Air Cooled Chillers – PSC

with Scroll Compressors

The PSC range of air cooled chillers has heremetic scroll compressors and is available with either the low GWP refrigerant, R452b or the older refrigerant R410a.

Depending on the refrigerant used, the available capacities for the PSC chillers are between 153kW and 1,342kW.

PSC Air Cooled Chiller – Overview

The PSC range of Air Cooled Chillers is available in two configurations, each with selectable options, so that you can decide what is most important for every installation.

The Basic and Better Code configurations, and the selectable options, are shown below:

To ensure the highest level of quality and reliability in our Chillers, all manufacturing and testing procedures are carried out according to ISO 9001:2015 Quality Management system and ISO 14001:2015 Environmental Management system.

  • Suction lines are insulated with closed cell foam insulation, then wrapped with a special protective material and then finally epoxy coated.  This gives further protection for the insulation against weather and other factors
  • Other exposed copper pipes and headers are epoxy coated, after being cleaned, to maintain pipe material and brazing protected against external conditions
  • All coil U-bends are protected with a painted galvanised steel cover plate, covering the entire U-bend coil side
Option No.
Opt 1
Opt 2
Opt 3
Opt 4
Opt 5
Opt 6
Opt 7
Opt 8
Opt 9
Opt 10
Opt 11
Opt 12
Opt 13
Opt 14
Opt 15
Opt 16
Opt 17
Opt 18
Opt 19
Opt 20
Opt 21
Opt 22
Opt 23
Opt 24
Opt 25
Opt 26
Opt 27
Opt 28
Opt 29
Opt 30
Opt 31
Opt 32
Opt 33
Opt 34
Opt 35
Opt 36
Opt 37
Opt 38
Opt 39
Opt 40
Opt 41
Opt 42
Opt 43
Opt 44
Opt 45
Opt 46
Opt 47
Opt 48
General
IP23 enclosure for indoor units
IP54 enclosure for all outdoor units
Higher IP classes for enclosures
Operating limit between 0°C and +40°C
Operating limit down to -15°C
Operating limit lower than -15°C
Nominal noise levels
Low noise axial fans (running at 700 rpm max)
Reduced noise level (compressor jacket)
Further reduced noise level (single skin compressor compartment)
Further reduced noise level (double skin compressor compartment)
C-channel base (welded, spray painted)
Cross beams made of tubular steel
Units electrostatically powder coated
Protective grille for lower compressor compartment
Vibration dampers (loose item)
CE/UKCA Mark incl. all conformities to specific regulations, labelling/documentation etc
Electrical
400/3/50 operating voltage, single point supply
400 V, no neutral
Non-fused electrical main switch
Fused electrical main switch
Simple cabling (without trunking)
Electrical wiring with cable ducts (trunking)
Controls comprise short cycling time protection
Motor thermal protection
Switch panel for power
Switch panel for controls
Circuit breaker for short circuit protection
Circuit breaker for mains power
Dual point power connections
Earth leakage relay
Power factor correction for units
Measurement devices for electrical current and voltage
Energy meter (for control of power consumption)
Socket with 230 V supply
Socket with 230 V supply with transformer
Bulk head light for switch cabinet
Controls
Microprocessor based controller (simple version)
Microprocessor based controller (programmable)
BMS communication gateway (BacNet, ModBus etc.)
Temperature sensors for cold water in/out
Frost protection (Evaporator leaving water temperature )
Touch screen controller
Remote control of chiller
Control of remote cold water pump (volt-free contact)
Compressors
Scroll compressors
VFD for one compressor on a unit (if not provided to comply with EcoDesign)
Circuit breaker per compressor
Starting contactors per compressor
Phase failure relay (overload protection, low voltage)
Rubber vibration isolators
External overload relays for compressors
Refrigeration Circuit
Liquid line solenoid valve (compressor controlled)
Shut off valves (suction, discharge)
Moisture indicator with sight glass
Electronic expansion valve [or thermostat where applicable]
High pressure switch
Low pressure switch
Pressure transducer (high and low side) for refrigerant circuit
Full refrigerant charge - R452b (GWP 698)
Full refrigerant charge - R410a (GWP 2088)
Refrigerant Piping
Single pressure relief valve
Dual pressure relief valves
Pressure gauges for high / low side
Filter drier (replaceable core)
Gas warning device (leakage detection)
Leak detection for selected refrigerants i.a.w. EN378 (e.g. R290)
Evaporator
Shell and tube
Brazed plate heat exchanger
Insulation 19 mm
Evaporator cladding - aluminium
Evaporator cladding - painted galvanized steel
Evaporator cladding - stainless steel
Trace heating for evaporator
Pressure differential switch (evaporator)
Water flow switch evaporator (loose item)
Water flow switch evaporator (fitted)
Condenser / Fans
Axial fans
VFD for fans
EC fans
External overload relays for fans
Microchannel condenser coils
Corrosion protection micro-channel coils (pre-coated)
Condenser coils made of Cu/Al
Condenser coils made of Cu/Cu
Corrosion protection Cu/Al or Cu/Cu (post coating)
Circuit breakers for fans
Protected condenser coils for uniform air flow
Fan control by on/off
Thermal protection of fan motors
Integrated free-cooling package (including valves, controls and sensors)
Separate free-cooling package (including valves, controls and sensors)
Hydraulics
Piping connections with Victaulic quick lock
Piping connections with DIN flanges
Standard positions for piping connections
Customer specific positions for piping connections
Integrated water buffer tank
Integrated cold water pump(s)
Basic Code Standard
Basic Code Options
Better Code Standard
Better Code Options

Unit Construction

  • Welded structural C-channel base painted with mono-component catalysed primer sprayed paint
  • Base is equipped with welded brackets for heavy duty lifting lugs
  • Easily accesible system components
  • Structural members are made from 15 gauge (1.8mm) tubular cross members that are semi welded with stainless steel fasteners.  All members and panels (side and roof) are painted with oven baked polyester electrostatic powder paint
  • Petra paint is certified up to 5000 hours salt spray (fog) test as per ASTM 117 A&B
  • Condenser coils are covered with protective panels to ensure uniform air distribution across the coil face area and provide additional protection for the coil from weather elements
  • A coil guard is placed on the lower part of the unit, all around the perimeter, to provide protection for the unit components
  • It is fabricated from gauge 18 (1.25mm) galvanised steel sheet metal and painted with Petra powder paint
  • The coil guard is fitted in place by spring loaded quick turn latch, and is supported by stainless steel hinges

Compressors

  • Suction gas-cooled hermetic scroll low sound compressor with superior efficiency
  • Robust design of a three Teflon impregnated bearings and integral cast iron housing for better compressor alignment
  • IP 54 enclosure class of terminal box
  • Scroll inherent durability with fewer moving parts and low motor strains
  • Spiral surfaces wear-in due to unique compliant design
  • Mounted on rubber-in-shear (RIS) vibration isolators
  • Equipped with operating oil charge, crank case heater, crank case oil sight, glass inherent solid state motor protector, suction strainer and short cycling delay timer protection
  • Maximum operating compressor of 2,900 / 3,500 rpm (5oHz)
  • Immediate internal pressure balancing (high side/low side) at shut off
  • High volumetric efficiency with no dead space design
  • Minimised pressure losses with uniform gas compression in the scroll pockets at low velocities
  • Minimised heat transfer losses because of a physical separation of suction and discharge gas
Scroll Compressor

Scroll Compressor

Condenser Coils

 

  • Petra manufactured V-shaped air cooled condenser coils are designed to deliver the duty with maximum performance for all design conditions
  • Coils are manufactured from seamless copper tubes mechanically expanded into aluminium fins
  • Type L heavy wall, seamless copper tubes are provided for the coil headers
  • The condenser coils are hydrostatic pressure tested in accordance with the UL 1995-2000 standard
  • All coils are pressure tested by dry air up to 3,100kPa under water
  • Coils undergo dry cleanse after manufacturing for maximum system cleanliness
  • Copper/copper condenser coils may be available, please call us for more information
  • Microchannel coils may be available, please call us for more information
  • Petra manufactured Cu/Cu condenser coils are available as an optional upgrade to the standard PSC chiller specification
  • Coils are manufactured from seamless copper tubes mechanically expanded into copper fins
  • Cu/Cu coils have approxiately twice the conductivity of Cu/Al coils and are therefore more efficient.  However, they are also more expensive and suitable for installation in corrosion-free environments
  • All coils are pressure tested by dry air up to 3,100kPa under water
  • Coils undergo dry cleanse after manufacturing for maximum system cleanliness
  • Petra manufactured Microchannel condenser coils are available as an optional upgrade to the standard PSC chiller specification
  • All coils are pressure tested by dry air up to 3,100kPa under water
  • Coils undergo dry cleanse after manufacturing for maximum system cleanliness

Polyurethane pre-coating (for aluminium fins)

  • A water based organic type pre-coated fin designed to give better retained performances compared to typical organic type
  • The topcoat is made of hydrophilic resin of polyvinyl alchohol mix with hydrophilic lubricants
  • It provides a better level of retained as well as improvement in the area of surface friction to help lengthen the life span of a punch dies
  • Paint is certified as  per ASTM 117 A&B up to 3,000 hours salt fog test

Polyurethane post-coating (for aluminium and copper fins)

  • Aliphatic Acrylic Polyurethane type, with high gloss finish with exceptional weathering performance characteristics
  • Used extensively in virtually all industrial markets, 134 VOC provides a smooth, durable finish that has superior resistance to corrosion, abrasion and chemical exposure
  • Paint is certified as per ASTM 117 A&B up to 3,000 hours salt fog test

Condenser Fans and Motors

  • Condenser fans are of the external rotor type
  • Seated-for-life ball bearings fitted throughout the range with an L10 life expectancy 0f approximately 40,000 hours depending on conditions of operation
  • The minimum enclosure standard is IP 54 in accordance with DIN40050 
  • The thermal class is 155 according to DIN EN 600034-1, IEC 62114 with class F insulation
  • Thermal contacts are fitted with external rotor motors
  • Embedded deep in the windings of the motors, the contacts are bi-metal cutout design which are temperature dependant.  Should the temperature of the motor rise to the limit, the bi-metal cut-outs activate and cut off the power, thereby providing full protection to the motor
  • EC Fans are available as an option

Low Ambient Control down to 0°C

  • Units can operate down to 0°C by using a combination of  on/off sequencing of the condenser fans and fan speed control
  • The fan speed is controlled through pressure transmitter of each refrigerant circuit via the unit controller with a speed regulation device

Low Ambient Control down to -17°C

  • In addition to the on/off sequencing of the condenser fans and speed control, a flooded condenser control design is used to enable the unit to operate at -17°C
  • Multiple on/off solenoid valves on each condenser with a suitable liquid receiver shall be added to control the amount of liquid flooding the condenser and maintain condenser head pressure within the permissible operating range
  • The liquid receivers used are designed and manufactured in accordance with Section VIII of  the ASME code and are marked with U or UM Code symbol stamps
  • Liquid receivers of 75mm through 150mm diameter are UL listed
  • These devices are used to permit the unit to operate in low ambient temperatures
  • Head pressure control can be applied by varying the speed for condenser fan motors

Heat Exchanger

  • High efficiency direct expansion (DX) shell and tube type coolers with inner grooved tubes to optimise efficiency
  • Coolers are tested and stamped for refrigerant side design pressure of 1,oookPa and for a water side working pressure of 1,500kPa
  • These working pressures comply with applicable sections of the ASME standard, and the European codes of ISPESL and TÜV
  • Coolers are equipped with internal water baffles in the shell which are fabricated from brass for maximum corrosion resistance
  • Coolers are provided with water vents and drain connection plugs and are insulated with 19mm closed cell foam insulation
  • Coolers are tested and stamped in accordance with ASME code

Petra Shell & Tube Evaporator

Petra Shell & Tube Evaporator

Cooler tape heater protection down to 0°C

  • Electrical resistance heating tape is wrapped around the evaporator shell to protect evaporator fluid contents from freezing at temperature down to 0°C ambient temperature
  • Continuous power supply to the chiller shall be provided to maintain operation of the heater for 24 hours, 7 days a week
  • This device will not protect external water pipe work connected to the unit for which additional frost protection measures are required

Cooler insulation material thickness

  • The cooler can be insulated with closed cell foam insulation of 25mm, 38mm or 50mm
  • The insulation density is 48kg/m³ with a k value of 0.035W/m.°K

Cooler cladding

  • Cooler cladding can be aluminium, stainless steel or painted galvanised steel (made from 22 gauge (0.7mm)
  • Cladding is applied over the cooler insulation

Refrigeration Circuit

Components of each refrigeration circuit:

  • Liquid line solenoid valve for models
  • Liquid line shut off valve for models
  • Liquid line moisture indicator sight glass
  • Replaceable core type filter
  • Chiller is fully charged with either R410a or R452b
  • High safety pressure switch (capsule type: factory pre-set)
  • Electronic expansion valve.  Electronically operated step motor flow control valves, intended for the precise control of liquid refrigerant flow.  Synchronised signals to the motor provdes discrete angular movement, which translates into precise linear positioning of the valve piston.  Easily interfaced with micrprocessor based controllers
Petra Electronic Expansion Valve

Petra Electronic Expansion Valve

  • Liquid, discharge and suction pipes are all hard copper pipes.  They are formed using automated CNC pipe-bending machines in order to minimise pipe-brazed joints which in turn increases system reliability
  • Epoxy paint is applied to all exposed copper piping systems of the refrigeration circuit
  • The hot gas bypass consists of a mechanical valve capacity regulator used to adapt compressor capacity to actual evaporator load.
  • It is installed in a bypass line between the high and low pressure sides of the refrigeration system and is designed for hot gas injection in the evaporator just after the expansion valve
  • The hot gas bypass valve is UL listed, file SA7200
  • The hot gas bypass valve allows additional capacity reduction for units operating below the minimum step of unloading for the compressor
  • If the hot gas bypass is installed on the lead compressor only, the lead/lag function (for the compressor) will be eliminated
  • Optional pressure gauges for monitoring the refrigeration discharge and suction pressure
  • Additionally, the gauges are used to verify suitable refrigerant charge and proper system performance
  • The gauges are Bourdon type, stainless steel housing, oil filled
  • Oil filling provides greater protection of the gauge internal environment from corrosive atmospheres
  • The gauges are provided with a dual scale of both PSI and BAR

Electrical

  • Free terminal for remote ON/OFF connection
  • Free terminal for general alarm output
  • Control voltage is 200-240V for all components
  • Single point power connection for each electrical panel
  • Starting contactors for compressors and condenser fan motors
  • Circuit breaker for each compressor
  • ON/OFF switch for each compressor
  • Control circuit breaker for short circuit protection
  • Short cycling protection for compressors (time delay)
  • Control transformer supplies all unit control voltage from main unit power supply to internal components such as (but not limited to) solenoid valves, compressor motor protector, compressor crank case heater and microprocessor controller
  • Microprocessor controller for full management of chiller operation and safety circuits
  • Power supply monitor (phase failure relay) used to protect the power circuit against over or under voltage conditions and against phase loss or loss reversing conditions 

  • NEMA 3X with IP 54 minimum enclosure standard electrical panel
  • Two separate panels, one for power and the other for control
  • Electrical panel is eqipped with a heavy gauge galvanised steel access door
  • Panel is painted with oven baked polyester electrostatic powder paint
  • Each door is equipped with external handle with key and tooled latch
  • Doors contain sealing heavy duty clip-on bulb gasket between the door and the panel that provides effective sealing
  • All doors have multiple hinges
  • Each door has a door retainer to keep the door open during service
  • Each door has a built-in pocket to accomodate a laminated wiring diagram and IOM documents
  • Separate electrical box for condenser fan motors located on condenser side
  • Power factor correction is used to improve the power factor level
  • Maximising the power factor improves system reliability, minimises voltage drops and gives better power quality
  • Advance safety capacitors with harmonic filters and a main microprocessor controller are provided to manage the required capacity for the capacity stages
  • Only one capacitor panel is needed for the chiller regardless of the number of compressors or fans
  • The power factor correction capacitor is usually installed in a separate electrical box, but this depends on the unit size.  Please call us to discuss if this is of interest to you
  • This is used to de-energise the power supply to the chiller during service or repair works because of the door interlock
  • It has an external handle that is installed on the the electric panel door
  • The switch has to be de-energised to open the electric panel
  • The disconnect switch can be supplied with either an integrated fuse or a non-fuse type
  • Ampere and volt meters are used to measure the power current and the voltage consumption
  • An ampere meter is used for each phase
  • The volt meter is used to measure the voltage of power supply between each phase and the other, and between each phase and neutral
  • The chiller maybe supplied with a dual power connection
    • One power entry for the compressors
    • The second power entry for the rest of the unit
  • Each power connection can be equipped with a separate main disconnect switch
  • The earth leakage relay is used in electrical installations with high earth impedence to prevent electric shock
  • It detects small stray voltages on the metal enclosures of electrical equipment and interrupts the circuit if a dangerous voltage is detected
  • Earth leakage relay can be supplied for the whole unit power supply of for each compressor
  • External overload for each compressor
  • External overload for each condenser fan motor
  • Circuit breaker for each condenser compressor
  • Circuit breaker for each condenser fan motor
  • NEMA 4X electrical panels made from galvanised steel
  • NEMA 4X electrical panels made from stainless steel

Controls

  • Petra’s microprocessor control system enhances the air cooled smart chiller operation by providing the intelligent chiller control technology
  • The microprocessor control helps in the accurate control of various operating parameters
  • The system provides complete status on all operations both locally and remotely
  • The operating history, static and dynamic, helps in commissioning, troubleshooting and system evaluation
  • It interfaces locally via an ethernet connection as well as the Building Management System
  • The microprocessor control offers a great deal of flexibility with adjustable set points and control options that can be set prior to activating a system, or even when the unit is operational
  • The microprocessor controller is designed to safeguard the system that is being controlled, minimise the need for manual intervention, and to provide a simple but meaningful user interface
Start Up

For initial start up the following conditions must be met:

  • Control circuit breaker must be switched to on
  • Energise the microprocessor control through keypad, remote start/stop, schedule or BMS command
  • Chilled water pump running
  • Flow has been proven
  • All safety conditions satisfied

When the water in temperature is above the target set point, the first compressor will start after the call for cooling is received.

The control strategy is designed to modulate the chiller capacity to maintain the control sensor reading within the specified control band.  To accomplish this, the microprocessor controller will constantly monitor the control value, its rate of change and position in relationship to the control band and make adjustments accordingly.

Capacity Control

The capacity control logic will control the sequence of operation for the compressor as follows:

  • If the chilled water-in temperature is above the set point, the chiller’s capacity control logic will ask for more capacity by adding a cooling step.  Once the step control has increased, the capacity control logic has a time delay before allowing the new step to increase again.  This time delay depends on how far the temperature is from the target set point
  • If the chilled water-in temperature is within the control band, special logic functions will maintain the chiller within the control band
  • If the chilled water-in temperature is below the control band, the chiller’s capacity logic asks for less capacity by subtracting from the steps.  Once the step has been decreased, the capacity control logic has a time delay before allowing more steps to be decreased again

Chilled Water Reset

This is a function of a signal from the building management system.

  • The value is used to adjust the control set point
  • The amount of the actual adjustment is proportionally based on the associated analog input value
  • The analog value can be between 0 and 10 volts

Operating Schedules

Operating schedules per day of the week and 8 holidays are supported by the microprocessor controller software

  • Each schedule contains a start and end time
  • If the time and day of the microprocessor controller clock is within these limits then the schedule is true and the system will be allowed to run
  • If not, the system will be off due to schedule

Electronic Expansion Valve Driver

  • This driver, with double pole stepper motor, is designed to control the electronic expansion valve in the smart chillers.
  • It controls refrigerant super heat and optimises the efficiency of the refrigeration circuit to guarantee the maximum flexibility

Ultra Cap Module

  • The ultra cap EVD module guarantees temporary power to the driver in case of power failures, for enough time to immediately close the connected electronic valves
  • This avoids the need to install a solenoid valve

Displayed Data

  • Leaving/ entering water temperature
  • Ambient temperature
  • Compressor discharge pressure
  • Compressure suction pressure
  • Suction super heat
  • Chiller load percentage
  • Compressor tiers
  • Digital input status
  • Output relays status
  • Protections status
  • Historical alarms
  • Schedule
  • Adjustable set point
 Safeties and Alarms

  • High discharge pressure
  • Low suction pressure
  • Low suction temperature
  • Freeze state
  • Flow switch (no flow protection)
  • Phase loss protection
  • Motor protector
  • Probe error alarm
  • Compressor overload
  • Condenser overload
  • Compressor short circuit
  • Condenser fan motor short circuit

 


PC Support for Mk IX Controller

  • Configuration of main unit control parameters
  • Monitoring of main system variables
  • Alarms management
  • Simplify commissioning operations
  • Customisation of user interface

Petra Touch Screen Controller – Optional

Within the hardwired structure, there are six features, as follows:

  1. Unit start/stop command
  2. Compressor run status
  3. Compressor trip status
  4. Condenser fan run status
  5. Condenser fan trip status
  6. General alarm

BMS Card

This card provides connection for:

  1. Modbus RTU – RS4 85 (standard)
  2. PCO WEB TCP / IP (optional)

    TCP/IP -SNMP BAC NET – email Modbus

  3. PCO NET (BAC NET MSTP RS4 85) (optional)
  4. LON Board (optional)
  5. Konnex Board (optional)

Petra BMS Card

USB in Microprocessor Controller

  1. USB Host: to connect a standard USB dongle for:
    1. SW application upgrade
    2. Download Pco logs
  2. USB device: to connect a PC (without external converter) for:
    1. SW application upgrade
    2. Download Pco logs
    3. Configure and monitor the unit by commissioning tool

Petra USB in Microprocessor Controller

Other Optional Accessories and Chiller Upgrades

Compressor Jacket

  • The compressor jackets consist of 9.5mm thick closed cell rubber sound insulation material inside a sound deflecting vinyl cover to provide superior sound reduction for scroll compressors

Standard Compressor Compartment

  • A standard compressor compartment is constructed from gauge 16 (1.5mm) thick galvanised steel sheet metal insulated with 9.5mm thick closed cell rubber insulation.  All sheet metal is painted with Petra powder paint

Advanced Compressor Compartment

  • The advanced compressor compartment is constructed from a double wall, heavy gauge galvanised steel
  • The wall is gauge 14 (2mm) outer skin and gauge 22 (0.7mm) perforated inner skin
  • There is a 50mm thick fibreglass insulation with a density of 48kg/m³ between the inner and outer skins

NB:

  1. The above options are available in certain combinations in order to achieve the lowest possible sound emissions.  
  2. Please take note that the compressor compartment installation might change the overall chiller dimensions
  • The water flow switch is supplied as a loose item for field installation
  • CE approved safety interlock to prevent operation operation of the chiller without evaporator water flow
  • The water flow switch functions as a safety that assumes water flow rate with the shell and tube (Barrel) cooler and sends a signal to shut off the chiller if no water flow exists due to pump failure or other causes
  • It is a paddle type flow switch
  • The paddle consists of three segents that can be removed or trimmed and sized to fit the water pipe size
  • The paddle is made of copper alloy
  • Pressure relief valves are installed in accordance with the requirments of the ASME (Boiler and Pressure Vessel Code Section VIII, Division 1)
  • The pressure is relieved by allowing the pressurised fluid to flow from an auxilliary passage out of the system to the atmosphere
  • The relief valve is designed to open at a pre-determined set pressure to protect pressure vessels and other equipment from being subjected to pressures that exceed their design limits
  • Heat Pump Chillers that may be used to provide heating in the winter are also available.  Please contact us for more information
  • Simultaneous heating and cooling chillers are also available to provide heating and cooling to different areas at the same time.  Please click here for more information, or get in touch here if this is of interest to you
  • The 120V single phase power supply is provided through the transformer that may be connected before or after the non-fused main disconnect switch
  • GFI socket is used to operate electrical devices on site, such as laptops, tablets and mobile phones

Control Transformer

  • The control transformer is to supply power input to auxillary compnents at 120 or 220 volts, such as (but not limited to) bulk head lights or the GFI Outlet

PSC Range of Air Cooled Chillers

The PSC range of Air Cooled Chillers is available with either refrigerant R452b or R410a.

The model references,  capacities, dimensions, sound data and operating weight is given in the tabs above, but for more detailed information please call us on 0118 988 0101.

Refrigerants

A refrigerant is a chemical substance used in heat pumps and refrigeration cycles.  The job of a refrigerant is to transport enthalpy (i.e. heat energy) from the evaporator of a refrigeration or air conditioning system to the environment.

What is a Refrigerant?

The difference between a simple coolant and a refrigerant is that a refrigerant in a refrigeration cycle can transport heat energy against a temperature gradient, so that the ambient temperature may even be higher than the temperature of the target to be cooled.

A coolant is only able to transport enthalpy along a temperature gradient to a point of lower temperature.

Each chemical substance may exist in different physical states (phases): solid – liquid – gaseous.  Between such states there exist phase transitions e.g. from a liquid to a gas and back again.  Many working fluids have been used for such purposes but the operation of initial chillers often resulted in deaths because the refrigerants used were toxic, examples are SO2, CH3Cl, ammonia (NH3).

Refrigerant Timeline

  • 1930 - CFCs Freon (R11) & Frigen (R12) manufactured.  Used as refrigerants
  • 1974   CFC ozone hypothesis
  • 1978   Confirmation of the hypothesis
  • 1995   Ban on the production and use of CFCs in new installations
  • 1998   Montreal Protocol
  • 1998   R12 is withdrawn from the market
  • 2000   Prohibition of HCFCs (R22)
  • 2006   First F-Gas Regulation 842/2006
  • 2015   Ban on the use of HCFCs
  • 2016   Kigali Amendment to the Montreal Protocol

A Bit of Chemistry

A look at the periodic table of the elements shows that almost all elements have one of the following properties:

  • solid
  • radioactive
  • unstable
  • noble gas
  • venomous or toxic

All these properties exclude such elements from being considered as a candidate for a refrigerant.

So what is left over…?

The answer is hydrocarbons i.e. compounds of carbon C and hydrogen H, such as methane, ethane, propane.

What are the requirements for an 'ideal' refrigerant?

  • large specific evaporation enthalpy
  • high volumetric cooling capacity
  • high thermal conductivity
  • high critical temperature
  • no temperature glide
  • low viscosity
  • non-flammable or explosive
  • no ozone depletion potential (no ODP)
  • no greenhouse effect (no or low GWP)
  • non-toxic
  • perceptible by odour on leaving
  • non-corrosive
  • compatible with lubricants

The table below shows the hydrocarbon elements with their halogenation, designation and gives examples of the refrigerants that have been in common use over recent years.

ElementsHalogenationDesignationAbbr.ComplianceExamples
C, Hnon-halogenatedhydrocarbonsHCsnaturalR290, CO2
C, Ffully-halogenatedhydrofluorocarbonsHFCsF-Gas regulationsR134A
C, F, Clfully-halogenatedchlorofluorocarbonsCFCsMontreal protocolR11
C, F, Hpartly-halogenatedhydrofluorocarbonsHCFCsF-Gas regulationsR407c, R410a
C, F, C, Cl, Hpartly-halogenatedhydrogen-fluoro-chloro-hydrocarbonHCFCsMontreal protocolR22

Methane CH4

CFCs, HCFCs and HFCs can be produced from the methane molecule CH4 by replacing the H-atoms with one of the halogen elements i.e. Fluorine, Chlorine, Bromine, Iodine

Petra UK - R11

CFC (R11)

fully-halogenated

1 atom Carbon / 3 atoms Chlorine / 1 atom Fluorine

Petra UK - R22

HCFC (R22)

partly - halogenated

1 atom each Carbon /  Chlorine / Hydrogen / 2 atoms Fluorine

Petra UK - R134a

HCFC (R134a)

partly-halogenated

2 atoms Carbon / 4 atoms Hydrogen / 2 atoms Fluorine

Petra UK - R290

HC R290

non-halogenated

3 atoms Carbon / 8 atoms Hydrogen

Refrigeration - Environmental Metrics

Environmental concerns have long been the driving force for the development of environmental friendly refrigerants.  Ongoing research in the fields of system design optimisation, energy efficiency improvements,and the search for new refrigerants, is important for both heat pump and refrigeration systems.  It is therefore helpful to have a transparent and easy to use reference protocol when designing air conditioning or refrigeration systems with low environmental impacts.

Three environmental metrics can be used when comparing the environmental impact of various refrigerants and refrigeration systems:

  • Global Warming Potential (GWP)
  • Total Equivalent Warming Impact (TEWI)
  • Life-Cycle Climate Performance (LCCP)

Each serves the similar aim of quantifying the impact of refrigerants on global warming.  Whilst not directly having a bearing on the environmental impact of the refrigerant, it is also important to be aware of the flammability class of a refrigerant as this will determine other areas of regulatory compliance.

In the tables below we consider the environmental impacts of the refrigerants that we currently use:

GWP

GWP is perhaps the most commonly used environmental metric. GWP is the index used to compare the global warming impact of an emission of a greenhouse gas in relation to the impact from the emission of similar amount of CO2. The impact is estimated over a time horizon of 100 years.  GWP is an easy metric to use. The smaller the GWP, the lower the contribution of a substance to global warming.

RefrigerantTypeOzone Depletion PotentialGlobal Warming Potential
R290HC03
R513aHFO/HFC blend0631
R452bHFO/HFC blend0698
R1234zeHFO07
R410aHFC02,088
R407cHFC01,774
R134aHFC01,430

Read more about Ozone Depletion Potential (ODP) here

TEWI

TEWI accounts for the global warming impact from both direct and indirect emissions and is calculated as a sum of both the direct effect of refrigerant released during the lifetime of the equipment, and the indirect impact of CO2 emissions from the fossil fuels used to generate the energy needed to operate the equipment throughout its lifetime. TEWI can be calculated using the equation below (UNIDO 2009):

TEWI = direct emissions + indirect emissions = (GWP×L×N)+(Ea×β×n) where:

L = annual leakage rate in the system, kg (3% of refrigerant charge annually)
N = life of the system, years
n = system running time, years
Ea – energy consumption, kWh per year ,
β – carbon dioxide emission factor, CO2-eq. emissions per kWh

LCCP

The LCCP indicator is used to measure all GWP data related to the refrigeration system's operation, including the environmental impact of substances emitted during the process of refrigerant production and transportation.

This environmental effect, together with environmental effects already accounted in TEWI, is known as the life-cycle climate performance (LCCP) and is intended to provide an overall picture of the environmental impact of different refrigerants.

LCCP is a holistic metric to quantify the effect of the refrigerant on the total lifetime system emissions.  

 

In practice, the LCCP is more complex than the TEWI metric to calculate, and an additional contribution of LCCP compared to the TEWI is negligible as can be seen from the table below which show a comparison between R290 and R410 for the same unit under identical operating conditions.

TEWI/LCCP ComparisonR290R410A
TEWI, kg CO2 equivalent37,77543,551
% of R410a87.14%100%
Direct emissions contribution to total TEWI%0.01%9.42%
LCCP, kg CO2 equivalent37,78045,398
% of R410a83,22%100%
% of TEWI0.01%4.72%

 

Pavel Makhnatch and Rahmatollah Khodabandeh / Energy Procedia 61 ( 2014 ) 2460 – 2463

Toxicity & Flammability

 

Toxicity and flammability

The safety classification of refrigerants consists of two alphanumeric characters (e.g. A2); the capital letter corresponds to toxicity and the digit to flammability.

Toxicity classification

Refrigerants are divided into two groups according to toxicity:

Class A - Refrigerants for which toxicity has not been identified at concentrations less than or equal to 400 ppm

Class B - Refrigerants for which there is evidence of toxicity at concentrations below 400 ppm.

Flammability classification

Refrigerants are divided into three groups according to flammability:

Class 1 - Refrigerants that do not show flame propagation when tested in air at 21°C/101kPa
Class 2 - Refrigerants having a lower flammability limit of more than 0.10 kg/m3 at 21°C/101kPa and a heat of combustion of less than 19 kJ/kg;
Class 3 - Refrigerants that are highly flammable as defined by a lower flammability limit of less than or equal to 0.10 kg/m3 at 21°C/101 kPa or a heat of combustion greater than or equal to 19 kJ/kg.

RefFlammability ClassLower Flammability Limit kg/m3Heat of Combustion MJ/kg
R290A3 Highly Flammable<0.1or   >19
R513aA1 Non-FlammableCannot be ignited
R452bA2L* Mildly Flammable>0.3and<19
R1234zeA2L* Mildly Flammable>0.3and<19
R410aA1 Non-FlammableCannot be ignited
R407cA1 Non-FlammableCannot be ignited
R134aA1 Non-FlammableCannot be ignited

* For EN 378 the 2L category is a proposal that is still under discussion.  However, the 2L category is used in ISO 817:2014 “Refrigerants — Designation and safety classification”

 

Petra UK - R452b

R452b

Details
  • Blend of R32 (67%), R125 (7%) and R1234yf (26%)
  • HFC/HFO
  • GWP - 675
  • Flammability class  - A2L
  • Low GWP replacement for R410a
  • Used in scroll compressors
Petra UK - R513a

R513a

Details
  • Blend of R1234yf (56%), R134a (44%)
  • HFC/HFO
  • GWP - 631
  • Flammability class  - A2L
  • Low GWP replacement for R134a
  • Used in screw and centrifugal compressors
Petra UK - R1234ze

R1234ze

Details
  • Chemical composition C3H2F4
  • HFO
  • GWP - 7
  • Flammability class  - A2L
  • Low GWP replacement for R134a
  • Used in screw and centrifugal compressors
Petra UK - R290

R290

Details
  • Naturally occuring element
  • Chemical composition C3H8
  • GWP - 3
  • Flammability class  - A3
  • Can be used in all types of compressors
Petra UK - R134a

R134a

Details
    • Chemical composition C2H4F2
    • HFC
    • GWP - 1,430
    • Flammability class  - A1
    • Used in screw and centrifugal compressors
Petra UK - R410a

R410a

Details
  • Blend of R32 (50%) and R125 (50%)
  • HFC
  • GWP - 2,088
  • Flammability class  - A1
  • Used in scroll compressors

More about Refrigerants

F-Gas Regulations

F-Gas Regulations

As a part of the EU, the UK was subject to the terms and conditions of legislation governing the emissions and supply of fluorinated greenhouse gases in Europe. With effect from 1st January 2021 however, these regulations will no longer apply in Great Britain and will be replaced.

read more
The Ozone Depletion Process

The Ozone Depletion Process

The ozone layer is one layer of the stratosphere and the stratosphere is the second layer of the Earth’s atmosphere. The stratosphere is the mass of protective gases that clings to our planet

read more

*All stated kW capacities are based on 35°C ambient temperature, 12/7°C water entering / leaving temperature and 50Hz power supply 

For improved efficiencies and to meet the criteria for EcoDesign (Tier 2), some chillers are supplied with a VFD for one compressor

PSC Model
50
55
65
75
85
95
105
110
115
120
125
135
145
155
170
180
190
200
215
225
235
250
265
285
315
335
355
380
400
420
445
Capacity
157.5
173
204.1
226.3
254.4
283.6
314.1
329.7
345.4
368.2
399.7
422
451.7
468.4
520.9
565.4
590.4
623.3
665.7
693.7
736.4
779.3
844
903.3
1000.2
1041.8
1130.7
1180.8
1246.6
1331.4
1387.5
EER
3.05
3.03
3.20
3.17
3.22
3.16
3.07
3.08
3.05
3.25
3.42
3.15
3.09
3.04
3.10
3.16
3.08
3.08
3.05
3.05
3.55
3.45
3.44
3.29
3.37
3.10
3.41
3.31
3.08
3.13
3.05
ESEER
5.06
5.00
5.28
4.49
4.47
4.58
4.65
4.72
4.71
4.52
4.96
5.68
5.72
5.70
5.56
5.60
5.75
5.81
5.85
5.91
5.98
5.89
5.80
5.78
5.75
5.58
5.83
5.83
5.55
5.60
5.45
SEPR
5.52
5.02
5.69
5.23
5.15
tba
5.23
5.41
5.27
tba
tba
5.95
5.96
6.05
5.95
5.99
5.89
5.97
5.59
5.95
5.88
5.86
5.82
5.79
5.64
5.79
5.81
6.00
5.89
5.92
5.94
SSCEE [%]
184
181.4
187.5
161.9
161.7
169.2
169.3
171.6
171.4
162.5
179.1
199.4
199.5
197.8
209.1
197.7
201
202
204.6
205.7
216.7
207.7
206.2
203.9
206.2
198.9
207.2
205.8
195.5
211.7
192.9
Shipping weight [kg]
1415
1445
2057
2291
2472
2702
2777
2804
2831
3604
3664
3724
3776
3928
4152
5195
5250
5310
5430
5480
7260
7380
7500
7606
8226
8352
9930
10041
10153
10391
10503
Length [mm]
3295
3295
3360
3360
3360
3360
3360
3360
3360
4740
4740
4740
4740
4740
4740
6120
6120
6120
6120
6120
8880
8880
8880
8880
8880
8880
11640
11640
11640
11640
11640
Width [mm]
1800
1800
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
2230
Height [mm]
2490
2490
2530
2530
2530
2530
2530
2530
2530
2530
2530
2530
2530
2530
2530
2570
2570
2570
2570
2570
2570
2570
2570
2570
2570
2570
2570
2570
2570
2570
2570
Sound power [dB]
91
92
92
91
92
92
94
94
95
93
94
94
95
96
97
95
96
97
97
98
96
97
97
98
99
100
98
99
100
100
101
Includes VFD?
Yes
Yes
Yes
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes

*All stated kW capacities are based on 35°C ambient temperature, 12/7°C water entering / leaving temperature and 50Hz power supply 

For improved efficiencies and to meet the criteria for EcoDesign (Tier 2), some chillers are supplied with a VFD for one compressor