An aluminum heat sink
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Fundamentals of Heat and Mass Transfer
- Hot air (43 °C) at 1 atm flows into a circular plastic duct 50 m long at a rate of 0.2 m3/s. If the friction loss, hL, in the pipe does not exceed 6 m. Determine the diameter of the duct, the velocity of the fluid, and the Reynolds number.arrow_forwardHot air at 1 bar and 80 degree Celcius enters a 8 m long uninsulated square duct of cross-section 20 cm x 20 cm that passes through the attic of a house at a rate of 150 L/s. The duct is observed to be constant surface temperature of 60 degrees Celcius. Determine (a) air film coefficient (b) the exit temperature of air (c) logarithmic mean temperature difference (d) the rate of heat loss from the duct to the attic space. From Table A-18, for air gives, density, ρ = 1.009 kg/m^3thermal conductivity, k = 0.0297 W/m degree celciusviscosity, v = 2.06 x 10^-5 m^2/sspecific heat, Cp = 1008 J/kg degree celciusPrandtl no., Pr = 0.706arrow_forwardTwo water reservoirs A and B are connected through a 40-m long, 2-cm diameter cast iron pipe with a sharp-edged entrance. The pipe also involves a swing check valve and a fully open gate valve. The water level in both reservoirs is the same, but reservoir A is pressurized by compressed air while reservoir B is open to the atmosphere at 88 kPa. The water temperature is 10°C. a. If the initial flow rate through the pipe is 1.2 L/s, determine the absolute air pressure on top of reservoir A. b. Determine the pressure just before the valvearrow_forward
- ....A journal bearing is to be used for a centrifugal pump where the shaft diameter is 50 mm and the bearing length is 80 mm. The ambient and bearing surface temperatures are 20°C and 45°C, respectively. Which of the following is the heat dissipated by the bearing if the heat dissipation coefficient is 280 W/m2-°C? Group of answer choices 56 W 14 W 73 W 28 Warrow_forwardOil whose temperature is constant at 20 ° C (ρ = 886 kg / m3, μ = 0.805 kg / m / s) It flows continuously and fully developed from its length. The pressure at the entrance of this 40 m length is 720 kPa, pressure at its outlet is measured as 101 kPa. Flow is laminar. Volume flow rates, average velocities, Reynolds numbers and Darcy friction factors a-That the pipe is horizontal b-The pipe makes 20 ° counterclockwise with the horizontal c-The pipe makes 15 ° clockwise with the horizontal. Calculate for situations.arrow_forwardAn oil has 0.62 inch steel tube, through which flows an oil. The properties of oil are as follows; μ = 0.034 lbs/ft-sec, μb = 0.044 lbs/ft-sec, μw = 0.004 lbs/ft-sec, and specific gravity at 60°F is 0.899. The oil neters at a temperature of t1 = 60°F and flows with an average velocity of 4 ft/sec. The inside surface area is 0.1613 ft2 per foot length, and the inside sectional area is 0.3019 in2. The length of one pass of the tube is 10 feet. Considering steam at 215°F surround the tubes. Assume that the inside surface temperature of the pipe is 210°F and a bulk temperature of 72°F. If the specific heat of oil is 0.5 btu/lbs-°F and its conductivity k = 0.08 Btu-ft/hr-°F-ft2, what is the temperature at the end of 10 feet pass. Answer: t = 61.18 °F Show the complete solution.arrow_forward
- An oil has 0.62 inch steel tube, through which flows an oil. The properties of oil are as follows; μ = 0.034 lbs/ft-sec, μb = 0.044 lbs/ft-sec, μw = 0.004 lbs/ft-sec, and specific gravity at 60°F is 0.899. The oil neters at a temperature of t1 = 60°F and flows with an average velocity of 4 ft/sec. The inside surface area is 0.1613 ft2 per foot length, and the inside sectional area is 0.3019 in2. The length of one pass of the tube is 10 feet. Considering steam at 215°F surround the tubes. Assume that the inside surface temperature of the pipe is 210°F and a bulk temperature of 72°F. If the specific heat of oil is 0.5 btu/lbs-°F and its conductivity k = 0.08 Btu-ft/hr-F-ft2, what is the temperature at the end of 10 feet pass. Show your complete solution and illustration.arrow_forwardAn oil has 0.62 inch steel tube, through which flows an oil. The properties of oil are as follows; μ = 0.034 lbs/ft-sec, μb = 0.044 lbs/ft-sec, μw = 0.004 lbs/ft-sec, and specific gravity at 60°F is 0.899. The oil neters at a temperature of t1 = 60°F and flows with an average velocity of 4 ft/sec. The inside ssurface area is 0.1613 ft2 per feet length, and the inside sectional area is 0.3019 in2. The length of one pass of the tube is 10 feet. Considering steam at 215°F surround the tubes. Assume that the inside surface temperature of the pipe is 210°F and a bulk temperature of 72°F. If the specific heat of oil is 0.5 btu/lbs-°F and its conductivity k = 0.08 Btu-ft/hr-F-ft2, what is the temperature at the end of 10 feet pass. Show your complete solution and illustration.arrow_forwardA desktop computer is to be cooled by a fan. The electronic components of the computer consume 80 W of power under full-load conditions. The computer is to operate in environments at temperatures up to 50°C and at elevations up to 3000 m where the atmospheric pressure is 70.12 kPa. The exit temperature of air is not to exceed 60°C to meet the reliability requirements. Also, the average velocity of air is not to exceed 120 m/min at the exit of the computer case, where the fan is installed to keep the noise level down. Specify the flow rate of the fan that needs to be installed and the diameter of the casing of the fan.arrow_forward
- Ethylene glycol at 40°C flows over a heated plate very wide, 6 m long, at velocity of 0.04 m/s. For a temperature = 90°C, determine: 1- the thickness of the hydrodynamic boundary layer at the end of the plate2- the thickness of the thermal boundary layer at the end of the plate3- the local and average heat transfer coefficient at the end of the plate4- the total heat flux transferred from the heated surface.arrow_forwardWater flows along a tube of diameter d = 6 mm with a velocity w = 0.4 m/s. The temperature of the tube wall t = 50°C. What should the length of the tube be to ensure a water outlet temperature tr2 = 20°C at a water inlet temperature twi = 10°C?arrow_forwardWhat is the value of the heat transfer coefficient for air at 37 ° C flowing at 5 m / s perpendicular to a 10 cm x 10 cm square pipe at 93 ° C? h = 23kcal / hm ^ 2 ° C around this valuearrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning