Can the VMGThermo package in HTRI6.0 be used directly?

Pure substances such as water and air should be usable, while mixtures and compounds are better avoided as their physical property data is uncertain.

I’m a beginner; at this stage I only perform calculations for heat exchangers with pure medium components. I have already checked the option for pure medium components in the “Control” section of the Htri design interface

What is this medium of yours? Water and air?

The heat-releasing medium flows in the tube side; it is pure-component hot water (liquid–liquid), for which water from the HTRI package (IAPWS 1997) was directly selected. The heat-absorbing medium is on the shell side; it is the pure compound 1,1,1,3,3-PENTAFLUOROPOPANE (liquid → vapor), and 1,1,1,3,3-PENTAFLUOROPOPANE from the VMGThermo package was chosen directly.

If the heat-releasing medium is hot water, the vapor weight fraction should be 0/0. If the heat-absorbing medium evaporates completely during the phase change, the vapor weight fraction should be 0/1. Try changing it and see

Thank you for your advice; I got the phase of this medium wrong before, but I’ve corrected it now. There were still problems when using the VMGThermo package, so I’ve switched to the REFPROP package, which can be used as a substitute. I still need to figure out what’s going on with the VMGThermo package. If calculated based on an outlet temperature of 80.6°C for the cold medium, a vapor-liquid mixture is obtained as a result. Therefore, the pressure of the heat medium was reduced to 0.6 MPa (A), and the outlet temperature was reduced to 70°C. Based on the results, the EMTD value is lower than the theoretical convective heat transfer coefficient obtained by manual calculation (47.4°C), indicating that the overall heat transfer coefficient is too low. Also, the flow velocities on the shell side and tube side seem to be low as well. I would appreciate it if an expert could advise me on how to optimize it.

This post was last edited by Tmacey on 2020-5-3 at 08:14. If the flow velocity on the tube side is low, a 2-tube or 4-tube arrangement can be used; on the shell side, the flow velocity can be increased by adjusting the spacing of the baffle plates, and as a result the heat transfer coefficient also increases. Check whether the pressure drop exceeds the allowable value. As for the temperature difference, this is the effective temperature difference, which is smaller than the logarithmic temperature difference calculated manually. Take a look at the detailed results to see what coefficients have been applied, resulting in such a small difference

This post was last edited by wanlirn on 2022-9-5 10:06. For this type of evaporator design, HTRI remains unreliable; try using Aspen EDR instead. Also, the fouling due to evaporation for a pure substance is 0.0006 – is that really that high?