Which device is used to meter refrigerant flow into the evaporator?

Which device is used to meter refrigerant flow into the evaporator?

• A. Receiver dryer
• B. Accumulator
• C. TXV
• D. Condenser

Answer: (C)

Controlling how much refrigerant enters the evaporator is essential to match cooling load and ensure the refrigerant fully vaporizes before returning to the compressor. The device that metes out that flow is the thermostatic expansion valve. It uses a temperature-sensing bulb attached to the evaporator (or its outlet) to monitor superheat and then modulates the valve opening accordingly. When more cooling is needed, the valve opens to permit more liquid refrigerant into the evaporator; when less is needed, it tightens to restrict flow. This keeps a proper amount of refrigerant flowing so the evaporator can vaporize it entirely and protect the compressor from liquid slugging. The other components have different roles: a receiver-dryer stores liquid refrigerant and removes moisture, an accumulator traps any liquid that might reach the compressor, and a condenser rejects heat and condenses high-pressure vapor. None of these meters refrigerant flow into the evaporator.

Controlling how much refrigerant enters the evaporator is essential to match cooling load and ensure the refrigerant fully vaporizes before returning to the compressor. The device that metes out that flow is the thermostatic expansion valve. It uses a temperature-sensing bulb attached to the evaporator (or its outlet) to monitor superheat and then modulates the valve opening accordingly. When more cooling is needed, the valve opens to permit more liquid refrigerant into the evaporator; when less is needed, it tightens to restrict flow. This keeps a proper amount of refrigerant flowing so the evaporator can vaporize it entirely and protect the compressor from liquid slugging.

The other components have different roles: a receiver-dryer stores liquid refrigerant and removes moisture, an accumulator traps any liquid that might reach the compressor, and a condenser rejects heat and condenses high-pressure vapor. None of these meters refrigerant flow into the evaporator.