Thermodynamics HW Solutions 915

Thermodynamics HW Solutions 915 -...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 12 Radiation Heat Transfer 12-25E "!PROBLEM 12-25E" "GIVEN" a=10 "[ft]" "epsilon_1=0.7 parameter to be varied" T_1=800 "[R]" T_2=1600 "[R]" T_3=2400 "[R]" sigma=0.1714E-8 "[Btu/h-ft^2-R^4], Stefan-Boltzmann constant" "ANALYSIS" "Consider the base surface 1, the top surface 2, and the side surface 3" E_b1=sigma*T_1^4 E_b2=sigma*T_2^4 E_b3=sigma*T_3^4 A_1=a^2 A_2=A_1 A_3=4*a^2 F_12=0.2 "view factor from the base to the top of a cube" F_11+F_12+F_13=1 "summation rule" F_11=0 "since the base surface is flat" R_1=(1-epsilon_1)/(A_1*epsilon_1) "surface resistance" R_12=1/(A_1*F_12) "space resistance" R_13=1/(A_1*F_13) "space resistance" (E_b1-J_1)/R_1+(E_b2-J_1)/R_12+(E_b3-J_1)/R_13=0 "J_1 : radiosity of base surface"
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: "(a)" Q_dot_31=(E_b3-J_1)/R_13 "(b)" Q_dot_12=(J_1-E_b2)/R_12 Q_dot_21=-Q_dot_12 Q_dot_1=Q_dot_21+Q_dot_31 1 Q 31 [Btu/h] Q 12 [Btu/h] Q 1 [Btu/h] 0.1 1.106E+06 636061 470376 0.15 1.295E+06 589024 705565 0.2 1.483E+06 541986 940753 0.25 1.671E+06 494948 1.176E+06 0.3 1.859E+06 447911 1.411E+06 0.35 2.047E+06 400873 1.646E+06 0.4 2.235E+06 353835 1.882E+06 0.45 2.423E+06 306798 2.117E+06 0.5 2.612E+06 259760 2.352E+06 0.55 2.800E+06 212722 2.587E+06 0.6 2.988E+06 165685 2.822E+06 0.65 3.176E+06 118647 3.057E+06 0.7 3.364E+06 71610 3.293E+06 0.75 3.552E+06 24572 3.528E+06 0.8 3.741E+06 -22466 3.763E+06 0.85 3.929E+06 -69503 3.998E+06 0.9 4.117E+06 -116541 4.233E+06 12-12...
View Full Document

This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

Ask a homework question - tutors are online