Final answer:
The motor in a semi-hermetic reciprocating compressor is cooled by the refrigerant suction gas, which absorbs heat from the motor before being compressed and cycled through the system.
Step-by-step explanation:
The motor in a semi-hermetic reciprocating compressor is cooled by the refrigerant suction gas. The compressor's design allows the refrigerant that is being drawn into the compressor to pass over and cool the motor windings. This cooling process is essential because as the electrically driven compressor works, it increases the temperature and pressure of the refrigerant, making it necessary to remove any heat generated to prevent overheating of the motor.
Within the refrigeration cycle, after the refrigerant leaves the evaporator, it is in a low-pressure, low-temperature gaseous state. In this state, it effectively absorbs heat from the motor before being compressed. Subsequently, the now higher-pressure gas is discharged into the condenser coils, releasing heat to the surrounding environment, condensing into a liquid, and continuing through the cycle.