Allied & ICAR Exam Bank • ALLIED_3792NAT • 2 Marks
Section 7: Dairy and Food Engineering
Heat and Mass Transfer
Subtopic: Water activity, sorption and desorption isotherms
Question Statement:
A counter-flow tubular milk pasteurizer #42 has hot water entering at T_h1 = 85 deg C and leaving at T_h2 = 65 deg C, while cold milk enters at T_c1 = 15 deg C and leaves at T_c2 = 52 deg C. The temperature difference at hot end is Delta T_1 = 85 - 52 = 33 deg C, and at cold end is Delta T_2 = 65 - 15 = 50 deg C. If Delta T_1 = Delta T_2 = 50 deg C, the Log Mean Temperature Difference (LMTD) in deg C is exactly:
Answer Key:
50
Step-by-Step Solution & Explanation
When Delta T_1 = Delta T_2 = 50 deg C, LMTD equals the common temperature difference of 50 deg C.