The use of a PCM heat accumulator to improve the efficiency of the district heating substation

Abstract

One of the ways to decrease atmospheric pollution resulting from low-emissions is the widespread use of district heating systems. An important problem for the efficiency of district heating systems is a significant source-end-users difference of heat demand. This causes increased return water temperature. A solution that can reduce that difference is modern heat storage technology. Therefore, the aim of this study was to determine the impact of new element of district heating system – phase change material heat accumulator – on the return water temperature distribution in the district heating substation and to improve its efficiency. As a result, the analysis of selection and use of a heat accumulator in the district heating substation was conducted. Also a method for determining the amount of heat for accumulation has been proposed. Using the TRNSYS software, two cases were compared for a heat substation with a thermal power of 150 kW: without and with the use of a heat accumulator. After using the PCM heat accumulator, the difference in average return water temperatures was reduced from 7.15K to the value of 2.29K. This allowed for the accumulation of 69.5% of surplus heat and improvement of the efficiency of the entire heating system by 22%.