Refrigeration, air-conditioning and cooling technology - 2007.pdf
Refrigeration, air-conditioning and cooling technology - 2007.pdf
Refrigeration, air-conditioning and cooling technology - 2007.pdf
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PLH_KKK_32_85.QXP 25.05.2007 10:11 Uhr Seite 57Examples for the pump selectionin the condenser circuitWell systemTo conduct heat away from the condenser, a wellsystem has been selected. The brine for the suctionwell lies 10 m under the floor of the installationroom for the refrigerating machine. Due tothe geodetic head difference, a submersiblepump system was selected. A pipeline length of30 m results between the submersible pump <strong>and</strong>the connection to the refrigerating machine.The suction side of the condenser lies 2 m underthe highest point of the pipeline to the sinkhole<strong>and</strong> has a total pipe length of 45 m. The heat capacityis 200 kW <strong>and</strong> should be conducted awayinto the well system with a temperature differenceof 6 K. The circulated volume is determinedas follows:Formula for volume flow V˙PUFormula for the pressure / the delivery head HH Ges = H geo + H AH A = H VL + H VACalculationH Ges = H geo + H VL + H VAH VL = R · IH VA = ZH VL = 100 · 75ρ · w 2Z = Σζ PaH VL = 7 500 Pa2V·PU =Q· N1.16 · ∆ϑm 3 /hZ = 114.13 ·999.6 · 1 22PaCalculationV·PU =2001.16 · 6V·PU = 28.74 m 3 /hm 3 /hZ = 57 127 PaResultH Ges = H geo + H VL + H VAH Ges = 120 000 Pa + 7 500 Pa + 57 127 PaH Ges = 184 627 PaThe desired pump head results from the pipelinerequirements. The total altitude difference is12 m. The pipeline material is PVC in a nominaldiameter of 100. The R value is 100 Pa/m at aflow rate of about 1 m/s. Based on the installedfittings, bends <strong>and</strong> the condenser resistance, theaddition of 8 bends, a suction valve <strong>and</strong> 2 shutoffvalves results in a value of 114.13.AbbreviationDescription1.16 Spec. heat capacity [Wh/kgK]∆Dimensioned temperature difference[K]10-20 K for st<strong>and</strong>ard systemsQ NH AH geoH GesH VLH VARHeat dem<strong>and</strong> [kW]Pressure loss of the system in PaGeodetic pressure head difference in Pa (1 m WS ˜ 10 000 Pa)Total pressure loss in PaPipeline pressure loss in PaFitting pressure loss in PaPipe friction resistance in Pa/mLPipe lengthζResistance values in Paρ Density of fluid in kg/m 3w 2 Flow rate in m/s 2ZΣPressure loss in fittings in PaTotal lossesWilo Planning Guide - <strong>Refrigeration</strong>, <strong>air</strong>-<strong>conditioning</strong> <strong>and</strong> <strong>cooling</strong> <strong>technology</strong> 02/2007 57
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