Evaporator Systems Flashcards
7 cards from real RSES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Evaporator Systems flashcards as text
What is the purpose of a suction line accumulator installed between the evaporator and compressor?
Answer: To prevent liquid refrigerant slugs from reaching the compressor
A suction line accumulator traps liquid refrigerant and oil, releasing only vapor to the compressor to prevent liquid slugging damage.
Which factor most significantly affects the air-side heat transfer performance of a fin-and-tube evaporator?
Answer: Fin spacing and fin surface cleanliness
Fin spacing determines airflow resistance and surface area, while cleanliness ensures that the full fin surface area is available for heat exchange.
A technician installs a TXV with a remote sensing bulb. Where should the bulb be clamped for proper superheat sensing?
Answer: On the suction line outside the refrigerated space, after the evaporator outlet
The TXV sensing bulb must be clamped on the suction line after the evaporator outlet to sense actual refrigerant superheat leaving the evaporator.
What effect does an excessively high evaporator fan speed have on evaporator performance in a low-humidity storage application?
Answer: Increased moisture removal from stored product due to greater air-to-coil contact
Higher fan speed increases the rate at which moist air contacts the cold coil, causing more moisture to condense and freeze on the coil and dehumidify the stored product.
During hot-gas defrost of a low-temperature evaporator, the system pressure may rise significantly. What component protects the low-side from excessive pressure?
Answer: A defrost pressure-relief or pressure-limiting valve on the evaporator outlet
A pressure-limiting or defrost relief valve vents excess pressure from the evaporator to the suction line or condenser to prevent low-side pressure from exceeding safe limits.
What is 'temperature difference' (TD) as applied to evaporator selection and why does it matter?
Answer: The difference between the air entering the evaporator and the evaporating refrigerant temperature, affecting humidity and capacity
TD determines how aggressively the coil pulls heat and moisture from the air; a higher TD increases capacity but also removes more moisture, affecting product quality.
A glycol chiller evaporator shows reduced capacity but the refrigerant side readings are normal. What is the most likely cause on the glycol side?
Answer: High glycol concentration reducing heat transfer and flow rate
Excessive glycol concentration increases viscosity and reduces the glycol-side heat transfer coefficient, significantly cutting the chiller's effective capacity.