Introduction to Variable Refrigerant Flow Systems Allen Anaya Application Consultant WM Carroll, LLC Ph: 505-268-6776 Cell: 505-385-7338 Fax: 505-255-1329

NM ASHRAE – Introduction to Variable Refrigerant Systems

1

Introduction to Variable Refrigerant Flow Systems

Allen AnayaApplication Consultant

WM Carroll, LLCPh: 505-268-6776Cell: 505-385-7338Fax: 505-255-1329

E-Mail: [email protected]

11/16/2010


2

Agenda

• What is VRF? –History – Concept

• How does VRF Operate? – Refrigerant– Compressor– Fan Coil

• Important Standards– ASHRAE Standard 15– AHRI-1230-2010

• VRF Benefits – Installation & Design Flexibility – User Comfort

• The Future of VRF in North America

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V R F

What is VRF?

Variable Refrigerant Flow

Also referred to as VRV ® – Variable Refrigerant Volume

VRV is a registered trademark

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• 1973 – Global oil crises • 1979 – New energy efficiency laws passes in

Japan • 1980 – Chiller design engineers challenged

with making a higher efficiency chiller • 1982 – The worlds first VRF System is launched

VRF History


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• VRF world first’s

VRF Global History

19901982

World’s first VRF system is developed

20071987

VRF is launched globally

2003

Worlds first R410A VRF

20081991 1998

First globally available heat recovery VRF

World’s first R407C VRF system is developed

Worlds inverter driven VRF

2005

First water cooled VRF system is launch in the USA

World’s first CO 2 VRF system is developed

Industry changing piping and defrost technology

6

VRF47%

Chillers/Central Plant25%

Packaged/Splits28%

Development of VRF Market Japan Buildings under 70,000ft2

• By 1996 VRF had established itself as a proven technology with 34% market share• With increased market acceptance as a replacement to traditional applied central

systems VRF achieved 47% market share by 2001– 9% share was taken from the chiller/central plant market – The 4% taken from the split and package section was through replacing VAV

projects and allowing customer to afford the “chiller” they originally wanted

VRF34%

Chillers/CentralPlant34%

Packaged/Splits32%

1996

2001

7

VRF32%


Packaged/Splits35%

Development of VRF Market Japan Buildings over 70,000ft2

• Further evidence of acceptance can be seen by the increase in VRF market share in the larger applications– 12% share taken from the chiller/central plant market

• This trend was common in Europe, Australia and now North America

VRF15%


Packaged/Splits40%

1996

2001


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VRF Concept

Pump

Pump

Coolingtower

Water piping

AHUFCU FCU

For cooling

For heating

2 heat sourcesManaged by

engineer

Complicated

Inefficient part load operation

Outdoorunit

indoorunit

Refrigerant piping

Space-conscious design

Simple system

Energy efficient

Individual controlRemotecontroller

Simple Operation

Chiller

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VRF


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VRF Concept

Top floor

Building floors

Space-conscious design

Simple system

Individual control

Simple Installation

Simple MaintenanceRemote controllers

Simple Operation

One Point Of Contact For Technical Support

One Manufacturer


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VRF Concept• Think of a VRF system as a chiller that circulates refrigerant to each zone

instead of water• A heat pump system is equivalent to a 2 pipe chiller

– Major benefit is smaller heat/cool changeover zones due to the modular build up

• A heat recovery system is equivalent to a 4 pipe chiller system

Cooling Cooling Heating Heating

Heat Pump Heat Recovery

12 Ton

6 Ton

6 Ton

Cooling Cooling Heating Heating


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VRF ConceptHEAT RECOVERY VRF


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VRF ConceptAdvanced Zoning Capabilities

• Total comfort for occupants– Office buildings– Hospitals– Assisted living facilities– Schools– Hotels– Retail space

• Reduced operating costs– Shut down zones that are not in use

• Variable capacity design enables maximization of diversity– Each zone is individually controlled


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VRF ConceptWhere does a VRF system position?

• VRF has the following attributes:-– Energy Efficient– Tight Temperature Control– Quiet Operation – The Ability To Have Many Zones– Large Capacity (Modular Build Up)– Centralized Plant (long piping)– Advanced BAS Control– Premium Specification & Priced Product

• Special Advantage of Modular Design: If you loose 1 condenser, you only loose a small part of the building; NOT the entire building.

• Modular design only requires installation of a zone as required; entire cooling and heating system does not have to be piped during initial construction

VRF competes most naturally as a chiller.(this doesn’t mean it can only compete with chillers)11/16/2010


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Agenda • What is VRF?

– History – Concept





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HEAT TRANSFER MEDIA

Water

8.98 Btuh/lb

88.2 Btuh/lb

Refrigerant

Air

0.46 Btuh/lb

VAV VWV VRF

How does VRF Operate?


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Inverter Drive SystemT(sec)

+V

-VFrequency (Hz)

T(sec)

+V

-VFrequency (Hz)

Inverter Box

• The inverter control adjusts the supply frequency• Thus the rotational speed of the compressor is controlled• Exactly the right amount of refrigerant gas is pumped to meet the cooling requirements

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Inverter = Energy Efficiency

Capacity is regulated when outdoor temperature changes

Startup time is reduced by 1/3

The start/stop cycle is repeated less frequently – reducing energy loss at startup

As room temperature nears set point capacity is automatically “throttled down”

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Other Inverter Benefits• Very low startup amperage• No locked rotor amps• No stress on windings or compressor frame• No “light flicker”• Lubrication of bearings increases before speed

increases• System pressures increase gradually reducing

noise and stress on piping• Quiet compressor startup

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Other Inverter Benefits• Longer Run Periods at Lower Capacities

– Better Dehumidification– Fewer compressor starts mean less wear and tear on

the compressor = longer life!– Lower compressor speeds = higher system efficiency

since the condenser coil surface remains large in relation to reduced capacity

– Higher efficiency = Lower electric bills!

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Inlet

Outlet

PID ControlSignal

ValveMechanism

Electronic Expansion Valve (EEV) Control• EEV’s receive ‘PID’ control feedback to adjust

refrigerant volume– Up to 2000 steps of control

Continual management of flow rate controls super heat and coil capacity for optimum performance and energy efficiency

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Proportional, Integral & Derivative (PID)• Electronic expansion valve using PID

– Continuously adjusts the refrigerant volume in response to load variations

– Comfortable room temperature is maintained without the wide temperature swings of a conventional system

T4

T2

T1

Controller(TSET)

CPU(PID Control)

LEGENDT1: Refrigerant Liquid Line Temp.T2: Refrigerant Suction Line Temp.T3: Return Air / Remote Sensor Temp.T4: Controller Temperature SensorTSET: Controller Set Point Temp.

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System Capacity Control

1 2 3 4

EACH INDOOR CONTROLS ITS CAPACITY VIA PID CONTROL AND AN E.E.V.

CONDENSING UNIT ADJUST THE INVERTER COMPRESSOR TO PROVIDE THE REQUIRED CAPACITY (Large or Small)

T3

T4

T2

T1

Controller(TSET)

CPU(PID Control)

LEGENDT1: Refrigerant Liquid Line Temp.T2: Refrigerant Suction Line Temp.T3: Return Air / Remote Sensor Temp.T4: Controller Temperature SensorTSET: Controller Set Point Temp.



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• Efficiency improved in all areas compared to conventional AC motors, especially at low speeds

DC Fan Motor Efficiency

Magnet

DC Fan MotorDC Fan MotorAC Fan MotorAC Fan Motor

70

80

90

100

10 20 30 40 50 60 70 80 90 100 110

Revolutions [rps]M

otor

Effi

cien

cy [%

]

DC Motor

AC Motor

Approx.40%

increase

Approx.20%

increase

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Overview of ASHRAE Std 15

• Specifies minimum safety requirements in the event of a refrigerant leak into an occupied space.

• Safety Issues:

1. Flammable refrigerants causing injury or death by fire.

2. Toxic refrigerants possibly causing injury or death by poisoning.

3. Non flammable and non toxic refrigerants causing injury or death by asphyxiation from oxygen displacement.

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Important Standards / Code Information


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Scope of Standard 15

• Scope• 2.1 This standard establishes safeguards for life, limb, health, and

property and prescribes safety requirements.• 2.2 This standard applies

a. To the design, construction, test, installation, operation, and inspection of mechanical and absorption refrigeration systems, including heat pump systems used in stationary applications,

b. To modifications including replacement of parts or components if they are not identical in function and capacity, and

c. To substitutions of refrigerant having a different designation.

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Basic Steps

• Determine volume of smallest occupied space (cu.ft.)• Determine refrigerant qty potential of the smallest

occupied space (lbs)• Check that refrigerant qty potential doesn’t exceed the

allowable Refrigerant Concentration Limit (RCL) per 1000cuft.

• Check routing of piping (must be non obstructive) in corridors, lobbies and versus the RCL requirements

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Compliance Responsibilities

• Specifies application, not manufacturing requirements.• Impossible for a unit to comply, only an application can comply.• Design engineer is responsible for assessment and compliance.

– ASHRAE Std 15 has an easy to follow “Users Handbook” that can be purchased by the Engineer / Contractor.

• All units should comply with mandatory U.S. manufacturing standards.

• ASHRAE Std 15 equivalent standards exist in Europe and Asia and are just as stringent. “Direct” systems such as VRF are the most common solution in these regions and are applied successfully to meet these standards

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Current Situation • All VRF Equipment is currently

sold under a waiver from the DOE– No available testing and rating

standard • This means that only full load

EER and COP can be published• Advantage can not be taken of

the true VRV system benefits:- – Part load performance – Low ambient heating capabilities


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AHRI 1230• The industry has been working on

the VRF testing and rating standard for the last 5 years– Now, the hard work has paid off!

• We are proud to announce that the VRF testing and rating standard, AHRI 1230, will be launched and the efficiency levels will be in ASHRAE 90.1 by January 2011



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AHRI-1230 Explanation of the Ratings • All efficiency values will be based on the total system performance

including:-– Outdoor unit power input – Power input of indoor units – Piping loss correction factors to reflect real life building performance

• With this; We can now promote efficiency levels for Ducted, Ductless and Mixed combinations

Rating Daikin VRVIII

PB Series Other VRF

System Full Load EER ?System Full Load COP ?System Low Ambient COP (17°F) ?IEER (Part Load Operation) ?SCH (Heat Recovery Mode) ?



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VRF/VRV Benefits

Outdoor Unit

Indoor Units

Main features Energy Saving Individual control Long refrigerant Piping Wide range of units Low Noise Level

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Users Comfort Accurate Temperature Control

30

25

20

15

10 20 30 40 50 60 70

Cooling mode with VRF System:

Min..

Conventional A/C

VRF system

Room

Te

mpera

ture

Down to 1F

VRF/VRV Benefits


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• Ductless operating sound levels as low as 28dB(A) • Ducted operating sound Levels as low as 35dB(A)

35

41

38

44

39

45

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

12 MBH 24 MBH 36MBH

Standard Ducted Sound Levels

Low Fan High Fan

28

31

29

3433

40

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

12 MBH 24 MBH 36MBH

Cassette Ductless Sound Levels

Low Fan High Fan

User Comfort Low Operating Sound

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VRF/VRV Benefits


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Lightweight, Small & Flexible• Indoor units are lightweight and compact

– Fit into nearly any ceiling space• Outdoor units don’t require special cranes or

lifting devices– Can be hauled using a hand-lift and the

building elevator• Installation by floor

– If necessary, installation can be done by floor

• No need to wait until the full system is installed to test the system sections

ConventionalSystem

VRVSystem

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VRF/VRV Benefits


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Refrigerant R-410A

Air

Water

Ø 1-1/8“ Ø 1/2“ Ø 2“ Ø 2“

Ø 25 ½“

49“

16“

24“

24“

or

Always twoducts needed

or

Reduced Intallation Space For 10 Tons capacity

VRF/VRV Benefits


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Advanced Controls Solutions

Fire alarm Security

Ethernet

Power supply facility

BMS

~

~

(for use in Lon Worksnetworks)

HRV

VRF/VRV Benefits


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• The Future of VRF in North America 11/16/2010


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Worlds First CO2 VRF• This year; the worlds first CO2 based VRF System was released for

sale in Europe – One of the most environmentally friendly refrigerants with

a GWP of 1• New Technologies

– New optimized swing compressor to handle the higher pressures and reduce leakage

– Dual stage intercooler to help control the refrigerant and reduce pipe dimensions

– New 3 row heat exchanger and pass pattern for optimum heat transfer

The Future of VRF in North America


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What’s Next: Domestic and Hot Water Heating

The Future of VRF in North America


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Conclusion• VRF provides and alternative, realistic choice to

traditional central systems.• It captures many of the features of chilled water

systems, while incorporating the simplicity of DX systems.

• Allows for the correct equipment selection with both air cooled and water cooled equipment

• It brings some of the latest technology to the market and provides a higher degree of reliability, comfort and energy efficiency that is expected from today's consumer.


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Introduction to Variable Refrigerant Flow Systems

Allen AnayaApplication Consultant

WM Carroll, LLCPh: 505-268-6776Cell: 505-385-7338Fax: 505-255-1329

E-Mail: [email protected]

Thank You!

11/16/2010

Documents

Introduction to Variable Refrigerant Flow Systems Allen Anaya Application Consultant WM Carroll, LLC Ph: 505-268-6776 Cell: 505-385-7338 Fax: 505-255-1329