HOT | COOL NO. 2/2022 - "Conversion from gas - Diversity...

Figure 2 View of data imported into the software

Figure 3 The calculated variant of upcoming distribution area in GF district heating network

a given street grid, in a short time. Consequently, the software has significantly reduced and simplified the process require to complete this study phase. New distribution networks - a variety of features Pipe dimensioning can be done following user-defined sim- ultaneity factors or with the Danish Standard DS439. Further- more, pipe design parameters such as maximum velocity, gradient, or pressure limit are considered. Moreover, the soft- ware provides complete pipe tables of major manufacturers, making the design of networks accurate and based on actual parameters. In the project, twin pipes were used for the new distribution ar- eas, and all three criteria were applied. The maximum network pressure of 10 bar was assumed to ensure low-pressure levels. The specified network criteria fulfilment has been verified in a further phase of the analysis performed in Termis. One of the advantages of the Comsof tool is the ability to de- fine the unit costs of pipelines construction on a given street type. The user can specify these costs depending on any prop- erty (e.g., the density of the utilities in the ground). In addition, service pipes and heat exchangers are part of the calculation. With this approach, the calculated investment costs can be brought significantly closer to reality. The software provides a vast number of ways of routing so that the calculations are as accurate as possible. For example, the trace can be carried in the middle of the road or sideways, depending on the de- clared construction costs.

Using this feature, it was possible to certain network configu- rations effectively, both construction and operating costs. The project covers approximately 6,000 new consumers, of which a significant percentage are single-family houses. Therefore, it was pragmatic to dimension the service pipes and calculate their construction costs. The verification stage After completing the calculations in a Comsof Heat, all new distribution networks were transferred into Termis software. This activity aimed to verify the diameters of the designed dis- tribution pipes and the preliminary diameters of the transmis- sion pipelines when combined with the existing network. This was performed by inspecting the whole system’s velocities, gradients, and pressures. Analyzing the system and the devel- oped distribution networks also allowed obtaining a variety of new knowledge. First, it provided a complete view of the con- ditions in the future network operation. Moreover, it enabled to proper study of the cases involving the partial failure of one or more of the heating centrals. Simulations of the developed network revealed that the di- ameter of some of the planned transmission pipes in the new areas could be reduced while maintaining the maximum sys- tem pressure of 10 bar. These operating conditions required an increase in the booster station pump head. However, without implementing the new distribution networks into the calcula- tion model, these conclusions could not have been reached. Furthermore, this phase confirmed that the previously select- ed dimensioning criteria in the Comsof software were fulfilled.

Figure 4 Sample results of Comsof Heat Designer calculations

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