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, EstoniaTraditional control concepts of DH substations arealways trade-off between users comfort and reducedcooling of DH water during idling and thus customershould have to some extent possibility to choose whichsolution prefers. In case of traditional concepts,decision is between longer waiting time for DHW andenergy savings or vice versa, if by-pass in substationis used. In non-circularly shaped networks, by-passshould be used anyway at least at the end of a streetline. The one of possible solutions how use by-passflow in better way can be proposed innovative conceptof whole year operated floor heating in bathrooms orsupply-supply recirculation. Both solutions will increaselevel of user comfort and at the same time also energyefficiency of DH system.LEDH is a promising solution for providing buildingswith DHW and space heating regarding fulfillingrequirements of modern society with reduced CO 2emissions and energy consumption. More detailedinvestigations by testing of different parameters andnumerical simulations are needed in order to optimizeLEDH concept.Future workIt will be very interesting to compare time delay ofsubstation for traditional DH with time delay for DHWproduced by LEDH substation. It is expected thattimed delay for LEDH will be higher because dynamicresponse is slowed down by lower temperaturedifference between DH water and desired temperatureof DHW, but on the other hand, lower temperaturedifference is in some extend compensated by biggerHEX. It is also suggested to rethink ―10 sec tap delaysuggestion‖ for different taping flows and purposes ofDHW use.REFERENCES[1] S. Froning, ―Low energy communities with districtheating and cooling‖, PLEA 2008 – 25thConference on Passive and Low EnergyArchitecture, Dublin,[2] Hovedrapport, ―Udvikling og Demonstration afLavenergifjernvarme til Lavenergibyggeri‖ 2009,(in Danish)[4] DVGW, ‖W551 - Trinkwassererwärmungs- undTrinkwasserleitungsanlagen‖ ,1993, Bonn, (inGerman)[5] Z. Liu, ―Effect of flow regimes on the presence ofLegionella within the biofilm of a model plumbingsystem‖, 2006, Journal of Applied Microbiology,Vol. 101, pp 437-442[6] F. Martinelli, ―A Comparison of Legionellapneumophila Occurrence in Hot Water Tanks andInstantaneous Devices in Domestic, Nosocomial,and Community Environments‖, 2000, CurrentMicrobiology, Vol. 41, pp. 374-376[7] W. Mathys, J. Stanke, et. al.,‖ Occurrence ofLegionella in hot water systems of single-familyresidences in suburbs of two German cities withspecial reference to solar and district heating‖,2008, Int. J. Hyg. Environ. Health, Vol. 211, pp.179-185[8] H. Kristjansson, ―Distribution Systems inApartment Buildings‖, Published at the 11th<strong>International</strong> <strong>Symposium</strong> on District Heating andCooling, August 31 to September 2, 2008,Reykjavik, ICELAND[9] T. Persson, ―District Heating for Residential Areaswith Single-Family Housing, paper IV‖, 2005,Doctoral Thesis, Lund Institute of Technology,Lund[10] Dansk Standard, ―DS 439 Code of Practice fordomestic water supply installations‖, 2009[11] P.K. Olsen, ―Low-Temperature District HeatingSystem for Low-Energy Buildings‖, 2009,http://www.fbbb.dk/Files/Filer/Peter_Kaarup_Olsen_-_COWI_29-10_2009.pdf[12] H., Boysen, J.E. Thorsen, ―Control Concepts forDH Compact Stations‖, Published in Euroheat andPower IIII 2004[13] O. Paulsen, ―Consumer Unit for Low EnergyDistrict Heating Net‖, Published at the 11th<strong>International</strong> <strong>Symposium</strong> on District Heating andCooling, August 31 to September 2, 2008,Reykjavik, ICELAND[3] EUROHEAT & POWER, ―Guidelines for DistrictHeating Substations‖, 2008, downloaded fromwww.euroheat.org in October 2009, pp 868