Food Processing Unit Operations Multiple Choice Questions on “Heat Transfer Applications – Batch Heat Exchangers”.
1. What is heat economizing?
a) The total cost of the heat exchanger and its maintenance cost
b) Interchange heat among the hot and cold fluids to conserve heat energy.
c) The capital cost of the heat exchanger unit
d) Amount of heat produced per day
Answer: b
Clarification: Heat economizing can be defined as the Interchange heat among the hot and cold fluids to conserve heat energy. The heat from the hot liquid is transferred to the cool liquid thus reducing the overall cost of the heating mechanism. This is especially achieved when the arrangement is in counter flow mechanism.
2. Who invented the heat exchanger?
a) Dr Richard Seligman
b) George Babcock
c) George Brayton
d) Benjamin Franklin
Answer: a
Clarification: Dr Richard Seligman invented heat exchanger. George Babcock invented boiler. George Brayton invented engine. Benjamin Franklin invented electricity.
3. What are the factors to be considered for designing a heat exchanger?
a) Thermal analysis
b) Hydraulic calculations
c) Pressure calculations
d) Thermal analysis and hydraulic calculations
Answer: d
Clarification: There are 2 factors to be considered for designing a heat exchanger. They are Thermal analysis and hydraulic calculations. The thermal analysis is a study of the physical and chemical properties of the fluid with respect to temperature under controlled temperature program. Hydraulic analysis refers to the study of fluid under different conditions.
4. Are these statements about the regenerative heat exchangerstrue?
Statement 1: Regenerators are commonly used in gas/gas heat recovery applications.
Statement 2: Regenerative heat exchangers are also known as capacitive heat exchangers.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: b
Clarification: Regenerative heat exchangers are also known as capacitive heat exchangers. The flow path consists of the matrix where heat from the hot fluid is captured in the matrix and then it is released to the cold fluid. Regenerators are commonly used in gas/gas heat recovery applications mainly in power stations. Static and dynamic are the two types of regenerators.
5. What are main advantages of continuous heat exchanger over batch heat exchanger?
a) Efficiency and cost
b) Quantity and cost
c) Efficiency and quality
d) Efficiency and quantity
Answer: d
Clarification: The two important merits of continuous heat exchanger over batch heat exchanger are efficiency and quantity. The efficiency of the continuous heat exchanger depends on the continuous cleaning and calibration. The quantity depends on the feed rate which is higher than the batch process. But continuous heat exchanger is expensive than a batch system.
6. Which of the following statements about two-phase heat exchangers are correct?
Statement 1: Two-phase heat exchangers undergo phase change during the heat transfer process.
Statement 2: It is used mainly in water-to-water heat transfer applications.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: a
Clarification: Two-phase heat exchangers undergo phase change during the heat transfer process. The phase change occurs in either or both the fluids thus resulting in liquid to gas or gas to liquid change. The two-phase heat exchangers includecondensers, boilers and evaporators.
7. The deposition of any undesired material on heat transfer surfaces is called _____________
a) fouling
b) debris
c) scaling
d) rubble