Research on Pipeline Characteristics and Energy Saving of Distributed Secondary Pump System for District Cooling

The distributed secondary pump system (DSPS) can reduce unnecessary throttling losses compared to the traditional centralized secondary pump system (CSPS). Based on the graph theory and Kirchhoff s law, a set of district cooling (DC) secondary pump system was established. The pipeline network characteristics and energy consumption of the two systems under variable load conditions were compared. The calculation results show that underflow does not occur in DSPS and more than 48.6% of pump energy consumption can be saved. In order to improve the accuracy of the study, the load changes are divided into four types, including full load, single-user load change, two user load changes, and three user load changes, for a total of 50 operating conditions. For greater operational stability of DSPS under variable load, especially at low load rate, some improvement measures have been proposed in the operating range of the variable frequency pump and the connection mode between the pump and the user. The optimization results illustrate that the adopted optimization methods can effectively reduce the maximum hydraulic imbalance degree of the secondary pipeline network and further save energy consumption of the pump by approximately 15.6% compared to that before the optimization. (C) 2019 The Authors. Published by Elsevier Ltd.