Carrier AquaEdge 19XR Series Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XR series: Installation instructions Start-up, operation and maintenance instructions

Contents

10REFRIGERATION CYCLEThe compressor continuously draws refrigerant vapor from thecooler at a rate set by the amount of guide vane opening and motorspeed. As the compressor suction reduces the pressure in the cool-er, the remaining refrigerant boils at a fairly low temperature (typ-ically 38 to 42°F [3 to 6°C]). The energy required for boiling is ob-tained from the water flowing through the cooler tubes. With heatenergy removed, the water becomes cold enough to use in an airconditioning circuit or for process liquid cooling.After taking heat from the water, the refrigerant vapor is com-pressed. Compression adds still more heat energy, and the refriger-ant is quite warm (typically 98 to 102°F [37 to 40°C]) when it isdischarged from the compressor into the condenser.Relatively cool (typically 65 to 90°F [18 to 32°C]) water flowinginto the condenser tubes removes heat from the refrigerant and thevapor condenses to liquid.The liquid refrigerant passes through orifices into the FLASC(Flash Subcooler) chamber (Fig. 6 and 7). Since the FLASCchamber is at a lower pressure, part of the liquid refrigerant flashesto vapor, thereby cooling the remaining liquid. The FLASC vaporis re-condensed on the tubes which are cooled by entering con-denser water. The liquid drains into a float valve chamber betweenthe FLASC chamber and cooler. Here the AccuMeter™ floatvalve forms a liquid seal to keep FLASC chamber vapor from en-tering the cooler. When liquid refrigerant passes through the valve,some of it flashes to vapor in the reduced pressure on the coolerside. In flashing, it removes heat from the remaining liquid. Therefrigerant is now at a temperature and pressure at which the cyclebegan. Refrigerant from the condenser also cools the oil and op-tional variable speed drive.The refrigeration cycle for a 19XRV chiller with two-stage com-pressor is similar to the one described above, with the followingexception: Liquid refrigerant from the condenser FLASC chamberlinear float valve or orifice plate flows into an economizer at inter-mediate pressure (see Fig. 7). As liquid enters the chamber, due tothe lower pressure in the economizer, some liquid flashes into avapor and cools the remaining liquid. The separated vapor flowsto the second stage of the compressor for greater cycle efficiency.A damper valve located on the economizer line to the compressoracts as a pressure regulating device to stabilize low load, low con-densing pressure operating conditions. The damper will back upgas flow and thereby raise the economizer pressure to permitproper refrigerant flow through the economizer valve during thoseconditions. The damper also is closed during start-up conditions toallow the second stage impeller to start unloaded.The subcooled liquid remaining in the economizer flows through afloat valve and then into the cooler.Fig. 6 — Refrigeration Cycle — 19XR(V) Single-Stage Compressora19-1550tf