Optimal design for treeshaped chilled water pipe network in district cooling systems

Develops an optimal design model on condition that the pressure drops of each parallel connection loop are equal. The objective function of the model is the annual costs of the system, including annual operating costs and depreciation costs of chilled water pumps, depreciation and maintenance costs of pipeline, and costs of chiller power consumption rising from cold loss through chilled water pipe wall. By a case study, obtains the following results: the treeshaped chilled water pipe network in district cooling systems should not be designed by equal specific frictional resistance or by equal velocity; the annual costs of the system obtained by the optimal model decrease by 17% than those by the equal velocity model and the economical benefit is remarkable; the differences of pressure drop of each segment pipeline are considerable by the equal velocity model, then the adjustment of the system is difficult and the pressure stabilization is destroyed easily, and the annual costs of the system increases.