Peak load shifting control on hot water supplied from district heating using latent heat storage system in apartment complex

District heating has been widely implemented in residences because of its environmental and economic advantages. The hot water load of residences generally peaks in the morning and at night because of the lifestyle of the residents. An imbalance in the heat load presents high capital costs and low operating efficiency of the district heating facilities. In this study, a latent heat storage system using a solid-liquid phase change material was developed for the peak load shifting control of hot water supplied from district heating in an apartment complex. The latent heat storage system was designed using a shell-tube structure and can store heat for more than 100 h using an insulation of 50 mm. A field demonstration was performed by installing the developed latent heat storage system in a machinery room in the basement of the apartment complex. The demonstration showed that the total heat flow of hot water during a day and its standard deviation with the latent heat storage are lower than those without latent heat storage by 2.69% and 59.9%, respectively. Therefore, the latent heat storage system is crucial in the peak load shifting of hot water in the apartment complex.