Food Engineering Multiple Choice Questions on “Unit Operations – Heat Transfer Equipment”.
1. Which of the following sentences is true?
a) Direct heating has higher heat transfer rates than indirect heating
b) Indirect heating has higher heat transfer rates than direct heating
c) Both of them have the same heat transfer rates
d) Cannot be determined
Answer: a
Clarification: Direct heating has higher heat transfer rates than indirect heating.
2. If _______ heating has higher heat transfer rates than _______ heating, then why is ________ difficult to be used.
a) Direct, Indirect, no difficulty, they’re used
b) Direct, Indirect, coil is difficult to clean and is prone to bacterial growth
c) Indirect, Direct, no difficulty, they’re used
d) Indirect, Direct, coil is difficult to clean and is prone to bacterial growth
Answer: b
Clarification: Direct heating has higher heat transfer rates than indirect heating, but, the coil is difficult to clean and is prone to bacterial growth.
3. In a jacketed vessel, the only way to increase the heat transfer rates is to increase the temperature difference.
a) True
b) False
Answer: a
Clarification: In a jacketed vessel, the only way to increase the heat transfer rates is to increase the temperature difference.
4. Which of the following is an advantage of using pumps as heat transfer equipment?
a) No stirrer required
b) Taking them to a heat exchanger where the area used for heat transfer can be easily changed
c) No stirrer required & taking them to a heat exchanger where the area used for heat transfer can be easily changed
d) None of the mentioned
Answer: c
Clarification: Both the mentioned statements are true.
5. External heat exchangers are gaining popularity as they’ve several advantages over conventional methods. Still, there is a major drawback. Which among the following is it?
a) Some shear-sensitive cells might get damaged due to abrasion
b) It is difficult for pumps to withstand high temperature without leakages of the fluid
c) All of the mentioned
d) None of the mentioned
Answer: c
Clarification: External heat exchangers are gaining popularity as they’ve several advantages over conventional methods. Still, there are drawbacks like some shear-sensitive cells might get damaged due to abrasion. Also, it is difficult for pumps to withstand high temperature without leakages of the fluid.
6. Which of the following is a parameter to be checked before choosing the shape of the pitch in heat exchangers?
a) Easiness to clean
b) High heat transfer
c) Cost
d) All of the mentioned
Answer: d
Clarification: All of the mentioned are valid reasons.
7. Statement 1: Difference between 1-1 and 1-2 heat exchanger is that 1-2 has both counter AND co current, whereas 1-1 has only co-current.
Statement 2: 1-2 heat exchanger requires a high pressure drop.
a) True, False
b) True, True
c) False, False
d) False, True
Answer: b
Clarification: Both the statements pertaining to heat exchangers are true.
8. Statement 1: Generally, in small scaled jacketed pans, food products like jams, sauces etc are made.
Statement 2: Baffles provide structural support to tubes, but they cannot prevent channeling.
a) True, False
b) True, True
c) False, False
d) False, True