[2] An array of electronic chips is mounted within a sealed rectangular enclosure, and cooling is implemented byattaching an aluminum heat sink (k = 180 W/m K). The base of the heat sink has dimensions of w1 = W2 = 100 mm,while the 6 fins are of thickness t = 10 mm and pitch S = 18 mm. The fin length is Lr = 50 mm, and the base of the heatsink has a thickness of Lb = 10 mm.L-ChipsWater u TElectronicpackage,PelecIf cooling is implemented by water flow through the heat sink, with uo = 3 m/s and To =temperature Tb of the heat sink when power dissipation by the chips is Pelec = 1800 W? The average convectioncoefficient for surfaces of the fins and the exposed base may be estimated by assuming parallel flow over a flat plate.Properties of the water may be approximated as k = 0.62 W/m-K, p = 995 kg/m3, Cp = 4178 J/kg-K, v = 7.73 x 10-7 m2/s,and Pr = 5.2.17°C, what is the basea.) Base temperature.А. 37.8°CB. 43.9°CС. 31.4°СD. 46.2°C

Answered: Image /qna-images/answer/60b63c42-d1c6-4d3a-b81e-8d7946d5a17c.jpg

Answered: [2] An array of electronic chips is…

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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As shown in the sketh below, a steam pipe of 0.12-m inside diameter is insulated with a layer of calcium silicate. 1. Ts. 1} Steam 12. T8.2} Insulation (a) If the insulation is 27.5 mm thick and its inner and outer surfaces are maintained at T1 = 800 K and T2 = 490 K, respectively. what is the rate of heat loss per unit length (q') of the pipe, in W/m? (b) Determine the rate of heat loss per unit length (q'), in W/m, and outer surface temperature T2, in K, for the steam pipe with the inner surface temperature fixed at T₁ = 800 K, inner radius r₁ = 0.06 m, and outer radius r₂ = 0.14 m. The outer surface is exposed to an airflow (To = 25°C) that maintains a convection coefficient of h = 25 W/m²-K and to large surroundings for which Tsur = To = 25°C. The surface emissivity of calcium silicate is approximately 0.8.
6. a. The heat flux applied to the walls of the biomass combustion furnace is 20 W/m2. The furnace walls have a thickness of 10 mm and a thermal conductivity of 12 W/m.K. If the wall surface temperature is measured to be 50oC on the left and 30oC on the right, prove that conduction heat transfer occurs at a steady state!b. Heating the iron cylinder on the bottom side is done by placing the iron on the hotplate. This iron has a length of 20 cm. The surface temperature of the hotplate is set at 300oC while the top side of the iron is in contact with the still outside air. To reach the desired hotplate temperature, it takes 5 minutes. Then it takes 15 minutes to measure the temperature of the upper side of the iron cylinder at 300oC. Show 3 proofs that heat transfer occurs transiently
The inside wall of a furnace is at 2100oF and the outside wall is at 300oF. The wall of a furnace must be designed to transmit no more than 220 Btu/hr-ft2. Two types of bricks are available for construction:TYPE A: k = 0.38 Btu/ hr-ft-R with an allowable maximum temperature of 1400oFTYPE B: k = 0.98 Btu/ hr-ft-R with an allowable maximum temperature of 2300oF Both types of bricks have the same dimensions (9” x 4.5” x 3”) but the cost for Type B brick is twice the cost of Type A brick. Illustrate the order of arrangement of bricks A and B in the furnace wall (with thickness, estimated temperatures at the interface between walls A and B and at the interior and exterior surface, the transport area and direction of transfer included)
Q. Steam in a heating system flows through tubes whose outer diameter is 5 cm and whose walls are maintained at a temperature of 130 °C. Circular aluminum alloy 2024-T6 fins k = 186 W/m.K of outer diameter 6 cm and constant thickness 1 mm are attached to the tube. The space between the fins is 3 mm, and thus there are 250 fins per length of the tube. Heat is transferred to the surrounding air at 25 °C, with a heat transfer coefficient of 40W/m².K. Determine: 1. The increase in heat transfer from the tube per meter of its length as result of adding fins. 2. The efficiency of the fins. 3. Temperature at mid-point of the fins. Note: Equations and any other data required can be taken from textbook/handbook. 130°C 25°C
A steel tube having k =46W/m•C has an inside diameter of 3.0 cm and a tube wall thickness of 2 mm is covered with a 3-cm layer of asbestos insulation [k =0.2 WN/m•C]. A fluid flows maintains inside tube surface temperature 223•C while the outside surface insulation temperature is 57 C. Calculate the heat lost by the tube per meter of length and what in the tube-insulator interface temperature?
You are designing a 3m x 3m floor with radiant heating. The floor has 12 parallel pex pipes (k = 40 W/mK) of L = 3m, OD = 25mm and ID = 20mm. Hot water (TInfintiy 1 = 90oC, h = 200 W/m2K) runs through the pipes continuously. The surface below the pipes is perfectly insulated. Above the pipes, there is a 3mm layer of bonding material (? = 12 W/mK) and a 9mm layer of tile (k = 2 W/mK). Above the tile, there is air (TInfinity 2 = 25oC, h = 20 W/m2K). Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), Hint: Assume that the “layer” of pipe starts at the center point (e.g. for conduction purposes, the pipe is OD divided by 2 thick). For convection, consider the entire pipe surface. a) What is the total heat rate entering the room above the floor? b) What is the temperature of the top of the tile?
14.3 The external brick wall of a building has a surface area A of 830 m² and thickness 8 of 300 mm. The wall has a thermal insulation on its outer sur- face. The thermal conductivity of concrete k is 1.6 W/m K and of insulation k; is 0.04 W/m K. The indoor and outdoor air temperatures are t₁ = 21°C and to = 3°C, respectively. The heat-transfer coefficients are h; = 14 W/m²K (on the inner surface) and h = 20 W/m²K (on the outer surface). Determine (1) the rate of heat loss through the wall without insulation and (2) the thick- ness of the insulation required to reduce the rate of heat loss by 60%.
Steel pipe (outer diameter 100 mm) is covered with two layers of insulation. The inner layer, 40 mm thick, has a thermal conductivity of 0.07 W / (m K). The outer layer, 20 mm thick, has a thermal conductivity of 0.15 W / (m K). Pipes are used to deliver steam with a pressure of 800 kPa. The temperature on the outer insulation surface is 24 ° C. If the pipe is 10 m long, determine the following: (assuming that the conduction heat transfer resistance of the steel pipe and the vapor convection resistance are negligible). a. Heat loss per hour. = Answer kJ / hour. b. Temperature between insulation layers. = Answer ° C.
Problem 6. ART TAT Consider the cylindrical pipe shown in the figure. Heat is being generated in the pipe wall at a rate of R in units of W/m³, and the thermal conductivity of the wall is k, the heat transfer coefficients at the inside and outside of the pipe are h; and ho, respectively. At a given location along the pipe axis, the temperature of the fluid flowing inside of the pipe is Ti and that at the outside is To i. ii. Find the expression for the temperature distribution in the pipe wall. Find the total heat transfer rate from the pipe to both fluids.
Find the thermal resistance r (in hr - °F/BTU) and the equivalent R-value (in hr ft?. °F/BTU) of a typical frame 20' x 7.5" wall consisting of a 0.5" plaster board on the inside of the room, nominai 2 x 4 studs, and a 0.5" sheathing on the outside. The spaces between the studs are filled with an R-15 insulating foam. What is the heat loss (in BTU) through this wall in four hours if the inside temperature is 72°F and the outside temperature is 32°F? (Assume that the 15% of the wall's area are studs and the remaining 85% is filled with the insulating foam. Assume that the air is moving outside the wall.) r= 0.0805 x hr: OF/BTU R=0.09 x hr ft2. F/BTU AQ = BTU
A square steel bar of side length w = 0.21 m has a thermal conductivity of k = 15.6 J/(s⋅m⋅°C) and is L = 2.7 m long. One end is placed near a blowtorch so that the temperature is T1 = 95° C while the other end rests on a block of ice so that the temperature is a constant T2. a. input an expression for the heat transferred to the cold end of the bar as a function of time using A=w^2 as the cross-sectional area of the bar. b. how much energy in joules was conducted in 1 hour, assuming t2=0*C c. input an expression for the mass of the water melted in one hour using Q1 from above and Lf in the latent heat of fusion. mw=
Problem 1 A hot water pipe is used for domestic applications is insulated with a layer of calcium silicate. If the insulation is 25 mm thick and its inner and outer surfaces are maintained at Ts,1 = 800 K and Ts,2 = 400 K, respectively. The outside diameter is 0.12 m. Given the thermal conductivity calcium silicate insulation equals to 0.09 W/m.K. A. Define the difference between lagged and unlagged pipes. B. Calculate the heat loss per unit length for this pipe.

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