Optimizing the pressure drop per unit length of district heating piping networks from an environmental perspective

摘要

The annual environmental impact of district heating (DH) piping networks was minimized by optimizing the pressure drop per unit length (PDPUL) of DH piping networks. An optimization model was developed to determine the optimal PDPUL and minimum annual total environmental impact (ATEI) of DH piping networks. An existing DH system in Yanan, China, was selected as a case study. Heat sources, operating strategies and design temperature regimes were considered in the calculations. Sensitivity analysis was conducted to analyze the effect of pump efficiency, heat source environmental impact point, electricity environmental impact point and service life of piping network on the optimization results. Results demonstrate that the optimization model can be used to determine the optimal PDPUL and minimum ATEI. Coal-fired combined heat and power plant (CFCHPP) and variable mass flow rate (MFR) operating strategies yield better environmental performance, respectively. However, reducing the design heat medium temperature is not beneficial to environment. Sensitivity analysis results show that the electricity environmental impact point and heat source environmental impact point have the greatest impact on the optimal PDPUL and minimum ATEI, respectively. The service life of piping network has the least effect on the optimal PDPUL and minimum ATEI.