What is the function of the metering device in a vapor compression system?

What is the function of the metering device in a vapor compression system?

• A. Dissipates heat to outdoor air
• B. Stores refrigerant during standby
• C. Increases refrigerant density
• D. Controls refrigerant flow and reduces pressure to the evaporator

Answer: (D)

The metering device’s job is to regulate how much refrigerant enters the evaporator and to create a pressure drop from the high-pressure liquid leaving the condenser to the low-pressure side of the evaporator. By restricting flow, it causes part of the liquid refrigerant to flash into vapor as it passes through, which cools the mixture and lets the evaporator absorb heat from the space. This flow control also helps maintain the proper evaporator pressure and set the desired superheat for efficient operation. The other options describe functions of other components: dissipating heat to outdoor air is the condenser’s role, storing refrigerant during standby is handled by a receiver or accumulator, and increasing refrigerant density isn’t the meter’s function—the meter reduces pressure and controls flow rather than changing density directly.

The metering device’s job is to regulate how much refrigerant enters the evaporator and to create a pressure drop from the high-pressure liquid leaving the condenser to the low-pressure side of the evaporator. By restricting flow, it causes part of the liquid refrigerant to flash into vapor as it passes through, which cools the mixture and lets the evaporator absorb heat from the space. This flow control also helps maintain the proper evaporator pressure and set the desired superheat for efficient operation. The other options describe functions of other components: dissipating heat to outdoor air is the condenser’s role, storing refrigerant during standby is handled by a receiver or accumulator, and increasing refrigerant density isn’t the meter’s function—the meter reduces pressure and controls flow rather than changing density directly.