application of controls

Application of ControlsApplication of Controls

CAV with Humidity ControlCAV with Humidity Control


CAV with Humidity ControlCAV with Humidity ControlCAV AHU dedicated to a special area:CAV AHU dedicated to a special area:

clean roomclean room textile factorytextile factory hospital operating theatrehospital operating theatre computer equipment roomcomputer equipment room

Environment requires humidity control Environment requires humidity control as well as temperature control - as well as temperature control -

energy efficiency is not as importantenergy efficiency is not as important


Return AirReturn Air

OutdoorOutdoorAirAir

Cooling CoilCooling Coil

Chilled WaterChilled WaterValveValve

FanFan Heater ElementsHeater Elements

CAV with Humidity ControlCAV with Humidity ControlTT

HH

Temperature sensor in spaceTemperature sensor in space

Humidity sensor in spaceHumidity sensor in space

Temperature and humidity Temperature and humidity sensors may alternatively be sensors may alternatively be

placed in return air ductplaced in return air duct


CAV with Humidity ControlCAV with Humidity ControlThe valve is controlled by the humidity The valve is controlled by the humidity sensor to achieve the humidity setpoint.sensor to achieve the humidity setpoint.

The heating elements are controlled by The heating elements are controlled by the temperature sensor to reheat the air the temperature sensor to reheat the air

to achieve the temperate setpoint.to achieve the temperate setpoint.

This works if outdoor air is used; if pre-This works if outdoor air is used; if pre-treated air is used, cooling request may treated air is used, cooling request may

be greater than dehumidification be greater than dehumidification request and valve is controlled by request and valve is controlled by

temperature sensor.temperature sensor.


HumidityHumidity TemperatureTemperatureCAV with Humidity ControlCAV with Humidity Control

HH

TT

S.P.S.P.

D.B.D.B.

P.B.P.B.

Cooling CoilCooling CoilCommandCommand

HeatingHeatingCommandCommand

S.P.S.P.

D.B.D.B.

P.B.P.B.


Mechanical ControlsMechanical Controls


Mechanical ControlsMechanical ControlsFCU ControlFCU Control

A temperature A temperature switch in the return switch in the return

air controls the 2 air controls the 2 position valveposition valve

A separate 3 speed A separate 3 speed switch is connected switch is connected

to the fanto the fan


Mechanical ControlsMechanical ControlsFCU ControlFCU Control

A temperature A temperature switch in the switch in the room controls room controls the 2 position the 2 position

valvevalve

The integral 3 The integral 3 speed switch is speed switch is

connected to the connected to the fanfan


Mechanical ControlsMechanical ControlsCondenser FanCondenser Fan

As the condenser As the condenser pressure pressure

increases, a fan increases, a fan is startedis started

As the pressure As the pressure continues to continues to

rise, a second rise, a second fan is startedfan is started

FromFromEvaporatorEvaporator

ToToCompressorCompressor


Mechanical ControlsMechanical ControlsCooling Tower FanCooling Tower Fan

As the As the temperature temperature

increases, the increases, the low speed low speed winding is winding is engagedengaged

As the As the temperature temperature continues to continues to rise, the high rise, the high

speed winding is speed winding is engagedengaged


Mechanical ControlsMechanical ControlsCold RoomCold Room

As the As the temperature temperature

increases, the increases, the compressors are compressors are

brought on in brought on in sequencesequence

Condenser fans Condenser fans controlled based controlled based

on pressureon pressure

C1C1 C2C2 C3C3 C4C4

EvaporatorEvaporator

ColdColdRoomRoom

CondenserCondenser


Mechanical ControlsMechanical ControlsCompressor Compressor

SafetiesSafeties

If the condenser If the condenser pressure is too pressure is too high or too low, high or too low, the compressor the compressor

will be shut will be shut downdown

If the lube oil If the lube oil pressure is too pressure is too

low, the low, the compressor will compressor will be shut downbe shut down


Chiller Plant IntegrationChiller Plant Integration


Chiller Plant IntegrationChiller Plant Integration Single seat user interfaceSingle seat user interface

Consolidation of informationConsolidation of information

Facility wide strategiesFacility wide strategies

Simplify operations / trainingSimplify operations / training


DataportIntegrator

DDCRS232

Local Area Network

Operator Workstation (PC)

NCU

Carrier Comfort Network

Chiller Plant IntegrationChiller Plant Integration


Chiller Plant IntegrationChiller Plant Integration Chilled Water Setpoint / Control PointChilled Water Setpoint / Control Point

Entering/Leaving Chilled Water Temp.Entering/Leaving Chilled Water Temp.

Entering/Leaving Condenser Water Entering/Leaving Condenser Water Temp.Temp.

Evaporator Refrigerant Temperature Evaporator Refrigerant Temperature and Pressureand Pressure

Condenser Refrigerant Temperature Condenser Refrigerant Temperature and Pressureand Pressure


Chiller IntegrationChiller IntegrationDischarge TemperatureDischarge Temperature

Bearing TemperatureBearing Temperature

Motor Winding TemperatureMotor Winding Temperature

Oil Sump TemperatureOil Sump Temperature

Oil Pressure TransducerOil Pressure Transducer

etc....etc....

In brief, anything visible from Control In brief, anything visible from Control Panel.Panel.


Chiller SequencingChiller Sequencing


0

50

100

150

200

250

TONS

1 x 300 TR Chiller



0

100

200

300

400

500

600

700

800

TONS

3 x 300 TR Chiller

1 Chiller on

2 Chillers on

3 Chillers on



0

100

200

300

400

500

600

700

800

TONS

3 x 300 TR Chiller +30 HP associatedpumps/fans each

1 Chiller on

2 Chillers on

3 Chillers on



0

100

200

300

400

500

600

700

800

TONS

3 x 300 TR Chiller +30 HP associatedpumps/fans each

Run 1 ChillerRun 2

Chillers Run 3 Chillers



IncreasingLoad

DecreasingLoad

Differential to preventshort cycling



Chiller SequencingChiller Sequencing1. Plot curves for all combinations of 1. Plot curves for all combinations of

chillerschillers including pumps and cooling towers including pumps and cooling towers

2. Take switchover points from graph2. Take switchover points from graph

3. Program switchover points with 3. Program switchover points with differentialdifferential

4. Use run time to choose lead and lag 4. Use run time to choose lead and lag chillers chillers


Chilled Water ResetChilled Water Reset

AHU 1

AHU 3

AHU 2

60%

75%

70%

Valve

6 Degrees

1000 Tons723 kW




AHU 1

AHU 3

AHU 2

60%

75%

70%

Valve

6 Degrees

1000 Tons723 kW

7 Degrees

68%

80%

76%658 kW



56

58

60

62

64

66

68

Time



RatioRatio Max. Reset*Max. Reset*

AHU 1AHU 1 8%/Deg8%/Deg 9.1 Deg 9.1 Deg

AHU 2AHU 2 6%/Deg6%/Deg 8.5 Deg 8.5 Deg

AHU 3AHU 3 5%/Deg5%/Deg 8.0 Deg 8.0 Deg* Assuming maximum valve position allowed is 85%



Chilled Water ResetChilled Water Reset1. Record step response of valve position 1. Record step response of valve position

forfor each AHU to measure system delay and each AHU to measure system delay and calculate ratio (%/Degree) calculate ratio (%/Degree)

2. Automatically reset chilled water 2. Automatically reset chilled water temperature temperature

3. Look for opportunities to add localized 3. Look for opportunities to add localized cooling to increase chiller savings cooling to increase chiller savings

application of controls

Documents

temperature increases

humidity setpoint

humidity controlhts

humidity sensors

humidity controlthe

speed switch

condenser pressure increases

humidity controlcav