Estimate the rate of heat loss per unit length from a 5-cm ID, 6-cm OD steel pipe covered with high-temperature insulation having a thermal conductivity of 0.11 W/(m K) and a thickness of 1.2 cm. Steam flows in the pipe. It has a quality of 99% and is at
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Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
- 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_forward3.14 A thin-wall cylindrical vessel (1 m in diameter) is filled to a depth of 1.2 m with water at an initial temperature of 15°C. The water is well stirred by a mechanical agitator. Estimate the time required to heat the water to 50°C if the tank is suddenly immersed in oil at 105°C. The overall heat transfer coefficient between the oil and the water is , and the effective heat transfer surface is .arrow_forward
- 10.8 The heat transfer coefficient of a copper tube (1.9-cm II) and 2.3-em OD) is on the inside and on the outside, but a deposit with a fouling factor of (based on the tube outside diameter) has built up over time. Estimate the percentage increase in the overall heat transfer coefficient if the deposit were removed.arrow_forwardLagged and unlagged pipes Hot water at 160 ⁰C is passing through a pipe, and it is lagged with a plastic covering. The coefficient of thermal conduction of the plastic is 0.2 Wm-1K-1 and the heat transfer coefficient is 16 Wm-2K-1. The ambient temperature surrounding the pipe is 25 ⁰C. Determine the critical radius and hence the maximum heat loss. Calculate the heat loss for varying thicknesses of lagging and plot this against the thickness. From the graph, estimate an optimal thickness of lagging and explain your reasons. You can use Excel for the calculations and plotting.arrow_forwardA pipe carrying the liquid at -20°C is 10 mm in outer diameter and is exposed to ambient at 25°C with convective heat transfer coefficient of 50 W/m2-K. It is proposed to apply the insulation of material having thermal conductivity of 0.5 W/m-K. Calculate the heat loss for 2.5 mm, 7.5 mm and 15 mm thickness of insulation over 1 m length. Which one is more effective thickness of insulation? note: include the diagram for solutionsarrow_forward
- Consider 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_forwardA steel tube, with a thermal conductivity of 50 W /m K, has an inner diameter of 20-mm and outer diameter of 26-mm. Hot gases flow over the tube with a convection heat transfer coefficient of 200 W/m2 K; while, cold water flows through the tube with a convection heat transfer coefficient of 8000 W/m2 K. What is the hot-side overall heat transfer coefficient in W/m2 K?arrow_forwardA cast iron pipe is used to transfer steam with an inlet temperature of 300 C. Inner radius of the pipe is 15 cm. The thickness of the pipe (k=25 W/(mK)) is 0.7 cm and there is an insulation (k=0.05 W/mK) over the pipe with a thickness of 5 cm. Environmental temperature is -8 C. Determine the steady heat loss from the pipe if the steam convection coefficient is 80 W/(m^2K) and environment convection coefficient is 25 W/(m^2K)? Is insulation thickness enough? a)197 W, yesb)207 W, yesc)147 W, yesd)150 W, noe)nonearrow_forward
- thick-walled tube of stainless steel [18% Cr, 8% Ni, k = 19 W/m · ◦C] with 2-cm inner diameter (ID) and 4-cm outer diameter (OD) is covered with a 3-cm layer of asbestos insulation [k = 0.2 W/m · ◦C]. If the inside wall temperature of the pipe is maintained at 600◦C, calculate he heat loss per meter of length. Also calculate the tube–insulation interface temperature.arrow_forwardWater flows through a cast steel pipe with k = 53 W/m-K with an outer diameter of 110 mm and 3.5 mm wall thickness. Calculate the thickness of insulation to be lagged on the pipe if the heat transfer per unit length is 6.5 W/m. The thermal conductivity of the insulation is 0.045 W/m-K. The water temperature is 15°C with convective heat transfer coefficient of 30 W/m2 -K while the outside air is -8°C and 18 W/m2 -K.arrow_forwardEnergy management and Audit question A steam main 150mm outside diameter containing wet steam at 28 bar is insulated with an inner layer of diatomaceous earth, 40mm thick, and an outer layer of 85% magnesia, 25mm thick. The inside surface of the pipe is at the steam temperature, and the heat transfer coefficient for the outside surface of the lagging is 17 W/m2 K. The thermal conductivities of diatomaceous earth and 85% magnesia are 0.09, and 0.06 W/m K respectively. Neglecting radiation, and the thermal resistance of the pipe water flow rate is 1400 kg/h. Taking the specific heat capacity of water as 4.19 kj/kg K, calculate; The required pipe length for parallel-flow The required pipe length for counter-flowarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning