Question 1 of 27070
Q
What is the primary purpose of the thermostatic expansion valve as used in most refrigeration plants?
A
regulate the box temperature
B
ensure that liquid refrigerant returning to the compressor has the proper superheat
C
maintain a constant degree of superheat at the evaporator coil outlet
D
maintain constant evaporator coil pressure independent of suction pressure variations
Question 1 / 270705eccef9dbacbc34ba4d45fae
Question 1 of 270705eccef9dbacbc34ba4d45fae

What is the primary purpose of the thermostatic expansion valve as used in most refrigeration plants?

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Question 1 of 27070
Q

What is the primary purpose of the thermostatic expansion valve as used in most refrigeration plants?

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🔍 Key Concepts

• Thermostatic expansion valve (TXV) function in a vapor-compression refrigeration cycle • Difference between box temperature control and evaporator outlet control • Meaning of superheat and why compressors must not receive liquid refrigerant

💭 Think About

• Think about where the sensing bulb of a thermostatic expansion valve is located and what variable it actually measures. • Ask yourself: is the valve trying to keep the room/box cold, the coil pressure fixed, or the condition (temperature vs saturation) of the refrigerant leaving the evaporator under control? • Consider what could happen to the compressor if the expansion valve did not perform its main protective function regarding liquid vs vapor at the suction.

✅ Before You Answer

• Confirm the definition of superheat: temperature of vapor above its saturation temperature at a given pressure. • Identify which choice describes control at the evaporator outlet, not in the refrigerated space or at the compressor suction line in general. • Verify which option describes a function that protects the compressor from liquid slugging while still allowing efficient evaporator use.