Final answer:
Refrigerant typically enters the compressor of a refrigeration system as a low-pressure gas, where it is then compressed and its temperature and pressure are raised.
Step-by-step explanation:
Under normal conditions, refrigerant enters the compressor of a refrigeration system as a low-pressure gas. The electrically driven compressor, which inputs work (W), raises the temperature and pressure of the gas. Once the gas is heated above the ambient temperature of the surrounding space, it moves to the condenser coils, where heat transfer occurs allowing the gas to condense into a liquid. The refrigerant then continues through the system, passing through a pressure-reducing valve and returning to the evaporator coils. During expansion in this part of the cycle, the liquid is cooled and becomes ready to absorb heat from the space being refrigerated, thus resuming the cycle.