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Many laptop computers are equipped with thermal management systems that involve liquid cooling of the central processing unit (CPU), transfer of the heated liquid to the back of the laptop screen assembly, and dissipation of heat from the back of the screen assembly by way of a flat, isothermal heat spreader. The cooled liquid is recirculated to the CPU and the process continues. Consider an aluminum heat spreader that is of width
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Fundamentals of Heat and Mass Transfer
- 3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.arrow_forward2.42 A circumferential fin of rectangular cross section, 3.7-cm OD and 0.3 cm thick, surrounds a 2.5-cm- diameter tube as shown below. The fin is constructed of mild steel. Air blowing over the fin produces a heat transfer coefficient of K. If the temperatures of the base of the fin and the air are and , respectively, calculate the heat transfer rate from the fin.arrow_forwardThe heat transfer coefficient for a gas flowing over a thin float plate 3-m long and 0.3-m wide varies with distance from the leading edge according to hc(x)=10x1/4Wm2K If the plate temperature is 170C and the gas temperature is 30C, calculate (a) the average heat transfer coefficient, (b) the rate of heat transfer between the plate and the gas, and (c) the local heat flux 2 m from the leading edge. Problem 1.18arrow_forward
- The wall of a 5 m high cylinderical steel tank (ks= 20 W/mK) of inner diameter 1.5 m and 200 mm thick contains hot oil at 100 C. On the outside of the tank 12 mm of spray urethane insulation is added to stop the oil from cooling. If the worst outside temperature is -6 , (hi = 16 W/m^2 K) and (ho = 5 W/m^2 K) how much heat needs to be added to keep the tank at 100 C for pumping reasons and what are the overall heat transfer coefficients Uo and Ui?arrow_forwardHeat Transfer Lesson The water will be heated from 10 (Degrees centigrade oC) to 90 (Degrees centigrade oC) while flowing through a smooth pipe with 1.5 cm inner diameter and 7 meters length.The entire surface of the pipe is equipped with an electric heater, which ensures uniform heating throughout.The outer surface of the heater is well insulated and therefore all heat generated in the heater in continuous operation is transferred to the water in the pipe.If the system provides 6 Liter / minute flow rate of hot water. (Thermophysical properties of water at 50 oC:ρ = 988 m3/kg, k= 0.6305 W/m oC, cp=4181 J/kg oC, Pr=3.628, μ= 0.0005471 kg/m.s ) a)Find the power of the resistance heater [W]. b)Calculate the inner surface temperature [oC] of the pipe at the outlet. c)Find the pressure drop [Pa]. d)Find the pump power [W] required to overcome this pressure drop.arrow_forwardConsider a closed cylindrical reactor vessel of diameter D= 1 ft, and length L= 1.5 ft. The surface temperature of the vessel, T1, and the surrounding temperature, T2, are 390 deg. F and 50 deg. F, respectively. The convective heat transfer coefficient, h, between the vessel wall and surrounding fluid is 4.0 Btu/h . ft . ⁰F. Calculate the thermal resistance in ⁰F .h/Btu.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning