Function method for dynamic temperature simulation of district heating network

• Published in: Applied thermal engineering 2017-08, Vol.123, p.682-688
• Main Authors: Zheng, Jinfu, Zhou, Zhigang, Zhao, Jianing, Wang, Jinda
• Format: Article
• Language: English
• Subjects: Calculation time; Computer simulation; Delay; Delay time; District heating; District heating network; Dynamic temperature simulation; Fourier series; Function method; Heat loss; Heating; Pipe; Relative attenuation degree; Series expansion; Specific heat; Substations; Temperature; Temperature distribution; Time lag
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2017.05.083

•A new physical method for dynamic temperature simulation of DHN was proposed.•Dynamic thermal conditions can be solved analytically and efficiently.•Method was validated at large and quick temperature changes and different flows.•Simulations of new method is agreed better with measurements than node method.•Compared with node method, the calculation time of new method is reduced by 37%. A thermal dynamic characteristic of district heating network was analyzed with an emphasis on simulating dynamic temperature distribution. Therefore, a new physical method (namely function method) and corresponding computer codes for dynamic temperature simulation were proposed. The function method takes into account variousfactors, such as flow time, heat capacity of the pipe and heat loss, in one single step by using Fourier series expansion as the mathematical basis to obtain the analytical solution of transient energy equation. Further, two key parameters, delay time and relative attenuation degree, were described to represent the time delay and heat loss respectively and were used to obtain the temperature distribution of the network. Moreover, the function method is validated by applying it to a real district heating network at different temperature change stages. For comparison purpose, the node method was also used, and the simulated supply temperatures at substations were compared with measurements. Comparisons of both methods were also performed considering different fluid velocities at heat source using numerical results. The results showed that the function method could be recommended to simulate the dynamic temperature of district heating network accurately and quickly for efficient system performance.