Configurations and exergy analysis of district heating substations based mainly on renewable energy

Abstract

The energy in the district heating system is transforming into a clean, low-carbon and integrated production and consumption mode to reduce greenhouse gas emissions and dependence on fossil energy. The district heating system has developed to the fifth generation currently, and the water temperature is continuously reduced, and thus the heating efficiency is improved. The proportion of renewable energy sources such as solar, wind, and geothermal energy in substations will continue to increase. In this paper, substation configurations of the fifth-generation district heating system are firstly reviewed, and the exergy analysis is applied to the thermodynamic simulation of the district substations. Thermal simulation models of several types of substations mainly based on solar water heating, water source- and air source- heat pumps or combined forms are developed, the conventional heat exchanger substation is also modeled to compare their performance. The optimization algorithm in Matlab/Simulink is used to solve the thermodynamic numerical model, and performance indicators such as exergy and efficiency are selected to evaluate the performance of these systems.