Important questions about Conduction With Heat Generation. Conduction With Heat Generation MCQ questions with answers. Conduction With Heat Generation exam questions and answers for students and interviews.

In case of heat conduction through plane wall, which one of the following is not a correct assumption?

Options

A : a. Steady state

B : b. Three dimensional heat flow

C : c. Volumetric heat generation must be constant

D : d. K must be constant

If Q X is heat generated in at distance ‘x’, then heat conducted out at a distance (x + d x) will be

Options

A : a. Q X + 3d (Q X) d x /d x

B : b. 2Q X + d (Q X) d x /d x

C : c. d (Q X) d x /d x

D : d. Q X + d (Q X) d x /d x

Notable example of uniform generation of heat within the conducting medium are (i) Energy of a nuclear reactor (ii) Liberation of energy due to some exothermic chemical reactions (iii) Resistance heating in electrical appliances Which of the statements made above are correct?

Options

A : a. 1, 2 and 3

B : b. 1 and 2

C : c. 1 and 3

D : d. Only 2

For a plane wall of thickness l with uniformly distributed heat generation q g per unit volume, the temperature t? at mid plane is given by

Options

A : a. t? = q g l²/2k +t w

B : b. t? = q g l²/4k +t w

C : c. t? = q g l²/8k +t w

D : d. t? = q g l²/16k +t w

The temperature drop in a plane wall with uniformly distributed heat generation can be decreased by reducing

Options

A : a. Wall thickness

B : b. Heat generation rate

C : c. Thermal conductivity

D : d. Surface area

Consider a slab of thickness ? with one side (x = 0) insulated and other side (x = ?) maintained at constant temperature. The rate of uniform heat generation within the slab is q g W/m³. Presuming that the heat conduction is in steady state and one dimensional along x direction, the maximum temperature in the slab would occur at x equal

Options

A : a. ?/2

B : b. Zero

C : c. ?/4

D : d. ?

There occurs heat conduction and internal heat generation at uniform rate within the conduction medium itself in the following cases (i) Drying of concrete (ii) Chemical processes (iii) Fuel elements in a nuclear reaction Choose the correct option

Options

A : a. 1 only

B : b. 2 only

C : c. 1 and 3

D : d. 1, 2 and 3

Suppose heat is conducted due to electrons Where, i = I/A and p is the resistivity, then

Options

A : a. q g = 2i² p

B : b. q g = 3i² p

C : c. q g = i² p

D : d. q g = 4i² p

In case when both the surfaces of plane wall are at different temperature, we get an expression i.e. T MAX – T W2 /T W1 – TW2 = (B + 1)²/4B What is the value of B?

Options

A : a. (q g) (?)²/2k (T W1 – TW2)

B : b. (q g) (?)³/3k (T W1 – TW2)

C : c. (q g) (?)?/4k (T W1 – TW2)

D : d. (q g) (?)?/5k (T W1 – TW2)

Which one of the following materials are quickly heated by applying high frequency?

Options

A : a. Textiles

B : b. Engines

C : c. Rubber

D : d. Coal

Generally heat generated depends on some parameters. It is directly proportional to

Options

A : a. Time

B : b. Conductivity

C : c. Voltage

D : d. Distance between plates

Consider a 1.2 m thick slab of poured concrete (k = 1.148 W/m degree) with both of side surfaces maintained at a temperature of 20 degree Celsius. During its curing, chemical energy is released at the rate of 80 W/m³. Workout the maximum temperature of concrete

Options

A : a. 30.73 degree celsius

B : b. 29.73 degree celsius

C : c. 28.73 degree celsius

D : d. 27.73 degree celsius

The insulating material used in dielectric heating is

Options

A : a. Coal

B : b. Silver

C : c. Coin

D : d. Wool

Unit of specific resistance is

Options

A : a. Ohm mm²/m

B : b. Ohm mm

C : c. Ohm/m

D : d. Ohm mm/m

What maximum thickness of concrete can be poured without causing the temperature gradient to exceed 98.5 degree Celsius per meter anywhere in the slab? Consider a 1.2 m thick slab of poured concrete (k = 1.148 W/m degree) with both of side surfaces maintained at a temperature of 20 degree Celsius. During its curing, chemical energy is released at the rate of 80 W/m³. Workout the maximum temperature of concrete

Options

A : a. 2.64 m

B : b. 3.64 m

C : c. 4.64 m

D : d. 5.64 m

Dielectric heating apparatus consists of

Options

A : a. 4 electrodes

B : b. Elemental strip

C : c. No Insulating material

D : d. 4 plates

A slab of insulating material of thickness 6 cm and thermal conductivity 1.4kJ/m hr deg is placed between and is in contact with two parallel electrodes, and is then subjected to high frequency dielectric heating at a uniform rate of 140,000kJ/m³ hr. At steady state coefficients of combined radiation and convection are 42 and 48 kJ/m² hr deg. If atmospheric temperature is 25 degree Celsius, find surface temperatures?

Options

A : a. 144.10 degree Celsius and 134.47 degree Celsius

B : b. 123.50 degree Celsius and 154.34 degree Celsius

C : c. 121.60 degree Celsius and 115.45 degree Celsius

D : d. 165.40 degree Celsius and 165.45 degree Celsius

A 25 mm diameter egg roll (k = 1 W/m degree) is roasted with the help of microwave heating. For good quality roasting, it is desired that temperature at the center of roll is maintained at 100 degree Celsius when the surrounding temperature is 25 degree Celsius. What should be the heating capacity in W/m³ of the microwave if the heat transfer coefficient on the surface of egg roll is 20 W/m² degree?

Options

A : a. 113.31 k W/m³

B : b. 213.31 k W/m³

C : c. 313.31 k W/m³

D : d. 413.31 k W/m³

The constants of integration are to be determined from the relevant boundary conditions which are (i) t = t w at r = R (ii) q g (? L R²) = -k (2 ? R L) (d t/d r) (iii) Increasing temperature gradient Choose the correct option?

Options

A : a. Only i

B : b. Only ii

C : c. i and iii

D : d. i and ii

A concrete column used in bridge construction is cylindrical in shape with a diameter of 1 meter. The column is completely poured in a short interval of time and the hydration of concrete results in the equivalent of a uniform source strength of 0.7 W/kg. Determine the temperature at the center of the cylinder at a time when the outside surface temperature is 75 degree Celsius. The column is sufficiently long so that temperature variation along its length may be neglected. For concrete Average thermal conductivity = 0.95 W/m K Average density = 2300 kg/m³