The efficiency of a counter flow heat exchanger is given by equation $3$

$=\frac{T_{co}-T_{ci}}{T_{hi}-T_{ci}}$

Where:

$T_{co}$ : cold water outlet temperature

$T_{ci}$ : cold water inlet temperature

$T_{hi}$ : hot water inlet temperature

Assuming $T_{ci}$ is constant, determine the combined uncertainty of heat exchanger efficiency using the method explained in the class notes.