External Drive (Open) System Cooling
In the external drive system, the compressor, as a rule, belt-driven by an electric motor. Compressor speed is usually much less than the speed of rotation of the motor. Small pulley used on the motor shaft. Larger pulley (flywheel) is used on the shaft of the compressor. The earliest of refrigeration systems. Fig. 3-5 illustrates an open system.
Liquid refrigerant (dark red), under high pressure, flows through the expansion valve. Then he enters the evaporator where it is under low pressure. It boils, evaporates, absorbing heat in the evaporator. When the compressor is running evaporation of the coolant (light blue), carried out through the suction line of the compressor. The refrigerant is compressed to high pressure (red light) before discharge into the condenser.
In capacitor pair (refrigerant evaporates) give up its latent heat of vaporization. It cools and returns to a liquid (dark red). Hence, the cycle repeats. Thermostatic bulb engine control shown.
Trigger mechanism on an external drive (open) engines is generally built into the engine.
External drive, the system requires a crankshaft seal of the compressor. Engine and compressor drive at atmospheric pressure. The pressure inside the crankcase will vary depending on the refrigerant and temperature. Sometimes it can be significantly greater than atmospheric pressure; in other cases it may be less. Refrigerant vapor we cannot allow the flow of air into the crankcase. And any of them can quickly ruin operation...
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