Oranges of 2.5-in-diameter
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HEAT+MASS TRANSFER ACCESS CODE
- 7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?arrow_forwardWater is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 13-m-long tube. The tube is equipped with an electric resistance heater, which provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat generated in the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 5 L/min, determine the power rating of the resistance heater. Also, estimate the inner surface temperature of the pipe at the exit.arrow_forwardA stainless steel ball (ρ = 8055 kg/m3, cp = 480 J/kg·K) of diameter D = 0.15 m is removed from the oven at a uniform temperature of 350°C. The ball is then subjected to the flow of air at 1 atm pressure and 30°C with a velocity of 6 m/s. The surface temperature of the ball eventually drops to 250°C. Determine the average convection heat transfer coefficient during this cooling process and estimate how long this process has taken. The average surface temperature is 300°C, and the properties of air at 1 atm pressure and the free stream temperature of 30°C are Pr = 0.7282, μs at 300°C = 2.934 × 10–5 kg/m·s, μ∞ = 1.872 × 10–5 kg/m·s, v = 1.608 × 10–5 m2/s, and k = 0.02588 W/m·°C. The average convection heat transfer coefficient during this cooling process is ____ W/m2·°C and time taken is ____ minutes.arrow_forward
- In a production facility, 3-cm-thick large brass plates (k =110 W/m·K, ρ= 8530kg/m3, Cp = 380 J/kg·K, and α= 33.9 x10-6 m2/s) that are initially at a uniform temperature of 25°C are heated by passing them through an oven maintained at 700°C. The plates remain in the oven for a period of 10 min. Taking the convection heat transfer coefficient to be h = 80 W/m2·K, determine the surface temperature ofthe plates when they come out of the oven. Solve this problem using analytical oneterm approximation method (not the Heisler charts). Can this problem be solved using lumped system analysis? Justify your answer. Answer: 445 ℃arrow_forwardCombustion gases passing through a 3-cminternal- diameter circular tube are used to vaporize waste water at atmospheric pressure. Hot gases enter the tube at 115 kPa and 250°C at a mean velocity of 5 m/s, and leave at 150°C. If the average heat transfer coefficient is 120 W/m2?K and the inner surface temperature of the tube is 110°C, determine (a) the tube length and (b) the rate of evaporation of water.arrow_forwardConsider water (at a temperature of 276 K ) flowing inside a cylindrical pipe, having a diameter of 0.1 m and a thin wall. Under specific circumstances, temperature at the wall of the pipe reaches 258 K that helps form a layer of ice on the inner side of the wall of the pipe. Temperature and convection heat transfer coefficient at the inner surface of the ice layer are 273 K and 1500m2⋅Kw, respectively. Determine how thick the ice layer should be?arrow_forward
- Pulverized coal particles are used in oxy-fuel combustion power plants for electricity generation. Consider a situation where coal particles are suspended in hot air flowing through a heated tube, where the convection heat transfer coefficient is 100 W/m2·K. If the average surface area and volume of the coal particles are 3.1 mm2 and 0.5 mm3, respectively, determine how much time it would take to heat the coal particles to two-thirds of the initial temperature difference.arrow_forwardOranges of 2.5-in-diameter (k= 0.26 Btu/h·ft·°F) and α= 1.4 10-6 ft2/s) initially at a uniform temperature of 78°F are to be cooled by refrigerated air at 25°F flowing at a velocity of 1 ft/s. The average heat transfer coefficient between the oranges and the air is experimentally determined to be 4.6 Btu/h·ft2·°F. Determine how long itwill take for the center temperature of the oranges to drop to 40°F. Use Heisler chart. Answer: 55.5 minarrow_forwardA long 10-cm-diameter steam pipe whose external surface temperature is 110°C passes through some open area that is not protected against the winds . Determine the rate of heat loss from the pipe per unit of its length when the air is at 1 atm pressure and 10°C and the wind is blowing across the pipe at a velocity of 8 m/s.arrow_forward
- q1: in low velocities what determines if the convection heat transfer mode is free or forced ?in terms of measurable quantitiesarrow_forwardOranges of 2.5-in-diameter (k = 0.26 Btu/h·ft·°F and a = 1.4 * 1026 ft2/s) initially at a uniform temperature of 78°F are to be cooled by refrigerated air at 25°F flowing at a velocity of 1 ft/s. The average heat transfer coefficient between the oranges and the air is experimentally determined to be 4.6 Btu/h·ft2·°F. Determine how long it will take for the center temperature of the oranges to drop to 40°F. Also, determine if any part of the oranges will freeze during this process.arrow_forwardAir enters a 20-cm-diameter 12-m-long underwater duct at 50°C and 1 atm at a mean velocity of 7 m/s, and is cooled by the water outside. If the average heat transfer coefficient is 85 W/m2 °C and the tube temperature is nearly equal to the water temperature of 5°C, determine the exit temperature of air and the rate of heat transferarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning