Chapter 3

Question 1

Diffusion

Answer 1

net transfer of energy by random molecular motion

Question 2

Thermal Resistance for Conduction

Answer 2

L/KA

Question 3

Thermal Resistance for Convection

Answer 3

1/hA

Question 4

T infinity

Answer 4

Temperature of Bulk Fluid

Question 5

q

Answer 5

Heat flow rate

Question 6

h

Answer 6

Heat transfer coefficient convection

Question 7

1/hA

Answer 7

Thermal Resistance convection

Question 8

L/KA

Answer 8

Thermal Resistance conduction

Question 9

Units for Rt

Answer 9

K/W

Question 10

Units for Rt’’

Answer 10

m^2*K/W

Question 11

hr meaning

Answer 11

Radiation heat Transfer Coefficient

Question 12

hr formula

Answer 12

hr= εσ(Ts+Tsur)(Ts^2+Tsur^2)

Question 13

saturated media

Answer 13

solid phase and a single fluid phase

Question 14

Unsaturated media

Answer 14

consist of solid liquid and gas phases

Question 15

ε

Answer 15

porosity-fraction of the volume of the voids over the total volume

Question 16

what is heat transfer of convection mostly due to

Answer 16

velocity

Question 17

heat rate composite wall

Answer 17

T inf1- Tinf/Sum RT

Question 18

RTotal

Answer 18

sum of all resistances

Question 19

As Roughness Increases, Contact Resistance _______________.

Answer 19

Increases.

Question 20

Rt cond in a cylindrical wall

Answer 20

=ln(r2/1r1)/ 2 πLk

Question 21

Rt

Answer 21

delta T/q

Question 22

qradiation

Answer 22

epsilon*sigma(Ts^4-Tsur^4)

Question 23

hr

Answer 23

epsilonsigma(Ts+Tsur)(Ts^2-Tsur^2)

Question 24

q”

Answer 24

Heat flux (W/m^2)

Question 25

Is the Temperature Distribution in a Cylindrical Wall with Steady State and no Heat generation linear or nonlinear? Why?

            T1-T2 T(r)=   --------------     * ln(r / r2) + T2
           ln(r1 / r2)

Answer 25

Nonlinear because of the ln(r) term

Question 26

Is the Heat Flux in a Cylindrical Wall with Steady State & No Heat Generated variable or constant? Why?

       (Ts1-Ts2) q"= -k  -----------
        r*ln(r2/r1)

Answer 26

Variable because of 1/r.

Question 27

Is the Heat Rate in a Cylindrical Wall with Steady State & No Heat Generated variable or constant? Why?

    2pi*L*k q = ------------* (Ts1-Ts2)
    ln(r2/r1)

Answer 27

Constant because there is no r term.

Question 28

Epsilon(f)

Answer 28

Fin Effectiveness

>1

Question 29

Eta(f): ηf

Answer 29

Fin efficiency <1