In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is

Question

Quizplus · Accepted Answer

The Log Mean Temperature Difference (LMTD) in a heat exchanger is a measure of the driving force for heat transfer. If the outlet temperatures of both fluids are the same, it means there is no temperature difference driving the heat transfer at the outlet end. Since LMTD is a logarithmic average of the temperature differences at the inlet and outlet, if the outlet temperature difference is zero, it significantly impacts the LMTD calculation. However, in practical terms, for the LMTD to be exactly zero, it would require the inlet temperature difference to also be zero, which contradicts the operation of a heat exchanger (where there's supposed to be a temperature difference to drive heat exchange). This scenario is theoretically possible in a very specific and idealized case where the heat capacity rates of the two fluids are equal and the heat transfer is perfectly efficient, leading to an equalization of outlet temperatures. Nonetheless, this is an idealized scenario, and the given options do not fully account for the complexities of real-world heat exchanger operations. The correct answer, based on the provided options and the theoretical scenario described, is B) 0, indicating a misunderstanding or oversimplification of the LMTD concept in the context of the question.

In a 1-1 Concurrent Heat Exchanger, If the Tube Side