Final answer:
The increase in evaporator pressure causes the expansion valve to open, allowing refrigerant to flow into the evaporator coils where it absorbs heat. The refrigerant is first compressed and heated, then it transfers heat to the room as it condenses, and finally it expands and cools through the expansion valve before returning to the evaporator coils.
Step-by-step explanation:
When evaporator pressure increases in a refrigeration cycle, the increased pressure will overcome the opposing forces of spring pressure and atmospheric pressure in an expansion valve, also known as an automatic expansion valve (AXV). As a consequence, this will cause the valve to open, allowing the refrigerant to flow through the valve and into the evaporator coils. As the refrigerant passes through the expansion valve, it expands and cools, turning from a high-pressure liquid into a low-pressure mixture of liquid and gas. This cool refrigerant then absorbs heat from the surrounding environment in the evaporator coils, thereby providing the desired cooling effect.
The electrically driven compressor in a refrigeration system compresses the refrigerant, raising its temperature and pressure, and forces it into the condenser coils. The heat transfer from the high-temperature gas to the cooler room air causes the gas to condense into a liquid. The condensed liquid then flows back through the pressure-reducing valve to the outdoor evaporator, repeating the cycle after being cooled through expansion.