Double Pipe Heat Exchangers

This quiz contains multiple-choice problems on dirt factor, heat transfer coefficients, construction and operation of double pipe heat exchanges, heat transfer and pressure drop calculations.

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Fouling factors increase the overall heat transfer conductance and, thus, decrease the overall heat transfer coefficient. True or false?

True

False

Which one of the following cannot be determined by knowing fouling factors?

When to clean the equipment

When the equipment will stop to work

Zero value for a new heat exchanger

Infinity value for an old heat exchanger

How many types of readily identifiable fouling exist?

Which one of the following is not a collective class of fouling?

Biological fouling

Deposition fouling

Chemical fouling

Iron fouling

Which of the following expressions do we use for the calculation of dirty overall heat transfer coefficient U{D}, given fouling factor R{f} and dirt factor R{d}?

(1/U{D}) = (1/U{C}) + R{D}

(1/U{D}) = (1/U{C}) + (1/R{D})

U{D} = U{C} + R{D}

U{D} = U{C} + (1/R{D})

Deposition fouling can be avoided or controlled by monitoring the fluid’s flow velocity so that sediments do not settle out. True or false?

True

False

The phenomenon of scaling on a heat exchanger’s surface due to the hardness of water where salts get deposited on the surface is an example of __ fouling.

Chemical

Deposition

Biology

Corrosion

Algal deposits on the tube surfaces of the heat exchanger belong to which class of fouling?

Chemical

Deposition

Biology

Corrosion

Which of the following fouling phenomena is under the operator’s control?

Chemical

Deposition

Biology

Corrosion

Nickel alloy-based heat exchangers are used to avoid __ fouling.

Chemical

Deposition

Biology

Corrosion

If we know the output and input temperatures of the heat exchanging fluids, which one of the following calculations is not required to determine the number of bends in tube for the equipment?

Pressure drop in the equipment

Overall heat transfer coefficients

Total heat transfer area required

Pipe length

Which of the following is the determining reason for heat transfer in double pipe heat exchangers?

Conduction

Natural convection

Forced convection

Radiation

The density of a fluid, its viscosity and thermal conductivity (K) are all measured at

LMTD

Mean temperature