12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaThere was not enough time to develop completelymodified control curves for the test objects during thepresent heating season. On the other hand, a controlcurve with an adaptive controller is never definitive;rather it increases as more operational points (differentoutdoor temperatures) are added and is then graduallymodified if outer conditions change. In order to receivevalues for the primary return temperature on a yearlybasis using the adaptive control algorithm, the newcontrol curve needs to be modified for the entiretemperature range. During the performed field studies,the reduction of the primary return temperature wasabout 3 °C. Even though the test period limited thenumber of tests, the temperature range was still ratherwide, including temperatures from -2 to 14 °C.It is plausible that certain circuits are more suitable fora variable flow rate, e.g., depending on hydraulicbalancing. It would also be possible to map out underwhich circumstances other heat emitters than radiators,such as fan coil heaters, can be included in a radiatorcircuit where the flow varies.ACKNOWLEDGEMENTThe Swedish District Heating Association, the SwedishEnergy Agency and Nordic Energy Research aregratefully acknowledged for financing this work.REFERENCES[1] Euroheat & Power, Guidelines for District HeatingSubstations, Downloaded from:http://www.euroheat.org/documents/Guidelines%20District%20Heating%20Substations.pdf,20081117.[2] Frederiksen, S., Wollerstrand, J., Performance ofdistrict heating house station in altered operationalmodes, 23rd UNICHAL-Congress, Berlin, 1987.[3] Gummérus, P., Petersson, S., Robust Fjärrvärmecentral(Robust District Heating Substation), ReportA 99-223, Dept. of Energy and Environment,Chalmers Univ. of Technology, Gothenburg, 1999.[5] Liao, Z., Swainson, M., Dexter, A.L., On the controlof heating systems in the UK, Building andEnvironment 40 (2005) 343-351.[6] Lindkvist, H., Walletun, H., Teknisk utvärdering avgamla och nya fjärrvärmecentraler i Slagsta(Technical evaluation of old and new districtheating substations in Slagsta), Report 2005:120,Swedish District Heating Association, 2005.[7] Ljunggren, P., Johansson, P.-O., Wollerstrand, J.,Optimised space heating system operation with theaim of lowering the primary return temperature,Proceedings from 11th <strong>International</strong> <strong>Symposium</strong> onDistrict Heating and Cooling, Reykjavik, 2008.[8] Peeters, L., Van der Veken, J., Hens, H., Helsen,L., D‘haeseleer, W., Control of heating systems inresidential buildings: Current practice, Energy andBuildings 40 (2008) 1446-1455.[9] Petitjean, R., Total hydronic balancing, Tour &Andersson Hydronics AB, Ljung, Sweden, 1995.[10] Skagestad, B., Mildenstein, P., District Heating andCooling Connection Handbook, published by the<strong>International</strong> Energy Agency (R & D Programme onDistrict Heating and Cooling), 2002.[11] Snoek, C., Yang, L., Frederiksen, S., Korsman, H.,Optimization of District Heating Systems byMaximizing Building Heating System TemperatureDifferences, Report 2002:S2, <strong>International</strong> EnergyAgency (R & D Programme on District Heating andCooling) & NOVEM, Sittard, 2002.[12] Trüschel, A., Hydronic Heating Systems – TheEffect Of Design On System Sensitivity, DoctoralThesis, Chalmers University of Technology,Gothenburg, Sweden, 2002.[13] Volla, R., Ulseth, R., Stang, J., Frederiksen, S.,Johnson, A., Besant, R., Efficient substations andinstallations, Report 1996:N5, <strong>International</strong> EnergyAgency (R & D Programme on DHC) & NOVEM,Sittard, The Netherlands, 1996.[4] Langendries, R., Low Return Temperature (LRT) inDistrict Heating, Energy and Buildings, 12 (1988)191-200.214