An aluminum heat sink
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Fundamentals of Heat and Mass Transfer
- In a cylindrical fuel element for a gas-cooled nuclear reactor, the heat generation rate within the fuel element due to fission can be approximated by the relation: g(r) = g_0 [1 - (r/b)^2] W/m^3 where b is the radius of the fuel element and g_0 is constant. The boundary surface at r = b is maintained at a uniform temperature T_0. Assuming one-dimensional, steady-state heat flow, develop a relation for the temperature drop from the centerline to the surface of the fuel element. For radius b = 2 cm, the thermal conductivity k = 10 W/m middot K and g_0 = 2 times 10^7 W/m^3, calculate the temperature drop from the centerline to the surface.arrow_forward(heat transfer ) thanks The velocity of the fluid flowing in parallel over a 500mmx500mm flat heater surface is U= 19 m/s and the inlet velocity temperature is T_∞15 C. The surface temperature of this plate is T_s140 C, the friction force is F_D=0.4 N and the surface area of the plate is A=0.32 m2. According to this;(F_D= 0.4N A=32 m2)a) Surface shear stressb) Find the coefficient of frictionc) Heat transfer coefficientd) What is the amount of heat transfer (electric power) that must be given to maintain a constant surface temperature?arrow_forwardTo cool hot oil, an engineer has suggested that the oil be pumped through a pipe submerged in a nearby lake. The pipe (external diameter = 15 cm) will be placed in the horizontal direction. The temperature of the outer surface of the pipe averages 125 ° C. The surrounding water temperature is assumed to be constant at 15 ° C. Pipe length 100 m. If it is assumed that there is no water movement. a. Determine the convective heat transfer coefficient of the outer pipe surface to the water. = ..... Watt / (m² ° C) b. Determine the heat transfer rate from the pipe to the water. = ..... kWarrow_forward
- Q2/ An aluminum sphere weighting 7kg and initially at a temperature of 533K is suddenly immersed in a fluid at 283K. if heat transfer coefficient between the sphere and fluid is 50W/m?.°C. Take density=2707kg/m3, specific heat=0.9KJ/kg.°C and thermal conductivity= 204W/m °C. إجابت * Determine the Bi number 0.00696 0.000696 0.0052 0.00052 0 أخری *.Determine the time required to cool sphere to 263K 26.28min 262.8min 52.56 min 525.6 min O أخریarrow_forward1 - A square chip, with side w = 5 mm, operates under isothermal conditions.The chip is positioned on a substrate so that its side and bottom surfaces are thermally insulated, while its top surface is exposed to theflow of a refrigerant at T∞ = 15°C. From reliability considerations, the chip temperature cannot exceed T = 85°C. The refrigerant being air, with a convection heat transfer coefficientcorresponding h = 200 W/(m2K), what is the maximum allowable power for the chip? Since the coolant is a dielectric liquid for which h = 3000 W/(m²K), what is the maximum allowed power?arrow_forwardWater enters a tube at 29°C with a flow rate of 460 kg/h. The rate of heat transfer from the tube wall to the fluid is given as qs′(W/m)=ax, where the coefficient a is 25 W/m2 and x(m) is the axial distance from the tube entrance. (a) Beginning with a properly defined differential control volume in the tube, derive an expression for the temperature distribution Tm(x) of the water. (b) What is the outlet temperature of the water for a heated section 31 m long? (c) Sketch the mean fluid temperature, Tm(x), and the tube wall temperature, Ts(x), as a function of distance along the tube for fully developed and developing flow conditions. (d) What value of a uniform wall heat flux, qs″ (instead of qs′=ax), would provide the same fluid outlet temperature as that determined in part 8.13b? For this type of heating, sketch the temperature distributions requested in part 8.13c.arrow_forward
- Determine conductive resistance (in K/W) of a 80 m^2 plane wall composed of 2 layers: Layer 1: brick, thickness δ1 = 620 mm, thermal conductivity λ1 = 0.310 W/(m.K) Layer 2: EPS, thickness δ2 = 52 mm, thermal conductivity λ2 = 0.026 W/(m.K) Evaluate the heat loss through this wall if indoor temperature is 22 C and outdoor temperature is -18 C.arrow_forward2.1. Consider the flow of oil at Ton in a 40-cm-diameter pipeline at an average velocity of 0.5 m/s. A 300-m-long section of the pipeline passes through icy waters of a lake at 0°C. Measurements indicate that the surface temperature of the pipe is very nearly 0°C. Disregarding the thermal resistance of the pipe material, determine (a) the temperature of the oil when the pipe leaves the lake, and (b) the rate of heat transfer from the oil p=893.5 kg/m³, Cp=1838 J/kg°C, k=0.146W/m°C, Pr=28750. D = 259,1× 10* m²/s Toil = 20 Carrow_forward3. For the one-dimensional, radial, steady heat flow through the cylindrical annulus shown below, what is the temperature, T₁, at the inner surface? TI Hot water flow Twater = 140 °F hin 60 Btu/hr-ft²-°F Cool air environment Tair= 70°F hout=4.2 Btu/hr-ft².°F Steel Pipe. Inner diameter = 1 inch Outer diameter = 1.5 inches thermal conductivity = 31 Btu/hr-ft-°F ************ *****************arrow_forward
- = 31. A circular fin of diameter D = 0.25 inches and length L 4 inches transfers heat at a rate Q = 5.66 Btu/hr to air. The convective heat transfer coefficient is 3.62 Btu/hr-ft²- °F and the temperature difference between the fin-wall interface and the air is 100 °F. What is the thermal conductivity of the fin? What is the temperature of the fin tip?arrow_forwardThe temperature distribution across a wall 0.25 m thick at a certain instant of time is T(x) = a + bx + cx², where T is in degrees Celsius and x is in meters, a = 200 C, b = -200 C/m, and c = 30 C/m². The wall has a thermal conductivity of 2.5 W/m.K. (a) Determine the heat flux into and out of the wall (q"in and q'out). (b) If the cold surface is exposed to a fluid at 100 C, what is the convection coefficient h? - Degree Celsius 200°C q" In- q'in q'out= h = Choose... Choose.... Choose... L₂x K = 2.5 W/m.k T(x)-200-200 x +30x² q" Out 142.7 C 11 L=0.25 m Fluid Too = 100 °C harrow_forwardAn incompressible fluid flows through a rectangular cross section duct, with width much larger than height of the cross section. The duct surface is heated at a uniform rate along its length. If the centreline of the flow is along the centre of the duct where y = 0, the distance from the centreline to the surface of the duct is b = 25 mm, and the thermal conductivity of the fluid is 0.6 W/mK, what is the local heat transfer coefficient in the developed region of the flow? Give your answer in W/m2K to 1 decimal place.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning