Problems encountered when exporting heat curves from Aspen Plus to HTRI: thermal siphon effect

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As the title suggests, there are two methods for importing data from ASPEN into HTRI: 1. ASPEN PLUS--EDR--HTRI; 2. ASPEN PLUS--save as a SUM file, then use the customize tool to export the .dat data, which is subsequently imported into HTRI. Next, let’s discuss the advantages and disadvantages of the two methods: 1: It can automatically generate heat curves for three different pressures (with the possibility to modify these pressures), but it lacks critical pressure data, which can be entered manually later. However, the following errors will occur: Vapor density (cold, ibar 1): Not all profile points were entered. Values will be assigned. Please ensure that both dew point and bubble point data (at vapor fractions of 1 and 0) for both the liquid and vapor phases are specified. Vapor viscosity (cold, ibar 1): Not all profile points were entered. Values will be assigned. Please ensure that both dew point and bubble point data (at vapor fractions of 1 and 0) for both the liquid and vapor phases are specified. Vapor thermal conductivity (cold, ibar 1): Not all profile points were entered. Values will be assigned. Please ensure that both dew point and bubble point data (at vapor fractions of 1 and 0) for both the liquid and vapor phases are specified. Vapor heat capacity (cold, ibar 1): Not all profile points were entered. Values will be assigned. Please ensure that both dew point and bubble point data (at vapor fractions of 1 and 0) for both the liquid and vapor phases are specified. Liquid density (cold, ibar 1): Not all profile points were entered. Values will be assigned. Please ensure that both dew point and bubble point data (at vapor fractions of 1 and 0) for both the liquid and vapor phases are specified. Liquid viscosity (cold, ibar 1): Not all profile points were entered. Values will be assigned. Please ensure that both dew point and bubble point data (at vapor fractions of 1 and 0) for both the liquid and vapor phases are specified. Liquid thermal conductivity (cold, ibar 1): Not all profile points were entered. Values will be assigned. Please ensure that both dew point and bubble point data (at vapor fractions of 1 and 0) for both the liquid and vapor phases are specified. Method 2: Directly export data from ASPEN PLUS to a .dat file, and then import it into HTRI. However, for thermosiphon reboilers, the following error occurs: This thermosiphon case specifies fewer than 3 pressures for the physical properties of the cold fluid. With the current fluid properties, the program’s ability to determine the saturation temperature at the exchanger inlet pressure may be compromised. This can result in either no liquid zone or an incorrectly sized liquid zone at the bottom of the exchanger. It is recommended that you specify additional pressure profiles and run the calculation again. The pressure profiles provided for the cold fluid do not cover the operating pressure range of the heat exchanger; as a result, the vaporization profile inside the exchanger may not be accurate. The software does not extrapolate beyond the specified reference pressure range, but rather uses the reference pressure that is closest to the relevant value for heat release and property data. It is recommended to use the maximum and minimum system pressures as reference pressures. None of the specified cold fluid heat release profiles correspond to pressures near the exchanger inlet pressure of 19 kPa (2.8077 psia). In low-pressure applications, Xist may not be able to accurately predict the saturation temperature at the exchanger inlet nor the length of the subcooled zone. Check the monitoring device (either on the shell side or tube side, depending on where the boiling fluid is located) to ensure that boiling begins at a temperature and pressure consistent with the entered heat release curves. If not, specify a pressure profile at or near the exchanger inlet pressure. This message is displayed when no pressure profiles fall within 10% of the exchanger inlet pressure, considering the operating pressure range (from the exchanger inlet pressure to the pressure at the bottom of the column). For this thermosiphon reboiler, it seems that only 1 heat release profile is specified within the operating pressure range. The lowest pressure should be at the bottom of the column, while the highest pressure should be at the exchanger inlet. To obtain the most accurate results, at least three pressure profiles should be specified within this range: one at the pressure at the bottom of the column, another at the exchanger inlet pressure, and at least one at an intermediate pressure. If these guidelines are not followed, Xist may not be able to accurately predict the saturation temperature at the exchanger inlet nor the length of the subcooled zone. I’m curious to know how others handle this issue Thank you very much