Design of Heat Exchangers: Master the Art of Thermal Exchange

Question 1

The effectiveness of a heat exchanger is measured as the ratio of:

Accepted Answer

Actual heat transfer rate to the maximum possible heat transfer rate

Answer

Surface area to volume

Answer

Temperature difference between the fluids to the log mean temperature difference

Answer

Flow rate to velocity

Question 2

Fouling in heat exchangers primarily leads to:

Accepted Answer

Increased thermal resistance

Answer

Increased heat transfer area

Answer

Reduced pressure drop

Answer

Improved fluid flow

Question 3

Which flow arrangement in a heat exchanger provides the highest heat transfer coefficient?

Accepted Answer

Counter-flow

Answer

Parallel flow

Answer

Cross-flow

Answer

Shell-and-tube

Question 4

The overall heat transfer coefficient (U) in a heat exchanger is:

Accepted Answer

Dependent on the individual heat transfer coefficients and the thickness of the wall

Answer

Independent of the individual heat transfer coefficients and the thickness of the wall

Answer

Equal to the sum of the individual heat transfer coefficients

Answer

Dependent on the fluid flow rates

Question 5

What is a primary advantage of using fins in a heat exchanger?

Accepted Answer

Increased surface area for heat transfer

Answer

Reduced fouling

Answer

Lower pressure drop

Answer

Improved fluid flow distribution

Question 6

Which material is commonly used for heat exchanger tubes due to its durability and corrosion resistance?

Accepted Answer

Stainless steel

Answer

Copper

Answer

Aluminum

Answer

Cast iron

Question 7

When selecting the optimal flow arrangement for a heat exchanger, which factors must be considered?

Accepted Answer

Heat transfer coefficient, pressure drop, and fouling susceptibility

Answer

Heat transfer coefficient and pressure drop only

Answer

Heat transfer coefficient and fouling susceptibility only

Answer

Pressure drop and fouling susceptibility only

Question 8

In a counterflow heat exchanger, the temperature difference between the fluids:

Accepted Answer

Decreases in the flow direction

Answer

Increases in the flow direction

Answer

Remains constant throughout the exchanger

Answer

Varies randomly

Question 9

Which of the following is NOT a common type of fouling that can occur in heat exchangers?

Accepted Answer

Cavitation

Answer

Scale deposition

Answer

Corrosion

Answer

Biological growth

Question 10

The fouling factor is used to account for the:

Accepted Answer

Resistance to heat transfer caused by fouling

Answer

Increase in heat transfer rate due to fouling

Answer

Decrease in pressure drop due to fouling

Answer

Change in fluid properties due to fouling

Question 11

Which of the following is NOT a primary design consideration for heat exchangers?

Accepted Answer

Materials of construction

Answer

Surface area

Answer

Flow arrangements

Answer

Fouling factors

Question 12

What does the effectiveness of a heat exchanger measure?

Accepted Answer

The ratio of actual heat transfer to maximum possible heat transfer

Answer

The ratio of heat transfer area to surface area

Answer

The ratio of outlet temperature difference to inlet temperature difference

Answer

The ratio of UA to C

Question 13

Which of the following is NOT a common type of heat exchanger?

Accepted Answer

Condenser

Answer

Shell-and-tube

Answer

Plate-and-frame

Answer

Extended surface

Question 14

What does the LMTD method primarily calculate?

Accepted Answer

Logarithmic mean temperature difference

Answer

Surface area of a heat exchanger

Answer

Overall heat transfer coefficient of a heat exchanger

Answer

Effectiveness of a heat exchanger

Question 15

In designing heat exchangers for seawater operation, which fouling factor is most crucial to consider?

Accepted Answer

Biological Fouling

Answer

Inorganic Fouling

Answer

Corrosion Fouling

Question 16

What is the main purpose of following heat exchanger design codes and standards?

Accepted Answer

Preventing failures and leaks

Answer

Reducing manufacturing costs

Answer

Increasing heat transfer rates

Answer

Limiting size and weight

Question 17

Which fouling factor estimation method considers the impact of fluid properties, heat exchanger design, and operating conditions on fouling formation?

Accepted Answer

Taborek's Method

Answer

Wilson Plot Method

Answer

Kern's Analogy Method

Answer

Fouling Resistance Method

Question 18

In designing the surface area of a heat exchanger, which of the following factors should be considered?

Accepted Answer

Overall heat transfer coefficient, fouling factor and inlet and outlet temperatures

Answer

Pressure drop only

Answer

Inlet temperature only

Answer

Fouling factor only

Question 19

In a shell and tube heat exchanger, the arrangement where the tubes make multiple passes through the shell is referred to as a:

Accepted Answer

Multi-pass shell

Answer

Parallel-flow shell

Answer

Cross-flow shell

Answer

Single-pass shell

Question 20

The purpose of the fouling factor in heat exchanger design is to:

Accepted Answer

Account for the accumulation of deposits on heat transfer surfaces, reducing their effectiveness

Answer

Increase the heat transfer coefficient

Answer

Ensure the heat exchanger operates at its maximum capacity

Question 21

Which of the following techniques can be employed to enhance heat transfer in a heat exchanger?

Accepted Answer

Using fins or extended surfaces, increasing fluid flow rates, or using fluids with higher thermal conductivities

Answer

Using a fluid with a lower viscosity

Answer

Decreasing the surface area of the heat exchanger

Question 22

The effectiveness of a counter-flow heat exchanger, compared to a parallel-flow heat exchanger, is:

Accepted Answer

Always higher due to the opposing flow directions, which maximize heat transfer

Answer

Equal, as both flow arrangements have the same heat transfer area

Answer

Lower, as the counter-flow arrangement creates a smaller temperature difference

Question 23

When designing a heat exchanger for a specific application, a key consideration is:

Accepted Answer

Selecting a heat exchanger type that aligns with the process requirements and constraints

Answer

Designing for the lowest possible cost, regardless of efficiency

Answer

Using the most advanced materials, even if they are not necessary

Question 24

The applicability of the LMTD (Logarithmic Mean Temperature Difference) method for heat exchanger analysis extends to:

Accepted Answer

Both counter-flow and parallel-flow heat exchangers, as it accounts for the varying temperature differences along the heat exchanger

Answer

Only counter-flow heat exchangers, as it relies on the opposing flow directions

Answer

Only parallel-flow heat exchangers, as it assumes a constant temperature difference

Question 25

The overall heat transfer coefficient for a heat exchanger represents:

Accepted Answer

The combined effect of the heat transfer resistances on both sides of the heat transfer surface

Answer

The heat transfer coefficient of the fluid with the higher thermal conductivity

Answer

The inverse of the heat transfer area