In an ECS system, where is the expansion valve typically mounted?

In an ECS system, where is the expansion valve typically mounted?

• A. Near the cabin
• B. Close to the evaporator
• C. Near the condenser
• D. Inside the duct

Answer: (B)

The expansion valve is placed on the low-pressure side of the system, right where the refrigerant goes into the evaporator, so it can meter the liquid refrigerant just before it enters the evaporator coil. By sitting close to the evaporator, the valve can deliver the correct amount of refrigerant at the evaporator inlet pressure, letting it expand and absorb heat efficiently as it boils off in the coil. That metering is tied to the evaporator’s load, helping maintain proper superheat and protecting the compressor from liquid refrigerant. If it were near the cabin, long refrigerant runs would dull metering accuracy and heat transfer efficiency; near the condenser it would still be on the high-pressure side and wouldn’t control flow into the evaporator; inside the duct isn’t part of the refrigerant circuit at all. So the best placement is close to the evaporator.

The expansion valve is placed on the low-pressure side of the system, right where the refrigerant goes into the evaporator, so it can meter the liquid refrigerant just before it enters the evaporator coil. By sitting close to the evaporator, the valve can deliver the correct amount of refrigerant at the evaporator inlet pressure, letting it expand and absorb heat efficiently as it boils off in the coil. That metering is tied to the evaporator’s load, helping maintain proper superheat and protecting the compressor from liquid refrigerant.

If it were near the cabin, long refrigerant runs would dull metering accuracy and heat transfer efficiency; near the condenser it would still be on the high-pressure side and wouldn’t control flow into the evaporator; inside the duct isn’t part of the refrigerant circuit at all. So the best placement is close to the evaporator.