HTRI mode selection
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In the examples provided with the software, why do you choose the "calculation" model? What is the difference between it and the "design" model? Has anyone used the "design" model? Can you tell me what the difference is. When I was simulating, when I selected "Calculation", I entered a shell diameter, and it calculated and gave the result. However, when I selected the "Design" model, the same data could not be calculated, and it would run incorrectly. Why is this?
When selecting a design, the heat exchanger software will calculate some heat exchangers based on its own standards, which may not necessarily include the heat exchangers you need.
When using design mode, you should make full use of the optimization function of various parameters of OPTION, and multiple options must be selected. The calculation mode is generally a calculation after various parameters are roughly determined or a calculation of reuse of existing heat exchangers.
The calibration and design input parameters are different. In design mode, Xist finds the smallest exchanger that meets a given performance specification and pressure drop constraints. Parameters that can be automatically varied are: 9 Shell type and diameter 9 Number of shells in series and parallel 9 Number, diameter and length of tubes 9 Number of tube passes 9 Baffle type, cut and spacing 9 Tube pitch The range over which each parameter is allowed to vary is user specified. In rating mode, the user specifies inlet stream conditions, the exchanger geometry, and either the duty or the outlet temperature of one stream. The program then uses energy balances to calculate missing outlet temperatures and, if not given, the duty. Based on these temperatures and the given geometry, the pressure drops and the achievable duty are computed along with the percentage over-design. The latter is based on the computed achievable duty versus the specified (required) duty; it is calculated as (UD/Ureq - 1) x 100. The program is most frequently used in this mode.
Generally, when designing a heat exchanger, you should design it first, use the results of the design, and then calculate it. Let's discuss and learn the specific intermediate details together.* .
There are few conditions required to check the calculation. It mainly depends on whether the basically designed equipment can achieve the expected export parameters and effects, as well as process requirements.
It must be stressed that software convergence and optimisation routines will not necessarily achieve a practical and economic design without the designer forcing parameters in an intuitive way. It is recommended that the design be checked by running the model in the rating mode. From a book on heat exchanger design, it is generally necessary to use the check mode after design, otherwise it will be inaccurate.