Heat Transfer Equipment

This quiz contains multiple-choice problems on heat transfer equipment classification, pipe wall temperature, plate type and double pipe heat exchangers, multipass heat exchangers, conduction and convection of heat transfer, shell and tube heat exchangers.

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What is the meaning of 1⁄2” OD, 5 BWG?

Wall thickness = 0.203″ and inner diameter = 0.094″

Wall thickness = 0.022″ and inner diameter = 0.478″

Wall thickness = 0.220″ and inner diameter = 0.060″

Wall thickness = 0.025″ and inner diameter = 0.450″

In a fluidised bed heat exchanger with hot gas flow, the temperature of the bed at fluidisation

Linearly increases

Uniform

Linearly decreases

Decreases but not linearly

A gas-to-fluid exchanger can be referred to as a compact heat exchanger if its hydraulic diameter, D{h}

≤ 6 mm

≤ 12 mm

≥ 6 mm

≥ 3 mm

A pipe’s velocity profile is independent of axial position, whereas its temperature profile is not. True or false?

True

False

The hydraulic diameter, D{h}, is defined as __, where A{0} is the minimum free-flow area on one fluid side of a heat exchanger and P is the wetted perimeter of flow passages of that side.

4*A{0}/P

A{0}/(4*P)

A{0}/P

8*A{0}/P

Consider a fluid at temperature of 22℃ entering a pipe of length 1m. The wall temperature is 92℃ on fully developed thermal flow. Determine the temperature of the bulk of the liquid at the exit (given λ = 0.5).

50 ℃

100 ℃

104 ℃

150 ℃

Which of the following are important design and operating considerations for extended-surface compact heat exchangers?
(1) Both fluids may have high or low heat transfer coefficients
(2) As the tubes are very narrow (low DH), the fluid used should not be corrosive as effective cleaning of tubes is not possible.
(3) The fluid pressure drop calculation is essential as a regulatory method to ensure long life of the tubes.
(4) Unlike shell and tube type heat exchangers, these are limited in operating pressure and temperature.

(1), (2), (3), and (4)

(1) and (4)

(2), (3), and (4)

(1) and (2)

The formula defines the temperature profile of a fully developed thermal flow in a pipe of length as L{bulk} – T{wall} = (Tinlet – T{wall}eλL. True or false?

True

False

Which of the following is not a classification based on the construction of heat exchanger?

Tubular

Plate-type

Multipass

Regenerative

A liquid is heated by passing it through a circular pipe (k{pipe} = 15 W/mK, viscosity = 2.5×10-5 Pa-s, C{p} = 1000 J/Kg-K, k{liquid} = 0.035 W/mK) of ID = 25mm and OD = 30mm with length L = 15 m. If Reynolds number is 79000, what is the outer surface average heat transfer coefficient?

773 KW/m^2K

83 KW/m^2K

104 KW/m^2K

43 KW/m^2K

Which are the three most common ‘shell and tube’ heat exchanger types out of the following?
(1) Fixed tube sheet design
(2) U-tube design.
(3) Floating head type
(4) Regenerator type

(1), (3), and (4)

(2), (3), and (4)

(1), (2), and (3)

(1), (2), and (4)

Given the convective heat transfer coefficient of the inner surface as 15 W/m^2K, OD = 30 mm, and ID = 25 mm, find the outer surface’s heat transfer coefficient.

15 W/m^2K

12 W/m^2K

12.5 W/m^2K

13.5 W/m^2K

Which of the following is not a characteristic of direct contact exchangers?

Only heat transfer occurs without any mass transfer

The exchanger construction is relatively not expensive

The fouling problem generally does not exist due to the absence of a separating wall (heat transferring surface) between the two fluids

Very high heat transfer rates are achievable

Which of the following is not an indirect contact type heat exchanger?

Shell and tube

Feedwater heater