How should prompt-related issues in HTRI’s output results be handled?
Thread Content
I would like to ask the experts here: if the following issues arise in the HTRI output reports, what methods can be used to address them? 1. The tube inlet velocity is greater than the inlet nozzle velocity, resulting in the momentum pressure drop between the inlet nozzle and the tube inlet not being taken into account in the calculations. This pressure drop can be significant in a vacuum condenser; therefore, it’s important to ensure that there is enough margin to accommodate this additional pressure loss. 2. The physical properties of the hot fluid have been estimated beyond the valid temperature range. It’s necessary to check these calculated values, as thermal analysis requires property values at both the bulk temperature and the surface/wall temperature. Please help me understand the reasons behind these issues and suggest ways to deal with them.
There are issues with both the pressure drop and temperature. Regarding the pressure drop, you might consider increasing the diameter of the heat exchange tubes. As for the temperature problem, please check your process parameters carefully~
The flow rate is too high, resulting in a large pressure drop. Try reducing the number of tubes and increasing the shell diameter.
This post was last edited by adog8207 on 2017-8-13 00:08. 1. The flow velocity at the inlet of the heat exchange tube on the pipe side is greater than that at the nozzle; the pressure drop resulting from this change in momentum is not included in the pressure drop calculation. The pressure drop in this section is quite important for vacuum condensers; it is necessary to ensure there is a margin for this pressure drop. The nozzles and the number of tubes can be adjusted to make the speeds at these two locations roughly equal. If it is not in a vacuum, this prompt can be ignored. 2. The properties of the hot-side fluid are obtained by extrapolation; check whether these values are reliable. Thermal analysis requires the overall temperature of the medium as well as the temperature at the surface/wall. This message indicates that the material properties entered do not cover the entire temperature range; during calculation, the software uses extrapolation to determine the properties for temperatures outside this range. For example, if the temperature of the hot fluid changes from 200 degrees to 40 degrees, and you only enter the property values for the range of 150 degrees to 40 degrees, the software will use extrapolation to calculate the property values for the range outside this temperature range (200 degrees to 150 degrees). Since the values obtained through extrapolation are not exactly the same as the actual values, a warning is given to prompt you to verify the property values. Generally speaking, the properties of multiphase fluids can be considered linear; therefore, this warning can be ignored. However, in cases involving condensation, it is still necessary to provide complete property data to obtain accurate calculations.
Thank you so much! Friend request sent.