Fundamentals of Heat and Mass Transfer Seventh Edition Problem – 1.40
Chips of width L = 15 mm on a side are mounted to a substrate that is installed in an enclosure whose walls and air are maintained at a temperature of Tsur =T=25C. The chips have an emissivity of ε = 0.60 and a max allowable temperature of Ts = 85 C. (a) If heat is rejected from the chips by radiation and natural convection, what is the maximum operating power of each chip? The convection coefficient depends on the chip-to-air temperature difference and may be approximated as h = C (Ts – T∞) 1/4, where C = 4.2 W/m2 K 5/4. (b) If a fan is used to maintain air flow through the enclosure and heat transfer is by forced convection, with h = 250 W/m2 -K, what is the maximum operating power?
Assumptions:
(a) Steady-state conditions.
(b) Chip is at a uniform temperature (isothermal).
(c) Radiation exchange between small surface and large enclosure.
All sample problems and notes are based on the following textbook: Fundamentals of Heat and Mass Transfer Seventh Edition
ISBN-13: 9780470501979
ISBN-10: 0470501979
Edition: 7
Author: Theodore L. Bergman, Adrienne S. Lavine, Frank P. Incropera, David P. DeWitt
Publication date: 2011
Publisher: Wiley
Format: Hardcover 1072 pages
