Faculty of Engineering - University of Iceland 1 District heating system modeling Marta Rós Karlsdóttir Reykjavík

The case study 127 m 2 appartment in a double family housing –Located in Reykjavík at new suburb in the eastern part of town (Norðlingaholt) –New concrete building, well insulated Heat capacity 86.4 MJ/°C Time constant hours Heat load factor kW/°C Base temperature Tb -3.8 °C Maximum mass flow kg/s Cost 5,363 IKR/month average Temperature data –Reykjavík1949 – 1990 –Minimum temperature °C –Degree days below 0°C and Tb Faculty of Engineering - University of Iceland 2

Distinctiveness of the district heating systems in Iceland The water is used directly from low temperature areas Hot water production by heating up fresh water in CHP Chemical composition of water For house heating and as hot tap water Mainly “Once through” systems

Space heating in Iceland by sources 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Fossil fuels Electricity Geothermal 90% 9% <1%

Use of Geothermal Energy District heating services Power plants Industry Greenhouses Swimming pools Fish farming

Steady state modelling Faculty of Engineering - University of Iceland 6

Steady state modelling Faculty of Engineering - University of Iceland 7

Dynamic modelling Challanges in project work Faculty of Engineering - University of Iceland 8

Dynamic modelling Longest cold spellSystem design Faculty of Engineering - University of Iceland 9

Conclusions Well insulated houses reduce the heat load on the system Transmission network –Mass flow has positive effect –Outdoor temperatures have negative effect Not immediate response between indoor and outdoor temperature due to building heat capacity Faculty of Engineering - University of Iceland 10

Faculty of Engineering - University of Iceland 11