Heat and Mass Transfer in Food Processing

Cold raw milk enters a pasteurizer at $T_{in} = 4^\circ\text{C}$ and is preheated in the regenerator to $T_{regen} = 65^\circ\text{C}$. Final pasteurization holding temperature is $T_{past} = 72^\circ\text{C}$. The regeneration efficiency $\eta_{reg} = \frac{T_{regen} - T_{in}}{T_{past} - T_{in}} \times 100 = \frac{65 - 4}{72 - 4} \times 100 = \frac{61}{68} \times 100$ in percent is (rounded off to one decimal place):