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.

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All Systems

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

Scroll 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

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

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

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:

Unit start/stop command
Compressor run status
Compressor trip status
Condenser fan run status
Condenser fan trip status
General alarm

BMS Card

This card provides connection for:

Modbus RTU – RS4 85 (standard)
PCO WEB TCP / IP (optional)
TCP/IP -SNMP BAC NET – email Modbus
PCO NET (BAC NET MSTP RS4 85) (optional)
LON Board (optional)
Konnex Board (optional)

Petra BMS Card

USB in Microprocessor Controller

USB Host: to connect a standard USB dongle for:
1. SW application upgrade
2. Download Pco logs
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:

The above options are available in certain combinations in order to achieve the lowest possible sound emissions.
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.

Elements	Halogenation	Designation	Abbr.	Compliance	Examples
C, H	non-halogenated	hydrocarbons	HCs	natural	R290, CO₂
C, F	fully-halogenated	hydrofluorocarbons	HFCs	F-Gas regulations	R134A
C, F, Cl	fully-halogenated	chlorofluorocarbons	CFCs	Montreal protocol	R11
C, F, H	partly-halogenated	hydrofluorocarbons	HCFCs	F-Gas regulations	R407c, R410a
C, F, C, Cl, H	partly-halogenated	hydrogen-fluoro-chloro-hydrocarbon	HCFCs	Montreal protocol	R22

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}

CFC (R11)

fully-halogenated

1 atom Carbon / 3 atoms Chlorine / 1 atom Fluorine

HCFC (R22)

partly - halogenated

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

HCFC (R134a)

partly-halogenated

2 atoms Carbon / 4 atoms Hydrogen / 2 atoms Fluorine

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.

Refrigerant	Type	Ozone Depletion Potential	Global Warming Potential
R290	HC	0	3
R513a	HFO/HFC blend	0	631
R452b	HFO/HFC blend	0	698
R1234ze	HFO	0	7
R410a	HFC	0	2,088
R407c	HFC	0	1,774
R134a	HFC	0	1,430

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 Comparison	R290	R410A
TEWI, kg CO₂ equivalent	37,775	43,551
% of R410a	87.14%	100%
Direct emissions contribution to total TEWI%	0.01%	9.42%
LCCP, kg CO₂ equivalent	37,780	45,398
% of R410a	83,22%	100%
% of TEWI	0.01%	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.

Ref	Flammability Class	Lower Flammability Limit kg/m³		Heat of Combustion MJ/kg
R290	A3 Highly Flammable	<0.1	or	>19
R513a	A1 Non-Flammable	Cannot be ignited
R452b	A2L* Mildly Flammable	>0.3	and	<19
R1234ze	A2L* Mildly Flammable	>0.3	and	<19
R410a	A1 Non-Flammable	Cannot be ignited
R407c	A1 Non-Flammable	Cannot be ignited
R134a	A1 Non-Flammable	Cannot 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”

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

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

R1234ze

Details

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

R290

Details

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

R134a

Details

- Chemical composition C₂H₄F₂
- HFC
- GWP - 1,430
- Flammability class - A1
- Used in screw and centrifugal compressors

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

Chillers, Condensers, Refrigerants

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.

The Ozone Depletion Process

Refrigerants

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

*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

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

3.05

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

5.55

5.60

5.45

SEPR

5.52

5.02

5.69

5.23

5.15

tba

5.23

5.41

5.27

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

3360

4740

6120

8880

11640

Width [mm]

1800

2230

Height [mm]

2490

2530

2570

Sound power [dB]

100

101

Includes VFD?

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

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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.

Dummy

Air Cooled Chillers

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Data Centre Air Conditioning

PSC Air Cooled Chiller – Overview

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PSC Range of Air Cooled Chillers

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?

Refrigerant Timeline

A Bit of Chemistry

What are the requirements for an 'ideal' refrigerant?

Refrigeration - Environmental Metrics

GWP

TEWI

LCCP

Toxicity & Flammability

R452b

Details

R513a

Details

R1234ze

Details

R290

Details

R134a

Details

R410a

Details

More about Refrigerants

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PSC Model

Capacity

EER

ESEER

SEPR

SSCEE [%]

Shipping weight [kg]

Length [mm]

Width [mm]

Height [mm]

Sound power [dB]

Includes VFD?