replace your Ammonia.fld file. When selecting the mixture, you must select "Ammonia (Lemmon)" instead of "Ammonia". If this new fluid does not appear, go to Substance/Specify Fluid Set, and select "All Fluids".
AMMONIAL.FLD
Last updated: June 6, 2013
For ammonia/water mixtures, there are a number of issues with the Tillner-Roth and Friend equations that have caused problems. These include a 6% error in the speed of sound in the liquid phase for pure ammonia (and thus in the mixture model with higher ammonia concentrations), and incompatibility with the latest excess Helmholtz mixture models. Both the ammonia equation of state and the mixture model are currently being refitted. With the 9.1 DLL, you will find that the new ammonia/water fits are extremely fast compared to the equations in version 9.0. However, the accuracy is not quite as good, and calculations will have slightly higher errors. This will change as we finalize the fits. To use the latest fits, copy the AmmoniaL.fld file below to your Refprop\Fluids directory. This will only work with version 9.1, not anything earlier. The AmmoniaL.fld file does not replace your Ammonia.fld file. When selecting the mixture, you must select "Ammonia (Lemmon)" instead of "Ammonia". If this new fluid does not appear, go to Substance/Specify Fluid Set, and select "All Fluids".
AMMONIAL.FLD
Last updated: June 6, 2013
