Impact of Domestic Hot Water Preparation Systems on District Heating Network Design and Operation
Abstract
With more ambitious energy efficiency standards in newly constructed buildings and increased renovation rates in existing buildings, domestic hot water (DHW) preparation systems are of increasing importance for the connected heat load, total heat demand, flow temperature requirements and return temperatures of residential buildings. This means, that the design and operation of district heating networks (DHN) is heavily impacted by the DHW preparation systems of its consumers. In this study, the impact of three DHW systems is investigated for a case study. The investigated systems are instantaneous DHW preparation and hot water storages, both at 60 °C as well as DHW preparation with buffer storages at 45 °C with heat exchangers on apartment level. Dynamic thermo hydraulic simulations of a DHN are conducted and the results analyzed with particular regard to (insufficient) flow temperature levels at the consumers which lead to the need for bypasses, bypass operation strategies and the impact on the total DHN return temperatures.