# Addition of fin to the surface increase the transfer if √(ηA/KP) is

1.  Equal to one

2.  Greater than one

3.  Less than one

4.  Greater than one but less than two

4

Greater than one

Explanation :
No Explanation available for this question

# Consider the following statements: 1. Under certain conditions, an increase in thickness of insulation may increase the heat loss from a heated pipe 2. The heat loss from an insulated pipe reaches a maximum when the outside radius insulation is equal to the ratio of thermal conductivity to the surface coefficient 3. Small diameter tubes are invariably insulated 4. Economic insulation is based on minimum heat loss from pipe Of these statements

1.  1 and 3 are correct

2.  2 and 4 are correct

3.  1 and 2 are correct

4.  3 and 4 are correct

4

1 and 2 are correct

Explanation :
No Explanation available for this question

# Consider the following statements. The Fourier heat conduction equation Q = - kA dT/dx Presumes 1. Steady – state conditions 2. Constant value of thermal conductivity 3. Uniform temperatures at the wall surface 4. One-dimensional heat flow Of these statements

1.  1, 2 and 3 are correct

2.  1, 2 and 4 are correct

3.  2, 3 and 4 are correct

4.  1, 3 and 4 are correct

4

1, 3 and 4 are correct

Explanation :
No Explanation available for this question

# In a long cylindrical rod of radius R and a surface heat flux of q0, then uniform internal heat generation is

1.  2q0/R

2.  2q0

3.  q0/R

4.  q0/R2

4

2q0/R

Explanation :
No Explanation available for this question

# Heat is mainly transferred by conducting convention and radiation in

1.  Insulated pipes carrying hot water

2.  Refrigerator freezer coil

3.  Boiler furnaces

4.  Condensation of steam in a condenser

4

Boiler furnaces

Explanation :
No Explanation available for this question

# A furnace wall is constructed as shown in the figure. The interface temperature T1 will be

1.  5600 C

2.  2000 C

3.  9200 C

4.  11200 C

4

9200 C

Explanation :
No Explanation available for this question

# Two rods, one of length L and the other of length 2 L are made of the same material and have the same diameter. The two ends of the longer rod are maintained at 1000 C. One end of the shorter rod is maintained at 1000 C while the other end is insulated. Both the rods are exposed to the same environment at 400 C. The temperature at the insulated end of the shorter rod is measured to be 550 C. The temperature at the mid-point of the longer rod would be

1.  400 C

2.  500 C

3.  550 C

4.  1000 C

4

550 C

Explanation :
No Explanation available for this question

# Two insulating materials of thermal conductivity K and 2K are available for lagging a pipe carrying a hot fluid. If the radial thickness of each material is the same

1.  Material with higher thermal conductivity should be used for the inner layer and one with layer and one with lower thermal conductivity for the outer

2.  Material with lower thermal conductivity should be used for the inner layer and one with higher thermal conductivity for the outer

3.  It is immaterial in which sequence the insulating material are used

4.  It is not possible to judge unless numerical values of dimensions are given

4

Material with lower thermal conductivity should be used for the inner layer and one with higher thermal conductivity for the outer

Explanation :
No Explanation available for this question

# For a given heat flow and for the same thickness, the temperature drop across the material will be maximum for

1.  Copper

2.  Steel

3.  Glass-wool

4.  Refractory brick

4

Glass-wool

Explanation :
No Explanation available for this question

# The temperature field in a body varies according to the equation T(x, y) = x3 + 4 xy. The direction of fastest variation in temperature at the point (1, 0) is given by

1.  3 i + 8 j

2.  i

3.  0.6 i + 0.8 j

4.  0.5 i + 0.866 j

4