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The Comfort Conditioning Solution Features and Benefits
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Variable Refrigerant Flow - VRFThe Comfort Conditioning Solution
Features and Benefits
1
• The compressor is the highest power-consuming component in the air-conditioning system
• Component optimization increases performance.
Air Conditioning System
• Expansion valves, fans, bypass solenoid valves also affect system performance
• Expansion valves, fans, bypass solenoid valves also affect system performance
2
What is a VRF System?
• A system that provides
▪ Climate control & zoning comfort
▪ Effective energy consumption by means of optimized inverter driven scroll compressor & temperature controls, producing highly responsive cooling and/or heating
VRF
3
What makes a VRF?
• Outdoor units with single or multiple variable speed DC compressors
• Single or multiple indoor units equipped with temperature sensing devices
• A factory suppliedzone temperature supervisory control, GUI and networking capabilities
VRF
4
VRF System & Inverter• The inverter reacts to indoor and outdoor
temperature fluctuation by varying the power consumption and adjusting the compressor speed to its optimum energy usage.
• The refrigerant is compressed to the required high pressure level
• Inverter provides superior energy efficiency performance
VRF
5
VRF Outdoor Fan Motor Control• Multi stage fan speed operation provides:
• Input power savings, lower steps have lower power consumption compared to higher steps.
• Optimizes condenser pressure control to achieve desired discharge pressure and ensure optimum mass flow through the system.
• Cycle stabilization provides optimum efficiency as compared to fix fan speed.
6
VRF Piping
• Improves refrigerant cycle efficiency by connecting multiple indoor units to a common liquid and suction line through the use of STA Separation Tube Assemblies and/or Headers and EEV Electronic Expansion Valves
VRF
7
Reduces piping cost and work• STA and or header diverts the common flow of
refrigerant to an individual evaporator. The flow of refrigerant is further metered by an EEV or Electronic Expansion Valve.
VRF
8
VRFVideo
9
VRF Benefits• Less copper versus multi-split • Eliminates most ductwork • Quicker installation• OEM software simplifies layout• Long piping lengths • Compact ductless system
VRF
10
Flexible piping design
Actual piping length
Height difference
377 – 540 Ft.*230 – 330 Ft.*
100 – 165 Ft.*
Suitable for apartment & office buildings too
100 to
165 ft.max.
Total piping length
VRF
* VARIES BY MANUFACTURER
11
Outdoor unit
Rectangular type L type Square type
Refrigerant piping
This extra-long piping system can also cope with buildings of various shapes.
Design freedom
Actual max. piping length 230 ft, Total max. piping length 377 ft*
*Varies by manufacturer
VRF
Indoor units
12
Design Software
Piping Layout Remote ControlSelection
JobCosting
VRF
13
Advanced Computer Controlled• Low energy consumption
• Inverter regulates compressor to its optimum energy usage
• Higher refrigerant performance with less power
VRF
14
Central Air Inefficiency
• VRF systems allows you to minimize inefficient ductwork.
– Save money
– Improve comfort
– Protect health
– Save Space
– Reduce Noise
Central
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According to D.O.E.
• “Typical duct systems lose 25 to 40 percent of the heating or cooling energy put out by the central furnace, heat pump, or air conditioner.”
• “Homes with ducts in a protected area such as a basement may lose somewhat less than this, while some other types of systems (such asattic ducts in hot, humid climates) often lose more.”
Central
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Central Air Inefficiency
• VRF systems minimize inefficient ductwork.
• VRF systems minimize inefficient ductwork.
Central
17
Multi-Split vs. VRF System• VRF systems allows you to minimize the refrigerant
path compared to a multi-zone mini-split.
Multi-Split VRF
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The heart of a VRF system• Inverter driven DC scroll compressor(s) provides
highly responsive cooling and/or heating by quickly varying in speed from 1,000 up to 6,000 rpm.
Outdoor unit
Scroll Compressor
DC Inverter Control Signal line
Senses the temperature of each room and optimizes operation.
Temperature Sensor
Temperature sensor
Indoor unit Indoor unit
VRF
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What Zoning does for Efficiency• Why cool spaces you do not occupy? • Individual zoning control of a VRF system
minimizes electrical usage.
VRF
0%10%20%30%40%50%60%70%80%90%
100%
Kitchen Living Bed-1 Bed-2 Dining
CentralVRF
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Effective comfort at lower cost• Reacts to indoor and outdoor temperature
fluctuation by varying power consumption and adjusting compressor speed to its optimum energy usage to achieve desired set point quickly and maintain it more closely.
VRFR
oom
tem
pera
ture
(deg
.) Set temperature
40 min. Time
Roo
m te
mpe
ratu
re (d
eg.) Set temperature
20 min. Time
Conventional Model Inverter
Revolution of COMPRESSOR Revolution of COMPRESSOR
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• Conventional: Room temperature drops rapidly when compressor turns OFF which result in an unstable room temperature
• Inverter: Range of room temperature change is small. Because after set temp is reached, compressor will not shut off to control temp but will maintain temp by decreasing or increasing revolution.
ON
Roo
m te
mpe
ratu
re (d
eg.)
Set temperature
TimeR
oom
tem
pera
ture
(deg
.)
Set temperature
Time
3 deg. 1 deg.
Conventional Model Inverter
ONRevolution of COMPRESSOR
OFF OFFON
Revolution of COMPRESSOR
Variable Refrigerant FlowVRF
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Connectable Capacity• Central Air 100%
Connectable Capacity
VRF
• VRF 50% to 150% Connectable Capacity
48,000 BTU
Central
48,000 BTU48,000 BTU
48,000 BTU 24,000 BTU
72,000 BTU
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Connectable Capacity• Ability to connect up to
150% of name plate rated indoor units*
* Varies by manufacturer• If all indoor units are
operated simultaneously system will not produce more than 110% of system capacity
• Example A:– 2-Story Building
Mixed Use. VRF stretches square footage covered by a single system when not all areas are occupied simultaneously
48,000 BTU Small Office used only during the day
24,000 BTUApartmentused only atnight
VRF
150%150%ConnectableConnectable
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Lack of Connectable CapacityMulti-Split
18K 9K 9K
18K9K 9K
Load Calculation 48,000 BTU Field Application 72,000 BTU
5K 5K
7K 5K4K
12K
10K
• 6 tons applied where load only calls for 4 tons• Higher equipment cost by installing two systems in
order to provide most rooms with individual control.
25
Example of Connectable Capacity VRF
Field application 69,000 BTU connectable capacity
Load calculation 48,000 BTUwithout party quests
5K 5K
7K 5K4K
12K
10K
Actual 51,750 BTU withall indoor units calling
6.75K 6.75K 5.25K 5.25K
10.5K 6.75K 5.25K 5.25K
Actual 48,000 BTU availablefor party with bedroom units off
9K 9K
14K9K 7K
9K 9K 7K 7K
14K9K 7K 7K
26
Benefits of Connectable Capacity
• Reduced equipment cost by not installing additional equipment when a system can be shared instead.
• The ability to flexible size for different loads.• Stretch square footage covered by over-sizing and
reducing capacity at each indoor unit by design
Multi-Split VRF
6-Tons when only 4-Tons required Indoor unit for every room yet 4-Tons
18K 9K 9K
18K9K 9K
9K 9K 7K 7K
14K9K 7K 7K
27
VRF Benefits
Lower equipmentcosts, more efficient
Up to 150% connectible
100% connectible100% connectible
ConnectibleCapacity
Flexible zoning. Cool the spaces you occupy not the spaces you don’t
Up to 16 zones. Wireless, wired, & group remotesInverter provides more stable room temp.
Up to 4 zones Wireless or wired remote
1 or 2 zones without expensive zoning controls
Zoning
Least energy consumption with greatest comfort
Variable speedcompressor at optimum speed and maximizesrefrigerant flow
Variable speedcompressor but refrigerant flow efficiency loss
Compressor runs at its maximum speed
EnergyConsumption
Quicker cooling, greater comfort, more stable room temperature
Shorter piping run with better refrigerant distribution
Long piping but efficient air flow with evaporator in A/C space
Short piping run but great efficiency loss in ductwork
RefrigerantCycle / AirDistribution
Greatest comfortLess temperature fluctuation
Quickest, Highly responsive piping and compressor combination ½ the time of a conventional unit
Quicker, Moderately responsive piping and compressorcombination
SlowlyUnresponsivecompressor
Cools off hot room
BenefitVRF SystemMulti-SplitCentral AirConceptVRF
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Flexible Remote ControlGroup RemoteController
Wireless Remote
Full FeaturedWired RemoteControl
SimpleWiredRemote
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Power line + ground /signal line + ground = 6 wires
Power line/signal line+ ground = 4 wires
Wiring A
Wiring B
Power line + ground /signal line + ground = 6 wires
Group Remote Controller
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Wiring systemWiring is simplified by using a daisy chain approach. In this case wiring provides power as well as communication signal in a three wire harness.
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Simplified Wiring
• NEC compliant• Disconnect switch may be required• Outdoor units requires 208/230V 40A single
phase or 3-phase, depends on BTU’s• Indoor units powered from the outdoor unit using
3 wires and ground. Usually 14AWG.• Indoor required two lines for power, typically
208/230 V single phase 15A.• 3rd line used for networking and data
communication
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3/8 Liquid3/4 Gas
1/4 Liquid5/8 Gas
1/4 Liquid3/8 Gas
1/4 Liquid5/8 Gas
1/4 Liquid1/2 Gas
3/8 Liquid, 3/4 Gas
3/8 Liquid3/4 Gas
Mix and Match Flexibility Large and Small Ceiling CassettesFrom 7-42K BTU
Condensing UnitCombinations from2Tons to 31.5 Tons
Wall Mount Coils from 7K to 36K BTU
Compact Duct Coilsfrom 7K to 18K BTU
Duct Type Coilsfrom 18K to 45K BTU
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Piping system
Refrigerant flow is accumulated by using STA separation tube assemblies in reverse and then dividing refrigerant flow to as many as 48 indoor units
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1. Short Term Stop Gap Method• All manufacturers test up to five evaporators under an agreed
upon test method to prove minimum EER efficiency (We estimate 1 year in development)
2. Interim Test Method• Develop test method for new ductless multi and VRF test
standard based on 210/240.(Tentatively draft ARI1230) (We estimate 2 years in development)
3. Long Term Method• Computer simulation through OEM software approved by ARI to
demonstrate efficiency regardless of combination (We estimate 3 years in development)
VRF
35
Equipment1 - Outdoor unit 1 - Indoor unit2 – Dampers2 – Thermostats
HALL
THERMOSTAT 2
THERMOSTAT 1
Two Temperature Controlled ZonesOne Air Flow Settings per ZoneTwo Temperature Controlled ZonesOne Air Flow Settings per Zone
Because room temperature sensor is housed in thermostat, the temp of only two rooms can be controlled.
Central
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Each indoor units has an
individual remote control
and a room temperature
sensor
Each indoor units has an
individual remote control
and a room temperature
sensor
Individual Temperature Control Individual Air Flow SettingsIndividual Temperature Control Individual Air Flow Settings
Equipment:1- Outdoor unit8 - Indoor units 8 - Remote controls
Equipment:1- Outdoor unit8 - Indoor units 8 - Remote controls
HALLWAY
VRF
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No Individual temperature/air flow settingsNo Individual temperature/air flow settingsCentral
Because set temperature is matched to living room, the ideal temperature cannot be selected for other rooms.
Because set temperature is matched to living room, the ideal temperature cannot be selected for other rooms.
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Individual units with temperature sensors in each room provide comfortable separate room temperatures matched to the room’s use.
Individual units with temperature sensors in each room provide comfortable separate room temperatures matched to the room’s use.
HALL
Individual temperature/air flow settingIndividual temperature/air flow settingVRF
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No Individual temperature/air flow settingNo Individual temperature/air flow setting
Heat-sensitive adults present in living room
Cold-sensitive infantPresent in the bedroom
When temperature and air flow are set to accommodate infant in bedroom, people in other rooms are too hot because setting are same in all rooms.When temperature and air flow are set to accommodate infant in bedroom, people in other rooms are too hot because setting are same in all rooms.
Individual air flow cannot be selected because there is one set air flow for all rooms.
Loud fan sound, rooms nearest indoor unit especially noisy, because large fan creates large air flow.
Central
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Temperature and air flow can be individually set according to the room usage conditions.
Quiet operation as low as 23db
VRF
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When direct sunlight or other disturbances change room load, system response for individual rooms is impossible because set temperature matched to living room.
Central
A.M. P.M.
Changing Sun Load
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When the heat load changes by direct sunlight or other disturbance, settings can be changed for each room. All the rooms can be kept comfortable.
Changing Sun LoadVRF
A.M. P.M.
43
Cool air also flows to unoccupied rooms so it takes time to reach set temperature.
The farther the room is from the indoor unit, the poorer the cooling. Large amounts of cool air flow to the outlets nearest indoor unit.
Ex: When returning home in the summerCentralTime to Reach Set Point
VRF
Full capacity concentrated at operating indoor units located in the rooms in which people returning home congregate, other units turned off.
Each room cooled quickly and evenly.
44
After cooling stoppedMold is easily produced with the condensed water as the nutrientSince the area of the duct is large; a large amount of mold is produced.
When cooling begins
Mold spores sticking to dust are blown into room
Inaccessible ducts are difficult to clean or remove mold.
Duct MaintenanceCentral
45
When cooling beginsIndoor units installed in each room with small duct area. Mold production and dust are suppressed.
Accessible ducts make periodic cleaning easy preventing mold production
VRFDuct Maintenance
After cooling stoppedSmall amount of condensation form on each indoor unit (duct)Since the area of the duct is small; mold production is minimized.
46
Variable Refrigerant Flow (VRF) technology provides effective comfort with low energy consumption.
The operational savings come from the zoning because only occupied spaces are conditioned.
The work of the refrigerant is adjusted with an inverter & and the flow further gauged with the EEV
VRF - Precise Modulation
47
Thermal Expansion Valve TXV• Susceptible to valve hunting: overfeeding and
starving of refrigerant flow to the evaporator.• Hunting can be reduced by relocating the
sensing bulb to a better location
TXV Operation is Totally Independent of Compressor Operation
TXV Operation is Totally Independent of Compressor Operation
48
Lack of TXV Integration• What standard TXVs do not do:
– Control evaporator pressure– Cycle the compressor– Control running time– Control room temperature
• Three main working forces on the TXV are:– Remote bulb or sensing bulb pressure (opening
force)– Spring pressure (closing force)– Evaporator pressure (closing force)
49
Thermal Expansion Valve TXV
• As evaporator load increases, available refrigerant will boil off more rapidly. If it is completely evaporated prior to exiting the vapor will continue to absorb heat (superheat).
Con
dens
er
Evap
orat
or
Compressor
TXV
50
TXV & Superheat• Super heat is heat added to a
substance above its saturation temperature. The amount of super heat in a system is a concern.
• To little: liquid refrigerant entering compressor washes out the oil causing premature failure
• To much: valuable evaporator space is wasted and possibly causing compressor overheating problems.
STOP
51
EEV – Positioning System• EEV function is to maintain the pressure
differential and also to distribute the right amount of refrigerant to each indoor unit.
• Fine control on the refrigerant flow provides a superior level of room temperature control & ensures no wastage of energy
EEV is responding directly to room temperature and room load
52
EEV – Positioning System• EEV = Stepper Motor + Expansion Valve• Stepper motor is a brushless, synchronous
electric motor that can divide a full rotation into a large number of steps, 500 steps/rev
• Primary characteristic is its ability to rotate a prescribed small angle (step) in response to each control pulseapplied to its windings
53
EEV – Positioning System• Expansion valve is the component that controls
the rate at which liquid refrigerant can flow into an evaporator coil
• Control algorithm is continuously providing signals to the EEV to open or close by small amounts to vary the amount of refrigerant being delivered to the evaporator meetingtargeted superheat.
54
Thermistors• A type of resistor used to measure temperature
changes, relying on the change in its resistance with changing temperature.
55
• Measurement By a sensor (thermistor) connected to the refrigerant cycle or the “space"
• DecisionMade in Advanced Computer Controller
• ActionTaken through an output device ("actuator") such as the stepper motor in the EEV or Variable speed inverter compressor
Control Loop Components
56
Control Loop at Local Evaporator
• The controller takes a measured value from the space (by means of a thermistor) and compares it with a reference SETPOINT value.
• The difference (or "error" signal) is then used to adjust a system component in order to bring the spaces' measured value back to its desired SETPOINT.
ΣSetpoint + error
- Room temperature
57
Control loop at local evaporator• The digital controller can adjust space outputs
based on the HISTORY and RATE OF CHANGE of the error signal, which gives more accurate and stable control.
58
Controller uses 3 correcting calculations”• Proportional control to improve the rise time • Integral control to eliminate the steady-state error • Derivative control to improve the overshoot
based on the rate of change of the error
Controller’s algorithm
59
PID CalculationsP: Handles immediate error, the error is multiplied by a
Proportional constant P, and added to controlled variable.
I: Controller output is proportional to the amount of time the error is present. Integral action eliminates offset. It looks atthe history of the error signal
D: Controller output is proportional to the rate of change of themeasurement or error. Controller output is calculated by the rate of change of the measurement with time.
60
So what’s an Inverter?• An inverter controls the operating speed of
a DC motor by controlling the frequencyand voltage of the power supplied to the motor.
• An inverter provides the controlled power. In most cases, the inverter includes a rectifier so that DC power for the inverter can be provided from mains AC power.
61
Inverter Principle
• Bridge Rectifier
Provides the same polarity of output voltage for any polarity of the input voltage. In other words, converts alternating current (AC) input into direct current (DC) output.
Diodes are used to rectify AC by blocking the negative or positive portion of the waveform
62
Diode Bridge• Alternating current
(AC) whose magnitude and direction vary cyclically (60Hz)
• Basic Operation:current flows to the right along the upper colored path to the output, and returns to the supply via the lower one.
• If supplied current direction changes output current direction remains the same, DC
• Result: Negative part of the waveform has been eliminated
Load
63
Inverter Principle• Smoothing Condenser
used to smooth the ripple voltage present in a pulsating DC voltage output of a power supply rectifier.
• Most modern electronic devices require a steady DC supply
64
Inverter Block Diagram
65
Inverter Control Video VRF
66
Inverter Principle• IPM (Inverter Power Module)
It is composed of 6 transistors and drives the motor by high speed signal switching.
• The drive voltage signal is transferred to the drive circuit from a microcomputer, and varies the supply frequency to the motor (PWM system) to rotate the motor.
• Currently, insulated gate bipolar transistors IGBT’s are used in most inverter circuits
67
PWM Pulse Width Modulation• Signal involves the modulation of its duty cycle, to
control the amount of power sent to a load.
• Many digital circuits can generate PWM signals outputs to control an electrical motor.
• Usually use a counter that increments periodically and is reset at the end of every period of PWM.
• If counter value is more than the reference value, the PWM output changes state from high to low.
68
PWM
69
DC Inverter Control Function Basic Circuit of 3-Phase Inverter
70
Why do I want an Inverter?• Benefits of an Inverter Air Conditioner:
– Compared to the common On-Off controlled compressor; the inverter controlled compressor is able to run at the proper revolution to provide the best efficiency and reduce losses.
– When the maximum capacity is not required, the compressor revolution is decreased. This means the input power decreases too, which results in increased system efficiency.
71
Power balance control technology achieves high operational efficiencies by detecting low pressure and high pressure and precisely controls the optimum refrigerant condition via refrigerant flow rate.
Efficient DC inverter scroll compressor varies capacity according to the load
Low Electric Consumption
72
Power Oil Return• Oil return is important to
ensure that there is adequate lubrication for the compressor, especially during part load operation.
• Reducing oil logging in the system improves heat exchange efficiency in the condenser and evaporators saving energy.
73
Effective use of heat exchanger
The outdoor unit can achieve the most efficient operation by matching the heat exchanger of the outdoor unit to the systems requirements and the required load capacity of the conditioned space.
Example
31.5 Tons31.5 Tons of availableheat exchangers
9 HP9 HP of compressors by using 3 outdoor units together
Max. 10.5 HP Max. 10.5 HP Max. 10.5 HP
74
• Quiet operation (varies by manufacturer)Normal operation mode: 57dB(A)Night operation mode 54 dB(A)
• Inverter compressor makes system even quieter when it is operating at slower RPMs
Operation / Comfort
75
Central remote controller
Up to 400 indoor units or 64 groups can be controlled. Central remote controller can control the system by selecting All Groups, User Defined Groups or Individual Remote Controller Groups
76
Central control by tenant
Individual control
Central remote controller
Central remote controller
Central remote controller
77
PC Control
Operating recordSchedule controlOperation control
List table displayFloor layout displayRotating 3-D display
Calculating electricity charges
PC controllerUp to 400 indoor
units or 400 groups can be controlled
78
PC controller (Calculating electricity charges)
Each tenant bill can be made by calculating function of PC controller
Electricity company
Total Electricity bill
PC controller Tenant-A
Tenant-B
Tenant-C
Tenant-D
Tenant-EMeter
Power supply
Apportioned charges
Tenant bill
Tenant bill
Tenant bill
Tenant bill
Tenant bill
The accumulated refrigerant time and indoor unit capacity.
79
BMS compatibility
BMS: Building Management System
80
Extensive monitoring and analyzing functions for maintenance
Simple connection by transmission adaptor and RS-232C cable (RS-232C cable field supplied).
Service tool (Software)
81
VRF - Summary
• Climate control & zoning comfort• Effective energy consumption • Inverter driven scroll compressor &
digital temperature controls, • Produces a highly responsive cooling
and/or heating.• Cooling/Heating only on demand
82
Thank Youfor your time and
attention.
We hope you will consider VRF technology for
your next project
