1 / 22

HVACR317 – Core for Refrigeration

HVACR317 – Core for Refrigeration. Solenoid Valves Pump Down Systems. Solenoid Valves. Solenoid Valves are a mechanical/electrical valve. The mechanical part is in the refrigeration or water line. The electrical portion is a coil that is attached to the top of the valve. Solenoid Valves.

osborn
Download Presentation

HVACR317 – Core for Refrigeration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HVACR317 – Core for Refrigeration Solenoid Valves Pump Down Systems

  2. Solenoid Valves • Solenoid Valves are a mechanical/electrical valve. • The mechanical part is in the refrigeration or water line. • The electrical portion is a coil that is attached to the top of the valve.

  3. Solenoid Valves

  4. Solenoid Valve • The valve in the closed position is not powered and the flow of liquid is being blocked by the plunger in the DOWN position. • In the closed position the coil does not produce any magnetic field as it is not powered.

  5. Solenoid Valve - Closed Valve is blocking flow of liquid.

  6. Solenoid Valve - Open • The valve opens when the coil is powered. • The coil generates a magnetic field and pulls the plunger into the up position. • This allows fluid flow through the central passage of the valve.

  7. Solenoid Valve - Opening

  8. Solenoid Valve - Open

  9. Solenoid Valves • In refrigeration solenoid valves mainly have two uses • Hot Gas By-Pass Defrost • Pump Down Systems

  10. Pump Down System • The solenoid in the pump down system is used in the liquid line prior to the metering device and after the receiver. • The solenoid is in the normally closed position. • When the thermostat calls for cooling the solenoid opens.

  11. Pump Down System • This releases refrigerant into the liquid line and raises the pressure of the system. • A pressure switch senses this pressure increase and turns on the compressor. • When the call for cooling is complete the thermostat de-energizes the solenoid

  12. Pump Down System • The solenoid closes and blocks the flow of refrigerant into the liquid line. • The refrigerant gets pumped into the receiver which is mounted after the condenser coil. • Once the refrigerant is pumped down into the receiver the pressure on the system drops.

  13. Pump Down System • Once the pressure has dropped to a pre-determined point the pressure switch opens and shuts off the compressor.

  14. Pump down system • The thermostat controls the solenoid - not the compressor. • The pressure switch controls the compressor. • The purpose of a pump down system is to prevent liquid refrigerant from migrating to the evaporator on off cycles.

  15. Pump down system • If liquid refrigerant is in the evaporator it will be sucked as a liquid into the compressor on start up. • Liquid refrigerant in the compressor can break valves, crank shafts and cause premature compressor failure.

  16. Pump Down Systems • Pump down systems are most often found on commercial freezers and low temp refrigerators. • Low temp systems • Medium temp systems

  17. Pump Down OFF Cycle EVAPORATOR C 20 CONDENSER 100 OFF MD OFF `

  18. Pump Down Starting Cycle EVAPORATOR C 35 CONDENSER 100 OFF ON MD

  19. Pump Down On Cycle EVAPORATOR C 40 CONDENSER 150 ON ON MD

  20. Pump Down Satisfied Cycle EVAPORATOR C 30 CONDENSER 150 ON OFF MD

  21. Pump Down OFF Cycle EVAPORATOR C 20 CONDENSER 100 OFF MD OFF `

  22. Pump Down Schematic L1 SS N R C S C1 Setpoint: 35 degrees F. Temp is 55 Degree F.

More Related