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Introduction to Heat Transfer
- The 4-mm-thick rear window of an automobile is defogged by passing warm air over its inner surface. Warm air temperature is at T,1 = 40C and corresponding convection coefficient is h1 =30 W/(m2·K). Outer ambient temperature T,2 = 5C and corresponding convection coefficient is h2 = 70 W/(m2·K). The size of the window is 0.5 m (height) 1.5 m (width). A. Draw two thermal circuits (one based on heat rate and one based on heat flux) considering the convection occurring over inner and outer surfaces and the conduction through the window. Show the equations for the thermal resistances in the circuits.B. Determine the total thermal resistance based on heat flux in m2K/W andoverall heat transfer coefficient U in W/m2K. Find the thermal conductivity of glass (sodalime at 300K)C. Determine the inner and outer temperatures of the glass (that are Ts,1 and Ts,2 shown above).arrow_forwardA 50-cm-diameter pipeline in the Arctic carries hot oil at 30◦C and is exposed to a surrounding temperature of −20◦C. A special powder insulation 5 cm thick surrounds the pipe and has a thermal conductivity of 7 mW/m · ◦C. The convection heat-transfer coefficient on the outside of the pipe is 9 W/m2 · ◦C. Estimate the energy loss from the pipe per meter of length. (Please give step-by-step solution)arrow_forwardDetermine whether the system shown in the figure is safe in terms of compression and shear forces if it is heated up to ΔT = 41 degrees. (The thermal elongation of the disc in thickness t is negligible.)arrow_forward
- A thick-walled tube of stainless steel with thermal conductivity k=19 W/m°C has inner diameter of 10 cm and outer diameter of 30 cm covered with 5 cm layer of asbestos insulation with thermal conductivity k= 0.2 W/m°C. If the inside of the pipe and outside of insulator temperature is maintained at 600°C and 107°C respectively. Determine the heat loss per meter length of pipe and the tube-insulation interface temperature.arrow_forwardThe inner diameter of a pipe made of %1 C steel used in the drying machine of a textile factory is D1 = 160 mm and the thread diameter is D₂= 170 mm. The pipe is insulated with 25 mm thick glass wool. The heat transfer coefficient between the air and the pipe surface at 90 °C temperature inside the pipe is 80 W/m²K. The temperature of the ambient air outside the insulation is 20 °C and the air comes perpendicular to the cat wool surface at a speed of 10 m/s. Find the total heat transfer coefficient according to the inside diameter of the pipe. Calculate the heat transfer per unit length of pipe per unit time ?arrow_forwardHeat Transfer Consider a infinitely long pin fin with uniform Ac cross sectional area Write ef effectiveness and Af efficiencyarrow_forward
- The length of one side of a cube-shaped freezer cabinet is 11.8 m. your closetits base is perfectly insulated against heat transfer and the inner surface temperature is –5 °C, the outer surface temperatureand it is 59°C. To ensure that the thermal load of the cabinet is not less than 0.59 kWThe thickness of the styrofoam foam insulation (k=0.03 W/mK) to be applied to the upper and side surfacesWhat should be less?arrow_forwardA 2 cm thick steel pipe (thermal conductivity 43 W/[m °C]) with 6 cm inside diameter is being used to convey steam from a boiler to process equipment for a distance of 40 m. The inside pipe surface temperature is 115°C, and the outside pipe surface temperature is 90°C. If there is 600kW of heat loss, what is the thickness of the pipe?arrow_forwardFind the minimum amount of diameter for the insulation of a spherical water tank? Radius of the tank is 10 m, thermal conductivity is 25 W/(m^2*K) and convective coefficient is 5 W/(m*K)arrow_forward
- Find the minimum amount of diameter for the insulation of a spherical water tank? Radius of the tank is 10 m, thermal conductivity is 25 W/(m^2*K) and convective coefficient is 5 W/(m*K) 8 m not sufficient information 10 m 20 m 15 marrow_forward1 mm thick copper plate (k=386 W/m-c) that are 15 cm x 20 cm in size if the thermal contact conductance on both sides of the copper plate is estimated to be 6,000 W/m-c, determine the % error involved in the total thermal resistance of the plate if the thermal contact conductance are ignored.arrow_forward/ Hot square plate (1 m ×1 m) is to be cooled by attaching aluminum circular pin fins (D=0.25 cm, L= 3 cm) distributed with distance 0.6 cm as illustrated in Figs.(1-a) & (1-b). If the fin base temperature is 100°C, cooling air temperature is 30°C and h= 35 W/m. °C. Determine the total rate of heat transfer from the finned plate and the effectiveness of the fins? Assume k= 237 W/m.°C and nr=tanh mL/ mL.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning