What device regulates how much liquid refrigerant enters the evaporator to achieve the desired cooling conditions?

What device regulates how much liquid refrigerant enters the evaporator to achieve the desired cooling conditions?

• A. Diffusers
• B. Condenser
• C. Metering devices
• D. Return registers

Answer: (C)

The device that regulates how much liquid refrigerant enters the evaporator is the metering device. After the refrigerant leaves the condenser, the metering device dramatically reduces its pressure, allowing the liquid to expand and partially flash into vapor as it enters the evaporator. This controlled expansion sets the amount of refrigerant that can absorb heat in the evaporator at a given load, which directly determines the cooling. A properly sized and controlled metering device keeps the evaporator from flooding with liquid (which can cause liquid slugging back to the compressor) or starving the evaporator (which reduces cooling capacity). Most systems use a control mechanism, such as a thermostatic or electronic expansion valve, to maintain an appropriate superheat at the evaporator outlet and ensure efficient operation. The other components don’t regulate refrigerant flow into the evaporator: a diffuser distributes air in the duct, the condenser rejects heat from the refrigerant, and return registers are part of the air distribution system.

The device that regulates how much liquid refrigerant enters the evaporator is the metering device. After the refrigerant leaves the condenser, the metering device dramatically reduces its pressure, allowing the liquid to expand and partially flash into vapor as it enters the evaporator. This controlled expansion sets the amount of refrigerant that can absorb heat in the evaporator at a given load, which directly determines the cooling.

A properly sized and controlled metering device keeps the evaporator from flooding with liquid (which can cause liquid slugging back to the compressor) or starving the evaporator (which reduces cooling capacity). Most systems use a control mechanism, such as a thermostatic or electronic expansion valve, to maintain an appropriate superheat at the evaporator outlet and ensure efficient operation.

The other components don’t regulate refrigerant flow into the evaporator: a diffuser distributes air in the duct, the condenser rejects heat from the refrigerant, and return registers are part of the air distribution system.