Doc. Code Emission Revision Date Page 09001 2009-04 · PDF fileDoc. Code Emission Revision Date Page 09001 2009-04 01 2009-06 2/36 17.9 - Oil Return to Compressor ..... 22 17.10 -

Doc. Code Emission Revision Date Page09001 2009-04 01 2009-06 1/36


This manual may not be reproduced in whole or part without prior permission from EMBRACO.


Page1. Introduction .............................................................. 032. Compressor Ranges ................................................ 053. Applications ............................................................. 054. Starting Torque Classification ................................... 065. Electric Motor Types ................................................. 066. Voltages and Frequencies ....................................... 077. Nomenclature Compressor Model ........................... 078. Compressor Label .................................................... 079. Compressor Electrical Components ........................ 0810. Wiring Diagram .......................................................0911. Basic Dimensions ................................................... 1012. Compressor Fixation .............................................. 1113. Compressor Cooling Types .................................... 1214. Oil Charge .............................................................. 1315. Compressor Handling ............................................ 1416. Preparation of Refrigerating System Components . 1517. Guide for the Use of R 744 ..................................... 16

17.1 - R 744 Properties .......................................... 1617.2 - Refrigerant Purity ......................................... 1717.3 - System Components Compatibility

and Contamination ...................................... 17 17.4 - Moisture ....................................................... 1717.5 - Filter Dryer ................................................... 1817.6 - Expansion Device ........................................ 1917.7 - Refrigerant Charge Determination .............. 2017.8 - Evaporator and Gas Cooler ......................... 21

Index


17.9 - Oil Return to Compressor ............................ 2217.10 - High Pressure Limit Control ....................... 2317.11 - Equalization Time for Suction and

Discharge Pressures ................................. 2318. Welding of Connection Tubes ................................ 2419. Installation of Filter Drier ......................................... 2520. Vacuum Operation ................................................. 2721. Refrigerant Charge Procedure ............................... 2822. Refrigerant Leakage Control .................................. 2923. Electric Supply ....................................................... 2924. Compressor Running Limits ................................... 30

24.1 - Maximum Temperature of Electric Motor Stator Windings ................................. 30

24.2 - Discharge Gas Maximum Temperature ....... 3024.3 - Discharge Gas Maximum Pressures ........... 3024.4 - Suction Gas Overheating ............................ 3124.5 - Running Time............................................... 3124.6 - Cycling ......................................................... 3124.7 - Compressor Operating Envelope ................ 3224.8 - Safety and Reliability Approval of

Customer Application .................................. 33AFFIDAVIT .................................................................... 34

Note: After replacement, the compressor and its accessories must have proper processing, and the components must be recycled according to the material group (ferrous, non-ferrous, polymers, oils, ...) directives. These recommendations are intended to minimize the adverse impacts that may be caused to the environment.


Introduction1

The design of a refrigeration system is a type of problem solving that involves many considerations and warnings. Design invariably requires the critical evaluation of the solutions by considering factors such as economics, safety, reliability, and environmental impact, before choosing a course of action. The vapour compression cycle has dominated the refrigeration market to date due to its advantages: high efficiency, low toxicity, low cost, and simple mechanical embodiments.

In recent years, environmental aspects are becoming an increasingly important issue in the design and development of refrigeration systems. Specially in vapor compression systems, the banning of CFCs and HCFCs due to their environmental disadvantages has made way for other refrigeration technologies which until now have been largely ignored by the refrigeration market. As environmental concerns grow, alternative technologies which use either inert gasses or no fluid at all become attractive solutions to the environment problem.

Regulations prescribe that CFCs and also HCFCs should no longer be used as refrigerants and HFCs seem to be only an interim solution. Looking for final choices and furthermore, taking into account regulations for greenhouse gas emissions, natural fluids become a promising alternative as refrigerants. Some of these refrigerants, like hydrocarbons and ammonia, are good choices from the point of view of performance, but they have flammability and toxicity characteristics. These characteristics lead these choices to be often refused by some end users, besides their vast use in domestic


(hydrocarbons) and industrial (ammonia) refrigeration. If non-toxic and non-flammable refrigerants are required, the focus emerges upon carbon dioxide (R 744 or CO2).

The use of R 744 as a refrigerant is recently considered for application in low capacity transcritical refrigeration cycle. Due to the properties of R 744, the pressure ratio of the refrigeration process is rather low compared to common refrigerant fluids, while the pressure difference is high. Furthermore, the volumetric capacity of R 744 is higher than traditional refrigerants. Those facts result in special demands regarding the design of suitable components, specially the driving mechanism, to be able to meet the requirements regarding the overall system performance, reliability and safety.

This document describes the features of the R 744 compressor developed by Embraco and all the information disclosed can be altered, as the knowledge on the application advances. The intention is to provide main information to our customers about R 744 compressor application and instructions/best practices on how to handle the R 744 compressors supplied. We recommend referring always to local safety standards and regulations. In the event any further information or clarification is needed, please contact Embraco technical team.


SeriesApplication

LBP MBP/HBP AC

EK No Yes No

Type Description

MBP-HBP

Medium/High Back Pressure

Models at medium/high evaporating temperatures, suitable for applications with evaporating temperatures higher than -20oC and lower than 10oC.

Table 1 indicates the applications available for the R 744 compressors you are receiving:

Table 1 - Compressor series - R 744 application

Compressor

Applications

Ranges

Table 2 - Applications

2

3


Table 3 describes the types of starting torque for the electrical motors of Embraco R 744 compressors currently available.

Table 3 - Electrical motor starting torque classification

Starting

Electric Motor Types

Torque Classification

Type Description

HST

High Starting Torque

MBP/HBP applications with CSR electric motor.Execution suitable for systems with expansion valve or capillary tube, with maximum unbalanced pressures at start up of 10 bar.

Type Description

CSR

Capacitive Start & RunThis motor type has high starting torque (HST) and can be applied either in systems with capillary tube or expansion valve (maximum differential pressure is 10 bar). The motor is characterized by a start capacitor with suitable capacitance connected in series with the start winding to get a high starting torque. A starting device (PTC) disconnects the start winding at the end of the start up. A permanent connected run capacitor is used to improve its efficiency.

Table 4 describes the different types of electric motors used in Embraco R 744 compressors.

Table 4 - Electrical motor types

4

5


Voltages

Nomenclature

and Frequencies

Compressor Model

Table 5 indicates the various rated voltages and frequencies with the corresponding operating ranges and minimum starting voltages of the compressors.

Table 5 - Voltages and frequencies

Embraco Code

Rated Voltage & Frequency

Voltage Working Range

@50 Hz @60 Hz

A 220-240V 50Hz 1~ 198 - 254V

U 220V/60Hz 1~ 198 - 242V

G 115V 60Hz 1~ 103V - 127V

Q 100V 50/60Hz 1~ 90V - 110V 90V - 110V

6

7

EK S 6 210 CD

= Standard EfficiencyE = Improved Efficiency 1st GenerationI = Improved Efficiency 2nd GenerationV = Improved Efficiency 3rd Generation

The first digit is the number of zeros that must be added to the lasttwo digits to obtain the cooling capacity (approx) in kcal/h at 50Hz.Eg.: 210 = 1000 kcal/h at 50Hz

CD = R 744 (CO2)

Refrigerant

1 - LBP - LST2 - LBP - HST

Cooling Capacity

Efficiency Level

Basic Type

S = Improved Efficiency 4th GenerationT = Improved Efficiency 5th GenerationU = Improved Efficiency 6th Generation

5 - M/HBP - LST6 - M/HBP - HST


Compressor

Compressor

Electrical Components

Label

The intended electrical components for Embraco R 744 compressor electric motor are indicated in Table 6. These components may be supplied by Embraco or directly by the manufacturer. In the event the customer decides to buy the electrical components directly from the manufacturer, Embraco´s electrical components approval process shall be followed.

9

8

A - Traceable serial numberB - Compressor code / Part numberC - Compressor designationD - Locked rotor amperage - LRA

Frequency - HzRefrigerant - R 744Number of phases - 1 PHNominal voltage of compressor - VAC

E - Logos indicate institute approval of compressor F - Bar code 39 (ratio 3:1 and 6.5 mils)

G - Paper: White Graphics: Black Size: 70 x 38 mm (2.76” x 1.50”)H - Date of manufacture I - Manufacturing plantJ - The orange band is the visual identification

used for 2XX V, 2XX-2XX V 60Hz compressors. The green band is used for 220-240 V~ 50Hz

compressors. The white band is used for 1XX V~, 115-127 V~

compressors.

G C

A I B

10 mm

H F

J

D E


Table 6 - Electrical components

Compressors can have different electrical components according to their version. IT IS IMPORTANT TO USE THE COMPONENTS SPECIFIED ON THE DATA SHEET OF THE COMPRESSOR.

Motor Type

Overload Protector

Starting device Capacitors

Current Relays

Voltage Relays PTC Start Run

CSR Yes No No Yes Yes Yes

10Wiring Diagram

In the picture above X is connected to terminal 1. Terminal 2 is connected to neutral. Line is connected to the overload protector.

Figure 1 - Wiring diagram


BasicDimensions

All dimensions in millimeter [mm].

Suction connector

Discharge connector

Process connector: must be sealed and must not be used.

11

Figure 2 - Frontal view

Figure 3 - Superior view

Figure 4 - Inferior view


12 CompressorFixation

Figure 5 indicates the wrong and right ways of fixing the compressor to the system.

Cabinet base

Bolt

Nut

Washer

Sleeve

Compressor base

Rubber dampers

CORRECTINCORRECT

Figure 5 - Rubber dampers


13CompressorCooling Types

Table 7 lists the cooling type intended for Embraco R 744 compressor.

Table 7 - Cooling type for Embraco R 744 compressor

Type Description

FFan cooling: the compressor requires forced cooling through the use of a fan.

Forced Cooling

Free air flow 270 m3/h or air speed of 3 m/s

The fan cooling compressor requires the use of a fan cooler (normally inlet type) positioned in such a way that the flow is introduced to the compressor perpendicularly to the cylinder head axis.

The thermal protector, if cooled by the air flow, may not trip and may not protect the compressor properly.

We suggest maintaining a distance of 0.2 to 0.3 m from between the compressor and the fan blades.

The fan cooler can be chosen according to the air flow indicated in Table 8.

Table 8 - Fan cooler characteristics


14Oil Charge

All Embraco R 744 compressors are always supplied with lubricant oil, as indicated in Table 9.

The maximum humidity content in the oil is 15 ppm for the moment of injection in the compressor.

Table 9 - Lubricant oil used in Embraco R 744 compressor

All Embraco R 744 compressors are charged with 150 cm3 of lubricant oil.

The minimum amount of oil in the compressor that guarantees the correct lubrication is 100 cm3.

Oil quantities below the minimum prescribed level will not allow the oil pump to prime and will cause wear, leading to a possible seizure of the mechanical parts.

SeriesOil Type

Type Viscosity @ 40oC [cSt]

EK Polyolester 68


CompressorHandling

15

The following figures show what is allowed in terms of compressor handling during assembly and transportation of compressor and refrigeration system. The indicated angles are maximum values. Forbidden handling is marked by a “X” and may cause damage to the compressor if performed. In any case it is NOT PERMITTED TO TURN THE COMPRESSOR UPSIDE DOWN.

Figure 6 - Ways of handling with the compressors during assembly and transportation


16 Preparationof Refrigerating

System Components

Cleaning (solid substances and non-condensable) and the reduced moisture in all the components of the refrigeration system are the primary concerns for good running and life of the compressor.

Embraco suggests the use of system components such as tubes, gas coolers, evaporators, oil separators, liquid receivers, valves, capillaries, etc., with moisture, solid residues and non-condensable gases contents reduced by 50% compared to what is prescribed by DIN 8964 Standard - and free of contaminants like chlorine based compounds, as well as non ester based oils.

Components shall remain sealed as long as possible before their assembly, and welding must be performed no later than 10 minutes after assembling the components.

To avoid residues during the welding process, it can be useful to blow out these components with nitrogen or dry air, with a dew point lower than -40oC before using them.


17

This section presents some guidelines for the use of R 744 as refrigerant fluid.

Guide forthe Use of R 744

17.1 - R 744 Properties

Basic thermophysical properties are given in Table 10 and ecological characteristics are given in Table 11.

Table 10 - R 744 physical characteristics

Due to the vast differences between systems and respective working fields typical of each application, the reliability of the equipment shall be defined by appropriate life and field tests. Embraco technicians are available for support of systems design, tests and validation of the applications before starting field tests and mass production.

All operations related to the use of refrigerants shall be performed in accordance with local laws, international standards and rules related to this subject.

Molecular Weight 44.01 kg/kmol Ref.: R 134a = 102.03 kg/kmol

Critical Temperature 30.98oC Ref.: R 134a = 101.06oC

Critical Pressure 73.77 bar Ref.: R 134a = 40.59 bar

Boiling Point -78.4oC Ref.: R 134a = -26.07oC

ODP (Ozone Depletion Potential) 0 Ref.: R 134a = 0

GWP (Global Warming Potential) 1 Ref.: R 134a = 1300 (100 years)

Table 11 - R 744 ecological characteristics


Purity Carbon Dioxide 99.95% Vol.

Water Content max 20 wtppm

Nitrogen < 5 ppm

Acid (Sulphur Dioxide) 0.1 wtppm

17.2 - Refrigerant Purity

The refrigerant recommended to be used both for tests and manufacturing shall follow the purity specifications in Table 12.

Table 12 - R 744 purity degree specs

17.3 - System Components Compatibility and Contamination

All refrigeration system component materials shall be compatible with the refrigerant and lubricant used in the compressor.

Substances containing chlorine, paraffin and silicone are not approved. Particular attention must be paid to internal cleanliness of the system. The above mentioned substances as well as any solids residues (dust, metal particles, etc...) must not be introduced into the system.

It is recommended the maximum level of contamination by other substances than the ones listed above to be 50% less than what is prescribed in DIN 8964.

17.4 - Moisture

In order to avoid problems that can shorten the life of the refrigeration system, use components that are supplied internally, dried and properly sealed, to prevent the entrance of moisture. These components should remain sealed until they are used.


It is recommended to avoid leaving the compressor and components exposed to the ambient for more than 10 minutes.

If there is any doubt regarding the presence of moisture in a component, it may be dried by blowing dry air (with a dew point below -40oC) through the internal surface for a sufficient period of time.

It is recommended to maintain moisture content in the system 50% lower than what is prescribed by DIN 8964.

The level of moisture present in the refrigeration circuit shall be below 40 ppm and after the system has been operating, the filter dryer should remove moisture from the system from a level below 20 ppm.

17.5 - Filter Dryer

It is strongly recommended to use a filter dryer that is compatible with refrigerant R 744 and the compressor oil. Always refer to the manufacturer of the filter dryer for proper selection. The filter dryer also has to comply with the same high pressure specification as the gas cooler. Solid core filter dryers are the preferable choice, although molecular sieves grains are also possible to be used. Field and life tests are recommended for approval of the filter dryer.

Consequences of high moisture content in the system are shown on table 13.


Table 13 - Inconvenient caused by moisture in the system

1 Ice build-upReduces the cross-sectional area of the capillary tube, or expansion valve, up to their complete obstruction.

2 Acid build-up

Causes serious problems in the compressor and to the molecular sieve of the filter. Typical marls and consequences are:

· Copper plating of valve plate, valve reeds, crankshaft bearings, etc.

· Etching of electric motor insulation by acids, with burning of motor windings.

· Destruction of the filter with disintegration of molecular sieve and build-up of dusts.

· Wear of reciprocating and rotating mechanical parts.

3 Oil contamination

Causes acidification and reduction of its lubricating power, with change of oil colour (brown). It can cause build-up of sludge, with subsequent poor lubrication of compressor.

17.6 - Expansion Device

Capillary Tubes: In case where a capillary tube is chosen as the expansion device, Embraco suggests to use the correlation from the article below as a first trial of sizing the capillary tube.

HERMES, C. J. L.; SILVA, D. L.; MELO, C.; GONCALVES, J. M.; ZIMMERMANN, A. J. P.. TRANSCRITICAL CARBON DIOXIDE FLOW THROUGH ADIABATIC CAPILLARY TUBES. PART II: MATHEMATICAL MODELING. In: 8th IIR Gustav Lorentzen Conference on Natural Working Fluids, 2008, Copenhagen. Proc. of the 8th IIR Gustav Lorentzen Conference on Natural Working Fluids. Copenhagen: Danish Technological Institute, 2008.

For every refrigeration system, the optimal sizing of the capillary tube shall be performed in laboratory following an appropriated procedure, in order to obtain the best working conditions and to avoid the return of liquid refrigerant to the compressor.


It is not recommended to use a capillary tube with an internal diameter smaller than 0.6 mm.

Expansion Valve: Should be selected according to the working temperatures and pressures characteristics of refrigerant R 744 and the refrigeration system it will be applied to.

17.7 - Refrigerant Charge Determination

Generally, the quantity of refrigerant R 744 introduced into the system is increased by 35% to 50% compared to the required charge of R 134a when using standard finned tube heat exchangers and the internal volume of the system sealed unit is kept the same.

If the original HFC system has a suction accumulator, then the information above is not valid. One can start the charging determination procedure using the same charge as the R 134a system and check the performance. Then it is possible to decide on which way to go.

For each system, the optimal refrigerant charge shall be determined in laboratory, following the appropriated procedure, in order to obtain the best working conditions and to avoid the return of liquid refrigerant to the compressor.

The maximum allowed refrigerant charge in a system using this compressor series is 500 g of R 744.

Systems approaching the maximum refrigerant charge should be tested for flooded start and liquid slugging.


17.8 - Evaporator and Gas Cooler

Gas Cooler: It is mandatory to perform hydrostatic pressure tests, in which the burst pressure must comply with IEC 60335-1 standard.

Note: For eventual tests on existing HFC or HC systems, the original condenser must be replace by a gas cooler with the aforementioned characteristics. Similar replacement is necessary for all other components of the system.

Copper tubes can be used as long as the hydrostatic specifications above are complied.

Evaporator: The mechanical strength of the evaporator shall comply with IEC 60335-1 standard.

Copper tubes can be used as long as the hydrostatic specifications above are complied.

System Volumes Balance: System internal volumes balance is needed, and it is more important when using R 744. An example of improper balance is when the high pressure side internal volume is too small compared to the low pressure side. This can lead to extreme operating conditions during normal pull-down and when abnormal situations occur i.e.: gas cooler fan failure, capillary tube blockage, also gas cooler area reduction due to fouling, etc.

These extreme operating conditions can put in danger both reliability and safety of the refrigeration system.

Internal volume of the high pressure side shall be large enough to lead to a maximum density of 0.65 g/cm3 when all the refrigerant charge is distributed in this volume.


17.9 - Oil Return to Compressor

Due to its intrinsic characteristics, CO2 compressors have higher OCR (Oil Circulation Rate) than HFC compressors. Therefore, it is very important to assure that there is no oil trap in the system circuit that can cause compressor failure. In order to do so, siphons and adverse height differences must be avoided. Top to down circuit is recommended on the heat exchangers. Specific tests, continuously running with low evaporating temperatures, if applicable, are recommended to check the oil return to the compressor. It is also recommended that the minimum flow speed shall not be less than 2 m/s, in order to allow the oil to flow back to the compressor together with the refrigerant. The figures below show examples of recommended and non-recommended circuits.

Figure 7 - Non-recommended circuit - oil trap

Figure 8 - Recommended circuit


17.10 - High Pressure Limit Control

The system shall be tested in abnormal working conditions like high ambient temperatures, high side heat exchanger fan failure, gas cooler area reduction due to fouling, and/or expansion device failure.

The maximum observed discharge pressure in abnormal working conditions shall not exceed 30 bar of the limit values described in the chapter Discharge Gas Maximum Pressures.

It is strongly recommend the installation of a pressure safety device (i.e. pressure switch) to limit the discharge pressure to the aforementioned value.

The compressor overload protector is not a pressure safety device and may not turn off the compressor in case of overpressure.

17.11 - Equalization Time for Suction and Discharge Pressures

Typically, the time for the suction and discharge pressures to equalize ranges from 3 to 6 minutes depending upon the application (HBP/MBP). This owes to the different appliances that have been tested in our application laboratory.

Compressor “off” periods lesser than 5 minutes must be avoided when using capillary tubes. This is to allow proper equalization, and also for the PTC to be cooled down, guaranteeing the compressor start-up.

When using expansion valves, it is important to check the values of allowable unbalanced pressures during compressor start-up. It is recommended that the system equalizes right before starting the compressor, in case of electronic controlling.


During brazing of the connectors on the compressor copper-plated steel tubes, the following instructions shall be observed:

· DO NOT ALLOW the torch flame to reach the housing during the welding of the compressor tube, in order to avoid overheating, damages to welding, and oil carbonization on the compressor’s internal walls.

· DO NOT ALLOW the torch flame to approach the hermetic terminal, in order to avoid the cracking of the glass insulating material of the three pins and subsequent gas leaks.

The welding of compressor connectors (copper-plated steel) to copper tubes can be done with 38% silver content welding material.

Proper welding is characterized by a good penetration of weld material, to guarantee a good mechanical resistance, and no leaks from the connection.

These characteristics are obtained with the use of suitable materials and a well performed welding (welding should be performed only by qualified technicians), as well as with a correct sizing of the tubes to be coupled, in order to guarantee the optimal clearance. A “tight clearance” determines a bad penetration of welding material, while a “large clearance” causes penetration of welding material and de-oxidizers inside the tube and compressor. Recommended value of diametrical clearance ranges from 0.1 mm to 0.6 mm. The most common values used by Embraco range between 0.15 mm to 0.3 mm.

Welding ofConnection Tubes

18


To limit internal contamination by de-oxidizing flux, we suggest applying small quantities of de-oxidizer on the connection tube after connecting it to the compressor tube.

During the welding operation, avoid overheating of the connection. This reduces the formation of oxide contaminants inside the tubes. It is suggested, during the welding operation, to blow nitrogen through the tubes.

With the use of R 744, the possibility of refrigerant gas leaks through defective welds is increased, due to its molecule size and high pressure levels associated to this refrigerant.

We also suggest taking particular care in performing welding and leak detection, which must be carried out with equipment that is sensitive to the refrigerant type used.

Installationof Filter Drier

19

• Make a small bend in the capillary to prevent it from going too far into the filter, approximately 15 mm (0.59”), see figures 9 and 10;

• Using a clamp, open up the two sides of the filter drier when brazing;

• Braze the filter into the gas cooler and capillary. Do not unnecessarily heat the body of the filter dryer, and take great care not to block the tubes.

• Install the fast coupling to make a vacuum on the high pressure side;

• The filter dryer must be installed in the vertical position with the capillary at the bottom (see figure 11).


This position prevents the desiccant grains from rubbing and releasing residues. It also helps to equalize pressure faster (capillary systems).

Figure 9 - Capillary tube

Figure 11 - Filter drier

Figure 10 - Inserting the capillary into the filter drier

15 mm(0.59”)

Gas cooler

Filter Drier

Capillary

Brazing - Do not forget to clean well the surface to be brazed.

Remember: blockage of the outlet tube will damage the compressor valve system.

Important

!


20Vacuum

Operation

It is critical to perform a proper evacuation of the refrigeration system, in order to ensure proper running of the refrigerating machine and to preserve the life of the compressor. A proper evacuation process assures that the air and moisture contents are below the allowed limits.

Based on the fact that POE oils are highly hygroscopic, the vacuum procedure requires great care. It is recommended that vacuum is made on both sides of the system with the vacuum level below 0.05 mbar for ten (10) minutes.

The vacuum level must be measured in the refrigeration system, not in the pump.

Use hoses as short and with large diameter as possible.

It is recommendable to install a check valve at the inlet of the vacuum pump.

Note: To avoid irreparable damages to the compressor, do not ever start it under vacuum (without refrigerant charge).


RefrigerantCharge Procedure

21

Laboratory controlled conditions: After the vacuum operation, the system must be charged with the refrigerant as follows:

1. Inject all refrigerant charge through a connection at the inlet of the capillary tube or dryer. If an expansion valve is used, one has to assure that it is open during the charging procedure, and at least for five (5) minutes later.

2. If it is not possible to follow procedure number 1 above: For a correct charge we suggest, after carrying out the vacuum, to pump part of the refrigerant into the low side of the system (as far as possible from the compressor suction port) to “break” the vacuum; then start the compressor to draw the remaining part of the charge. Vapour phase refrigerant must be used in this procedure in order to avoid liquid compression.

Mass production conditions: After the vacuum operation, inject all refrigerant charge through a connection at the inlet of the capillary tube or filter dryer. If an expansion valve is used, same place is recommended and one has to assure that the valve is open during the charging procedure, and at least for 5 minutes after the completion of refrigerant injection.

The process connector shall not be used by the refrigeration system manufacturer for any process. This tube is only used for oil charge during the compressor manufacturing process, and must be sealed by the refrigeration system manufacturer.

Use charging equipment suitable for R 744.


A refrigeration system can work normally for the entire life of the compressor, only if attention is given to proper installation. One of the most important aspects is the absence of refrigerant leaks.

It is estimated that a 10% leak of the refrigeration charge over 10 years of running the compressor will still allow for proper running of the refrigerating system.

With the new refrigerant R 744, the possibility of leak through improper welding increases, due to the molecular size of R 744 combined with the very high pressure levels. Thus, it is critical that accurate controls of leak are performed on the welding points with methods and equipment suitable to the applied refrigerant type.

Refrigerant

Electric Supply

Leakage Control22

23

The compressor assembled in the refrigeration system shall be connected to a voltage supply within the limits indicated in the chapter Voltages & Frequencies. Due to voltage drops in the supply circuit, the voltage must be measured at the compressor hermetic terminal.

The compressor shall be grounded.


Sizing of the components of the refrigerating system must be performed in a way that the limits indicated below are not exceeded. During operation in the field, the system can face some factors that worsen the working conditions, such as gas leaks, reduction of the gas cooler effectiveness due to fouling, et. Owing to these factors, it is recommended to size the system with a good margin of safety, allowing the system to operate within the prescribed limits.

24.1 - Maximum Temperature of Electric Motor Stator Windings

· 130oC max, under normal running conditions.

· 140oC max, under tropical and extreme voltage conditions.

24.2 - Discharge Gas Maximum Temperature

· Maximum temperature indicated in Table 14, measured in the discharge tube at a distance of 50 mm from compressor housing, under continuous running conditions.

24.3 - Discharge Gas Maximum Pressures

Maximum discharge pressure under continuous running and under “pull-down” is indicated in Table 14.

24CompressorRunning Limits


Table 14 - Discharge gas maximum limits

24.4 - Suction Gas Overheating

· Maintain the suction gas temperature at same levels as HFC’s (min 3oC), taking care that there is no liquid return to the compressor.

· Do not exceed 32oC at the inlet of the compressor (measured in the suction line 200 mm far from the suction tube).

24.5 - Running Time

· Size the systems for maximum 80% of normal running time.

· 100% is allowed only under heavy duty and high ambient temperature conditions.

24.6 - Cycling

The systems shall be sized for maximum 5 cycles / hour (average cycling) when empty.

Compressor with PTC starting device shall be re-started after a minimum time of 5 minutes from the off period.

The trip of the thermal/current protection requires that the compressor re-start occurs after the necessary time for the protector to reset.

Maximum Discharge Pressure Maximum Gas Discharge Temperature

bar (abs) kgf/cm2 (abs) oC

120 119 160


24.7 - Compressor Operating Envelope

The Compressor Operation Envelope (“COE”) is defined by the diagram presented below and indicates the limits of evaporating, condensing, ambient, and return gas temperatures.

The compressor can operate only within the limits of evaporating temperatures and discharge pressures defined by the dashed area, at the indicated conditions of ambient and return gas temperatures.

It is important to point out that in the event the system operates outside the COE, it will operate at higher pressures and temperatures, and can cause early defects in the compressor.

Figure 12 - Compressor operating envelope


24.8 - Safety and Reliability Approval of Customer Application

Before starting any mass production of the compressor R 744 application, it is strongly recommended to accomplish the following testing program:

1. Evaluate abnormal operating conditions and failure mode combinations of the Customer system;

2. A first trial field test shall be made with twenty (20) units (the whole refrigeration system) manufactured as close as possible to the final Customer manufacturing process. The duration of this first field test shall be of three (3) months minimum. After that, a TDA (Tear Down Analysis) of five (5) units is recommended; and

3. A second trial field test shall be made with one hundred (100) units (the whole refrigeration system) manufactured following the final Customer manufacturing process. The duration of this second field test shall be six (6) months minimum.


AFFIDAVIT

We hereby, on behalf of ______________________________, a company duly organized and existing under the laws of ______________________________, with head office located at ______________________ (“Company”), declare that we received this R 744 Application Manual, read it and have already clarified with the engineers from Whirlpool S/A - Embraco Compressor and Cooling Solutions Business Unit, each and every technical information set forth hereinabove, specifically regarding the possible safety consequences and impacts of using and encompassing the CO2 Compressor into its system.

We also declare and comprise that the contents of this R 744 Application Manual will be deployed among all technicians and engineers, who are Company’s employees and/or services providers.

Furthermore, we completely understand that this R 744 Application Manual sets forth all the procedures and cares to avoid any damage consequence of using the CO2 Compressor during and thereafter its application into our products. Thus, we agree to endeavour our best efforts to comply with all the guidelines and instructions.

PLACE:

DATE:

SIGNATURE:

NAME:

TITLE:


AFFIDAVIT

We hereby, on behalf of ______________________________, a company duly organized and existing under the laws of ______________________________, with head office located at ______________________ (“Company”), declare that we received this R 744 Application Manual, read it and have already clarified with the engineers from Whirlpool S/A - Embraco Compressor and Cooling Solutions Business Unit, each and every technical information set forth hereinabove, specifically regarding the possible safety consequences and impacts of using and encompassing the CO2 Compressor into its system.

We also declare and comprise that the contents of this R 744 Application Manual will be deployed among all technicians and engineers, who are Company’s employees and/or services providers.

Furthermore, we completely understand that this R 744 Application Manual sets forth all the procedures and cares to avoid any damage consequence of using the CO2 Compressor during and thereafter its application into our products. Thus, we agree to endeavour our best efforts to comply with all the guidelines and instructions.

PLACE:

DATE:

SIGNATURE:

NAME:

TITLE:

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If after these instructions you still have doubts, please do not hesitate to call us.

Write to Embraco:Process and Product Technology Group

Group for Assistance in ApplicationRua Rui Barbosa, 1020 - Caixa Postal 91

CEP 89219-901 - Joinville - SC - Brazil


Documents

Doc. Code Emission Revision Date Page 09001 2009-04 · PDF fileDoc. Code Emission Revision Date Page 09001 2009-04 01 2009-06 2/36 17.9 - Oil Return to Compressor ..... 22 17.10 -