Electricity demand analysis of a primary pump system in a district heating system
Abstract: This report provides data and an analysis within the framework of modeling and simulation of District Heating Systems (DHS) in China. Two students from the Royal Institute of Technology (KTH) performed this field study at Zhejiang University (ZJU), in the year of 2018. During the last decades, China has made a substantial economic development with a dramatic increase in BNP which is transforming China into an industrialized country. Improving the life conditions, and managing the urbanization of such a big population, causes challenges when this transformation must be sustainable to meet the climate goals. In this transformation process, DHS play an important role in terms of providing fair living conditions. To optimize these systems, and thus make energy reductions when possible, is the key foundation that will enable the expansion of effective DHS and enhance sustainable development. By modeling and simulating DHS, different configurations can be compared and the best configuration alternatives can be found. This report focuses on comparing Conventional Central Circulating Pump system (CCCP system) and Distributed Variable Speed Pumps system (DVSP system) to determine the most electric energy efficient configuration of a DHS. The results were used to compare the outcome of previous studies claiming that the DVSP system is more efficient than the CCCP system. In this project, a primary pump system of a DHS in the Guizhou province, China, was investigated. In order to compare the two different configurations of the DHS, two steady state models were created in the district energy optimization software Termis. One model for each configuration. Further, four scenarios were simulated for a specified set of input data. In scenario I and II, the electricity demand in a DVSP system during winter and summer respectively, were investigated. In scenario III and IV, the same simulations were made but for a CCCP system. All simulations indicated that the electricity demand in a DVSP system were lower compared to a CCCP system. This is due to the fact that no throttling of hydraulic head is needed in a DVSP system because it provides the correct pressure change necessary for every consumer heat load. Further, the largest reductions occurred during the winter period when the heat load was higher. This is because a greater heat load is correlated with a greater saving potential. Accordingly, the simulation results confirmed previous studies about DVSP systems being a more electric energy efficient configuration of a District Heating (DH) network.
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