Heat Transfer 3rd. Edition by S. P. Venkateshan | 9783030583378 | 3030583376 | Holooly

Heat Transfer [EXP-6785]

160 SOLVED PROBLEMS

Question: 17.7

A 2 cm thick slab of ice is at 0 °C throughout. At t = 0 both surfaces of the ice slab are suddenly raised to a temperature of 10 °C and kept at that value thereafter.Determine the time taken for complete melting of the slab and the energy that has entered the slab in this time.

Verified Answer:

We follow the notation used in the text. The prope...

Question: 5.5

A bar of length L of uniform cross section is perfectly insulated over its lateral surface. The bar is initially at a constant temperature of T0 throughout. For t > 0, the two ends of the bar are maintained at zero temperature. Obtain the solution to the problem using Eqs. 5.74 and 5.75. Discuss th

Verified Answer:

Step 1 In this case

f (x) = T_{0}[/latex...

Question: 4.11

A brass tube of 6mm ID and 7mm OD has short integral fins of height 7mm and 0.3mm thickness arranged with a spacing of 3mm. The heat transfer coefficient to the hot fluid at 75^◦C flowing inside the tube is 270W/m^2^◦C. The fins and the external surface of the tube are exposed to air at 20^◦C with

Verified Answer:

Step 1 The nomenclature for this problem is bas...

Question: 5.8

A cable whose surface temperature is 100 ◦C has a diameter of 10 cm. Its center is at a depth of 1 m under soil whose thermal conductivity is known to be 1 W/m◦C. Determine how much heat it will lose per meter length if the soil surface temperature is 30^◦C. Make a plot of the temperature variation

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Step 1 Nomenclature used in this problem follows...

Question: 10.10

A circular disk of diameter 1 m and at 600 K is kept directly opposite to a disk of diameter 0.5 m and 400 K. The distance between the two disks is 0.3 m. Both the disks have an emissivity of 0.6. The room in which the two disks are placed is very large and is at a temperature of 300 K.

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Step 1 The nomenclature used in the problem is int...

Question: 4.5

A conical spine of a material of thermal conductivity k = 45W/m^◦C, base diameter of db = 3mm and length L = 100mm is used to remove heat from a parent surface maintained at Tb = 120^◦C. Fin loses heat to an ambient at a temperature of Tamb = 20^◦C via convection with a uniform heat transfer coeffi

Verified Answer:

Step 1 Radius of cross section of spine at its ...

Question: 3.2

A copper sheet of dimensions 50 × 100 × 2 mm is exposed on both sides to an ambient fluid at 25^◦C with an average heat transfer coefficient of 7W/m^2^◦C. Is it proper to consider the copper sheet as a lumped system for transient analysis? If the answer is yes, determine the time constant of the fi

Verified Answer:

Properties of copper are taken from Table I.4. The...

Question: 16.8

A cylinder of diameter D = 0.1m, length L = 0.15m is maintained at a uniform temperature of Tw = 60 °C in still air at T∞ = 20 °C. The two flat ends of the cylinder are perfectly insulated. Compare the heat loss from the cylinder if its axis is (a) horizontal and (b) vertical.

Verified Answer:

We base the thermo-physical properties of air at [...

Question: 5.10

A cylindrical heating element of diameter 0.1 m and length 2 m is driven tightly into a hole drilled in the ground. Heat is produced in the heater electrically at a rate of 100 W. The heater surface temperature is measured at ten locations along the length of the heater. It is found that the averag

Verified Answer:

Nomenclature used here is according to that in Fig...

Question: 4.3

A fin of triangular section is made of an aluminum alloy of thermal conductivity equal to k = 185W/m^◦C. It has a base thickness of 2yb = 3mm and a length of L = 56 mm. The lateral surfaces of the fin are cooled by air at Tamb = 25^◦C with a heat transfer coefficient of h = 47W/m^2^◦C. Howmuch heat

Verified Answer:

From the given data

y_{b} = 1.5mm = 0.0015 ...

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