Chapter 12 Radiation Heat Transfer12-44 Two long parallel cylinders are maintained at specified temperatures. The rates of radiation heat transfer between the cylinders and between the hot cylinder and the surroundings are to be determined. Assumptions1Steady operating conditions exist 2The surfaces are black. 3Convection heat transfer is not considered.AnalysisWe consider the hot cylinder to be surface 1, cold cylinder to be surface 2, and the surroundings to be surface 3.Using the crossed-strings method, the view factor between two cylinders facing each otheris determined to be FsD sD12222−=−×=+−∑∑Crossed stringsUncrossed stringsString on surface 1(/ )πor 099.0)16.0(5.016.05.022222221=π⎟⎠⎞⎜⎝⎛−+=π⎟⎠⎞⎜⎝⎛−+=−DsDsFDD(2) (1) sT3= 300 K ε3= 1 T2= 275 K ε2= 1 T1= 425 K ε1= 1 (3) The view factor between the hot cylinder and the surroundings is
This is the end of the preview.
access the rest of the document.