Consider using the experimental methodology of Problem4.70 to determine the convection coefficient distributionabout an airfoil of complex shape.
Accounting for conduction in the metal sheathing andradiation losses to the large surroundings, determine theconvection heat transfer coefficients at the locationsshown. The surface locations at which the temperaturesare measured are spaced 2 mm apart. The thickness ofthe metal sheathing is
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Introduction to Heat 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_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_forwardHeat sterilization of lumber, timbers, and pallets is used to kill insects to prevent their transfer between countries in international trade. This is analogous to food sterilization by heat. A typical requirement here is that the slowest heating point of any wood configuration be held at 56 °C for 30 minutes. Consider hot air heating of wooden boards that maintains their surface temperature at 70 °C. The boards are stacked outside and in the winter time they can be considered to be at 0 °C when they are brought in for heating. The thermal diffusivity of the wood is 9*10-8 m2/s. Calculate the time from the start of heating for a 2.5 cm thick board to reach a sterilization temperature of 56 °C at its slowest heating point. Calculate the heating time when four such boards are stacked together. Calculate the ratio of the two heating times (for a single board versus when they are stacked), and explain the ratio. Note: You’re free to make assumptions regarding any value you think…arrow_forward
- Heat sterilization of lumber, timbers, and pallets is used to kill insects to prevent their transfer between countries in international trade. This is analogous to food sterilization by heat. A typical requirement here is that the slowest heating point of any wood configuration be held at 56 °C for 30 minutes. Consider hot air heating of wooden boards that maintains their surface temperature at 70 °C. The boards are stacked outside and in the winter time they can be considered to be at 0 °C when they are brought in for heating. The thermal diffusivity of the wood is 9*10-8 m2/s. Calculate the time from the start of heating for a 2.5 cm thick board to reach a sterilization temperature of 56 °C at its slowest heating point. Calculate the heating time when four such boards are stacked together. Calculate the ratio of the two heating times (for a single board versus when they are stacked), and explain the ratio. Note: You’re free to make assumptions regarding any value you…arrow_forward= A long rod of 60-mm diameter and thermophysical properties p 8000 kg/m³, c C = 500 J/kg-K, and k = 50 W/m-K is initially at a uniform temperature and is heated in a forced convection furnace maintained at 750 K. The convection coefficient is estimated to be 1000 W/m².K. What is the centerline temperature of the rod when the surface temperature is 570 K? The centerline temperature of the rod is i K.arrow_forward1. A closed container filled with hot coffee as shown below is in a room whose air and walls are at fixed temperature much lower than the coffee. Identify all heat transfer process that contributes to cooling of the coffee. Draw schematics, make necessary assumptions (black body, thickness, materials and convection coefficient) and find the heat flux and temperature of all points of heat transfer if the temperature of coffee and outside surrounding is at 95°C and 28°C respectively. Hot coffee Cover Air space Plastic flaskarrow_forward
- 3. A food product with 80% moisture content in a 7 cm diameter can wants to be frozen. The density of the product is 1000 kg / m³, the thermal conductivity is 1.0 W / (m K), and the initial freezing temperature is -2 ° C. After 11 hours in the freezing medium -30 ° C, the product temperature becomes -10 ° C. Estimate the convection heat transfer coefficient of the freezing medium. Assume the can as an infinite cylinder. h = Answer W / (m² K).arrow_forwardThermal treatment of a steel cube, of 10 cm side length, L, requires a two step cooling process. In the first step, the cube at the uniform temperature of 500°C is placed in air where it is cooled to 250°C. In the second step, it is moved to large oil bath of temperature 20°C where the heat transfer coefficient at all surfaces is the same and equal to h = 50 W m-2 K-1. %3D Calculate the total amount of energy lost by the cube and show that the lumped capacitance method can be used to calculate the temperature during the second step of cooling. Calculate the time necessary to reduce the cube temperature to 50°C. Thermal properties Density = 8000 kg m-3 Cp= 480 J kg-1 K-1 k = 30 W m-1 K-1. %3Darrow_forwardIn infinitely long parallel plates, Biot number and Fourier number are 0.2 and (10).Find the temperature distribution at center, temperature distribution at plate surface, andactual to maximum heat transfer ratio. uses charts/table also if neededarrow_forward
- The main body of plenum is a steel vessel of diameter 0.1meters has two semicircle domed ends. During operation is will contain mix of fuel and air at approximately 250OC. The wall of the vessel is 0.03meters thick and the plenum is 0.45meters long. Estimate the rate of heat loss from the vessel when the outside air temperature is 45OC. The thermal conductivity of steel is 45 W/m K and the surface heat transfer coefficient on the air side is 8 W/m2 . On the inside it is 65W/m2 . If it was possible to clad the plenum calculate the reduction in the rate of heat loss. Assume the lagging would be 5mm thick and has a thermal conductivity of 0.05 W/m.arrow_forwardHeat Transfer Question Please solve step by step Derive the equation for critical thickness of insulation for spherical systems.arrow_forwardRead the question carefully and give me right solution according to the question. A solid copper sphere (k = 393 W/mK), 10 mm in diameter, initially at 800C is placed in an air stream at 300 C. The temperature is dropped to 650C after 61 seconds. Calculate the value of convection coefficient. Assume properties as ρ= 8925 kg/m3, C = 397 J/kg K.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning