The flooded evaporator has fluctuating recirculation rates due to?

A flooded evaporator experiences fluctuating recirculation rates primarily due to the heat load induced into the heat exchanger. When there are variations in the heat load, such as changes in the temperature or mass flow rate of the fluid being cooled, this directly affects the amount of refrigerant that can evaporate in the evaporator section. If the heat load increases, the system may not be able to evaporate enough refrigerant to keep up with the demand, leading to fluctuations in the recirculation rate as the system attempts to balance the evaporated refrigerant with the incoming heat.

In contrast, the expansion valve and metering valve set points primarily regulate the refrigerant flow and pressure, but they do not directly cause the fluctuations in recirculation rates. The pump differential pressure is also important for ensuring adequate flow through the system, but it is not the primary factor influencing fluctuations in a flooded evaporator; instead, it more directly impacts the overall efficiency and performance of the refrigerant cycle. Thus, the correct understanding centers around heat load variations as the key driver of fluctuating recirculation rates in a flooded evaporator context.