In a continuous High-Temperature Short-Time (HTST) milk pasteurizer equipped with a plate heat exchanger regenerator, cold raw milk is heated from $4^\circ\text{C}$ to $65^\circ\text{C}$ by hot pasteurized milk, before entering the hot water heating section to attain the final pasteurization temperature of $72^\circ\text{C}$. The regenerative efficiency (regeneration percentage) of the pasteurizer is ________ % (round off to 1 decimal place).
Answer Key:
89.7
Step-by-Step Solution & Explanation
Regenerative efficiency is defined as:
$\eta_{reg} = \frac{\text{Temperature rise achieved in regenerator}}{\text{Total required temperature rise}} \times 100$
$\eta_{reg} = \frac{65 - 4}{72 - 4} \times 100 = \frac{61}{68} \times 100 = 89.7058\% \approx 89.7\%$