Operational Optimization And Algorithm Of City Hot Water District Heating System

The rapid development of central heating, the heating network has expanding, the heating load increased, and with the size of the heating pipe network increases, the operating costs of the system began to grow, hydraulic and heat conditions of the entire pipe network become very complex. With the end user increasing, the system put much higher forward to the pipeline network running adjustment method. In order to meet the user and save the running costs of heating pipe network, the urban heating system operation optimization is imperative.This paper take the city heating pipe network as the study of subject. An operational cost equation of a primary network in a district heating system is set up. taking the supply water temperature and the water flux as variables,. The optimization objective of the equation is to minimize the operational cost, and its constraints are operational characteristics of the primy network. The operational cost including the cost of heat loss and the circulating pump power consumption. Take the part of heat loss consumption, this paper use the method of least squares polynomial fitting, basis of the original formula. This method not only ensure the accuracy of the values, but also simplifies the tedious process. Optimization method use genetic algorithms and nonlinear programming algorithm, based on the guidance of the theory, use Matlab and Visual C#program. According to the characteristics of the model, select the appropriate parameters and methods, then get the optimal solution. The genetic algorithm procedures are simple and randomization, however, the nonlinear programming algorithm the course of running is simple and straightforward. Compared the calculates of two algorithms, this paper found the error less than4%, so genetic algorithms and nonlinear programming algorithm are reasonably practicable for this topic. This paper put forward three adjustments, such as centralized quality adjustment, multistage quantity adjustment, and quality-quantity regulation. By comparing the optimal water temperature, the circulation flow rate, and the operational cost equation, the result show the operational cost equation of alone quality-quantity regulation is less than half of the centralized quality adjustment, but more than13.5%to the multistage quantity adjustment. This is due to the circulating pump power consumption costs has a large proportion of the cost of energy consumption, but also the How ratio is less than multistage quantity adjustment. Take into the minimum system running energy cost, this article presented the mixed adjustment, the system uses quality-quantity regulation when the outdoor temperature at-8℃to-3℃. then when the outdoor temperature raised-2℃to5℃. the system uses multistage quantity adjustment. The system running cost is less16.3%than quality-quantity regulation, but also the by brid adjustment not only save a lot of operating costs, but also possesses the characteristics of each tune.