How should prompt-related issues in HTRI’s output results be handled?
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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 sufficient 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. I hope the experts can help identify the reasons for these issues and suggest ways to resolve them.
Has it been solved, OP? I also want to ask these two questions
The flow rate in the pipe train is too high; adjust the design by increasing the number of heat exchange tubes. This issue also occurs frequently in the second case – I’m not sure how to deal with it
The first point states that, for the calculated tube-side condensation case, the fluid flow velocity at the inlet of the tube bundle is higher than that at the inlet opening of the tube sheet, resulting in a pressure drop due to the change in fluid momentum (acceleration). This type of resistance loss is not included in the HTRI pressure drop calculations, which warrants attention, especially for condensers operating under vacuum. In fact, if there is still some margin between the allowable pressure drop and the calculated pressure drop, there is no need to pay attention to this warning message. Otherwise, the acceleration pressure drop can be estimated based on the difference in the two velocity heads. Article 2 states that if the property data entered by the user or imported by the process simulation software only covers the range from the inlet temperature to the outlet temperature of the material, the software needs not only the properties of the material at its nominal temperature but also those at the pipe wall temperature in order to calculate the correction factors for the effect of the wall temperature on the membrane heat transfer coefficient and pressure drop. Therefore, when the software calculates the properties of the pipe wall temperature, it involves extrapolation calculations outside the range of valid property temperatures, which may lead to deviations. The solution is to provide property data over a wider temperature range, including wall temperature conditions. For example, if a hot fluid cools from 150 degrees to 100 degrees and the wall temperature is estimated to be between 60 and 70 degrees, then the property parameters, which provide data for a temperature range of 150/50 degrees, can prevent this warning from appearing. The same applies to cold fluids: additional property data at a temperature slightly higher than the outlet temperature are provided to cover wall temperature conditions.