American Standard CH530 manual Cooling Cycle, Compressor 1 or 2 2 Stage

Page 10

General Information

Cooling Cycle

Duplex Chillers have two refrigerant circuits that operate as their own independent circuits. These circuits are discussed as individual chiller refrigeration units in the following discussion. The sequence of operation of the two refrigeration circuits is discussed in a later section.

When in the cooling mode, liquid refrigerant is distributed along the length of the evaporator and sprayed through small holes in a distributor (i.e., running the entire length of the shell) to uniformly coat each evaporator tube. Here, the liquid refrigerant absorbs enough heat from the system water circulating through the evaporator tubes to vaporize.

The gaseous refrigerant is then drawn through the eliminators (which remove droplets of liquid refrigerant from the gas) and first- stage variable inlet guide vanes, and into the first stage impeller.

Note: Inlet guide vanes are designed to modulate the flow of gaseous refrigerant to meet system capacity requirements; they also prerotate the gas, allowing it to enter the impeller at an optimal angle that maximizes efficiency at all load conditions.

Compressor 1 or 2 (3 Stage) Compressed gas from the first-stage impeller flows through the fixed, second-stage inlet vanes and into the second-stage impeller.

Here, the refrigerant gas is again compressed, and then discharged through the third-stage variable guide vanes and into the third stage impeller.

Once the gas is compressed a third time, it is discharged into the condenser. Baffles within the condenser shell distribute the compressed refrigerant gas evenly across the condenser tube bundle. Cooling tower water circulated through the condenser tubes absorbs heat from the refrigerant, causing it to condense. The liquid refrigerant then passes through orifice plate ‘‘A’’ and into the economizer.

The economizer reduces the energy requirements of the refrigerant cycle by eliminating the need to pass all gaseous refrigerant through three stages of compression. See Figure 3. Notice that some of the liquid refrigerant flashes to a gas because of the pressure drop created by the orifice plates, thus further cooling the liquid refrigerant. This flash gas is then drawn directly from the first (Chamber A) and second (Chamber

B)stages of the economizer into the third-and second-stage impellers of the compressor, respectively.

All remaining liquid refrigerant flows through another orifice plate ‘‘C’’ to the evaporator.

Compressor 1 or 2 (2 Stage)

Compressed gas from the first-stage impeller is discharged through the second-stage variable guide vanes and into the second-stage impeller. Here, the refrigerant gas is again compressed, and then discharged into the condenser.

Baffles within the condenser shell distribute the compressed refrigerant gas evenly across the condenser tube bundle. Cooling tower water, circulated through the condenser tubes, absorbs heat from the refrigerant, causing it to condense. The liquid refrigerant then flows out of the bottom of the condenser, passing through an orifice plate and into the economizer.

The economizer reduces the energy requirements of the refrigerant cycle by eliminating the need to pass all gaseous refrigerant through both stages of compression. See Figure 6. Notice that some of the liquid refrigerant flashes to a gas because of the pressure drop created by the orifice plate, thus further cooling the liquid refrigerant. This flash gas is then drawn directly from the economizer into the second-stage impellers of the compressor.

All remaining liquid refrigerant flows out of the economizer, passes through another orifice plate and into the evaporator.

10

CDHF-SVU01C-EN

Image 10
Contents X39640670030CDHF-SVU01C-EN Read these carefully Contents About this manual General InformationLiterature change Unit NameplateGeneral Information = 560 3 stage 935 2 stage Y = 500 3 stage 835 2 stage Commonly Used Acronyms Control Optional PackagesOverview General Duplex unit components front viewGeneral Duplex unit components 2 stage compressor Cooling Cycle Compressor 1 or 2 2 StagePressure enthalpy curve 3 stage compressor Pressure enthalpy curve 2 stage compressor TechView Chiller Service Tool DynaView Human InterfaceSoftware States Figure Power Up DiagramSoftware Operation Overview Diagram Timeline Text FiguresCDHE/F/G sequence of operation auto to running Staging Second Compressor OnStaging Second Compressor Off Satisfied SetpointCDHF/G sequence of operation lead 1/lag Fixed Sequence Compressor 2 / Compressor CDHE/F/G sequence of operation lead 2 lagSequencing Balanced Starts and Hours CDHF/G sequence of operation equalize starts and hoursSimultaneous Compressor Start/ Stop CDHF/G sequence of operation combined startRestart Inhibit Free Starts Restart Inhibit Start to Start Time SettingRestart Inhibit Clear Restart InhibitSurface Temperatures Oil and Refrigerant PumpOil refrigerant pump circuit 1 or Base Loading Control Algorithm 20 100 percent RLAGeneral Information Ice Machine Control Sequence of operation ice making running to ice makingHot Water control Control Panel Devices and Unit Mounted Devices Unit Control Panel UCPUnit Control Panel UCP Variable water flow through the evaporator User-defined language supportOperator Interface DynaView main processorOperator Interface Chiller Stop Prevention/Inhibit Feature How It WorksTop Level Mode Description System Reset Reference Main Screen Chiller Operating ModeCircuit Operating Mode Main Screen Data Fields TableDiagnostic Screen Back button provides navigation back to the chiller screen Operator Interface Report Menu ReportsReport name System Condenser Report name System EvaporatorReport name Circuit Evaporator Report name Circuit CondenserHistoric Diagnostics Log Report name System Ashrae Chiller LogSetting Tab screens provides a user Header ScreenFeature Settings ChillerDisplay Settings System Mode OverridesCircuit Mode Overrides PurgeOperator Interface Operator Interface Operator Interface Operator Interface Operator Interface IPC3 Definitions Bus Management Interprocessor CommunicationInter Processor Communications IPC3 BindingControl System Components Control panel components layoutControl System Components Control Panel Devices Maximum Capacity Relay Machine Shutdown Manual Reset MMRHead Relief Request Output Compressor Running RelayRefrigerant Monitor Input 1A17 ExopCdrp Condenser Refrigerant Pressure Output Trmm TRM4 Tracer Comm 4 interfaceEpro Enhanced Protection Condenser Pressure Output Temperature basedCdrp Refrigerant Pressure Output Option 1A15 Pressure basedRefrigerant Differential Pressure Indication Output Gbas Generic Building Automation System Percent RLA OutputExternal Current Limit Setpoint Module CharacteristicsExternal Chilled Water Setpoint Ecws Wpsr WFC Water Pressure Sensing Option1A13, 1A18, 1A19, 1A20 Dual Binary input module 1A8, 1A9, 1A11, 1A12 Quad Relay Output Status1A14 Communication interface Module 1A15, 1A16, 1A17, 1A21 Dual Analog Input/output Module Recommended Length to Run external Output signalsAnalog Input Unit mounted devices Control System Components Control System Components Electrical Sequence Control Sequence of OperationUCP and Wye-Delta Starter Control Circuits Delay time 200 msec. Opens 2K1 Control Sequence of Operation Control Sequence Operation Test and start timing sequenceAFD Momentary Power Loss MPL Protection Machine Protection Adaptive ControlCurrent Overload Protection Overload trip time versus percent RLACurrent Limit Protection Phase Loss ProtectionReverse Rotation Protection SoftLoading Differential to Start or StopMinimum and Maximum Capacity Limit Leaving Water Temperature Cutout Evaporator LimitLow Refrigerant Temperature Cutout Head Relief RelayCutout strategy Condenser Limit Restart Inhibit High Vacuum Lockout Oil Temperature Control Maximum Reset Controls Chilled Water Reset CWROutdoor Air Temperature Return WaterConstant Return Values for start reset typesDegrees of Reset EquationReset Ratio Outdoor air temperature versus degrees of resetReset function for return CWR Reset Ratio = 50% Return CWR Unit Startup Unit Start-Up ProceduresDaily Unit Start-Up Seasonal Unit Start-Up Live Electrical ComponentsToxic Hazards ModeOil Pump Heater Operation Unit Shutdown ProceduresUnit Shutdown Seasonal Unit ShutdownMoisture Contamination Periodic MaintenanceDaily Maintenance and Checks Record Keeping FormsHazardous Voltage w/Capacitors Weekly MaintenanceNormal Chiller Operating Characteristics Every 3 MonthsOff-Season Maintenance Annual MaintenanceHeater Damage Oil MaintenanceOil Change Procedure Compressor Oil ChangeOil Filter Replacement Replacing Oil FilterOther Maintenance Requirements MaintenanceOil Supply System Problems Hazardous Voltage w/ CapacitorsRotary valve in drain position Front View with Refrigerant PumpContains Refrigerant Refrigerant ChargeCleaning the Condenser Recovery and Recycle ConnectionsLeak Testing Proper Water TreatmentControl Settings Adjustments Cleaning the EvaporatorUnit Corrosion Damage Purge System Unit Preparation103 104 105 106 107 108 109 110 111 112 113 114 115 Trane