Vrf

Variable Refrigerant Flow - VRF The Comfort Conditioning Solution Features and Benefits

Air Conditioning System • The compressor is the highest power-consuming component in the air-conditioning system

Expansion valves, valves, •• Expansion fans, bypass bypass solenoid solenoid fans, valves also also affect affect valves system performance performance system • Component optimization increases performance.

1

What is a VRF System?

VRF

• 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 2

What makes a VRF?

VRF

• Outdoor units with single or multiple variable speed DC compressors • Single or multiple indoor units equipped with temperature sensing devices • A factory supplied zone temperature supervisory control, GUI and networking capabilities 3

VRF System & Inverter

VRF

• 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

4

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.

5

VRF Piping

VRF

• 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 6

Reduces piping cost and work

VRF

• 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.

7

Video

VRF

8

VRF Benefits • • • • • •

VRF

Less copper versus multi-split Eliminates most ductwork Quicker installation OEM software simplifies layout Long piping lengths Compact ductless system

9

Flexible piping design

VRF

Suitable for apartment & office buildings too Total piping length

377 – 540 Ft.*

Actual piping length

230 – 330 Ft.*

Height difference

100 – 165 Ft.*

* VARIES BY MANUFACTURER

100 to 165 ft. max.

10

Design freedom

VRF

This extra-long piping system can also cope with buildings of various shapes. Rectangular type

Outdoor unit

L type

Square type

Indoor units Refrigerant piping

Actual max. piping length 230 ft, Total max. piping length 377 ft* *Varies by manufacturer

11

Design Software

Piping Layout

Remote Control Selection

VRF

Job Costing

12

Advanced Computer Controlled

VRF

• Low energy consumption • Inverter regulates compressor to its optimum energy usage • Higher refrigerant performance with less power

13

Central Air Inefficiency Central

• VRF systems allows you to minimize inefficient ductwork. – Save money – Improve comfort – Protect health – Save Space – Reduce Noise 14

According to D.O.E. Central

• “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 as attic ducts in hot, humid climates) often lose more.” 15

Central Air Inefficiency

VRF •• VRF systems systems minimize minimize inefficient inefficient ductwork. ductwork.

Central

16

Multi-Split vs. VRF System • VRF systems allows you to minimize the refrigerant path compared to a multi-zone mini-split. Multi-Split

VRF

17

The heart of a VRF system

VRF

• 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. Scroll Compressor

DC Inverter Control

Signal line

Temperature Sensor

Temperature sensor

Indoor unit

Indoor unit

Outdoor unit

Senses the temperature of each room and optimizes operation. 18

What Zoning does for Efficiency

VRF

• Why cool spaces you do not occupy? • Individual zoning control of a VRF system minimizes electrical usage. 100% 90% 80% 70% 60%

Central VRF

50% 40% 30% 20% 10% 0% Kitchen

Living

Bed-1

Bed-2

Dining

19

Effective comfort at lower cost

VRF

• 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. Set temperature

40 min.

Inverter Room temperature (deg.)

Room temperature (deg.)

Conventional Model

Time

Revolution of COMPRESSOR

Set temperature

20 min.

Time

Revolution of COMPRESSOR

20

Variable Refrigerant Flow

VRF

• Conventional: Room temperature drops rapidly when compressor turns OFF which result in an unstable room temperature Conventional Model

Inverter Set temperature

3 deg.

Revolution of COMPRESSOR

ON

ON OFF

ON OFF

Time

Room temperature (deg.)

Room temperature (deg.)

Set temperature

1 deg.

Revolution of COMPRESSOR

Time

• 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. 21

Central

Connectable Capacity

• Central Air 100% Connectable Capacity

VRF

• VRF 50% to 150% Connectable Capacity

48,000 BTU

48,000 BTU

24,000 BTU

48,000 BTU

72,000 BTU

48,000 BTU

22

Connectable Capacity 24,000 BTU Apartment used only at night

150% Connectable

VRF

• 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

48,000 BTU Small Office used only during the day

• Example A: – 2-Story Building Mixed Use. VRF stretches square footage covered by a single system when not all areas are occupied simultaneously 23

Lack of Connectable Capacity Multi-Split Load Calculation 48,000 BTU

10K

12K

7K

4K

5K

5K

5K

Field Application 72,000 BTU 18K 9K

18K

9K

9K

9K

• 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. 24

Example of Connectable Capacity Load calculation 48,000 BTU without party quests

Actual 51,750 BTU with all indoor units calling 6.75K

10.5K 7K

10K

12K

4K

5K

9K

9K

9K

7K

7K

5.25K

5.25K

5K

5K

Field application 69,000 BTU connectable capacity 14K

VRF

7K

7K

6.75K

6.75K

5.25K

5.25K

Actual 48,000 BTU available for party with bedroom units off 9K

14K

9K

9K

7K

25

Benefits of Connectable Capacity Multi-Split

VRF 9K

14K

18K 9K

18K

7K

7K

9K

9K

9K

6-Tons when only 4-Tons required

9K

9K

7K

7K

Indoor unit for every room yet 4-Tons

• 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

26

VRF Benefits Benefit

VRF

Concept

Central Air

Multi-Split

VRF System

Cools off hot room

Slowly Unresponsive compressor

Quicker, Moderately responsive piping and compressor combination

Quickest, Highly Greatest comfort responsive piping and Less temperature compressor fluctuation combination ½ the time of a conventional unit

Refrigerant Cycle / Air Distribution

Short piping run but great efficiency loss in ductwork

Long piping but efficient air flow with evaporator in A/C space

Shorter piping run with better refrigerant distribution

Quicker cooling, greater comfort, more stable room temperature

Energy Consumption

Compressor runs at its maximum speed

Variable speed compressor but refrigerant flow efficiency loss

Variable speed compressor at optimum speed and maximizes refrigerant flow

Least energy consumption with greatest comfort

Zoning

1 or 2 zones without expensive zoning controls

Up to 4 zones Wireless or wired remote

Up to 16 zones. Wireless, wired, & group remotes Inverter provides more stable room temp.

Flexible zoning. Cool the spaces you occupy not the spaces you don’t

Connectible Capacity

100% connectible

100% connectible

Up to 150% connectible

Lower equipment 27 costs, more efficient

Flexible Remote Control Group Remote Controller

Simple Wired Remote

Full Featured Wired Remote Control Wireless Remote 28

Group Remote Controller Wiring A

Power line/signal line + ground = 4 wires

Power line + ground /signal line + ground = 6 wires

Wiring B

Power line + ground /signal line + ground = 6 wires 29

Wiring system Wiring is simplified by using a daisy chain approach. In this case wiring provides power as well as communication signal in a three wire harness.

30

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 31

Mix and Match Flexibility 1/4 Liquid 1/2 Gas Duct Type Coils from 18K to 45K BTU

1/4 Liquid 5/8 Gas 3/8 Liquid 3/4 Gas

Compact Duct Coils from 7K to 18K BTU

Large and Small Ceiling Cassettes From 7-42K BTU

1/4 Liquid 3/8 Gas

Condensing Unit Combinations from 2Tons to 31.5 Tons

3/8 Liquid 3/4 Gas Wall Mount Coils from 7K to 36K BTU 1/4 Liquid 5/8 Gas

3/8 Liquid, 3/4 Gas

32

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

33

VRF

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)

34

Two Temperature Temperature Controlled Controlled Zones Zones Two One Air Air Flow Flow Settings Settings per per Zone Zone One

Central

Equipment

1 - Outdoor unit 1 - Indoor unit 2 – Dampers 2 – Thermostats

THERMOSTAT 2

room 8 Because temperature

HALL THERMOSTAT 1

sensor is housed in thermostat, the temp of only two rooms can be controlled.

35

VRF

Individual Temperature Temperature Control Control Individual Individual Air Air Flow Flow Settings Settings Individual Equipment: Equipment:

1-Outdoor Outdoorunit unit 1Indoorunits units 88--Indoor Remotecontrols controls 88--Remote

HALLWAY

Each indoor indoor Each units has has an an units individual individual remote control control remote and aa room room and temperature temperature sensor sensor

9

36

Central

NoIndividual Individualtemperature/air temperature/airflow flowsettings settings No

8

Because set set Because temperature isis temperature matched to to matched living room, room, living the ideal ideal the temperature temperature cannot be be cannot selected for for selected other rooms. rooms. other

37

VRF

Individualtemperature/air temperature/airflow flowsetting setting Individual

9 HALL

Individual units units Individual with temperature temperature with sensors in in each each sensors room provide provide room comfortable comfortable separate room room separate temperatures temperatures matched to to the the matched room’s use. use. room’s

38

No Individual Individual temperature/air temperature/air flow flow setting setting No Central

Heat-sensitive adults present in living room Cold-sensitive infant Present in the bedroom

8

Individual air flow cannot be selected because there is one set air flow for all rooms.

8

Loud fan sound, rooms nearest indoor unit especially noisy, because large fan creates large air flow.

Whentemperature temperatureand andair airflow floware areset setto toaccommodate accommodateinfant infantininbedroom, bedroom, When peopleininother otherrooms roomsare aretoo toohot hotbecause becausesetting settingare aresame sameininall allrooms. rooms. people 39

VRF

9

Temperature and air flow can be individually set according to the room usage conditions.

9

Quiet operation as low as 23db 40

Changing Sun Load

Central

8 When direct sunlight or other disturbances

change room load, system response for individual rooms is impossible because set temperature matched to living room. A.M.

P.M.

41

VRF

9

Changing Sun Load

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. A.M.

P.M.

42

Time to Reach Set Point

Central

Ex: When returning home in the summer

VRF

8 9 farther the room is from the 8 The indoor unit, the poorer the cooling. Large amounts of cool air flow to Each room cooled quickly and 9 evenly. the outlets nearest indoor unit. Cool air also flows to unoccupied rooms so it takes time to reach set temperature.

Full capacity concentrated at operating indoor units located in the rooms in which people returning home congregate, other units turned off.

43

Central

Duct Maintenance

After cooling stopped

When cooling begins

is easily produced Mold spores sticking to 8 Mold 8 with the condensed water dust are blown into room as the nutrient

8

Since the area of the duct is large; a large amount of mold is produced.

ducts are 8 Inaccessible difficult to clean or remove mold.

44

VRF

Duct Maintenance

After cooling stopped

When cooling begins

9

Small amount of condensation form on each indoor unit (duct)

9

9

Since the area of the duct is small; mold production is minimized.

Indoor units installed in each room with small duct area. Mold production and dust are suppressed.

9

Accessible ducts make periodic cleaning easy preventing mold production

45

VRF - Precise Modulation 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

46

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

TXVOperation Operationisis TXV TotallyIndependent Independentof of Totally CompressorOperation Operation Compressor

47

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) 48

Thermal Expansion Valve TXV Condenser

Evaporator

TXV

Compressor • 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). 49

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.

STOP

• 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. 50

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

51

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 pulse applied to its windings

52

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 meeting targeted superheat.

53

Thermistors • A type of resistor used to measure temperature changes, relying on the change in its resistance with changing temperature.

54

Control Loop Components • Measurement By a sensor (thermistor) connected to the refrigerant cycle or the “space" • Decision Made in Advanced Computer Controller • Action Taken through an output device ("actuator") such as the stepper motor in the EEV or Variable speed inverter compressor 55

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. Setpoint

+

Σ

error

- Room temperature 56

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.

57

Controller’s algorithm

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

58

PID Calculations P: 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 at the history of the error signal D: Controller output is proportional to the rate of change of the measurement or error. Controller output is calculated by the rate of change of the measurement with time.

59

So what’s an Inverter? • An inverter controls the operating speed of a DC motor by controlling the frequency and 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.

60

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

61

Diode Bridge

Load

• 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 62

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

63

Inverter Block Diagram

64

Inverter Control Video

VRF

65

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

66

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.

67

PWM

68

DC Inverter Control Function Basic Circuit of 3-Phase Inverter

69

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.

70

Low Electric Consumption 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 71

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. 72

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 Tons of available heat exchangers

9 HP of compressors Max. 10.5 HP

Max. 10.5 HP

Max. 10.5 HP

by using 3 outdoor units together

73

Operation / Comfort • 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

74

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

75

Central remote controller

Central control by tenant

Central remote controller

Central remote controller Individual control

76

PC Control Rotating 3-D display

Floor layout display

List table display

Calculating electricity charges Up to 400 indoor units or 400 groups can be controlled

PC controller

Operation control

Schedule control

Operating record 77

PC controller (Calculating electricity charges) Each tenant bill can be made by calculating function of PC controller

Power supply Electricity company

Meter

Tenant bill Tenant-E Tenant bill Tenant-D

Total Electricity bill

Tenant bill Tenant-C Tenant bill Tenant-B

Apportioned charges Tenant bill

PC controller

Tenant-A The accumulated refrigerant time and indoor unit capacity.

78

BMS compatibility

BMS: Building Management System

79

Service tool (Software) Extensive monitoring and analyzing functions for maintenance

Simple connection by transmission adaptor and RS-232C cable (RS-232C cable field supplied). 80

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 81

Thank You

for your time and attention. We hope you will consider VRF technology for your next project 82