1. A 0.4-cm-thick, 12-cm-high, and 18-cm-long circuit board houses 80 closely spaced logic chips on one side, each dissipating 0.04 W. The board is impregnated with copper fillings and has an effective thermal conductivity of 30 W/m·K. All of the heat generated in the chips is conducted across the circuit board and is dissipated from the back side of the board to a medium at 40°C with a heat transfer coefficient of 52 W/m²·K.(a) Determine the temperatures on the two sides of the circuit board.(b) Now a 0.2-cm-thick, 12-cm-high, and 18-cm-long aluminum plate (k=237 W/m·K) with 864 2-cm-long aluminum pin fins of diameter 0.25 is attached to the back side of the circuit board with a 0.02-cm-thick epoxy adhesive (k=1.8 W/m·K). Determine the new temperatures on the two sides of the circuit board.

Answered: Image /qna-images/answer/7247e61e-2a98-46ed-8713-2a905da31c74.jpg

Answered: 1. A 0.4-cm-thick, 12-cm-high, and…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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40°C water with hwater = 800 W/m² K is flowing in a Pyrex tube. The inner and outer diameters of the tube are 25 mm and 35 mm. A thin metallic heater element bonded to the outer surface of the tube is being used to heat the water by transferring 600 W/m of thermal energy to the water flowing in the tube. The Pyrex tube and heater are covered with a 10-mm thick layer of foam insulation. The outer surface of the foam insulation is exposed to air at T = -5°C with hair = 12 W/m².K. The heater = air element must generate more than 600 W/m, because part of the heat being generated is lost to the air surrounding the foam insulation. Assume kp = 1.30 W/m K for Pyrex and k = 0.026 W/m K for the foam insulation. a) Find the temperature of the heater element needed to transfer 600 W/m of thermal energy to the water in the tube. b) Find the total rate at which the heater element must generate thermal energy. Water Pyrex tube, kp = 1.30 W/m.K = 40°C water hwater = 800 W/m².K Heater element Tair=…
A glass window with an area of 0.625 m² is installed in the wooden outside wall of a room. The wall dimensions are 25 x 3.05 m. The wood has a k of 0.151W/m.K and is 3.05 cm thick. The glass has a k of 0.692W/m.K and is 5.0 mm thick. The temperature of the inside room is 27°C and outside air temperature is 268K. (1)What is the heat loss through wooden wall and glass window q(W) ? (2) What are the total heat loss?
A 0.5-ampere current is flowing through a long electrically conducting cylindrical rod. The diameter of the rod is 6 mm, the electrical resistance of the rod is R = 2000 /m, and k =0.9 W/m K for the rod. The rod is encased in a 2-mm thick Pyrex tube and a 20°C liquid is flowing over the outer surface of the Pyrex tube. The convection heat transfer coefficient for the liquid h= 800 W/m2 . K. The interfacial conductance (contact resistance) at the interface between the rod and the Pyrex tube is h = 1200 W/m² - K. a) Compute the rate of heat generation in the rod and use it compute the volumetric rate of heat generation. b) Find the temperature drop across the interface between the outer surface of the rod and the inner surface of the Pyrex tube. c) Find the temperature at the center of the rod.

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