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, EstoniaThe sawtooth variation seen in the measurements in [6]is seen in this measurement as well and should befurther investigated.A large difference between the pool and coiltemperature is desirable to minimize the relative errors.It is also important to assure that steady-stateconditions are established before starting thetemperature decline.The final result, the obtained thermal conductivity:5( T) 0.0235 10 10 T ( ºC), 500.0285 (5)is in reasonable agreement with the declared λ 50 =0.0255 W·m -1·K -1 for a newly manufactured pipe. Thispipe piece had been in store for some time and had nodiffusion barrier. The temperature-dependent part ofthe thermal conductivity is in well agreement with [12].REFERENCES[1] U. Jarfelt, Test apparatus of pipe insulation.Doctoral thesis. Chalmers University ofTechnology, Göteborg (1994)[2] European standard EN 253:2009, District heatingpipes - Preinsulated bonded systems for directlyburied hot water networks – Pipe assembly of steelservice pipe, polyurethane thermal insulation andouter casing of polyethylene, Brussels, Belgium.(2009)[3] European committee for standardization. Europeanstandard EN ISO 8497:1996, Thermal insulation-Determination of steady-state thermal transmissionproperties of thermal insulation for circular pipes,Brussels, Belgium. (1996)[4] Danish District Heating Association. Developmentof an experimental set-up for measuring the heatconduction properties of flexible pipes, Project nr.2006-05, Århus, Danmark. (2006), In Danish,available at Dansk Fjernvarmes F&U-Konto,www.danskfjernvarme.dk[5] District Heating Association (2008), Heat planDenmark, Ramboll Danmark A/S and AalborgUniversity, (2008), In Danish, available at DanskFjernvarmes F&U-Konto, www.danskfjernvarme.dk[6] C. Reidhav and J. Claesson, A transient method todetermine temperature-dependent thermalconductivity of polyurethane foam in district heatingpipes, Building Physics 2008 - 8 th Nordic<strong>Symposium</strong>, Copenhagen, Denmark, (2008)[7] C. Persson and J. Claesson, Prediction of heatlosses from district heating twin pipes, The 11 th<strong>International</strong> <strong>Symposium</strong> on District Heating andCooling, August 31 to September 2, Reykjavik,Iceland, (2008)[8] C. Persson and J. Claesson, Numerical solution ofdiffusion problems using conformal coordinates.Application to district heating pipes, ReportDepartment of Civil and EnvironmentalEngineering, Chalmers University of Technology,Göteborg, Sweden (2008)[9] S. Peng, P. Jackson, V. Sendijarevic, K.C. Frisch,G.A Prentice, A. Fuchs, Process Monitoring andKinetics of Rigid Poly(urethane-isocyanurate)Foams, Journal of Applied Polymer Science,(2000) Vol 77, 374-380[10] R. Zevenhoven, Treatment and disposal ofpolyurethane wastes: options for recovery andrecycling, Helsinki University of Technology,Report TKK-ENY-19, Espoo, Finland, June (2004).[11] BING, Federation of European Rigid PolyurethaneFoam Associations, Thermal insulation materialsmade of rigid polyurethane foam (PUR/PIR),ReportNo1 October (2006)[12] U. Jarfelt and O. Ramnäs, Thermal conductivity ofpolyurethane foam – best performance,10 th <strong>International</strong> <strong>Symposium</strong> on District Heatingand Cooling, Sept 3-5, Hanover, Germany, (2006).95