air cooled packaged systems airah back to basics · compare a digital compressor in a package unit...

Air Cooled Packaged Systems

AIRAH Back to Basics

What’s changed?

• New Refrigerants – R410a

• MEPS – EER / AEER / SEER

• Manufacturing Technologies

• Research, Development and Testing

• New technologies, controls, reliability

• Energy Modelling

• Energy Costs

• What is life cycle – is it driven by corrosion, a compressor failure, time or Energy consumption

• Exact refrigeration engineering science: Sound engineering, optimum balance points, specifically designed and circuited evaporator and condenser coils, selecting components at the correct duty points and correct refrigeration distribution and velocity.

• Raw materials go in one end of the building a fully formed air conditioner comes out the other.

• Volume assembly lines has ensured lower costs and internationally competitive pricing.

• Components are well known and very reliable brands

Manufacturing Technologies

3Air Cooled Packaged Units – AIRAH Back to Basics

• Air Conditioning Manufacturing Engineers are specialists in refrigeration engineering science focused on the design of balanced integrated systems of a package or a split.

• Product/industry expertise - we understanding local climates and conditions we design our products to excel in these conditions.

• Testing rooms insure compliance to MEPS

• Test room controllable temperature range -15C to +60C

• Anechoic chamber for sound level testing

• Fan testing chamber

• Calorimeter room for capacity testing – MEPS or Just R&D

Research & Development


What has not changed?

• Heat transfer

• Refrigeration cycle

• It’s too hot or it’s too cold

• I need it now

• How does that work ?

• This is not working ?

The system has been the same since 1834We just know how to control and balance it better now


How the humble old packaged machine has changed

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10 years ago Today

Cooling

Capacity50.3

Cooling

Capacity55.7 + 11%

Power Input 24.9Power

Input14.2 - 43%

EER 2.01 EER 3.15 + 56%

Air Cooled Packaged Units – AIRAH Back to Basics

• Latest technology in variable compressor control – Digi, VRF

• Electronic Expansion Valves (EEV) - Superior refrigeration system balance and control under all load conditions

• EC Motor Plug Fans - EC Fan capabilities for system performance and part load performance

• Latest in Self Diagnostics and BMS interface capabilities

• Latest in coil design technologies

Technologies changing the face of refrigeration


• We must understand the differences between the inverter compressor and the digital compressor and NOT get confused with trying to compare a Digital compressor in a package unit to a VRF system – VRF system uses an inverter compressor, uses varied refrigerant mass flow, uses EC motors and variable air flow which all contribute to the VRF efficiency, where as a package system with a digital compressor uses the digital compressor for load and or capacity control with no refrigerant mass flow actual reduction is the pulsating on/off unload / loaded state, nor is there a use of EC motors or variable air flow.

• Both are very different technologies and before we can talk about benefits of one over the other these questions need to be asked.

• What’s the application, part load opportunities , comfort, process etc

• Is there part load opportunity or will the machine run at full load all the time

• What is the load sensible or latent

• What is the cooling profile

Digital and variable compressor technologies


• Inverter compressor: uses an external variable frequency drive - to control the speed of compressor. The refrigerant flow rate is varied by the change in the speed of compressor. The turndown ratio depends on the system configuration and manufacturer. It modulates from 10% up to 115% at full capacity with a single inverter. (can differ from manufacturer)

• The variable frequency drive controls the speed of compressor motor. The compressor is specifically designed to run at different motor speeds to modulate cooling output .Variable speed operation requires an appropriate compressor for full speed operation and a special compressor lubrication system. Proper oil management is a critical requirement to ensure compressor lifetime. Proper oil management provides proper lubrication for scroll set at low speed and prevents excess oil from being injected into the circuit when operating at full speed.

Variable Compressor


• This technology is inherent in its simplicity. The standard Copeland® Scroll™ has a unique feature called axial compliance. This allows the fixed Scroll™ to move in the axial direction, by very small amounts, to ensure that the fixed and orbiting scrolls are always loaded together with the optimal force.

• This optimal force holding the 2 scrolls together at all operating conditions ensure the high efficiency of Copeland® scrolls. The Digital Scroll™ operation builds on this principle.

• The Digital Scroll™ operates in two stages - the "loaded state", when the solenoid valve is normally closed and "unloaded state", when the solenoid valve is open. During the loaded state the compressor operates like a standard Scroll™ and delivers full capacity and mass flow. However, during the unloaded state, there is no capacity and no mass flow through the compressor.

• If you look at actual data of a machine and just look at the EER of it with a digital compressor, remember as the compressor unloads the amps drop and the suction pressure increases – so the gains when unloaded are reduced running amps. The digital compressor in isolation is a capacity modulation device not an energy efficiency device, however when used in a well controlled machine with an EC evaporator plug fan, electronic expansion valves and or Economy cycle all controlled and system balanced significant efficiency gains can be realised.

Variable Compressor - Digital


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Variable Capacity Compressor

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Digital Scroll Compressor Benefits

• 10% - 100% wide capacity modulation

• Fast cooling and heating

• Higher part load efficiency due to matching room heat load

• Precise temperature control with improved comfort

• Better humidity control as constant coil temperature

• No oil return issue

• Simple electronics, no EMI issues

• Easy to install, service and maintain


Digital Compressor Efficiency


Control

Controllability allows close control air supply giving your space superior comfort

Close Comfort Control


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With variable compressor technology, EEV, EC fan technologies and economy cycle all being controlled and monitored by the unit controller, makes for energy optimisation for both heating and cooling.

The unit controller, is the key to your systems energy efficiency. It’s responsible for:

• control

• balance

• safety

• optimum plant efficiency

• continually monitoring and adjusting system performance, with changing outdoor temperatures.


Unit Control

Technology Gains Versus Costs


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Efficiency

Energy & Cost Saving Features

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• Variable capacity compressors

– Digital and Inverter

• EC Motors

• Economy cycle

• EC Plug Fans

• EEV for optimised refrigerant flow

• How we control / balance the system


Economy Cycle

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The Economy Cycle presents significant energy savings by utilising outside ambient air to cool the space.

When the outside ambient air is below the set point required, the compressor is cycled off, outside air dampers open, and the supply air fan continues to run, bringing cool air in from outside.

The main benefits:

• Reduced power consumption

• Reduced compressor run hours

Requires the installation of motorized dampers & corresponding controls that can monitor outside air temperature.


EC Motors & Plug Fans

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EC Plug Fans offer many benefits when applied to Packaged Air Conditioners

• High Efficiency of 90 - 95% = Lower Input Power

• Lower air temperature rise in airstream

• Infinite Fan Speed Control

• Increased static pressure limits - Plug Fan

• Longer motor life resulting from lower running temperatures

• Longer bearing life due to soft start feature

• Suitable for 240V supply

• Quiet operation – slow ramp up


EC Fan Efficiency

EC vs AC - Power Input to Fans

Fan size: ebmpapst A3G800


EC Motor & Plug Fans

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Plug fan option alone gives you a 12% EER increase


Electronic Expansion Valves

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EEV’s provide more efficient control of the refrigerant flow, and also reduce the condensing pressure in the system


Electronic Expansion Valves

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• Low condensing pressure

• High cooling capacity

• High efficiency

• Refrigeration Balance


Variable and Fixed Expansion


Discover up to 50% annual energy savings with latest technologies

y Energy savings


Running cost savings with new technologies and control


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Based on: Hours of operation: 4745 hours per year (8am to 9pm, 365 days per year) Occupancy: variable to simultaneous peak of 580 personsPeak cooling load – 124kWr GTH/84.6kWr GTSH, (ACADS CAMEL 5.10.2) Plant configuration – 3 x 55kWr Rooftop PAC unitsEnergy calculations using ACADS BEAVER 7.11.0

0

Spring / Autumn - Shoulder• Dry Mode providing

humidity control• Part load efficiencies

• Digital / Inverter compressors

• Plug fans• Electronic valves• Economy Cycle

Year round – Plant considerations

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Summer - Peak cooling load

• Large Coils cope with a hot summer

• EC condenser fans lowering running costs

• Dry Mode providing humidity control Winter - Peak heating load

• Large Coils providing low ambient heating

• Inverter compressors and EC condenser fans provide efficient heating


Refrigeration Guide Lines

• Nominal Conditions: 27/19 C / 35 C ambient R410a

• SHR between 0.8 and 0.85

• SH – between 3-5 K Target

• SC –3 to 5 K Target

• DSH – 25 K Target

• SST – 5 and 13 C (vary with balance)

• SCT – 45 – 55 C (+60)

• HP – Trip 4200 KPa

• DT – 80 - 95 C (100 - 110 C)

• Evap TD – 10 - 15 C at .8 to .85 SHR

• Evap TD – 6-8 C at .5 to .75 SHR

• Cond TD – 12 - 15 C target

• Evap Abs. Press – 1060 kPa

• Cond Abs. Pressure – 3400 kPa

Packaged Systems Single or Split


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Where has HGBP gone ?

• Hot gas bypass was recommended when the load on an evaporator varies and operation of the air conditioning system is desired at lower than design conditions.

• Hot gas bypass provides an artificial load on the evaporator by introducing a portion of high pressure, high temperature gas to the evaporator / suction side of the system.

• In the past we use HGBP for – high % outside air, variable air flow systems, coil velocities below 1.5 M/S or (30 -35 L/S per KW), modulating periods of load, cooling below 20 C ambient.

• HGBP set to open at +1-2C and close at 4-5 C coil temperature

• NOW WHAT’S CHANGED – TECHNOLOGY HAS

• Variable compressors – Digital / VRF

• Electronic Expansion Valves

• Variable Speed Fans – Evaporator EC type

• Head pressure control – condenser fans

• R410a and MEPS brought about new and efficient coil designs

• All controlled by the machines to ensure part load, superheat is maintained under all conditions 3-5 K, discharge superheat is maintained 20K, modulating and controlling all these new technologies to deliver close temperature control, conditions, system stability, balance and machine safety.

Technology is the new HGBP

How external conditions change the

operating system

SAQL/S

EATC

TCKW

SHR SSTC

E-TDDBC

EVAP ABS

PRESS kPa

SCTC

C-TDC

THRKW

AMB

5000 27/19 90 .83 9 12.4 1060 55.3 15 113.6 35

6000 27/19 92 .90 10 11.5 1091 55.8 15.2 116.4 35

5000 27/22 96 .59 12 9.4 1154 56.8 15.8 121.2 35

6000 27/22 98 .64 13 8.6 1187 57.3 16.2 123.8 35

90 KW MachineSupply air flow & wet bulb effect


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SAQL/S

EATC

TCKW

SHR SSTC

E-TDDBC

EVAP ABS

PRESS kPa

SCTC

C-TDC

THRKW

AMB

5000 27/19 90 .83 9 12.4 1060 55.3 15 113.6 35

6000 27/19 92 .90 10 11.5 1091 55.8 15.2 116.4 35

5000 27/22 96 .59 12 9.5 1154 56.8 15.8 121.2 35

6000 27/22 98 .64 13 8.6 1187 57.3 16.2 123.8 35

Air Flow & WB Effect


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Air flow drives SHR .83 -.9

Capacity KW

Entering Coil Wet Bulb Drives

SHR

SAQL/S

EATC

TCKW

SHR SSTC

E-TDDBC

EVAP ABS

PRESS kPa

SCTC

C-TDC

THRKW

AMB

5000 27/19 102 .78 7.8 13.3 1018 40.3 15 119.8 20

6000 27/19 104.8 .84 8.9 12.2 1052 40.9 15.4 123 20

5000 27/22 109.6 .57 10.6 10.3 1108 41.8 16.1 128.2 20

6000 27/22 112.4 .60 11.7 9.3 1144 42.4 16.5 131.4 20

Ambient Effect


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Ambient Drives Ref effect

35 C = 90 KW20 C = 102 KW

0

2

4

6

8

10

12

14

30% 40% 50% 60% 70% 80% 90% 100% 110% 120%

Evap Temp V Nominal Air Volume - Fixed Speed Compressor

% Supply Air Fan

EV AP

TEMP

c

0

2

4

6

8

10

12

14

20% 30% 40% 50% 60% 70% 80% 90% 100%

Evap Temp V Variable Air Volume – Digital Compressor

% Supply Air Fan

EV AP

TEMP

C

Digital scroll lowers refrigerant flow rate, producing a higher evaporator temperature

Piping Splits

Piping Systems


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• Use Clean and sealed refrigeration grade pipe

• Cut only with pipe cutter

• Use long radius elbows (reduce PD)

• Use nitrogen when welding / testing

• Oil traps typically 8 m (refer manufacturers data)

• Insulation both is now recommended

• Evacuate min 500 microns 15 mins (smaller systems – 90KW)

• Refrigerant charge – SH 3-5 K when (21-27 C indoor / 24-35C amb.)

• Pipe sizes – typically recommended by manufacturer

• Oil – only added on extended pipe runs – refer manufacturer

• Typically – rotary compressors – PVE

• Typically – Scroll compressors – POE

• R410a – not mineral oil

• Crankcase heaters – all compressors over 8 m pipe

• Refrigerant – typically base charge (10M) and add grams /m past

• Typically above 60 M – extra suction accumulator is required

• Line loss – 6 to 8 % between 13 and 19 mm suction line

• Suction Line bend – 16 MM = 0.30M / 19 mm = 0.45M

R22 – R410a

R22-R410a Repair, Replace ???


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Repair or replace: Questions to make the right decision

• AIRAH Life span recommendations – AIRAH hand book

• Internal environment impacts on life span – hours of operation

• External environment – geographical location, ocean, desert

• Economical environment – is the machine being maintained

• Availability of parts

• ROI – return on investment – can cost thousands of Dollars to replace a compressor when a new machine may cost 3 times this to purchase but have a EER 40% improvement

• The right advice to get the balance right cost V age / lifespan

• Many service companies now employ a “predicted service schedule” where history shows that this machine has a failure every 6 months so they schedule maintenance for every 5 months ---- Costs V predicted failure

• Refrigerant issues / GWP / ODP

• Do you replace like for like or ---- Air V Water

• Technical advice to make the right decision

• Warehouses• Shopping Centres• Retail• Bulk Storage• Temperature controlled warehousing• Pharmaceuticals etc.

• Supermarkets

• Conference Centres

• Community Buildings

• Data Centres

• Switch rooms

• Aquatic / Sports centres

• Schools

• Cinemas

• Museums

• Commercial offices

Applications


OptionApplication

DigiComp

EEV EC PlugEvap

HPC EC CondFans

EconomyCycle

Dry ModeReheat

HLI StockSTD

High Sensible X X X

High Latent X X X XHigh

Ambient X X X X X XLow Ambient

Cooling X X X X X X

Low AmbientHeating X X X X X

DehumLoad X X X X X X X X

Hot Start X X X X X XEfficiency X X X X X XComfort Cooling X X

Application Matrix

Thank you

air cooled packaged systems airah back to basics · compare a digital compressor in a package unit...

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