Heat Transfer – A Practical Approach 2nd. Edition by Yunus A Cengel | 9780072458930 | 0072458933 | Holooly

Heat Transfer – A Practical Approach [EXP-6586]

170 SOLVED PROBLEMS

A Wall with Various Sets of Boundary Conditions Consider steady one-dimensional heat conduction in a large plane wall of thickness L and constant thermal conductivity k with no heat generation. Obtain expressions for the variation of temperature within the wall for the following pairs of boundary

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SOLUTION This is a steady one-dimensional heat co...

Analogy between Heat and Mass Transfer Heat transfer coefficients in complex geometries with complicated boundary conditions can be determined by mass transfer measurements on similar geometries under similar flow conditions using volatile solids such as naphthalene and dichlorobenzene and utilizing

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SOLUTION Air is blown over a body covered with a ...

Analysis of Heat Conduction in a Chip A chip is dissipating 0.6 W of power in a DIP with 12 pin leads. The materials and the dimensions of various sections of this electronic device are as given in the table below. If the temperature of the leads is 40°C, estimate the temperature at the junction of

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SOLUTION The dimensions and power dissipation of ...

Boiling Eggs An ordinary egg can be approximated as a 5-cm-diameter sphere (Fig). The egg is initially at a uniform temperature of 5° C and is dropped into boiling water at 95° C. Taking the convection heat transfer coefficient to be h = 1200 W/m^ 2 ⋅ °C, determine how long it will take for the

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SOLUTION An egg is cooked in boiling water. The c...

Centerline Temperature of a Resistance Heater A 2-kW resistance heater wire whose thermal conductivity is k = 15 W/m ⋅ C, has a diameter of D = 4 mm and a length of L = 0.5 m, and is used to boil water (Fig). If the outer surface temperature of the resistance wire is Ts = 105 C, determine the

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SOLUTION The surface temperature of a resistance ...

Chilling of Beef Carcasses in a Meat Plant The chilling room of a meat plant is 18 m × 20 m × 5.5 m in size and has a capacity of 450 beef carcasses. The power consumed by the fans and the lights of the chilling room are 26 and 3 kW, respectively, and the room gains heat through its envelope at a

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SOLUTION The chilling room of a meat plant with a...

Choosing a Fan to Cool a Computer The desktop computer shown in Figure 15–53 is to be cooled by a fan. The electronics of the computer consume 75 W of power under full-load conditions. The computer is to operate in environments at temperatures up to 40°C and at elevations up to 2000 m, where the

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SOLUTION A desktop computer is to be cooled by a ...

Combined Convection and Radiation Condition A spherical metal ball of radius r0 is heated in an oven to a temperature of 600 F throughout and is then taken out of the oven and allowed to cool in ambient air at T∞ = 78 F, as shown in Figure. The thermal conductivity of the ball material is k=8.3 Btu/h

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SOLUTION The ball is initially at a uniform tempe...

Combined Convection, Radiation, and Heat Flux Consider the south wall of a house that is L = 0.2 m thick. The outer surface of the wall is exposed to solar radiation and has an absorptivity of α = 0.5 for solar energy. The interior of the house is maintained at T∞1 = 20 C, while the ambient air

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SOLUTION We take the direction normal to the wall...

Condensation and Freezing of Moisture in Walls The condensation and even freezing of moisture in walls without effective vapor retarders is a real concern in cold climates, and it undermines the effectiveness of insulations. Consider a wood frame wall that is built around 38 mm × 90 mm (2×4 nominal)

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SOLUTION The thermal and vapor resistances of dif...

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