Conduit Pressure Analysis and Renewal Effect of a District Heating and Cooling Plant

Abstract

The Seaside Momochi District Heating and Cooling (DHC) plant in Fukuoka, which has been operated for more than 25 years, directly uses seawater as heat source water. The current system COP is nearly 1.00, the improvement of which is a focal point in renewal of the DHC plant. The purpose of this study is, through renewal, to present a proposal for a new management and control method of DHC including customers as well as plants. For optimal plant control, energy loss in the whole system should be analysed in detail. In this study, as a kind of energy, pressure distribution is investigated in focus on regional conduit. First, for comprehension of renewal effect, the system COP after renewal is simulated. By optimization of the operation priority order, the system COP is calculated to be about 1.20 at least. Then, for water supply system, pressure loss inside regional conduit is calculated to be very small. By minimization of the energy loss including regional conduits and customer receiving facilities, the total pump water power could be reduced by more than 40 percent. This means that further consideration of supply pump control and system management would significantly contribute to effective energy saving.