Question

provide a short answer explaining why it is true or false.

book used is fundamentals of heat and mass transfer 7th edition

A. Once an engineer chooses a material, the heat transfer properties of that material are independent of the operating conditions (e.g. temperature or pressure) True or False?

B.Fin efficiency is the ratio of the heat transfer using the fin to the heat transfer using a non-conduction fin. True or False?

C. The boundary conditions applicable to 2D conduction (Chapter 4) are different from those applicable to 1D conduction (Chapter 3). True or False?

D

. A bolt with number >> 1 is cooling from 200°F to 70°F

1. The temperature profile within the bolt will remain fairly homogenous as the average ______ temperature drops.
2. The outside of the bolt will cool down fast but the inside of the bolt will stay hot for a longer time.
3. The bolt will not cool down.
4. The bolt seems to be made from copper material cooling in air.

Answer 1

(a)

Answer: False

Properties will alter with temperature.

For calculation, we assume properties at bulk mean temperature.

(b)

Answer: False

Fin efficiency is the ratio of actual heat transfer to maximum heat transfer that fin can do that is considering it at base temperature.

(C)

Answer: True

Because in 1 D conduction we assume each plane as an isotherm plane but in 2D conduction, planes are not isotherm plane.

(D)

Answer:b

Because the convection coefficient is more than the conduction coefficient if biot no is more than1