Air Conditioning Components

Transcription

1 Air Conditioning Components

2 Agenda AC Components Compressor & Clutch Condenser Receiver-drier or Accumulator Expansion Valve or Orifice Tube Evaporator

3 Compressor 2 primary purposes Increase pressure & temperature Circulate refrigerant Engine driven pump via belt Compressor capacity to move refrigerant is primary determinant of the heatremoving capability of the system

4 Compressor Therefore larger compressor = larger BTU capacity of system 3 basic types Piston Rotary vane Scroll type

5 Piston compressor Pistons may be arranged inline, V, axially or radially Intake stroke Compression stroke

6 Piston compressor

7 Piston compressor

8 Piston compressor

9 Rotary compressor Usually cylindrical in shape Reduced noise & vibration (balance) More cylinders = balance

10 Rotary compressor

11 Rotary compressor

12 Rotary compressor

13 Rotary compressor

14 Rotary compressor

15 Variable compressor Same as swash plate rotary compressor Pressure sensed by the low or suction side of the system changes the swash plate angle Changes cubic inch displacement

16 Variable compressor

17 Variable compressor

18 Compressor Clutch Belt driven compressor without variable displacement needs to have compressor shut off Clutch controlled electrically (electromagnetic clutch) By AC control panel or by system demands Most OT system require compressor on/off to control evaporator temp

19 Compressor Clutch Components: Drive plate attached to compressor shaft Drive pulley mounted on bearings that are attached to the compressor housing Magnetic coil mounted in behind pulley, does not rotate

20 Compressor Clutch

21 Compressor Clutch

22 Compressor Clutch

23 Clutch problems Slippage load Slippage voltage Clutch heat electrical resistance Air gap Electrical shorts

24 Condenser Function: To remove heat from refrigerant Receives hot compressed refrigerant gas from compressor Outside air flows over fins of condenser and heat is transferred to the air Temperature lowered below boiling point

25 Condenser Construction: Coiled tubing in a series of fins (surface area) Refrigerant moves from top to bottom (heat rises) Older systems one tube bent into multiple S shapes Newer systems side manifolds for multiple paths for flow

26 Condenser Installation: directly in front of radiator for full airflow

27 Condenser

28 Condenser

29 Condenser

30 Condenser

31 Condenser

32 Condenser

33 Receiver/drier(Accumulator) Function: Serve as a storage tank for refrigerant Absorb any moisture in AC system RD receives liquid refrigerant from condenser and holds until needed by evaporator Capacity varies according to operating conditions ½ pound extra

34 Receiver/drier(Accumulator) Location: Usually used in TXV systems Mounted in liquid line between condenser and expansion valve

35 Receiver/drier(Accumulator)

36 Receiver/drier(Accumulator)

37 Receiver/drier(Accumulator) Sight glass indicator for amount of moisture Undercharge bubbles Cloudy moisture Oil streaks Clear

38 Receiver/drier(Accumulator)

39 Accumulator Used in CCOT systems Restriction placed in inlet to evaporator and is fixed in size High engine speeds and low heat load, evaporator floods with liquid Liquid and compressors do not mix Accumulators will collect liquid and store until

40 Accumulator

41 Accumulator

42 Accumulator

43 Accumulator

44 Evaporator Similar to condenser in construction Receives refrigerant from metering device as low pressure liquid Liquid receives enough passenger compartment heat, refrigerant changes state to vapour Evaporator flooding too much liquid refrigerant enters = poor cooling

45 Evaporator Outlet temperature 4-16F higher than liquid inlet Blower speed vs temperature absorption & volume

46 Evaporator

47 Evaporator

48 Evaporator

49 Evaporator

50 Evaporator

51 Metering devices Orifice Tube TXV Designed to provide a restriction to cause a pressure (high side) and then cause a pressure drop (low side) and therefore temperature drop Meter refrigerant into evaporator

52 Orifice tubes Plastic tubes installed in the liquid line between the condenser outlet and the evaporator inlet Screens to remove contaminants Calibrated metal orifice tube to meter refrigerant flow

53 Orifice tubes

54 Orifice tubes

55 CCOT system operation Compressor is turned on and off to control refrigerant flow and pressure Pressure switch, mounted after evaporator monitors outlet pressure (temperature) As pressure increases (liquid refrigerant absorbs heat and temperature increases) compressor will turn on and allow more liquid refrigerant

56 CCOT system operation When pressure drops too low, (too low temperature) the pressure switch reacts and turns off the compressor (flooded evap)

57 TXV Thermal expansion valves have modulating action Fluctuate open/closed in order to keep evaporator output temperatures stable

58 TXV - construction A sensing bulb with a temperature reactive gas is in contact with the evaporator outlet tube Spring pressure on the bottom of the valve will try to keep it closed The pressure in the sensing bulb acts upon the diaphragm and forces the valve open against spring pressure

59 TXV - construction

60 TXV - construction

61 TXV - construction Internally vs externally balanced Internal balance tubes connect pressure from evaporator inlet to bottom side of TXV diaphragm This allows for balanced pressures and smoother, less abrupt metering

62 TXV - construction

63 H-valve - construction Two passages evaporator inlet and outlet with a pressure sensitive diaphragm in an H shaped housing Temperature sensitive element on the evaporator outlet controls the orifice size on the evaporator inlet

64 H-valve - construction

65 H-valve - construction Two passages evaporator inlet and outlet with a pressure sensitive diaphragm in an H shaped housing Temperature sensitive element on the evaporator outlet controls the orifice size on the evaporator inlet