Optimal design of pipe network of district cooling system based on genetic algorithm

Pipe network of district cooling system(DCS) has the characteristics of large investment and high operating cost. Genetic algorithm (GA) is considered to optimize the pipe network design in the study. The detailed method and steps of optimization are investigated. The mathematical model of the global optimal design of DCS is firstly established in which the objective function is annual equivalent cost involving of the initial investment, operation cost, depreciation and maintenance cost. As for the constraints, hydraulic stability is also considered in this study besides the ordinary factors such as pipe diameter, flow velocity, flow needed by users, flow equilibrium and circuit pressure equilibrium. Integer code technology in GA is applied in pipe diameter coding. Referring to different constraints, the corresponding process methods are provided respectively. The fitness function is set up to evaluate the goodness of the individual of a population. The methods of genetic operators are developed in the occasion. An optimal design on a practical example is carried out applying GA, meanwhile, a traditional design is also made. The results demonstrate that GA is useful to optimize DCS pipe diameter design in reducing investment and operating cost by comparison with a traditional method. In addition, the influence of hydraulic stability factor on system economics is especially analyzed.