Retro-commissioning of a heat source system in a district heating and cooling system

To improve the energy performance of a district heating and cooling (DHC) plant, the expected performance of the plant was studied using simulations based on mathematical models. A model of the entire heat source system with an embedded module that automatically determines the on/off status of heat source equipment using cooling/heating loads was developed and validated using measured actual performance data. The mean error between the simulated and measured total energy consumption was 4.2%. Using the developed model, four proposals for improving the plant operation were simulated to determine potential energy savings. The simulation results show that the four proposals, reducing pipe resistance, optimization of chiller subsystem, improving the operation of chilled-hot water switchover thermal storage tanks, and optimizing the operational control of an external thermal storage tank, can reduce the energy consumption of the thermal storage pumps by 24%, chiller subsystem by 1.4%, and energy consumption and costs of the entire plant by 6% and 2.7%, respectively. If all of four proposals were applied, total power consumption and energy costs could be reduced by 11.0% and 8.2%, respectively.