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Sketch:
Direct expansion system:
.refrigeration system
→ evaporator coil situated inside the space to be refrigerated.
→ no duct and piping required
- The evaporator coil extracts the heat from the air inside.
- The compressor draws low pressure refrigerant vapour and delivers the high pressure refrigerant vapour through an oil separator to the condenser.
- The condenser liquefies the refrigerant.
- The liquid refrigerant from the condenser passes through the filter dryer, solenoid valve and thermostatic expansion valve to the evaporator.
Checks
Before starting the refrigeration plant,
- Check the oil level in the crank case of the compressor.
- Insufficient oil wears down the components.
- In extreme cases, it may lead to seizure of the compressor.
- Check whether the cooling water inlet and outlet valves to the condenser are open.
- Insufficient flow of cooling water results in improper condensation which in turn increases the compressor discharge side pressure.
- Open the compressor outlet valve, condenser inlet valve, receiver outlet valve, filter drier inlet valve and outlet valves.
- Check whether power supply is available to the compressor motor.
- Ensure the compressor is in manual mode.
During start
- Open the compressor inlet valve by half a turn and start the compressor.
- Open the compressor inlet valve slowly to fully open position.
- Change the operation of the compressor to automatic mode.
- Check the amperage of the compressor.
During operation:
- Check the compressor suction, discharge, and oil pressure.
- Inspect the compressor unit and check for any abnormality and vibration.
- Check the compressor oil level and check whether the oil returns from the oil separator to the crankcase
During auto Stopping:
- As the temperature reaches the set value, the thermostatic switch will cut off the compressor.
- The blower will continue to run.
- When the air temperature increases, the compressor will cut in.
To shut down for longer duration:
- To shut down for prolonged period, close the condenser liquid receiver outlet valve.
- The liquid refrigerant is collected inside the condenser receiver and the compressor stops due to low pressure.
- Shut the refrigerant line valves.
- Shut the condenser cooling water inlet and outlet valves.
- Switch off the power supply.
| AIR CONDITIONING SPECIFICATION | |
| SPECIFICATION | AIR CONDITIONING PLANT |
| Refrigerant | R-404 A |
| Cooling method | direct expansion system |
| Heating method | steam coil |
| Humidification | steam spray |
| Compressor | four cylinder, reciprocating |
| Condenser | horizontal shell & tube type |
| Main power source | 440 v AC, 60 Hz, 3 phase |
| Control circuit power source | 220 v AC, 60 HZ, 3PHASE |