POSSIBILITIES OF APPLYING A LOW-TEMPERATURE CENTRALIZED HEAT SUPPLY NETWORK IN A MULTI-APARTMENT BUILDING DISTRICT

Lithuania‘s district heating (DH) network tends to maintain high heat transfer temperatures, which limit the efficiency of the system. The aim of this study is to assess the impact of DH and reduced heat transfer temperature in the building on space heating and the possibility of reducing the heat transfer temperature (down to 60 °C) in the DH network by looking at different scenarios and the heat demand of buildings. Three alternatives were analysed: the installation of a temperature-lowering module (mixing unit) in the thermal chamber and the retro-fitting of existing piping and heating appliances, where the temperature of the DH fluid is lowered up to 60 °C and the temperature of the radiators is lowered to 60/40/20. The possibility of lowering the DH heat transfer temperature without upgrading the network by installing heat pumps individually in the buildings or in the heat chamber is examined. An hourly data analysis of a 2-year heating system model for a typical building showed that lowering the DHW temperature to 60 °C and leaving the existing area of heating appliances in the building will not meet the heat demand of the buildings.