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, EstoniaGRP pipesflexible pipepipeline laying techniqueself-compacting materialreuse of excavated soilcombined laying withother supply pipesstacked layinginsulation as a castingcompoundinsulating backfilltrench-less layingtechniquesnominal diameter< DN 150nominal diameter> DN 150+ ++ 0 ++ + 0 + ++ - +++ -- ++ + ++ 0 ++ 0 ++ ++new district heating line ++ + + ++ ++ ++ ++ - + ++renovation measure 0 - 0 ++ ++ 0 -- ++ + --construction site in anurban areaconstruction site in arural areayet to be built housingestate+ ++ -- ++ 0 + + + 0 +++ + ++ 0 ++ ++ ++ + + 0+ + ++ + + ++ ++ - + 0existing housing estate + ++ -- ++ + + + - 0 ++NOMENCLATURER λ,jacketinsulance of the jacket pipeλ sthe coefficient of thermal conductivity forthe soilR αinsulance of the convective heat transferinside the pipeλ iλ i,50 °Cλ Cλ steelthe coefficient of thermal conductivity forthe PUR insulationthe coefficient of thermal conductivity forthe PUR insulation at 50 °Cthe coefficient of thermal conductivity forthe jacket pipethe coefficient of thermal conductivity forthe service pipeR 0R λ,embedmentD iD 0D insulationD Csurface transition insulanceinsulance of the insulating material usedin the embedmentinner diameter of the service pipeouter diameter of the service pipeouter diameter of the PUR insulationouter diameter of the jacket pipeλ embedmenαR hR sR iR λ,steelt the coefficient of thermal conductivity forthe insulating material used in theembedmentheat transfer coefficientinsulance of the heat exchange betweenflow and return pipeinsulance of the soilinsulance of the insulation materialinsulance of the service pipeT flowT returnT soilT i,averageT fluidU flowU returnflow temperaturereturn temperaturetemperature of the soilaverage temperature of the PURinsulationflow or return temperatureheat loss coefficient for the flow pipeheat loss coefficient for the return pipe303