1688. The interchange factor for radiation heat transfer from surface ‘x’ to surface ‘y’ in case of an infinite parallel planes with emis-sivities εx & εy is given by September 7, 2025 by Admin Εx + εy Εx . εy 1/εx + 1/εy (εx + εy)/(εx + εy – εx . εy) ✅ The correct answer is option D.
