Refrigeration Systems Student Resource Package No: NR … 1819204546... · Refrigeration Systems...

Refrigeration Systems

Refrigeration Systems Compiled By: G Riach & R Baker Ultimo 2005 1


Student Resource Package No: NR 18/19/20/45/46(excluding 6)

Nominal Student Hours: 72 Hours.

Delivery: Competence in this training program can be achieved through either a formal education setting or in the workplace environment.

Recognition of Prior Learning: The student/candidate may be granted recognition of

prior learning if the evidence presented is authentic and valid which covers the content as laid out in this package.

Package Purpose: This package provides the student with the underpinning knowledge to identify various types, of domestic refrigeration and commercial refrigeration systems together with their operational characteristics.

Suggested Resources: Australian Refrigeration and Air Conditioning Vol 1&2.

Various Manufacturers Service and Installation Manuals.

Assessment Strategy: The assessment of this package is holistic in nature and requires the demonstration of the knowledge and skills identified in the student package content summary. To be successful in this package the student must show evidence of achievement in accordance with the package

Competence: This package should be supported by workplace exposure to the various applications under the guidance of a licensed mentor.



Assessment:Grade Code: 72

GRADE CLASS MARK (%)

DISTINCTION >=83CREDIT >=70PASS >=50

Assessment Events:

1. Theory Test Domestic Refrigeration 30%

2. Theory Test Coolrooms / Freezer RoomsMerchandising Cabinets 40%

3. Theory Test Beverage Dispensing Equipment 30%Total Marks: 100%

Theory Tests: Short answer Questions / electrical drawingsThis assessment covers the contents of this student resource package.

Content Summary:

Domestic Refrigeration (Refer to Stage 2 Student Resource Package)

Coolrooms & Freezer Room: 3

Merchandising Cabinets: 22

Beverage Dispensing Equipment: 36

Beverage Cooler (Temprite) systems and associated equipment: 36

Glycol Systems: 43

Ice Making Machines: 45

Postmix Refrigeration systems: 53



Coolroom & Freezer Rooms

Section No: 2

Purpose: The purpose of this section is to provided you with the relevant knowledge and

skills in regards to food preservation

Food Preservation: (ARAC, page 1.5)Refrigeration is the most widely used means of preserving food in its original fresh state.Refrigeration involves the use of low temperature as a means of preservation of perishables by eliminating or retarding the activity of spoilage agents.The degree of temperature required to adequately preserve various fruits, vegetables and meats varies with the length of time the product is to be stored.Note: Product storage data table 1.2 ARAC page 1.9

HACCPHACCP stands for Hazard Analysis Critical Control Point (and its pronounced hass-up). HACCP emerged as a result of collaborative work between the Pillsbury Company, US Army Natick Laboratories and the National Aeronautic and Space Administration (NASA). A system for preventing food safety hazards was required for application to foods intended for the space program. (Think about vomiting in a space suit.) The only alternative was end product testing and, if certainty was to be assured, a 100% sampling rate would be required leaving little or no products for the astronauts to eat. Process control emerged as a solution.

Since then, HACCP has been taken up by food companies around the world, to help control the food production process. It is usually part of a wider quality assurance program.

Basically, a HACCP program means finding out where the really serious problems occur, monitoring these steps so you know if there are problems, and fixing any problems that arise.

As for us, our responsibility is to ensure that our part of the process i.e. correct temperatures and humidity’s are maintained at all times and that adequate monitoring and logging procedures are in place.

Note: Product storage data table 1.2 ARAC page 1.9

Coolroom / Freezer Room Construction:

Modern refrigerated coolrooms / freezer rooms are constructed of rigid self supporting Insulated panels. Both inner and outer skins are made form white powder coated steel sheeting (colorbond). The insulation sandwiched between the inner and outer skins can be either polystyrene foam (PSF) or polyurethane foam (PUF).

The panels are designed so that each panel slips into each other without the need of extruded strips and are joined using a suitable sealant (mastic) and rivets. Kit type rooms are also available and the panels are locked together by a cam lock system, using a large Allen key.



Thermal Conductivity:Thermal conductivity is known as the k Factor of a material and is a measurement of the rate at which heat will travel through a material that is 1 metre x 1 metre x 1 metre at a temperature difference of 1 Kelvin (1k).

The K factor of a material = W/m.K (watts per metre Kelvin)

Power coated steel sheet on both sides approx 0.7mm thick

Insulation

Self supporting coolroom / freezer rooms insulated panels

1m

1m 1m

16ºC

15°C



Table 1 Insulating Material “k” Factor

Material k Factor

Polyurethane 0.025 W/m.K

Polystyrene (0ºC) 0.032 W/m.K

Polystyrene (-18°C) 0.030 W/m.K

Fibreglass batt 0.035 W/m.K

brick 0.81 W/m.K

Concrete 1.44 W/m.K

U Factor:

The U factor is the overall coefficient of heat transmission in watts per square metre per Kelvin.To find the U factor of a material use:

U = k factor of material kThickness of material (in metres) x

The U factor of a material is measured in W/m 2. K(Watts per square metre Kelvin).

Example: 1Determine the U factor of the following

Construction of room 75mm polystyrene foam k factor 0.032 w/m.K

0.032 = 0.4267 W/m2. K.0.075

Example: 2Determine the U factor of the following

Construction of room 100mm brick k factor 0.81 W/m.K

0.81 = 8.1 W/m2.K.0.10



Room Temperature Wall ThicknessRoom Temperature Recommended Wall

ThicknessU Factor

75 mm (PSF) 0.426 W/m2.K

+ 2°C

50mm (PUF) 0.50 W/m2.K

150mm (PSF) 0.20 W/m2.K- 20ºC

100mm (PUF) 0.25 W/m2.K

Determining the U Factor of a Composite Material

Often the floor and walls of a coolroom / freezer room are made of more then one material. This is known as a composite wall or floor.

When installing a coolroom on a raised concrete floor it is common practice for a panel of PSF to be placed in a recessed hole in the floor and a layer of concrete to be poured over it. Note: drawing below.

PSF Insulation

Concrete Floor

Vapour Barrier (Plastic sheet)

Concrete StructureRecessed floor known as “set down”. Heated floor required if slab suspended.



Calculating the U factor of a Composite Material:

The following details relate to the calculation required to determine the U Factor of a composite material:

X-Thickness of each material in metres

K- Factor of each material. W/mK

The following formula applies; U = 1X1 + X2 ……….etcK1 k2

Where: U = total U Factor of the composite materials in W/m2.KX = thickness of each of the individual components in metresk = k factor of each individual component in W/m.K.

Example:Calculate the overall U factor for a coolroom floor consisting of 75mm polyurethane foam and 100mm of concrete.

1 1 = 0.325 w/m2.K0.075 + 0.10 3 + 0.0694440.025 1.44

Transmission Load:Before obtaining plant and equipment for the installation of a coolroom or freezer room a thorough transmission load and product load should be determined to ensure correct refrigeration capacity and equipment selection.

To determine the transmission load (heat leakage) of a coolroom the following applies:Formula: Q = U x A x td

Where: Q = heat leakage in watts or kWU = overall U factorA = complete outside area in metres squareTd = the temperature difference between the ambient

and the room operating temperatures.



Coolroom details:

The coolroom is constructed from 75mm polyurethane foam rigid panels.Design operating temperatures of 3ºC with an ambient of 28°C.

Note: When determining the total transmission load you may have to do the floor separately due to the temperature difference.

Step.1 Determine the outside surface area of the walls ane ceiling: 2 x 2.5 x 3.2 = 16m2

2 x 2.5 x 4.2 = 21m2

2 x 3.2 x 4.2 = 26.88m2

Total area = 63.88 m2

Step.2 Determine the U factor of polyurethane foam:

Table 1 k factor = 0.25w/mK U factor = k factor of material 0.025 = 0.3333 w/m2.K

Thickness of material 0.075

Step.3Determine the temperature difference:

28°C - 3ºC = 25K td = 25K

Step.4Determine the total transmission load from the gathered information above:

Q = U x A x td Q = 0.3333 x 63.88 x 25 Q = 532.33 watts.

2.5m2

4.2m2

3.2m2

Determining the transmission load for the attached coolroom

3°C Ambient 28ºC



Total Capacity for a Medium Temperature Coolroom (3°C)

Aim: To determine the refrigeration capacity for coolroom in accordance with the following details:

Transmission load as above in step 4. Product load Product pull down temperature time Air change load.

Determine the total refrigeration capacity for the above coolroom in accordance with the following details:

Transmission load 532.33 watts 500 kg fresh beef entering at 34ºC and cooled down to 3°C. 16 hours pull down time Specific heat capacity of fresh beef equals 3.22 kJ/kg/K above freezing. Temperature difference = 31K

Method: Q = mass x specific heat x temperature difference

Q = 500 x 3.22 x 31Q = 49910 kJ The heat removed in kilojoules must be converted to kilowatts

kW (kJ/s) = kilojoules 3600(seconds/hr) x 16(hrs)

Product load = 49910 = 49910 = 0.866 kJ/s or 0.866 kW3600 x 16 57600

Product load 0.866 kW + Transmission load 0.532 kW = 1.398 kW total load.

Note: It should also be noted that there are other factors that may have to be included in the total heat load calculation for a particular coolroom or freezer room such as the air change, evaporator fans, light loads, glass door inserts, people, forklifts and heat of transpiration.

If you require further details in the determination of transmission and product loads etc this will be covered in more detail in the HVAC & Refrigeration Diploma Course No:290.



Medium temperature coolroom (3°C)

Typical Coolroom/ freezer construction of a kit room, these rooms are purchased in kit form and the polyurethane injected panels are locked together using a large Allen key.

Forced draught cooler orInduced draught coolerFDC or IDC

Metering device

Liquid line

Liquid line filter drier

Sight glass

Suction lineMedium temperature

coolroom with an average room temperature = 3ºC

Condensing unit



M3~

N

O/L

K1

K1-1

K1-2

K1-3

L1

L2

L3

HPLP

LLSV

tº

M

Medium temperature coolroom (3°C) incorporating a pump down cycle.

Evaporator Fan Motor

M

M

K1- 4

Electrical wiring diagram medium temperature coolroom



Note: The following two control circuit diagrams can also be used to control medium temperature coolrooms.

K1

t° LP HP O/L

M

A N

K1

LP HP O/L

M

A N

t°



At this point you should be able to set all the controls on each of the above circuit to maintain an average room temperature of 3ºC.

Example:In the space provided below determine the thermostat, low and high control settings for a medium temperature coolroom. The room is operating on R404A with an average room temperature of 3°C, SST of -3°C and an outside ambient temperature of 36º.

SST = 457 kPaCut out = 2ºC

Room thermostat: Average room temperature = 3ºCCut in = 4ºC

Low pressure control: Cut out = 100 kPaCut in = 560 kPa = 3ºC

Please note that the above LP cut-in settings are designed to ensure that the evaporator is defrosted prior to compressor re-starting. Lower cut-ins may be set if an alternative form of defrosting i.e. timer is used.

High pressure control Cut out = Ambient + 15 + 5 Safety factor36 + 15 + 5 = 56ºC = 2525 kPaAutomatic or manual reset.

Freezer Rooms:Low temperature freezer rooms operate at a much lower saturated suction temperature (SST) than a medium temperature coolroom and for this reason they require regular defrosts.Freezer rooms can normally operate with a SST of between -15ºC down to -35°C and therefore require the following additional components:

Defrost timer Defrost heater Drain heater High limit safety thermostat Fan delay (low pressure control or thermostat) Anti – sweat heater around door jamb and relief ports Suction line accumulator Oil Separator Crankcase pressure regulating valve. MOP TX valve



Subject:Electromechanical Defrost Timer:The defrost timer activates the defrost cycle. This type of timer is driven by a synchronous motor, geared down to 24 hour function and allows for a set number of defrosts and duration. This can be adjusted by the technician to suit each individual application.

Most low temperature freezers have four defrost periods per day with a duration set at approximately 25 minutes. The termination of the defrost cycle can either be from time, temperature or pressure.

Types of Defrost Timers: Time initiated time termination Time initiated time or pressure termination Time initiated time or temperature termination Electronic Timers.(are replacing electromechanical defrost timers)

Defrost Heaters:The defrost heaters are energised by the defrost timer and are required to remove the ice that has accumulated on the evaporator. This is done by heating the evaporator coil and at the same time raising refrigerant temperature. Note: all the ice on the coil should be removed at approximately 8ºC.

Drain HeaterAs the ice melts on the evaporator the drain heater keeps the water warm allowing it to flow freely to the outside drain.

High Limit Safety ThermostatThe high limit safety thermostat is designed to de-energise the defrost and drain heaters if the evaporator temperature rises above a predetermined thermostat settingUsually set to close at approximately -10°C and open at around 14ºC.Note this thermostat opens on rise (OOR) and closes on fall (COF).

Fan Delay Thermostat (Reverse Acting Low Pressure Control)The reverse acting thermostat or low pressure control fan delay controls are designed to delay the period before the evaporator fans start up and usually close at a SST of around -10°C and open at 0ºC.

This type of control removes the possibility of hot air and water from being blown onto the product on the completion of the defrost cycle.

Anti -Sweat HeatersSmall wattage heater fixed to the inside of the door jamb to prevent any moisture or ice forming around the door. The floor at the door will have a threshold heater fitted if the concrete floor is set down.

Suction Line AccumulatorDesigned to collect excess liquid refrigerant and allows the compressor to draw vapour and oil back.



Crankcase Pressure Regulating Valve (CPRV)At the completion of a defrost cycle the evaporator pressure can exceed 600 kPa and for thisreason a CPRV is installed in the suction just before the compressor and can be adjusted to control the pressure of the vapour entering the compressor regardless of the evaporator and suction line pressure. Installing the valve to close to the compressor may cause hunting.

CPRV adjustment is accomplished by fitting service gauges and a clamp on ampere meter around one of the active wires at the compressor.The valve is adjusted by increasing or decreasing the spring pressure until the full load amperes of the compressor is between 90 & 100 % FLA. This must be done during compressor start up following defrost.

Types of refrigerant:The preferred refrigerants used for low temperature applications within the industry areR404A / R507 A. However some systems may still have R502, R12 or R22.

Relief PortsSome times referred to as explosion or implosion ports. These devices are inserted in the freezer wall and used to balance the external and internal air pressures as to save the room from being structurally damaged. They have hinged flaps internally and are heated. The number and size increase proportionally with room volume.

Typical Cold room installation Showing IDC and weather proof lighting.



Low Temperature Freezer Room

Cross-section of freezer room relief port

Forced draught coolerFDC or Induced draught cooler

Metering device

Low temperature freezer room with an average room temperature = -18ºC, operating on R404A.

Suction line accumulator

CPR valve

DTDefrost timer LP

Reverse acting LP fan delay

Note: A relief port is installed in one of the walls of the freezer room to balance any air pressure differences.

Heated drain must beTrapped and Insulated.



Low Temperature Freezer Room Insulation Thicknesses (Australia)

Room Temperature Polystyrene Polyurethane

-10ºC to -20ºC 100-150 mm 75-100 mm

-20ºC to -35ºC 150-200 mm 100 mm to 150 mm

Note: If unsure about the type of panel thickness required for the application, consult the manufactures.

Factors to consider when selecting panel thickness: Ambient temperature. Is room exposed to direct sunlight? Relative humidity. Span (distance between walls). Height of walls. Load bearing.



Low Temperature Freezer Wiring Diagram



Review Questions Section No: 2

Q.1 Name two types of insulation material used in the construction of coolrooms and

freezer rooms:

Q.2 What is meant by the terms transmission and product load:

Q.3 List four factors that determine the refrigeration capacity of a coolroom or freezer

room plant

Q.4 List four additional components that are required for a freezer room in comparison to

a medium temperature coolroom:

Q.5 List three types of defrost timers and their operation methods:

Q.6 What is the purpose of the drain heater on a freezer room?

Q.7 Describe the operation of a reverse acting low pressure control:



Q.8 Why and where is an anti-sweat heater used?

Q.9 What is the purpose of a suction line accumulator?

Q.10 Describe how you would adjust a crankcase pressure regulator:

Q.11 A medium temperature coolroom operates on R134a at an average room temperature

of 3°C with an evaporator TD of 6K and an outside ambient of 36ºC. In the space

provided indicate the following control settings: (Note show all working).

Room thermostat

Low pressure control

High Pressure control

Q.12 A low temperature freezer room operates on R404A at a room temperature of -20°C



With an outside ambient of 35ºC. In the space provided indicate the following

control settings:

Room thermostat

Fan delay thermostat

High limit safety heater thermostat

Defrost timer (Time initiated time or pressure terminated)

Low pressure safety control

High pressure safety control.

Q.13 Describe the construction and operation of a relief port.

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Merchandising CabinetsSection No: 3

Purpose: The purpose of this section is to provide you with the underpinning knowledge to identify the various types of merchandising cabinets their application, construction and operational characteristics.

Supermarket Merchandisers: (ARAC, page 7.10)Supermarket merchandising cabinets have been constructed over the years to provide customers with the opportunity of self service and the type of cabinets are as follows:

Multi-deck open display cases Single deck, well type cases Reach in cabinets

Multi – Deck Display CasesThe multi-deck display cases are used to refrigerate and display dairy produce, cheese and cooked meats at a temperature of around 3ºC. The evaporator coil is usually installed in the bottom of the cabinet with fans forcing air up and over the product. Note: evaporator fans operate continuously.

A well directed air curtain is designed to keep cold air in the cabinet and reduce air spillage to a minimum. These cases loose approx 60% of air circulated.

Most multi-deck display cases are designed with removable ends so as they can be connected end to end to increase the length to meet the customer’s requirements.

Low front Type Multi-Deck dairy



Single Deck Well Type CasesThe single deck case is designed as a meat, fruit or vegetable merchandiser and can also be redesigned as a freezer in a single width or double. These cabinets have much less air spillage than up right merchandisers because the cold air circulating is heavy and falls down over the product.

Anti-sweat heaters are installed under the cabinet’s stainless steel rub rail to prevent water from condensing on the rub rail and dropping onto the floor.

Denotes Air flow

DrainEvaporator fan

Evaporator

Light

Load line

Defrost heater

Single deck case



M

O/LL

K1

K1-1

K1-2

K1-3

L1

L2

L3

HP

M

Most cabinets have a number of evaporator fan motors.

M

t° LP

Note: Defrost timer time initiated time or pressure

termination.

N

Cabinet ant-sweat heater element

Defrost heater, if fitted



Multi-Deck Display CasePiping Circuit Diagram

Denotes Air flow

DrainEvaporator fan

Evaporator

Light

Load line

Defrost heater

LP/HP

DT

EPRV


Defrost timer



Low Temperature Merchandising Cabinet

It should be noted that the evaporator fans on these cabinets operate continuously even through the defrost cycle. The reason for this is to ensure that the supply and return air ducts do not accumulate any ice which may restrict air flow and reduce capacity.

RACEWAY

EvaporatorDefrost heater

FanDrain

Air delivery Air returnWide island freezer



Electrical Wiring Circuit Low Temperature Case

Diagram

M

O/L

K1

K1-1

K1-2

K1-3

L1

L2

L3

HP

M


M

t° LP

High limit safety thermostat close at approximately - 10°COpen at 8°C

Note: Defrost timer time initiated time and or pressure

termination. Compressor has a belt driven drive motor.

N

Defrost heater

Drain heater

t°


Isolator

Isolator



Low Temperature Merchandising CabinetPiping Circuit Diagram

LP/HP

DT

EPRV CPRV


Oil separator

Defrost timer



Multi – Deck Display CaseElectrical wiring Diagram

M

O/LL

K1

K1-1

K1-2

K1-3

L1

L2

L3

HP

M


M

t° LP

Note: Defrost timer time initiated time or pressure

termination.

N


Defrost heater, if fitted



Piping Circuit Diagram

Cabinet Capacities: FreezersThe following details approximate cabinet ratings per length:

Length of Cabinet

Type of Cabinet Saturated Evaporator

Temp

Store ConditionsA/C 24°C 60 % RH

Cabinet capacity

Store ConditionsNon / Air

32ºC 60% RHCabinet capacity

2448 mm (8 ft) Single Island - 35°C 1190 watts 1320 watts

3870 mm (12 ft) Single Island - 35°C 1780 watts 1980 watts

2448 mm (8 ft) Rear wall - 35°C 1190 watts 1320 watts

3870 mm (12 ft) Rear wall - 35°C 1780 watts 1980 watts

Recommended Control Settings:

Type of cabinet Refrigerant LP cut / cut out EPR valve ThermostatCut in / cut out

Frozen food R22 62kPa /158 kPa 62 kPa -26°C / -22°CIce cream R22 36 kPa / 140 kPa NA -29°C / -25°C

Frozen food R404A 90 kPa / 185 kPa 110 kPa -26°C / -22°CIce cream R404A 70 kPa / 165 kPa NA -29°C / -25°C

Note: Defrost timer has a maximum of 4 defrosts / 24 hoursDefrost duration of approximately 40 minutes.Temperature over ride: 8°C.Pressure over ride: 668 kPa for R404A and 540 kPa for R22.

LP/HP

DT

EPRV


Defrost timer



Reach in Merchandiser cabinetsReach in merchandisers are available in self contained or remote units in a variety of temperature ranges from medium temperature to low temperature applications. With the majority using forced draught evaporators the location of the evaporator can either be at the top or the bottom of the cabinet.

Low temperature freezer cabinets are automatic in operation and require a number of defrosts per day to keep the evaporator clear of ice.

Force draught evaporator

Glass doors, may be heated

Adjustable shelves

Reach in Merchandiser cabinet

3 degree Celsius to –25 degree Celsius



Problems associated with self –service reach-in cabinets are as follows: Placing stock above the load limit line Drain blockage due to poor house keeping (product spillage and unattached labels). Overloading cabinet with warm product. Cost of operation. Poor thermal hold over.

Cabinet temperatures, saturated evaporator temperatures and types of refrigerant for various cabinets

Application CabinetTemp

Refrigerant Suction Temp(SST)

Meat merchandising 0ºCR134aR22

R404A-10°C

Dairy multi-deck 3 to 5ºCR407AR507R134a

-4 to -10°C

Freezer double width -20ºCR22

R404A -32°C to -36°C

Reach in frozen food -20ºCR404AR507 -25°C-32°C

Reach in ice cream -25ºCR404AR507 -36°C

Installation:To ensure the correct installation procedures are implemented you should check with the manufacturers requirements and site conditions in regards to the following factors,

Refrigeration capacity for each cabinet Installation and location of each cabinet Refrigeration components required Supply and electrical control circuits Correct adjustment of all controls. Type of refrigerant. Drainage requirements. Site Access. Weight of stocked cabinets.



Control Circuits (Systems)The majority of supermarket merchandising and display cabinets utilise computer-operated systems where all the parameters are programmed in to provide automatic control and feedback through an alarm system. Typical systems in use are: CPC, Phasefale and Danfoss.




Q.1 List three different types of supermarket merchandising cabinets:

Q.2 Where is the evaporator normally located in a multi-deck display cabinet?

Q.3 Why do most multi-deck display cases have removable ends?

Q.4 Why do single well deck cases have less air spillage than upright merchandising

cases?

Q.5 Anti sweat heaters are installed under the cabinets rub rail for what reason?

Q.6 List three problems associated with self service cabinets:

Q.7 Explain why the evaporator fans in a low temperature island freezer cabinet operate

continuously:



Q.8 What is the purpose of the air curtain on a Multi deck open Cabinet?

Q.9 List three common refrigerants that are used in dairy multi deck cabinets:

Q.10 Give five factors that should be taken into account prior to installing supermarket

equipment:

`



Beverage Dispensing EquipmentSection No: 4

Purpose: the purpose of this section is to provide with the relevant knowledge and skills in the application and operation of various beverage cooling systems and ice making systems that are used in the presentation of beverages in the hotel, club and restaurant industries.

Beverage Coolers (Temprite) Reference (ARAC, pages 5.4 & 7.20)

Instantaneous beverage coolers (IBC) were one of the most familiar evaporators encountered in hotels and clubs. Although single IBC are encountered large hotels or clubs may connect as many as six IBC to the one condensing unit. In this situation two, three or more condensing units may share the load of ten, fifteen or more IBC distributed throughout the hotel or club so that the failure of one unit would not adversely effect the total number of IBC’s and thus trading would continue virtually uninterrupted. IBC’s are fully flooded evaporators. The liquid level is controlled by a low side float and needle and seat (cartridge).

Installation requirements of IBC’s:

Surge Tank: This tank or vessel should be installed above the suction line so that the excess suction pressure but not oil can be contained in this component. The vessel is sized in such a way that for every one kilowatt motor power it should accommodate at least 50 litres (0.05m3). Its purpose is that by increasing the volume of the suction line it absorbs suction line pressure line fluctuations and prevents the condensing unit from short cycling.



Constant Pressure Valve (750 valve): This valve is fitted to each IBC to maintain a constant SET above the freezing point of the beverage. The constant pressure valve is similar to an EPR valve but far more accurate.

Example: Standard strength beer freezes at approximately -2ºC.Refrigerant 134a SET = 202 kPa = 1°CRefrigerant R22 SET = 413 kPa = 1°C

The adjustment is done by fitting a set of gauges to the inlet side of the EPRV and adjusted to the selected minimum pressure / temperature required. The valve

bellows can be lubricated by the removal of an 1/8th BSP plug and the insertion of refrigerant oil. Oil Separator: An oil separator must be fitted to any refrigeration system that has an

IBC so that the possibility of oil entering the evaporator of an IBC is reduced. Accumulated oil in the evaporator of an IBC reduces the amount of refrigerant and thus capacity.

The oil separator is installed between discharge line and condenser as close to the compressor as possible and should be charged with the recommended oil before installation. The oil return line from the separator and compressor should be as short as possible.



LP / HP Control Settings:

Low Pressure Control Setting:Cut out: Should be a reasonable low pressure to ensure a long off cycle

Example = 21 kPa (134a)100kPa (R22)

High Pressure Control Setting:Cut out: Example = Ambient + TD + 5K safety factor

Ambient temperature = 35ºCSaturated Condensing Temperature = 40°CTemperature difference = 15K

Cut out = 35 + 15 + 5 = 50ºC = 1220 kPa for 134a

Cut in = Can either be manual or automatic reset with a fixed differential.

M3~

N

O/L

K1

K1-1

K1-2

K1-3

L1

L2

L3

HPLP

LLSV

tº

M

Evaporator Fan Motor

M

M

K1- 4

Electrical wiring diagram beverage cooling system

Condenser fans

Compressor

Coolroom or bottleCabinet circuit



Refrigeration circuit diagram beverage cooling system

IBC1

IBC2

Coolroom Evaporator

Note: addition hand line valves can be installed in the suction and liquid line manifolds for additional bottle cabinets if required.

EPRV

Surge tank

IBC

Beverage flows from the coolroom to the IBC at 4°C. The temperature is further reduced in the IBC to 2°C where it is transferred via the beer tap into a glass for consumption.

Note: CO2 is used as the pressure to force the beer from the kegs to the glass.

Coolroom used to store package beer and beer kegs at around 7ºC.

CO2 gas cylinder and regulator

Beer Kegs

Heater

Pressurerelief



Bottle Cabinets (Hotels / Clubs)The following details a range of bottle cabinets that are used in clubs, hotels and restaurants

Control circuit diagram

SLSV

A N

LP

M

M

Evaporator fan motors

Cabinet light circuit

LP

Under bar bottle cabinet

Low pressure control

Liquid lineForced draught evaporator (FDC)Usually two or three fan motor.

Suction line solenoid valve



Operation of under bar cabinet:The under bar bottle cabinet is usually part of the complete beverage cooling system. This is obtained by the addition of further suction and liquid line hand line valve connections on each of the manifolds.

The cabinet temperature is controlled by the low pressure control which cycles the suction line solenoid valve on the evaporators saturated refrigerant pressure temperature. Note: evaporator fans operate continuously.

Temperature control: (Refrigerant R134a) Place a compound pressure gauge on the evaporator side of the suction line

solenoid valve.

Set the cabinet low pressure control to cut in at 3°C (225 kPa)

With the main condensing unit in operation place a thermometer in the return air steam of the cabinet.

Adjust the low pressure control to cut out at approximately 2ºC.With an evaporator temperature difference of around 6 K the cut out pressure would equal 161 kPa (SET = -3°C.

Temperature controlled by cycling a liquid line solenoid valve by a cabinet thermostat which senses the return air or evaporator coil temperatures.

Under bar bottle cabinet

Liquid line solenoid valve

Forced draught evaporator (FDC)Usually two of three fan motors.

Suction line



Under Bar Bottle Cabinet

LLSV

A N

tº

M

M

Evaporator fan motors

Cabinet light circuit



Glycol Systems

Glycol systems have become the most popular system and have been designed to replace beverage cooling systems and are manufactured to fit into a standard glass rack.

The chiller plate is basically a plate heat exchanger has no moving parts and can chill two, four or six beverages.

Each chiller plate is individually controlled by a digital thermostat which is adjustable to suit the required application.

The DX evaporator is mounted within a glycol bath which includes a small agitator motor to ensure an even glycol temperature. The temperature of the glycol bath is controlled by a thermostat in series with a liquid line solenoid valve which feeds refrigerant to the TX valve (this type of control relies on a pump down cycle).

Mix ratio of around 30% glycol and 70 % water and should be regularly checked with a refractometer.

Note: To become competent with current glycol systems it may be necessary for you to under take on the job workplace training under the guidance of a licensed mentor, attend manufacturers and or suppliers training program on their product range.

Water Duct Systems:This system is used for large hotel installations. It uses a simple refrigeration system that combines the chilling of beer in the keg room by IDC’s as well as continuously cooling the beer as it flows through the dispensing tap, by using a chilled water heat exchanger.

The “water duct” is a simple heat exchanger that has the beer in a centre tube and chilled water in the outer tube.

Water Duct

One condensing unit is used for both the coolroom and chilled water. The chilled water tank is simply a TX valve fed coil in an insulated tank filled with the circulating water.

The circulating pump must have the capacity to maintain water flow in all circuits during peak loads. It runs continuously during trading hours.

The coolroom contains the kegs as well as the water tank and circulating pump.

Beer

Water



Typical Piping Diagram for Glycol Chiller Plate System

The above circuit represents a glycol system using one plate heat exchanger and beer line. In the majority of hotels and clubs there are a number of different beers available and for that reason the number of plate heat exchangers and fonts may have to be increased to meet the consumers; needs.

Note: one chiller plate can have six different beer circuits

The glycol and beer lines are enclosed in 25mm of insulation called a python.

Glycol lines

Chiller plate heat exchanger

Circulating glycol pump

Beer font

DX evaporator in glycol bath

Beer line

Beer kegs stored in coolroom at 7ºC

Beer gas cylinder and regulator



Ice Making Machines

Reference (ARAC, page 4.18)Self contained ice making machines can be split into two categories and they are as follows:

1. Ice FLAKE machines2. Ice CUBE machines.

Each category has many sub-groups as many of these machines are grouped mainly by the shape of the ice cube they dispense. It must also be noted that the machines are controlled electronically, electro-mechanically or a combination of both

1. Ice Flake Machines:These machines continuously deliver an irregularly shaped ice flake and are often referred as “crushers”or “flakers”.This type of system relies on specially designed tubular evaporators into which a slowly revolving auger with minimal wall clearance is fitted. The auger motor power is around 300watts and the gearbox driving the auger may require heavy duty gear box oil during routine service. The auger bearings should be replaced approx every two years.

FLAKERSFLAKERSOPERATING PRINCIPLES OPERATING PRINCIPLES -- REFRIGERANTREFRIGERANT

COMPRESSOR

EVAPORATOR

AIR COOLEDCONDENSER

ACCUMULATOR

CAPILLARY TUBE

DRIER

Figure .1.



FlakersFlakers

FLOAT VALVE

OPERATING PRINCIPLES OPERATING PRINCIPLES -- WATERWATER

WATER SEAL

PLASTIC SPOUT

Figure .2.

FLAKERSFLAKERS

GEAR REDUCER

DRIVE MOTORCOUPLING

BOTTOM BEARING

WATER SEAL

AUGER

ICE BREAKERPLASTIC

SPOUT

TOP BEARING

OPERATING PRINCIPLES OPERATING PRINCIPLES -- MECHANICMECHANIC

Figure .3.



FLAKERSFLAKERS

After two-three

minutes the first

pieces of flakes ice

are discharged

through the spout

of the freezer

dropping down into

the storage bin.

IceIce Being Forced Thru Breaker by Being Forced Thru Breaker by AugerAuger

Figure .4.

COMPONENTS COMPONENTS -- MECHANICAL SYSTEMMECHANICAL SYSTEM

••WATER SEALWATER SEAL

•• AUGERAUGER

•• ICE BREAKERICE BREAKER

FLAKERSFLAKERS



Figure .5.

2. Ice Cube Machines:Ice cube machines are often given particular names based on the cube shape they produce. This shape is determined by the design of the evaporator, water circulation and harvesting methods. The most common types of ice makers produce cubes by running or spraying water over an evaporator which is manufactured to the shape of the cube required (see figure .9.). The evaporator temperature, typically ranges from -6 degrees at the beginning of the freezing cycle to -12 degree prior to harvest (defrost). Ice Cubers consist of two main circuits the first being the refrigeration circuit and the second being the water circuit.OperationRefrigeration Cycle (refer to figure 6)During the refrigeration cycle and with the assistance of a compressor the warm refrigerant vapour is remove from the evaporator and pumped to the condenser under high pressure where it is transformed into a liquid. From the condenser the refrigerant passes thru a filter drier and then onto the expansion device. The expansion device will either be a thermostatic expansion valve or a capillarytube. The liquid refrigerant the passes thru the expansion device and into the evaporator. On entering the low pressure evaporator the high pressure liquid vaporizes and absorbs the water travelling over the evaporator. This process continues until sufficient ice has formed on the evaporator. For the machine to know when the ice thickness is correct (and to initiate a defrost) several methods are used.

Defrost initiation methods Time and temperature. With this method a thermostat is attached to the

evaporator. Once the evaporator has reached a pre determine temperature it supplies power to a defrost timer. The timer then times out for approx 15 minutes and then commences a defrost.

Water level. With this method an electronic control module look at the level of the water in the water reservoir, it does this buy sensing earth leakage thru probes positioned at different levels in the tank. Once the level has dropped to the desired level the machine assumes that the water has now been converted to ice and initiates a defrost.

Ice thickness sensors. There sensor are position on a bracket at a pre determine distance, once the ice builds up on the evaporator and touches the sensor the defrost is initiated. These sensors take the form of either a mechanical thermostat type or an electronic type were to probes allow a small current to pass between them once the ice hits them. An electronic module senses the current and initiate a defrost.

Defrost Cycle (refer to figure 7)Once the defrost cycle has been initiated a solenoid valve is energized. This solenoid valve passes hot gas form the compressor directly into the evaporator. This causes the evaporator to heat up, and any ice that has formed to fall away from the evaporator and into a storage bin.



Defrost terminationDefrost termination is either accomplished by the following methods,

Thermostatically. This method employs a thermostat which is attached the evaporator. Once the evaporator reached the desired temperature and the ice has left the evaporator plate. The thermostat breaks the supply of power to the hot gas solenoid and forces the system back into refrigeration mode.

Magnetic and Micro switches. (refer to figure 10) With the gravity cascade type machines a hinged door covers the water cascade. During the defrost cycle the ice falls of the plate and forces the hinged door open as it falls into the bin. As the door opens it actives a micro switch or magnetic switch which sends a signal to the electronic controller to terminate the defrost and restart the refrigeration cycle.

MaintenanceAll Machine require regular maintenance. Most manufacturers supply recommended maintenance shedules. However water and air quality does have a large bearing on the frequency of maintenance. Therefore each installation should be evaluated seperately. With regardes to filtration, water filter not more than 5 micron rating should be used.



OPERATING PRINCIPLES OPERATING PRINCIPLES -- FREEZEFREEZE

CompressorCompressor

Hot Hot gas gas

valvevalve

EvaporatorEvaporator

Air cooledAir cooled

condensercondenser

Figure .6.

OPERATING PRINCIPLES OPERATING PRINCIPLES -- HARVESTHARVEST

CompressorCompressor

Hot Hot gas gas

valvevalve

EvaporatorEvaporator

Air cooledAir cooled

condensercondenser

Figure .7.



Figure .8.

MODULAR SERIESMODULAR SERIES

The machine remains in

the freezing cycle with the

ice that become thicker ….

FREEZING CYCLEFREEZING CYCLE

Figure .9.

MODULAR SERIESMODULAR SERIES

….

FREEZING CYCLEFREEZING CYCLE



OPERATING PRINCIPLESOPERATING PRINCIPLES

In this picture the ice can

be seen forcing the

hinged door open. A

micro switch is attached

to the door. The switch

sends a signal to stop the

defrost. If the door stays

open i.e the bin is full

the machine will stop.

Figure .10.

The most important program on the maintenance of the cubermachines is the cleaning/sanitizing to be done on regular base as detailed here below:

•• Sanitizing: Sanitizing: Every monthEvery month

•• Cleaning:Cleaning: Every sixEvery six

On next slides will be shown the procedure for sanitizing and cleaning.

MAINTENANCEMAINTENANCE

Figure .11.



Postmix Refrigeration Systems

(Reference to manufacturers catalogues)Counter top refrigeration systems can be broken down into two categories. These are:

Mechanical Ice-Cooled.

Mechanical Refrigeration:The dispenser is mounted on the counter serve top and contains the refrigeration unit within the dispenser. Inside this unit the refrigeration system develops an ice block inside a water bath area it also contains stainless steel cooling coils for water, soda water and syrup. A small agitator motor runs continuously and assists in the efficient removal of heat from the product coils and carbonator tank.

To carbonate the soda water a carbonator is installed inside the water bath to maintain maximum carbonation. Note with exception to the ice bin type where the carbonator is positioned outside the storage bin area either in the base of the unit or directly Under the counter.

The syrup is supplied to the dispenser by stainless steel CO2 driven diaphragm pumps and a bag in box package.

The water filter should be positioned as close to the unit as possible and accessible at all times.

The syrup ratio or brix: The taste of the finished product is dependent on the correct ratio of soda water to syrup. This can be checked by using a syrup separator to separate the syrup from the soda water or plain water at the dispensing valve. Or commonly a refractometer is used.

A ratio cup is used to measure the two products and has two chambers calibrated in mls or cc’s.

Adjustment of the syrup ratio is done by adjusting the soda water first. The soda water adjustment screw is on the left hand side of the faucet and should be adjusted for a nominal flow of 5 ounces of water in three seconds. Once the soda flow rate is set the syrup can be adjusted as per the correct ratio that is found on the Bag in Box.



Typical Countertop Dispensing Refrigeration System

Ice – CooledThis type of dispenser consists of a stainless steel storage bin with an aluminium plate that has stainless steel cooling coils, the soda water, clean water and syrup cooling cast into it. Ice fills the storage bin and acts as a refrigeration medium to cool the product passing through the coils. This ice can be supplied by an ice maker fitted to the dispenser or from an outside source.

The carbonator is positioned outside the storage bin either in the base of the unit or directly under the counter.

Coola Cola

Syrup BoxesWater Filter

10KgCO2Bottle

1000mm



Typical Ice-Cooled Dispensing System

Coola Cola

Syrup Boxes

Water Filter

10KgCO2Bottle

1000mm

Remote Syrup boxes

Water Pump& Carbonator

Ice bin




Q.1 Describe the purpose of the surge drum when used within a beverage cooling system:

Q.2 State the main purpose of a constant pressure valve (750 valve) and why is it used in

preference to an EPR valve:

Q.3 Why must an oil separator be installed in an instantaneous beverage cooler (IBC)?

Q.4 Name two methods of controlling the cabinet temperature of under bar bottle

cabinets:

Q.5 Describe in your own words the main advantage of a glycol system in comparison to

a beverage cooling system (IBC).

Q.6 State the major disadvantage of a Temprite (IBC) system?

Q.7 List two types of ice making machines and their major differences:



Q.8 Describe two types of postmix refrigeration systems and their operational

characteristics:

Q.9 What does the term “brix” mean?

Q.10 In an ice-cooled counter top refrigeration system the ice can be provided by what two

means?

Q.11 Describe how you would adjust a beverage cooler (Temprite) to maintain a saturated

evaporator temperature of -1ºC:

Q.12 What drives the diaphragm pumps on a post mix refrigeration system?

Q.13 Why is it necessary for the compressor to operate during the harvest cycle on ice-

cube machine?

Q.14 What type of evaporator is an IBC?



Q.14 When adjusting the syrup ratio on a postmix dispenser what should be adjusted first?

Q.15 State the main purpose of the agitator motor in a postmix mechanical refrigeration

system:



Saturated Pressure / Temperature Chart for Common RefrigerantsR12 R134a R409a R22 R502 R408a R404a R500 R717

OC kPa kPa kPa kPa kPa kPa kPa kPa kPa-70 -89 -81 -74 -87 -90

-66 -85 -75 -67 -83 -87

-62 -81 -68 -57 -78 -82

-58 -76 -60 -46 -71 -76

-54 -69 -48 -34 -64 -69

-50 -62 -71 -37 -19 -23 -23 -55 -60

-46 -54 -64 -63 -22 -2 -8 -6 -44 -50-42 -43 -55 -54 -6 16 11 15 -33 -37-38 -32 -45 -43 10 41 34 39 -18 -22-34 -18 -32 -31 32 70 60 66 -3 -4-30 -1 -17 -16 63 98 89 97 16 18-28 5 -9 -7 80 115 105 114 35 30-26 11 0.3 2 91 132 123 133 45 46-24 21 10 11 106 151 141 152 54 60-22 32 20 21 126 171 161 173 65 76-20 44 31 33 145 191 181 195 76 89-18 56 43 44 165 214 203 219 87 105-16 70 56 57 185 235 227 243 100 124-14 85 69 71 207 260 251 270 118 145-12 103 84 85 231 284 277 297 134 165-10 116 99 100 254 313 305 326 156 190-8 131 115 117 284 340 334 357 174 215-6 150 133 134 310 369 364 390 193 241-4 165 151 152 334 400 396 424 215 269-2 184 171 172 361 435 430 460 239 2990 207 191 192 396 470 465 496 262 3282 224 213 214 430 508 502 537 285 3624 248 236 237 465 547 541 579 314 3976 270 260 262 504 586 582 623 340 4338 292 286 287 542 620 625 669 367 47310 323 313 314 584 668 670 716 398 51312 344 341 342 622 718 716 766 422 55514 372 371 372 668 767 765 819 454 60516 402 402 404 716 810 816 873 490 65418 432 434 437 769 860 869 929 530 70420 465 469 471 814 910 920 989 569 75522 497 505 507 866 967 980 1049 610 81124 531 543 545 917 1020 1040 1119 651 86826 571 582 585 975 1080 1100 1179 695 93028 605 623 626 1040 1145 1170 1249 740 99530 644 666 670 1107 1207 1240 1329 785 106532 683 711 715 1165 1270 1310 1399 832 113034 724 758 762 1230 1340 1380 1479 875 120336 765 807 811 1300 1410 1460 1559 925 127738 824 858 863 1378 1482 1530 1639 980 136940 860 911 920 1448 1558 1610 1729 1038 144942 912 966 970 1525 1644 1700 1819 1098 154344 962 1024 1030 1610 1725 1790 1909 1155 163046 1010 1063 1090 1688 1807 1880 2009 1215 172248 1060 1145 1150 1770 1887 1970 2109 1278 182050 1118 1210 1220 1855 1977 2060 2209 1348 191452 1172 1277 1290 1950 2070 2160 2319 1420 200554 1236 1347 1360 2050 2165 2270 2429 1489 211056 1300 1419 1430 2140 2265 2370 2549 1560 222958 1362 1494 1500 2245 2378 2480 2659 1635 236660 1428 1571 1580 2345 2475 2590 2789 1714 2515



Answers to Review Questions:

Section No: 2

Q1. Polystyrene & Polyurethane.

Q.2 Heat leakage into the room & Heat removed from the product.

Q.3

Transmission load

Product Load

Product pull down temperature time.

Air change load.

Q.4 Defrost timer, Defrost timer, Drain heater, High limit safety thermostat, Fan delay, Suction line accumulator, Oil separator, CPR Valve, Anti-sweat heater around door jam and implosion port.

Q.5 Time initiated time termination Time initiated time or pressure termination Time initiated time or temperature termination Electronic timers.

Q.6 To allow defrost water to drain freely and prevent it from freezing.

Q.7 The reverse acting low pressure fan delay control is designed to delay the evaporator fan on start up to prevent the possibility of hot air and water blowing onto the product on completion of the defrost cycle.

Q.8 Ant-sweat heaters are used to prevent moisture or ice forming around the door.

Q.9 Suction line accumulator collects excessive liquid refrigerant and allows the compressor to draw it back as a vapour.

Q.10 CPR Valve adjustment is accomplished by fitting service gauges and a clamp on ampere meter around one of the active wires at the compressor. The valve is adjusted `by increasing or decreasing the spring pressure until the FLA amperes of the compressor is between 90 and 100% FLA.



Q.11 SET = 167 kPaCut out = 2ºC

Room thermostat: Average room temperature = 3ºCCut in = 4ºC

Low pressure control: Cut out = 100kPaCut in = 226 kPa = 3ºC


Q.12. SET = -30ºC = 97 kPa.

Cut out = -21ºC Room thermostat: Average room temperature = - 20ºC

Cut in = -22ºC

Fan delay thermostat Cut in = -10ºCCut out = 0ºC

High limit safety thermostat Cut out = 8ºCCut in = -10ºC

Defrost timer 4 defrosts per day each approx 40 minutes.Pressure override 623kPa = 6ºC

Low pressure control Cut out = 20 kPaCut in = 100 kPa



Section No: 3

Q.1

Multi deck display cases

Single deck well type cases

Reach in cabinets.



Q.2 In the bottom of the cabinet

Q.3 So that they can be connected end to end

Q.4 Because the cold air circulating is heavy and falls down over the product.

Q.5 To prevent water from condensing on the rub rail and dropping onto the floor.

Q.6

Placing stock above the load limit line

Drain blockage due to poor house keeping

Overloading cabinet with warm product.

Q.7 So that supply and return air ducts do not accumulate any ice.

Q.8 To keep cold air in the cabinet and reduce air spillage to a minimum.

Q.9 R407A, R507, R134a.

Q.10

Refrigeration capacity of each cabinet

Installation and location of each cabinet

Refrigeration components required

Supply and electrical control circuits

Correct adjustment of all controls

Type of refrigerant.




Section No: 4

Q.1 By increasing the volume of the suction line the surge drum absorbs suction line pressure fluctuations and prevents the condensing unit from short cycling

Q.2 Constant pressure valve is fitted to each IBC to maintain a constant SET above the freezing point of the beverage. Constant pressure valve is similar to an EPR valve but far more accurate.

Q.3 To reduce the possibility of oil entering the evaporator of an IBC.

Q.4 Low pressure control to cycle a suction line solenoid valve Thermostat to cycle a liquid line solenoid valve.

Q.5 Uses much less refrigerant than an IBC and is manufactured to fit into a standard glass rack

Q.6 Amount of refrigerant contained in the temprite.

Q.7 Ice flake machine, delivers irregularly shaped ice flake Ice cube machine, delivers ice cubes.

Q.8 Mechanical: contains a refrigeration unit within the dispenser. Ice cooled: ice is contained in a storage bin and acts as the refrigeration

medium.

Q.9 The syrup ration.

Q.10 By an ice maker fitted to the dispenser or from an outside source.

Q.11 Adjustment is done by fitting a set of gauges to the inlet side of the EPRvalve and adjusted to the selected minimum pressure / temperature required.

Q.12 CO2 or Beer gas.

Q.13 Because the hot gas injected into the plate evaporator allows the ice slab to slide down onto the cutting grid.

Q.14 Soda water flow rate has to be adjusted first.

Q.15 To assist in the efficient removal of heat from the product coils and carbonator tank.

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