Section 3
3.1.1Refrigeration Unit - Front Section
The unit is designed for the majority of components to be accessible from the front (see Figure 3.1). The unit model number, serial number, and parts identification number can be found on the nameplate left of the compressor.
The function of the upper or lower makeup air vent is to provide ventilation for commodities that require fresh air circulation. A manually operated venting system is located in the upper left access panel.
The optional eAutoFresh vent system is to moderate the atmospheric level in the container in response to cargo respiration. When transporting frozen cargo loads the vent will be closed. The upper left access panel contains the vent slide and motor assembly. It may be removed to allow entry into the evaporator section where the CO2 sensor and drive pack are located.
Figure 3.1 Refrigeration Unit − Front Section
1.Access Panel (Evap Fan #1) / TXV / HTT)
5.Unit Serial Number, Model Number, and Parts Identification Number (PID) Plate
7.TransFRESH Communications Connector
8.Interrogator Connector (Front Left)
10.Lower Fresh Air Makeup Vent Location (Blank Cover Shown)
11.TIR (Transports Internationaux Routiers) Sealing Provisions - Typical All Panels
12.Upper Fresh Air Makeup Vent or eAutoFresh (Automatic Vent) panel
13.Access Panel (Evaporator Fan #2) / Humidity Sensor / Return Temperature Sensor
- - - - -
The evaporator section (Figure 3.2) contains the return temperature sensor, humidity sensor, thermostatic expansion valve, dual-speed evaporator fans (EM1 and EM2), evaporator coil and heaters, defrost temperature sensor, heat termination thermostat, and heat exchanger.
The evaporator fans circulate air through the container by pulling it in the top of the unit, directing it through the evaporator coil where it is heated or cooled, and discharging it at the bottom.
The evaporator components are accessible by removing the upper rear panel (as shown in Figure 3.2 below).
Figure 3.2 Evaporator Section − Units with Center Access Panel
2.Return Recorder Sensor (RRS) / Return Temperature Sensor (RTS)
5.Defrost Temperature Sensor (DTS)
6.Heater Termination Thermostat (HTT)
8.Hermetic Thermostatic Expansion Valve
10.Interrogator Connector (Rear) (ICR)
- - - - -
The compressor section includes the compressor (with high pressure switch), power cable storage compartment, and autotransformer.
This section also contains the suction modulating valve, discharge pressure regulating valve, discharge temperature sensor, and discharge/suction pressure transducers.
The supply temperature sensor, supply recorder sensor, and ambient sensor are located at the right side of the compressor.
3.Compressor Sight Glass View Port
5.Supply Temperature Sensor (STS)
10.Discharge Temperature Sensor
11.Discharge Pressure Regulating Valve
13.Quench Valve Temperature Bulb
18.Compressor Crankcase Heater
20.Suction Pressure Transducer
21.Discharge Pressure Transducer
- - - - -
3.1.5Air-Cooled Condenser Section
The air-cooled condenser section (Figure 3.4) consists of the condenser fan, condenser coil, receiver with sight glass/moisture indicator, quench valve, liquid line service valve, filter-drier, condenser pressure transducer, and fusible plug.
The condenser fan pulls air in through the bottom of the coil and discharges it horizontally out through the condenser fan grille.
7.Condenser Motor Mounting Bracket
10.Fusible Plug (Rupture Disc - Alternate)
11.Condenser Pressure Transducer
12.Sight Glass/Moisture Indicator
- - - - -
3.1.6Water-Cooled Condenser Section
The water-cooled condenser section (Figure 3.5) consists of a water-cooled condenser, sight glass, quench expansion valve, rupture disc, condenser pressure transducer, filter-drier, water couplings, and water pressure switch. The water-cooled condenser replaces the standard unit receiver.
Figure 3.5 Water-Cooled Condenser Section
4.Condenser Pressure Transducer
10.Self Draining Coupling (Water Out)
- - - - -
The control box (Figure 3.6) includes the manual operation switches, circuit breaker (CB-1), compressor, fan and heater contactors, control power transformer, fuses, keypad, display module, current sensor module, controller module and the communications interface module.For units with three-phase evaporator fan motors, two additional contactors, PA & PB, are installed, see 2 & 3 below.
3.1.8Communications Interface Module
The communications interface module is a slave module which allows communication between the refrigeration unit and a ship system master central monitoring station. The module will respond to communication, and return information over the ships main power line. Refer to the master system technical manual for further information.
Figure 3.6 Control Box Section
2.Evap Fan Contactor PA (3-Phase only)
3.Evap Fan Contactor PB (3-Phase only)
6.Communications Interface Module
7.Controller/DataCORDER Module (Controller)
11.Remote Monitoring Receptacle
15.Interrogator Connector (Box Location)
17.Evaporator Fan Contactor - E1
18.Evaporator Fan Contactor - S1
19.Evaporator Fan Contactor - S2 or EF
20.Evaporator Fan Contactor - E2 or ES
22.Circuit Breaker (CB1) - 460V
- - - - -
a. Compressor / Motor Assembly |
Number of Cylinders |
6 |
Model |
06DR |
|
CFM |
41 |
|
Weight (Dry) |
118kg (260 lb) |
|
Approved Oil |
Castrol Icematic |
|
Oil Charge degrees |
3.6 liters (7.6 U.S. pints) |
|
Oil Sight Glass |
The oil level range, with the compressor off, should be between the bottom and one-eighth level of the sight glass. |
|
b. Expansion Valve Superheat |
Verify at -18°C (0°F) container box temperature |
4.5 to 6.7°C (8 to 12°F) |
c. Heater Termination Thermostat |
Opens |
54° (+/-3) C = 130° (+/-5) F |
Closes |
38° (+/-4) C = 100° (+/-7) F |
|
d. High Pressure Switch |
Cutout |
25 (+/-1.0) kg/cm2 = 350 (+/-10) psig |
Cut-In |
18 (+/-0.7) kg/cm2 = 250 (+/-10) psig |
|
EXPLOSION
HAZARD: Failure to follow this WARNING can result in death, serious
personal injury and / or property damage. |
||
e. Refrigerant |
R-134a |
Conforming to AHRI standard 700 specifications. |
f. Refrigerant Charge |
Unit Configuration |
Charge Requirements − R-134a |
Water-Cooled Condenser |
4.9kg (10.75 lbs) |
|
Receiver |
4kg (8.75 lbs) |
|
NOTE: When replacing components (g.), (h.) and (i.), refer to installation instructions included with replacement part. |
||
g. Fusible Plug* |
Melting point |
99°C = (210°F) |
Torque* |
6.2 to 6.9mkg (45 to 50ft-lbs) |
|
h. Sight Glass / Moisture Indicator |
Torque |
8.9 to 9.7mkg (65 to 70ft-lbs) |
i. Rupture Disc |
Bursts at |
35 +/- 5%kg/cm2 = (500 +/- 5%psig) |
Torque (P/N 14-00215-03) |
1.4 to 2mkg (10 to 15 ft-lbs) |
|
j. Condenser Pressure Transducer |
Condenser Fan Starts |
Condenser fan will start if condenser pressure is greater than 14.06kg/cm2 (200psig) OR the condenser fan is OFF for more than 60 seconds. |
Condenser Fan Stops |
Condenser fan will stop if condenser pressure is less than 9.14kg/cm2 (130psig) AND the condenser fan remains ON for at least 30 seconds. |
|
k. Unit Weight |
Refer to unit model number plate. |
|
l. Water Pressure Switch |
Cut-In |
0.5 +/-0.2kg/cm2 (7 +/-3psig) |
Cutout |
1.6 +/-0.4kg/cm2 (22 +/-5psig) |
|
m. Discharge Pressure Regulating Valve |
Factory Setting |
32.7 +/-2.5kg/cm2 (72 +/-5.5psig) |
* Rupture Disc, part number 14-00215-04 may be installed as an alternate for the receiver mounted fusible plug.
a. Circuit Breaker |
CB-1 |
Trips at 29 amps |
|
CB-2 (50 amps) |
Trips at 62.5amps |
||
CB-2 (70 amp) |
Trips at 87.5amps |
||
b. Compressor Motor |
Full Load Amps (FLA) |
17.6amps @ 460VAC (with current limiting set at 21 amps) |
|
c. Condenser Fan Motor |
|
380 VAC, Single Phase, 50 Hz |
460 VAC, Single Phase, 60 Hz |
Full Load Amps |
1.3 amps |
1.6 amps |
|
Horsepower |
0.43 hp |
0.75 hp |
|
Rotations Per Minute |
1425 rpm |
1725 rpm |
|
Voltage and Frequency |
360 − 460 VAC +/- 2.5 Hz |
400 − 500 VAC +/- 2.5 Hz |
|
Bearing Lubrication |
Factory lubricated, additional grease not required. |
||
Rotation |
Counter-clockwise when viewed from shaft end. |
||
Single-Phase Evaporator Fan Motors |
|||
d. Evaporator Fan Motor(s) |
|
380 VAC/50 Hz |
460 VAC/60 Hz |
Full Load Amps High Speed |
1.6 |
2.0 |
|
Full Load Amps Low Speed |
0.8 |
1.0 |
|
Nominal Horsepower High Speed |
0.70 |
0.84 |
|
Nominal Horsepower Low Speed |
0.09 |
0.11 |
|
Rotations Per Minute High Speed |
2850 rpm |
3450 rpm |
|
Rotations Per Minute Low Speed |
1425 rpm |
1725 rpm |
|
Voltage and Frequency |
360 − 460 VAC +/- 1.25 Hz |
400 − 500 VAC +/- 1.5 Hz |
|
Voltage & Frequency using power autotransformer |
180 − 230VAC +/-1.25 Hz |
200 − 250VAC +/-1.5 Hz |
|
Bearing Lubrication |
Factory lubricated, additional grease not required |
||
Rotation |
CW when viewed from shaft end |
||
Three-Phase Evaporator Fan Motors |
|||
e. Evaporator Fan Motor(s) |
|
380 VAC/3 PH/50 Hz |
460 VAC/3 PH/60 Hz |
Full Load Amps High Speed |
1.0 |
1.2 |
|
Full Load Amps Low Speed |
0.6 |
0.6 |
|
Nominal Horsepower High Speed |
0.49 |
0.84 |
|
Nominal Horsepower Low Speed |
0.06 |
0.11 |
|
Rotations Per Minute High Speed |
2850 rpm |
3450 rpm |
|
Rotations Per Minute Low Speed |
1425 rpm |
1725 rpm |
|
Voltage and Frequency |
360 − 460 VAC +/- 1.25 Hz |
400 − 500 VAC +/- 1.5 Hz |
|
Bearing Lubrication |
Factory lubricated, additional grease not required |
||
Rotation |
CW when viewed from shaft end |
||
f. Evaporator Coil Heater |
Number of Heaters |
6 |
|
Rating |
750 watts +5/-10% each @ 230 VAC |
||
Resistance (cold) |
66.8 to 77.2 ohms @ 20°C (68°F) |
||
Type |
Sheath |
||
g. Fuses |
Control Circuit |
7.5 amps (F3A, F3B) |
|
Controller/DataCORDER |
5 amps (F1 & F2) |
||
Emergency Defrost |
5amps (FED) |
||
Drain Line Heater |
5 amps (FDH) |
||
Humidity Power Transformer |
5amps (FH) |
||
h. Compressor Crankcase Heater |
180watts @ 460VAC |
||
i. Humidity Sensor |
Orange wire |
Power |
|
Red wire |
Output |
||
Brown wire |
Ground |
||
Input voltage |
5vdc |
||
Output voltage |
0 to 3.3vdc |
||
Output voltage readings verses relative humidity (RH) percentage: |
|||
30% |
0.99V |
||
50% |
1.65V |
||
70% |
2.31V |
||
90% |
2.97V |
||
j. Controller |
Setpoint Range |
-30 to +30°C (-22 to +86°F) |
|
3.4Safety and Protective Devices
Unit components are protected from damage by safety and protective devices listed in the following table. These devices monitor the unit operating conditions and open a set of electrical contacts when an unsafe condition occurs.
Unsafe Condition |
Safety Device |
Device Setting |
|---|---|---|
Excessive current draw |
Circuit Breaker (CB-1) − Manual Reset |
Trips at 29 amps (460VAC) |
Circuit Breaker (CB-2, 50 amp) − Manual Reset |
Trips at 62.5 amps (230VAC) |
|
Circuit Breaker (CB-2, 70 amp) − Manual Reset |
Trips at 87.5 amps (230VAC) |
|
Excessive current draw in control circuit |
Fuse (F3A & F3B) |
7.5 amp rating |
Excessive current draw by controller |
Fuse (F1 & F2) |
5 amp rating |
Excessive current draw by emergency defrost circuit |
Fuse (FED) |
5 amp rating |
Excessive condenser fan motor winding temperature |
Internal Protector (IP-CM) − Automatic Reset |
N/A |
Excessive compressor motor winding temperature |
Internal Protector (IP-CP) − Automatic Reset |
N/A |
Excessive evaporator fan motor(s) winding temperature |
Internal Protector(s) (IP-EM) − Automatic Reset |
N/A |
Abnormal pressures / temperatures in the high refrigerant side |
Fusible Plug − Receiver Rupture Disc − Water-Cooled Condenser |
99°C = (210°F) 35kg/cm2 = (500psig) |
Abnormally high discharge pressure |
High Pressure Switch (HPS) − Automatic Reset |
Open at 25kg/cm@ (350psig) Close at 18kg/cm@ (250psig) |
Starting at the compressor (see Figure 3.7, upper schematic), the suction gas is compressed to a higher pressure and temperature.
The gas flows through the discharge service valve into the pressure regulating valve. During periods of low ambient operation, the discharge pressure regulating valve modulates the flow of refrigerant to maintain a pre-set minimum discharge pressure. Refrigerant gas then moves into the air-cooled condenser. When operating with the air-cooled condenser active, air flowing across the coil fins and tubes cools the gas to saturation temperature. By removing latent heat, the gas condenses to a high pressure/high temperature liquid and flows to the receiver, which stores the additional charge necessary for low temperature operation.
When operating with the water-cooled condenser active (see Figure 3.7, lower schematic), the refrigerant gas passes through the air-cooled condenser and enters the water-cooled condenser shell. The water flowing inside the tubing cools the gas to saturation temperature in the same manner as the air passing over the air-cooled condenser. The refrigerant condenses on the outside of the tubes and exits as a high temperature liquid. The water-cooled condenser also acts as a receiver, storing excess refrigerant.
The liquid refrigerant continues through the liquid line service valve, the filter-drier (which keeps refrigerant clean and dry), and a heat exchanger (that increases sub-cooling of the liquid) to the thermostatic expansion valve (TXV).
As the liquid refrigerant passes through the variable orifice of the expansion valve, the pressure drops to suction pressure. In this process some of the liquid vaporizes to a gas (flash gas), removing heat from the remaining liquid. The liquid exits as a low pressure, low temperature, saturated mix. Heat is then absorbed from the return air by the balance of the liquid, causing it to vaporize in the evaporator coil. The vapor then flows through the suction tube back to the compressor.
The TXV is activated by the bulb strapped to the suction line near the evaporator outlet. The valve maintains a constant superheat at the coil outlet regardless of load conditions.
The TXV is a mechanical device that regulates the flow of liquid to the evaporator coil in order to maintain a relatively constant degree of superheat in the gas leaving the evaporator regardless of suction pressure.
The flow of liquid to the evaporator is regulated by a variable orifice which opens to increase refrigerant flow (decrease superheat), or closes to decrease refrigerant flow (increase superheat). The variable orifice is controlled by the temperature sensing bulb which is strapped to the suction line near the evaporator outlet.
During periods of low load, the suction modulating valve (SMV) decreases flow of refrigerant to the compressor. This action balances the compressor capacity with the load and prevents operation with low coil temperatures. In this mode of operation, the quench valve will open as required to provide sufficient liquid refrigerant flow into the suction line for cooling of the compressor motor. The quench valve senses refrigerant condition entering the compressor and modulates the flow to prevent entrance of liquid into the compressor.
The refrigeration system is also fitted with a condenser pressure transducer, which feeds information to the controller. When operating on the air-cooled condenser, the controller programming will operate the condenser fan so as to attempt to maintain discharge pressures above 130psig in low ambients. At ambients below 27°C (80°F), the condenser fan will cycle on and off depending on condenser pressure and operating times.
1.The condenser fan will start if the condenser pressure is greater than 200psig OR the condenser fan has been OFF for more than 60 seconds.
2.The condenser fan will stop if the condenser pressure is less than 130psig AND the condenser fan has been running for at least 30 seconds.
At ambients above 27°C (80°F), condenser pressure control is disabled and the condenser fan runs continuously.
On systems fitted with a water pressure switch, the condenser fan will be off when there is sufficient pressure to open the switch. If water pressure drops below the switch cut out setting, the condenser fan will be automatically started. When operating a system fitted with a condenser fan switch, the condenser fan will be off when the switch is placed in the “O” position. The condenser fan will be on when the switch is placed in the “I” position.
Figure 3.7 Refrigeration Circuit Schematic
