Refrigeration, air-conditioning and cooling technology - 2007.pdf

PLH_KKK_32_85.QXP 25.05.2007 10:11 Uhr Seite 75EXAMPLES FOR THE PUMP SELECTION IN THE VAPORISER CIRCUITHydraulic decoupler in vaporiser circuitThe circuit of a vaporiser system, including thehydraulic decoupler, is specified with a pressureloss of 5.85 m. The pump must achieve a deliveryhead of at least 5.85 m. The circulated volume isdetermined as follows:Hydraulic decoupler in vaporiser circuitFormula for volume flow V˙PUV·PU =Q· N1.16 · ∆ϑm 3 /hCapacitorsVaporiserAbbreviation Description1.16 Spec. heat capacity [Wh/kgK]∆Dimensioned temperature difference[K]2-12 K for standard systemsQ NHeat demand [kW]To minimise the operating and maintenancecosts, a glandless pump, Wilo-Stratos 80/1-12,is selected. It is advantageous that this pumpcircuit does not have to be equipped with a regulationvalve for the concrete duty point setting.This is set using the reference value control ofthe pump.Calculation223V·PU =1.16 · 4m 3 /hCavitation can be ruled out since this is a closedcircuit. For protection, the vaporiser circuit shouldhave its own safety valve and be equipped withits own diaphragm extension vessel for a volumeexpansion of 5 to 7 %.V·PU = 48.1 m 3 /hA pump with a flow rate of Q = 43.1 m 3 /h andH = 5.85 m is to be selected.Delivery head H [m]14131211109876543210 512 m max10 m8 m6 m4 mmin2 m10 15 20 25 30 35 40 45 50 55 60 65 70Flow Q [m³/h]Operating data specificationsFlow 48.1 m 3 /hDelivery head5.85 mPumped fluidWaterFluid temperature 16 °CDensity 0.9989 kg/dm 3Kinematic viscosity 1.11 mm 2 /sVapor pressure0.1 barHydraulic data (duty point)Flow 48.1 m 3 /hDelivery head5.85 mPower consumption P1 1.37 kWWilo Planning Guide - Refrigeration, air-conditioning and cooling technology 02/2007 75