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

PLH_KKK_32_85.QXP 25.05.2007 10:11 Uhr Seite 42GENERATOR CIRCUITS IN THE VAPORISER PARTVariable volume flow in the vaporiser circuitVaporiser circuit with variable volume flow via a hydraulic decouplerMMMMCapacitors VaporiserVaporiser circuit with variable volume flow by means of a valve circuitMMMAn overflow from the feed to the return of thedecoupler circuit ensures that the volume flowremains constant and that a malfunction in thecontrol of the vaporiser performance is ruledout. The pump is to be dimensioned based onthe pressure loss in the vaporiser and the resistancesover the decoupler. The volume flow forthe vaporiser capacity is the required pump flow.To ensure the load capacity, the pipeline forconnection to the decoupler might have to bedesigned larger than what the vaporiser capacityrequires. In modern refrigerating machines, thepump capacity can be adapted to the requirementsof the load via temperature regulation.The minimum volume flow for the vaporiser isguaranteed by the speed limitation of the pumpdrive.In some modern refrigerating machines, thepump capacity can be adapted to the requirementsof the load via differential pressure regulation.The minimum volume flow for the vaporiserand/or the pump can be ensured by theoverflow part. The overflow volume must be solarge that it is guaranteed that the supply line tothe load is kept cold. The complete volume flowfor the load and the overflow part for the pumpcapacity must be taken into account. Three-wayvalves in front of the loads are only requiredwhen a longer connection line is necessary.If the connection is near the distribution line,the time until cold fluid is there is usually acceptable.Right now there are only a few possible applicationsfor regulating the pump capacity betweenzero and the nominal volume. On the one hand,cooling generators are not necessarily suitablefor this, and on the other hand, circulationpumps require a minimum volume flow for selfcoolingand self-lubrication. More details canbe found in the respective catalogues.CapacitorsVaporiserVaporiser circuit with variable volume flow over the loadMMCapacitorsVaporiser42 Subject to change without prior notice 02/2007 WILO AG