Consider the thin integrated circuit (chip) of Problem3.150. Instead of attaching the heat sink to the chipsurface, an engineer suggests that sufficient coolingmight be achieved by mounting the top of the chiponto a large copper
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Introduction to Heat Transfer
- Find the rate of heat transfer if the cylinder in a stainless steel rod.k = 15 W/m·K (8.7 Btu/h·ft·F), L = 1 m (3.3 ft), Th = 200 C (392 F), Tc= 100 C(212 F), A = 5 cm2 (0.8 in2).arrow_forwardThe thermal conductivities of wood is kwood = 0.1W/(m°C)and air is kair = 0.0234W/(m°C). Part A If the temperature of the room is 20°C and outside is 10°C, find the rate of heat flow for a wall of wood with area = 10 m² and thickness of 5cm. O 60 W O 304 W O 34 W O 200 W O 100 W Submit Request Answer Part B The wall of wood with thickness of 5cm is now replaced with two layers of wood and a gap of air between the wood. Each layer of wood has a 2.5cm thickness and the gap is 1cm. The rate of heat flow will, decreases. increases. stay the same. Submit Request Answer Part C The temperature in the air gap will be, O 20°C, between 10°C and 20°C, O 10°C,arrow_forward! * The thermal conductivity of a sheet of rigid, extruded insulation is reported to be k= 0.029 W/m. K. The measured temperature difference across a 20-mm-thick sheet of the material is T1 T2 = 10°C. The heat flux and heat rate through a 2 m x 2 m sheet of the insulation is 16.5 W/m² and 68 W Option 1 14.5 W/m² and 29 W www. Option 2arrow_forward
- Homework O H.W. 1: The walls of a refrigerator are typically constructed by sandwiching a layer of insulation between sheet metal panels. Consider a wall made from fiberglass insulation of thermal conductivity k; = 0.046 W/m.K and thickness L, = 50 mm and steel panels, each of thermal conductivity k, = 60 W/m.K and thickness L, = 3 mm. If the wall separates refrigerated air at T = 4 C from ambient air at T,. = 25 C, what is the heat gain per unit surface area? Coefficients associated with natural convection at the inner and outer surfaces may be approximated as h, = h, = 5 W/m?.K. %3D %3D L; = 0.050 m K K Lo = 0.003 m Refrigerated air Ambient air Too.i = 4°C hi = 5 W/m2-K To,o = 25°C ho = 5 W/m2-K %3D Panel (2) kp = 60 W/m-K Insulation k; = 0.046 W/m-K 22 Warith Alanbiyaa (Dr. ALI M) Heat Transfer Page 11 ofarrow_forwardQ. 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°Carrow_forwardQ. 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. Effectiveness of the fins 4. Temperature at mid-point of the fins. Note: Equations and any other data required can be taken from textbook/handbook. 130°C 25°Carrow_forward
- VI.2 A coolant is transported in a pipe with external wall temperature of -30 °C and with outer diameter of 10 cm. The tube is thermally isolated by two layers: 1) an internal layer of foamed polypropylene with thermal conductivity of 0.08 W.m.K and thickness of 10 cm, and 2) an external felt layer with thermal conductivity of 0.05 W.m.K and thickness of 5 cm. Temperature of the outer surface is 25 °C. Calculate the heat flow from the surroundings to the tube with length of 100 m. What is the temperature on the boundary between polypropylene and felt layers? Result: The heat flow from the surroundings is approx. 1.77 kW. Temperature between layers of isolation is 8.8 °C.arrow_forwardAs2 Calculate the temperature 7 cm into the mineral wool layer from the warm side measured in one wall that is built from the outside in according to the following material layers: Wood panel ventilated R = 0.20 m2K / W Mineral wool 200 mm λ = 0.033 W / mK Plastic foil R ≈ 0 m2K / W Plasterboard 13 mm λ = 0.22 W / mK The temperature outside is -10 ◦C and inside 22 ◦C. The heat transfer resistors are on the inside Rsi = 0, 13 and on the outside Rse = 0, 04 m2K / Warrow_forwardThe wall of an furnace consists of three materials having, kA = 20 W/m. K and kc = 50 W/m. K, and known thickness, LA = 0.30 m and Lc= 0.15 m. The third material, B, which is sandwiched between materials A and C, LB = 0.15 m. Under steady-state operating conditions, the outer, inner surface temperature and heat transfer coefficient is To=20°C, T,i= 500 °C, and hi 25 W/m². K. What is the value of KB? =arrow_forward
- Q#01: Write a short note on What are the best possible solutions to increase the heat transfer rate of a body.Which material will transfer more heat? Either a material with thermal conductivity ? = 121 or ? = 22 . Justify your answer. Explain the Fouling phenomenon. What is the effect of fouling on heat transfer rate?arrow_forwardProblem: Conduction related Uniform internal heat generation at q =6.0×10^7 W/m3 is occurring in a cylindrical nuclear reactor fuel rod of 60-mm diameter, and under steady-state conditions the temperature distribution is of the form T\left(r\right)=a+br^2T(r)=a+br2, where T is in degrees Celsius and r is in meters, while a = 900°C and b = -5.26 × 10^5 °C/m^2. The fuel rod properties are k = 30 W/m · K, ρ = 1,100 kg/m^3, and cp = 800 J/kg · K. (a) What is the rate of heat transfer per unit length of the rod at r = 0 (the centerline) and at r = 30 mm (the surface)? (b) If the reactor power level is suddenly increased to q2dot = 10^8 W/m^3, what is the initial time rate of temperature change at r = 0 and r = 30 mm?arrow_forwardThe cross-sectional area of a conical piece made of pure aluminum has a diameter D = a.x ^ 1/2 and a = 0.5m ^ 1/2.The left edge surface of the part is at x1 = 25 mm, and the right edge surface is x2 = 125 mm. Edge temperatures are T1 = 600K and T2 = 400K and the side surface is completely insulated.a) Assuming that the heat conduction is one dimensional, write a relation for the temperature distribution T (x).b) Calculate the heat transfer.arrow_forward
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