Fundamentals of Momentum, Heat, and Mass Transfer 5th. Edition by James R. Welty Charles E. Wicks Robert E. Wilson Gregory L. Rorrer | 9780470128688 | 0470128682

Heat Transfer

Fundamentals of Momentum, Heat, and Mass Transfer

94 SOLVED PROBLEMS

4 SOLVED PROBLEMS

Question: 17.2

A long steam pipe of outside radius r2 is covered with thermal insulation having an outside radius of r3. The temperature of the outer surface of the pipe, T2, and the temperature of the surrounding air, T∞, are fixed. The energy loss per unit area of outside surface of the insulation is described ...

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In Example 3 of Chapter 15, the thermal resistance...

Question: 30.2

Estimate the distance a spherical drop of liquid water, originally 1 mm in diameter, must fall in quiet, dry air at 323 K in order to reduce its volume by 50%. Assume that the velocity of the drop is its terminal velocity evaluated at its mean diameter and that the water temperature remains at ...

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The physical system requires a combined analysis o...

Question: 31.8

A packed tower is to be used to reduce the ammonia concentration in the gas stream from 4 to 0.3% by volume. A water stream is fed to the top of the tower at a rate of 231 g/s and the gas is fed countercurrently at a rate of 0.2 m³/s. The tower, which is packed with 2.54-cm (1-inch) Raschig rings, ...

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The concentration of the three known streams may b...

Question: 30.6

Consider the remediation trench shown in Figure 30.7, a very simple process to treat contaminated wastewater before discharge to a lake or river. The remediation trench consists of a narrow outdoor open channel with an air sparger aligned along the bottom of the trench. Wastewater containing a ...

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We wish to design an aerated remediation trench to...

Question: 30.4

Trichloroethylene (TCE), a common industrial solvent, is often found at low concentrations in industrial waste waters. Stripping is a common process for removing sparingly soluble, volatile organic solutes such as TCE from aqueous solution. A wetted-wall column is used to study the stripping of TCE ...

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Relevant physical property data are provided below...

Question: 27.3

Recall the drug capsule described in Example 2. The present drug capsule consists of a 0.652-cmdiameter spherical bead (radius of 0.326 cm) containing a uniform initial concentration of 68.9 mg/cm³ dramamine. (a) what is the residual concentration of dramamine at the center of the spherical bead ...

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This problem is readily solved using the charts gi...

Question: 24.5

Estimate the liquid diffusion coefficient of ethanol, C2H5OH, in a dilute solution of water at 10°C. The molecular volume of ethanol may be evaluated by using values from Table 24.5 as follows: VC2H5OH = 2VC + 6VH + VO VC2H5OH = 2(14.8) + 6(3.7) + 7.4 = 59.2 cm³/mol ...

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10^{\circ} \mathrm{C}

, the visco...

Question: 30.1

A horizontal chemical vapor deposition (CVD) reactor for growth of gallium arsenide (GaAs) thin films is shown in Figure 30.2. In this process, arsine (AsH3), trimethyl gallium (Ga(CH3)3), and H2 gases are fed into the reactor. Inside the reactor, the silicon wafer rests on a heated plate called a ...

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At sufficiently high flowrate within the reactor, ...

Question: 27.4

An oak pole having an initial uniform moisture content of 45 wt% is placed in a drying kiln where its surface moisture is maintained at 15 wt%. Under the specified drying conditions, the drying was controlled by the internal diffusion of liquid water to the surface. If the maximum moisture content ...

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This problem is readly solved using the charts giv...

Question: 24.3

Reevaluate the diffusion coefficient of carbon dioxide in air at 20°C and atmospheric pressure using the Fuller, Schettler, and Giddings equation and compare the new value with the one reported in example 2. ...

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\begin{aligned} D_{A B} & =\frac{10^{-...

Question: 15.1

A steel pipe having an inside diameter of 1.88 cm and a wall thickness of 0.391 cm is subjected to inside and outside surface temperature of 367 and 344 K, respectively (see Figure 15.3). Find the heat flow rate per meter of pipe length, and also the heat flux based on both the inside and outside ...

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The first law of thermodynamics applied to this pr...

Question: 6.2

As a second example, consider the situation shown in Figure 6.6. If water flows under steady conditions in which the pump delivers 3 horsepower to the fluid, find the mass flow rate if frictional losses may be neglected. ...

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Defining the control volume as shown by the dashed...

Question: 14.2

A system like the one shown in Figure 14.7 is to be assembled to pump water. The inlet pipe to the centrifugal pump is 12 cm in diameter and the desired flow rate is 0.025 m³/s. At this flow rate, the specifications for this pump show a value of NPSH of 4.2 m. The minor loss coefficient for the ...

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The quantity desired, y, is given by

y={\fr...

Question: 9.2

A rotating shaft, as illustrated in Figure 9.6, causes the fluid to move in circular streamlines with a velocity that is inversely proportional to the distance from the shaft. Find the shape of the free surface if the fluid can be considered inviscid. ...

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As the pressure along the free surface will be con...