19-Part Definitions

Compressor

• The heart of the system
• Convert low temp/low-pressure gas to high temp/high-pressure gas
• Does not tolerate liquid (causes slugging)-the compressor will probably be damaged
• Various types - Reciprocating, scroll, rotary, etc

Muffler

• Receives high-pressure gas from the compressor
• Has baffles inside it with expansion chambers to smooth out pulses of high-pressure gas
• The primary purpose is pulsation smoothing, not noise reduction

Oil Separator

• Separates oil from the hi-pressure refrigerant coming from the Muffler
• Helical type - uses a centrifugal vortex action causing the refrigerant to spin inside the Separator. Since oil is heavier than refrigerant, the refrigerant molecules are thrown against the outside wall of the separator, where they slide down the wall to the bottom of the Separator.
• Impingement type - has metal screens at the input and output of the Separator, where the oil condenses on the lower-temperature screen grids and slides down to the bottom of the Separator.
• In both types, a high oil level opens a float valve, returning the high-pressure oil to the low-pressure side of the compressor through an oil return line.
• NOTE that the output tees to 2 places - the Condenser and the Hot Gas Defrost Valve.

Condenser

• Receives high-temperature high-pressure refrigerant vapor from Oil Separator.
• Converts that gas to a liquid
• Rejects latent and sensible heat to environment
• The end of the Condenser has high-pressure subcooled liquid (subcooled means below saturation temperature).
• Larger than Evaporator due to Heat of Compression

Liquid Receiver Tank

• Receives high-temperature liquid from the Condenser.
• The Receiver is a liquid storage tank that stores high-pressure liquid until RCV calls for it.
• On the output is the Liquid Receiver Service Valve, also known as the King Valve.
  1. Usually welded directly to the Receiver.
  2. Permits the technician to do 3 things:
     • Allows charging of the high side while system is running - Very Dangerous, even if you know EXACTLY what you are doing. This is a dangerous procedure and YOU COULD DIE.
     • Shut off the flow of refrigerant from the Receiver, enabling "pump-down".
     • The King Valve lets us access the state of the system with our gauges.
• Also on the Receiver is a Pressure Relief Valve
  1. Safety Device - Will open up when pressure is too high and send liquid to surge tank (NOT the environment)
  2. 3 types - Solder, Spring Reset, Carbon Disk
     • Solder - Blows when temperature is too high and is good for only 1 time
     • Spring Reset - Blows when pressure is too high. Same type as a water heater, which is a ball-type valve. Will open when refrigerant pressure exceeds spring pressure. After release, valve will reset. View this valve as a spring-resettable pressure-relief valve.
     • Carbon Disk - Blows around 16 psi on Chillers and purges Refrigerant to environment. On more modern systems, will purge to a tank.

  Filter Drier

  • Contains dessicant (i.e., Charcoal, silica gel, activated alumina, molecular sieve) to absorb moisture
  • Filters solid particulate matter (CRUD) through fiber filters or metal screens

  TXV - Thermostatic Expansion Valve

  • The brain of the system, controls flow based on temp
  • Decides how much liquid is required
  • Convert high-pressure liquid to low-pressure liquid
  • Used in a non-critical charge system.
  • Can have extra port for External Equalizer Tube feedback of pressure from outlet of Evaporator

  Evaporator

  • Convert low-pressure liquid to low-pressure gas
  • Absorbs latent and sensible heat from surrounding space

  Accumulator

  • Stores liquid until vaporized sensibly
  • A passive safety device for the compressor.

  Vibration Dampener

  • Helps absorb compressor or environmental vibration
  • Minimizes vibration damage to system
  • Can be braid or several flat coils of tubing

  Suction Filter

  • Removes CRUD and acid from system (typically after compressor burnout)
  • Types of acid are hydrochloric, hydroflouric and nitric.

  Sight Glass

  • Provides technician a glimpse of the state of the system
  • Round bubbles or low level - low in refrigerant
  • Long bubbles - Non-condensible gases in system
  • Green eye - Minimum moisture in system; yellow eye - moisture present
  • Installed between filter drier and RCV

  Liquid Line Solenoid Valve (LLSV)

  • Thermostatically controlled, electro-magnetic valve that controls the temperature of the high temperature box, by controlling th flow of refrigerant to the TEV.

  External Equalizer Tube (EET)

  • 1/4in. tube that equalizes nothing
  • Pressure feedback to TXV from Evap outlet due to drop in pressure inside Evap on large-capacity systems.
  • Hookup is 6-12in downstream from TXV sensing bulb

  Evaporator Pressure Regulator (EPR)

  • Controls temperature in higher-temp Evaps on multi-evap systems
  • Maintains back-pressure to raise evap temp to pre-determined setting

  Check Valve

  • Permits one-way flow of refrigerant.
  • Used in Multi-Evap systems on lowest-temp Evap to prevent refrigerant backflow from higher-temp Evaps.

  Compressor Pressure Regulator

  • Controls pressure returning to Compressor to make system performance more acceptable and to prevent damage to compressor.
  • Control compression ration and compensate for pulses of gas from EPR valve