Layers of 23-cm-thick meat slabs
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Heat and Mass Transfer: Fundamentals and Applications
- A pipe in a manufacturing plant is transporting superheated vapor at a mass flow rate of 0.3 kg/s. The pipe is 10 m long, has an inner diameter of 5 cm and pipe wall thickness of 6 mm. The pipe has a thermal conductivity of 17 W/m.K, and the inner pipe surface is at a uniform temperature of 120 °C. The temperature drop between the inlet and the exit of the pipe is 7 °C, and the constant pressure specific heat of vapor is 2190 J/kg.°C. If the air temperature in the manufacturing plant is 25°C, determine the heat transfer coefficient as a result if convection between the outer pipe surface and the surrounding air. T(r) = 120°C Superheated Air, 25°C r2 vapor r1 0.3 kg/s L = 10 m Tin-Tout = 7°Carrow_forwardAn ordinary egg can be approximated as a 5.5-cm-diameter sphere whose properties are roughly k=0.6 W/m.oC and a=0.14 x 10-6 m2/s. The egg is initially at a uniform temperature of 8 oC and is dropped into boiling water at 97 oC. Taking the convection heat transfer coefficient to be h=1400 W/m2.oC, determine how long it will take for the center of the egg to reach 70oC.arrow_forwardIn a dairy operation, milk at a flow rate of 0.25m3/hr and a cow-body temperature of 38.6°C must be chilled to a safe-to- store temperature of 13°C. Cold water at 2.2°C is available at a flow rate of 0.94m3/hr. The density and specific heat of milk are 1030 kg/m3 and 3860 J/kg.K, respectively. The density and specific heat of water is 1000 kg/m3 and 4187 J/kg.K. The chilling process is done by a double pipe counter-flow exchanger with an overall heat transfer coefficient U=1000 W/m2.K. The pipe of the heat exchanger has a 50-mm diameter with negligible thickness. Determine the pipe length L required. Select one: O a. 2.28 m O b. 4.28 m O c. 3.28 m O d. 1.28 marrow_forward
- A hot dog can be considered to be a 12 cm long cylinder, whose diameter is 2 cm and whose properties are p = 980 kg/m3, cp = 3.9 kJ/kg · K, k =1.25 W/m · K, and a = 2 × 10–7 m2 /s. Consider a hot dog initially at 5 C which is dropped into boiling water at 100 C. The heat transfer coefficient at the surface of the hot dog is estimated to be 500 W/m2 · K and the hot dog can be considered to be cooked when its center temperature reaches 90 C.arrow_forwardIn a production facility, 3-cm-thick large brass plates(k = 110 W/m·K, r = 8530 kg/m3, cp = 380 J/kg·K, and a =33.9 * 1026 m2/s) that are initially at a uniform temperatureof 25°C are heated by passing them through an oven maintainedat 700°C. The plates remain in the oven for a period of10 min. Taking the convection heat transfer coefficient to beh 5 80 W/m2·K, determine the surface temperature of theplates when they come out of the oven. Solve this problemusing analytical one-term approximation method (not theHeisler charts). Can this problem be solved using lumpedsystem analysis? Justify your answer.arrow_forwardA short brass cylinder (p = 8530 kg/m³, cp=0.389 kJ/kg-K, k=110 W/m-K, and a = 3.39×10−5 m²/s) of diameter 4 cm and height 20 cm is initially at a uniform temperature of 140°C. The cylinder is now placed in atmospheric air at 20°C, where heat transfer takes place from the cylinder 15 min after the start of the cooling by convection with a heat transfer coefficient of 40 W/m2.K. Solve this problem using the analytical one-term approximation method. Interpolate table 4-2 to obtain constants ₁ and A₁. For Biot number values less than 0.01 approximate it as 0.01 for use in Table 4-2. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. 20 cm Brass cylinder 4 cm TiºC Ambient air 20°C Calculate the center temperature of the top surface of the cylinder. The center temperature of the top surface of the cylinder is 61 °C.arrow_forward
- water 4-26 Steel rods (p = 7832 kg/m³, c, = 434 J/kg-K, and k = 63.9 W/m-K) are heated in a furnace to 850°C and then quenched in a bath at 50°C for a period of 40 s as part of a hardening process. The convection heat transfer coefficient is 650 W/m²K. If the steel rods have diameter of 40 mm and length of 2 m, determine their average temperature when they are taken out of the water bath.arrow_forward1. In a meat processing plant, 2 cm-diameter spherical meat balls (k=0.45 W/m-K and a=0.91×10-7 m²/s) that are initially at 25 °C are to be cooled by passing them through a refrigeration room at -10 °C. The heat transfer coefficient in the cold room is 9 W/m²-K. If surface of the meat balls is to be cooled to 3 °C, determine how long the meat balls should be kept in the refrigeration room. What will be the center temperature of the meat balls at the end of the process?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
- Oranges 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 pipe in a manufacturing plant is transporting superheated vapor at a mass flow rate of 0.3 kg/s. The pipe is 10 m long and has an inner diameter of 5 cm and a wall thickness of 6 mm. The pipe has a thermal conductivity of 17 W/m·K, and the inner pipe surface is at a uniform temperature of 120°C. The temperature drop between the inlet and exit of the pipe is 7°C, and the constant pressure specific heat of vapor is 2190 J/kg·°C. If the air temperature in the manufacturing plant is 25°C, determine the heat transfer coefficient as a result of convection between the outer pipe surface and the surrounding air.arrow_forwardStainless steel ball bearings (p=8085 kg/m², kJ/kg.°C) having diameter of 1.2 cm are to k=15.1 W/m°C, and C=0.480 be quenched in water. The ball leaving the oven at a uniform temperature of 900°C and is exposed to air at 30°C and with a convection coefficient of 125W/m².°C. Determine the time necessary to reach its surface to 850°C.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning