Accounting for the regulation of district heating (DH) system

The basic regulation formula (RF) based on direct-connection DH system is widely used to operate the DH systems, but the formula maybe not suitable for indirectconnection DH system. Here indirect connection means that the working fluid circulated in CHP and the primary network is not the same medium that flows in the secondary network. Therefore, this paper deduces the regulation formula for indirect-connection DH system. According to accuracy analysis, we find that the applicability of the regulation formula should be based on three conditions: 1) The design indoor temperature and volume specific heat load of all buildings are the same; 2) The same type of heating devices are used in the buildings after each substation or all heating devices are deemed as a big radiator with average performance; 3) The supply and return water temperatures in primary and secondary sides are the same for each substation. If the three conditions cannot hold true at the same time, then the accuracy of regulation formula should be analyzed first.