Operating & Maintenance of Ship Refrigerator!!!

1. GENERAL

1.1 SPECIFICATION

• REFRIGERATION SYSTEM           CONDENSING UNIT
• MODEL NO. : RKS 3 FB
• REFRIGERANT                      R-22 DIRECT EXPANSION SYSTEM
• OPERATION METHOD               REFRIGERATING MACHINE IS OPERATED
• AUTOMATICALLY BY THERMOSTAT IN EACH COLD CHAMBER
• DEFROSTING METHOD               HOT GAS CIRCUIT OPERATED MANUALLY
• SAFETY DEVICE                     HIGH PRESSURE SWITCH
• SAFETY VALVE
• POWER SOUCE                     MAIN CIRCUIT AC 440V, 3Φ, 60HZ
• CONTROL     AC 220V, 1Φ, 60HZ
• NOTE                              CONTROL DEVICE SETTING PRESSURE

1.2 HIGH PRESSURE SWITCH

• CUT OUT: 19KG/CM2
• CUT IN: MANUAL RESET

1.3 LOW PRESSURE SWITCH

• CUT OUT: 0.2 KG/CM2
• CUT IN: 1.2KG/CM2

 

2. BRIEF INSTRUCTION

 There are compressor, condenser, expansion valve and evaporator, 4 main equipments in refrigeration system.

The compressor is a device to pump and compress the low pressure refrigerant vapor into the condenser where, at high pressure, it is condensed to a liquid refrigerant.

 

1) Type: Multi-cylinder high speed type, Model: T-700 TAKAGI, JAPAN

The condenser is a device to provide a heat transfer surface for condensing refrigerant vapor. The refrigerant vapor from the compressor is discharged into the condenser where it is cooled and condensed on the outside of the water tubes. Sea water circulating inside the tubes carries away the heat of refrigerant as it condenses.

 

2) Type: Horizontal shell and tube type, Mode: SC-M 5LS1

The expansion valve is a device to control the quantity of liquid refrigerant admitted to the evaporator in such a way as to keep practically the entire coils filled with evaporating refrigerant. The valve, therefore, serves to feed the evaporator with enough refrigerant liquid to maintain the required pressure and to provide sufficient suction superheat to prevent liquid refrigerant from returning to the compressor with suction gas under varying load conditions.

 

3) Model: Danfoss: TEX 2-0.7 for meat room and vegetable room

The evaporator is a device in which the low temperature and low pressure liquid refrigerant from the expansion valve evaporates itself taking heat from the air in the cool room where the evaporator is located.

 

4) Type: Forced air cooler type with ceiling mount 

There are also other sets such as low pressure switch, high pressure switch, solenoid valve, oil separator, temperature controller, dry filter, evaporating regulating valve and so on.

 

 3. OPERATING PRINCIPLE

• Refrigeration plant is used for controlling temperature of meat room and vegetable room where provisions are keeping on board ship. The principle of refrigerating plant is transferring temperature of provisions to sea water by refrigerant.
• The refrigerant is circulated by the compression pressure of the compressor. Firstly, the compressor discharges high pressure and high temperature refrigerant to the condenser through oil separator which is used to separate oil back to compressor crank case.
• In the condenser, the temperature of the refrigerant is transferred to sea water as the condenser is cooling by sea water. Then the refrigerant becomes high pressure and low temperature as it is passed through the condenser to expansion valve.
• After passing through the expansion valve, the refrigerant becomes low pressure and low temperature as the expansion valve is designed to reduce pressure which also reduces temperature by increasing volume of the refrigerant.
• Then the refrigerant is passing to the evaporator which is located in meat room and vegetable room where provision are keeping. After the refrigerant pass through the evaporator, it becomes low pressure and high temperature. Because the temperature of the provision have been transferred to it.
• Then the pressure of the refrigerant is increased by the compressor and discharged to repeat the process until the provision rooms’ temperature drop to desired setting temperature.
• In auto mode, if the cold rooms’ temperature drop to setting temperature, the flow of the refrigerant is cut off by solenoid valve which is located in front of the expansion valve and controlled by thermostat in the cold rooms.
• As the solenoid valve cut off, there isn’t refrigerant flowing to the evaporator and pressure back to compressor drop . The compressor is stopped by low pressure switch.

4. RESEACHING ELECTRIC DRAWING

1) Power line

• From the source 3phase,440V 60Hz, passes through breaker(NFB), ammeter(A), MC for compressor(52C), OCR for compressor(51C) and to the compressor motor(MC). And also the source lines goes through to the fan motor (MF)
• From the source line R & T passes through two fuses EF1 & EF2 and to the two transformers (440V/220V) and (440V/30V). 30V is supplied to the space heater and 220V is supplied to control system.

2) Control line

• When breaker (NFB) is on, white lamp (WL) is lighted and if water pressure switch (63WP), high pressure switch (63CH) and OCR for compressor (51C) is in normal condition, auxiliary relay(X1) energized, (X7) energized.
• When change over switch for fan (CS10) is closed, MC for fan (52F) energized,  green lamp for fan running(GL2) is lighted and the fan motor is running.
• In auto operation, when low pressure switch(63EL) energized, auxiliary relay(X3), hour meter(HM), MC for compressor(52C) are continue energized and the green lamp for compressor running(GL1) is lighted. The compressor motor is running.
• The thermostat (23C1) & (23C2) from vegetable room and meat room controls the solenoid valve (20L1) & (20L2). When solenoid valves energize, green lamp (GL3) & (GL4) are lighted.